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Sample records for cervicothoracic junction case

  1. Biomechanical Determination of Distal Level for Fusions across the Cervicothoracic Junction

    PubMed Central

    Cheng, Ivan; Sundberg, Eric B.; Iezza, Alex; Lindsey, Derek P.; Riew, K. Daniel

    2015-01-01

    Study Design In vitro testing. Objective To determine whether long cervical and cervicothoracic fusions increase the intradiscal pressure at the adjacent caudal disk and to determine which thoracic end vertebra causes the least increase in the adjacent-level intradiscal pressure. Methods A bending moment was applied to six cadaveric cervicothoracic spine specimens with intact rib cages. Intradiscal pressures were recorded from C7–T1 to T9–10 before and after simulated fusion by anterior cervical plating and posterior thoracic pedicle screw constructs. The changes in the intradiscal pressure from baseline were calculated and compared. Results No significant differences where found when the changes of the juxtafusion intradiscal pressure at each level were compared for the flexion, extension, and left and right bending simulations. However, combining the pressures for all directions of bending at each level demonstrated a decrease in the pressures at the T2–T3 level. Exploratory analysis comparing changes in the pressure at T2–T3 to other levels showed a significant decrease in the pressures at this level (p = 0.005). Conclusions Based on the combined intradiscal pressures alone it may be advantageous to end long constructs spanning the cervicothoracic junction at the T2 level if there are no other mitigating factors. PMID:26225276

  2. Compressive Cervicothoracic Adhesive Arachnoiditis following Aneurysmal Subarachnoid Hemorrhage: A Case Report and Literature Review

    PubMed Central

    Rahmathulla, Gazanfar; Kamian, Kambiz

    2014-01-01

    We present the case of a 55-year-old woman with diffuse adhesive arachnoiditis in the posterior fossa and cervicothoracic spine following posterior inferior cerebellar artery aneurysmal subarachnoid hemorrhage (SAH). She underwent aneurysm clipping with subsequent gradual neurologic decline associated with sensory disturbances, gait ataxia, and spastic paraparesis. Magnetic resonance imaging revealed diffuse adhesive arachnoiditis in the posterior fossa and cervicothoracic spine, syringobulbia, and multiple arachnoid cysts in the cervicothoracic spine along with syringohydromyelia. Early surgical intervention with microlysis of the adhesions and duraplasty at the clinically relevant levels resulted in clinical improvement. Although adhesive arachnoiditis, secondary arachnoid cysts, and cerebrospinal fluid flow abnormalities resulting in syrinx are rare following aneurysmal SAH, early recognition and appropriate intervention lead to good clinical outcomes. PMID:25083391

  3. Compressive Cervicothoracic Adhesive Arachnoiditis following Aneurysmal Subarachnoid Hemorrhage: A Case Report and Literature Review.

    PubMed

    Rahmathulla, Gazanfar; Kamian, Kambiz

    2014-08-01

    We present the case of a 55-year-old woman with diffuse adhesive arachnoiditis in the posterior fossa and cervicothoracic spine following posterior inferior cerebellar artery aneurysmal subarachnoid hemorrhage (SAH). She underwent aneurysm clipping with subsequent gradual neurologic decline associated with sensory disturbances, gait ataxia, and spastic paraparesis. Magnetic resonance imaging revealed diffuse adhesive arachnoiditis in the posterior fossa and cervicothoracic spine, syringobulbia, and multiple arachnoid cysts in the cervicothoracic spine along with syringohydromyelia. Early surgical intervention with microlysis of the adhesions and duraplasty at the clinically relevant levels resulted in clinical improvement. Although adhesive arachnoiditis, secondary arachnoid cysts, and cerebrospinal fluid flow abnormalities resulting in syrinx are rare following aneurysmal SAH, early recognition and appropriate intervention lead to good clinical outcomes.

  4. ‘Serpent in the spine’: a case of giant spinal ependymoma of cervicothoracic spine

    PubMed Central

    Arrifin, Arlizan; Kaliaperumal, Chandrasekaran; Keohane, Catherine; O'Sullivan, Michael

    2012-01-01

    We describe a case of giant spinal ependymoma of cervicothoracic spine in a 30-year-old lady who presented with progressive spastic paraparesis and significant combined upper and lower motor neuron signs in her lower limbs over a 1-year period. She also had upper limb small muscle wasting with absent reflexes and diminished sensation. She was wheel chair bound with involvement of sphincters. Neuroimaging revealed a uniformly enhancing intramedullary lesion from C2–T3 level with associated syringomyelia. She underwent a complete excision of this World Health Organisation (WHO) II cellular ependymoma, resulting in significant clinical outcome and improvement in bladder and bowel function. PMID:22739334

  5. 'Serpent in the spine': a case of giant spinal ependymoma of cervicothoracic spine.

    PubMed

    Arrifin, Arlizan; Kaliaperumal, Chandrasekaran; Keohane, Catherine; O'Sullivan, Michael

    2012-06-27

    We describe a case of giant spinal ependymoma of cervicothoracic spine in a 30-year-old lady who presented with progressive spastic paraparesis and significant combined upper and lower motor neuron signs in her lower limbs over a 1-year period. She also had upper limb small muscle wasting with absent reflexes and diminished sensation. She was wheel chair bound with involvement of sphincters. Neuroimaging revealed a uniformly enhancing intramedullary lesion from C2-T3 level with associated syringomyelia. She underwent a complete excision of this World Health Organisation (WHO) II cellular ependymoma, resulting in significant clinical outcome and improvement in bladder and bowel function.

  6. Operative management of a non-traumatic cervico-thoracic spondylolisthesis: a case report

    PubMed Central

    2012-01-01

    Introduction In contrast to spondylolisthesis of the lumbar spine, non-traumatic cervico-thoracic spondylolisthesis is a very rare lesion. Even minor changes in the displacement of the vertebrae or the cord can lead to cervical myelopathy and paralysis. Since only a few cases have been well-documented, there is currently no clear preference between operative techniques. Case presentation We describe the case of a 63-year-old Caucasian man with a 13 mm spondylolisthesis between C7 and T1. Within a few months, a progressive cervical myelopathy developed as he began to suffer pain and loss of function of his digits and was no longer able to walk unassisted. In an interdisciplinary collaboration between neurological and orthopedic surgeons, a ventral-dorsal-ventral approach was performed on one vertebral section. The ventral removal of the intervertebral disc was followed by laminectomy and dorsal instrumentation. A new application technique was established by inserting bicortical screws into the transverse processes of T2 and T3. The structure was subsequently stabilized by the ventral insertion of a Harms basket. The procedure was successful as it halted progression of the myelopathy. The patient demonstrated improved sensitivity and recovered the ability to walk unassisted. He has now been able to walk unassisted for two years postoperatively. Conclusion This paper describes a successful treatment for a very rare case of cervico-thoracic spondylolisthesis. The technique of inserting bicortical screws into the transverse processes is a fast, safe and successful method that does not require the use of intraoperative radiographs for placement of the bicortical screws into the transverse processes. PMID:22686409

  7. Surgical removal of a denture with sharp clasps impacted in the cervicothoracic esophagus: report of three cases.

    PubMed

    Toshima, Takeo; Morita, Masaru; Sadanaga, Noriaki; Yoshida, Rintaro; Yoshinaga, Keiji; Saeki, Hiroshi; Kakeji, Yoshihiro; Maehara, Yoshihiko

    2011-09-01

    We report three cases of successful surgical removal of a denture with sharp clasps impacted in the cervical esophagus. Patient 1 was a 57-year-old woman institutionalized for over 30 years for schizophrenia, patient 2 was a 62-year-old man hospitalized for brain paralysis, and patient 3 was a 64-year-old man suffering cerebral hemorrhage sequelae. All three patients swallowed a denture accidentally. Chest X-rays showed the denture with sharp clasps in the cervicothoracic region of the esophagus, and endoscopy revealed that it was lodged in the esophageal mucosa. The denture was subsequently removed by cervical esophagotomy. All three patients had a good clinical postoperative course without any complications. Thus, we recommend surgery via a cervical approach to remove a denture with sharp clasps impacted in the cervicothoracic esophagus, with intraoperative endoscopic examination for esophageal injury.

  8. Chronic Expanding Hematoma in the Dorsal Cervicothoracic Region as a Long-Term Complication of Retained Bullet Fragments: Case Report

    PubMed Central

    Ahmad, Saima; Ehmed, Salman; Blume, Terri; Fai, Emmanuel K; Khan, Agha S

    2016-01-01

    Chronic expanding hematoma is a rare pathology, which has not been previously described as a complication of gunshot injury with retained bullet fragments. Because of the similar characteristics of chronic expanding hematoma to malignancy, it can present a diagnostic challenge for clinicians. Imaging and biopsy evaluation is needed to reach a conclusive diagnosis and implement appropriate treatment. In this case report, we will discuss the development, diagnosis, and management of a chronic superficial cervicothoracic mass in a patient who presented 30 years post-gunshot injury with retained bullet fragments.  PMID:27917326

  9. [Postoperative complications in patients with cervicothoracic injuries].

    PubMed

    Tatarinova, E V; Pogodina, A N; Korovkina, E N

    2014-01-01

    The results of the diagnosis and treatment of 117 patients with cervicothoracic injuries were analyzed. Different complications were observed in 51 (43.6%) cases. The main reasons contributing to the development of complications included late diagnosis of lesions of trachea and esophagus, acute blood loss, inadequate hemostasis during surgery.

  10. Cervicothoracic spinal cord and pontomedullary injury secondary to high-voltage electrocution: a case report

    PubMed Central

    2012-01-01

    Introduction High-voltage electrical injuries are uncommonly reported and may predispose to both immediate and delayed neurologic complications. Case presentation We report the case of a 43-year-old Caucasian man who experienced a high-voltage electrocution injury resulting in ischemic myelopathy and secondary paraparesis. Conclusion High-voltage electrocution injuries are a serious problem with potential for both immediate and delayed neurologic sequelae. The existing literature regarding effective treatment of neurologic complications is limited. Long-term follow-up and multidisciplinary management of these patients is required. PMID:22974044

  11. The MURCS Association: Mullerian Duct Aplasia, Renal Hypoplasia and Cervicothoracic Somite Dysplasia - A Case Report.

    PubMed

    Akhter, N; Begum, B N; Newaz, M

    2015-07-01

    We report on a 22 years old lady with aplasia of uterus and most of the vagina with normal secondary sexual characteristics, unilateral renal hypoplasia and anomalies of cervico throacic somites (MURCS Association), growth retardation, cardiac defect and congenital urethrovaginal fistula. Although there is a broad spectrum of anomalies described with MURCS association genitourinary fistula is not yet reported and reviewed in published articles. The relevance of this paper is to show the importance of further investigation in cases of primary amenorrhoea with mullerian agenesis to establish that the patient has MURCS association and not simply MRKH (Mayer Rokitansky-Kusterhauser Syndrome) syndrome. Consequently we should provide guidance to the patients and their families about the best way to conduct the case including genetic counseling and family screening.

  12. Discrete or diffuse intramedullary tumor? Contrast-enhanced intraoperative ultrasound in a case of intramedullary cervicothoracic hemangioblastomas mimicking a diffuse infiltrative glioma: technical note and case report.

    PubMed

    Vetrano, Ignazio G; Prada, Francesco; Nataloni, Ilaria F; Bene, Massimiliano Del; Dimeco, Francesco; Valentini, Laura G

    2015-08-01

    Hemangioblastomas are benign, highly vascularized intramedullary lesions that may also extend into the intradural space. Surgery represents the standard therapy, with the goal of obtaining complete resection even at the risk of neurological morbidity. MRI is the gold standard for diagnosis and assessment of intramedullary tumors. Nevertheless, sometimes MRI may not accurately differentiate between different types of intramedullary tumors, in particular if they are associated with syringes or intra- and peritumoral cysts. This could subsequently affect surgical strategies. Intraoperative ultrasound (ioUS) has become in the last few years a very useful tool for use during neurosurgical procedures. Various ioUS modalities such as B-mode and Doppler have been applied during neurosurgical procedures. On the other hand, the use of contrast-enhanced ultrasound (CEUS) is not yet well defined and standardized in this field. We report a case of a young patient harboring a cervicothoracic intramedullary tumor, for which the preoperative neuroradiologi-cal diagnosis was in favor of a diffuse astrocytoma with nodular components whereas ioUS demonstrated 3 distinct intramedullary nodules. CEUS showed highly vascularized lesions, compatible with hemangioblastomas. These findings, particularly those obtained with CEUS, allowed better definition of the lesions for diagnosis, enhanced understanding of the physiopathological aspects, and permitted the localization of all 3 nodules, thus limiting spinal cord manipulation and allowing complete resection of the lesions, with an uneventful postoperative neurological course. To the best of our knowledge, this is the first report of the use of intraoperative CEUS in a case of intramedullary hemangioblastoma.

  13. [Diagnosis and treatment of cervicothoracic injuries].

    PubMed

    Tatarinova, E V; Pogodina, A N; Abakumov, M M

    2014-01-01

    It analyzed the diagnosis and treatment results of 123 patients with cervicothoracic injuries for 21 years. The frequency of cervicothoracic injuries among all patients with cervical injuries was 5.7%. Preoperative and postoperative diagnosis included radial and endoscopic methods. The complications rate was 43.6%. The most severe complications were observed in patients with delayed diagnosis of trachea and esophagus injuries.

  14. [MRI evaluation of cervicothoracic CSF hypotension].

    PubMed

    Maraval, A; Brugieres, P; Combes, C; Thomas, P; Blanc, R; Gaston, A

    2006-06-01

    We propose studying signs of cervicothoracic CSF hypotension by MRI. Axial T1-weighted GRE sequence with and without saturation bands positioned above and below the selected image plane, MR venography and MR Angiography with contrast administration are helpful to confirm the venous nature of the epidural thickening and to make the differential diagnosis with infectious or neoplastic epiduritis.

  15. Subaxial cervical and cervicothoracic fixation techniques--indications, techniques, and outcomes.

    PubMed

    Pelton, Miguel A; Schwartz, Joseph; Singh, Kern

    2012-01-01

    The subaxial and cervicothoracic junction is a relatively difficult area for spine surgeons to navigate. Because of different transitional stressors at the junction of the smaller cervical vertebrae and the larger thoracic segments, proximity to neurovascular structures, and complex anatomy, extreme care and precision must be assumed during fixation in these regions. Lateral mass screws, pedicle screws, and translaminar screws are currently the standard of choice in the subaxial cervical and upper thoracic spine. This article addresses the relevant surgical anatomy, pitfalls, and pearls associated with each of these fixation techniques.

  16. [Pyeloureteral junction syndrome in children. Apropos of 178 cases].

    PubMed

    Juskiewenski, S; Moscovici, J; Bouissou, F; Vaysse, P; Guitard, J

    1983-01-01

    The authors review 178 cases of anomalies of the pyelo-ureteric junction, with a total of 189 anomalies. Almost one half of the cases were less than 5 years old (47.2%) and about 1/4 were less than 1 year old (24.7%). In girls, the incident which reveals the diagnosis is most often an infection and in boys, it is pain or haematuria. 26% of the cases had an associated urological lesion (23 cases of vesico-ureteric reflux, 8 cases of renal stones, 5 cases of mega-ureter and 4 cases of horseshoe kidney). 133 children were operated, essentially by resection of the pyelo-ureteric junction with an upstream by-pass. From the 126 cases with sufficient follow-up, 48 (38.1%) obtained great improvement, 63 (50%) a moderate improvement and 15 (11.9%), a stabilisation of the dilatation. In all cases except 3, the pyelo-ureteric junction was perfectly catheterizable. The histological lesions of the junction were variable and difficult to systematise, but usually extended beyond the junction to involve a large part of the pelvis. The variability of the caliceal dilatation makes any attempt at classification difficult. The authors recommend cystography in every case, as associated reflux was discovered in 16% of cases. Retrograde uretero-pyelography is practically no longer indicated. The isotope kidney scan with DTPA technetium, with a hyper-diuresis test, is often used, as it gives an idea about the clearance of filtration and about the degree of obstruction. Quantitative DMSA kidney scan can reveal the effects on the renal parenchyma. Conservation of the isthmus of a horseshoe kidney never interferes with the uretero-pyelic re-implantation. After correction of the anomaly of the uretero-pyelic junction, 5 cases of unilateral reflux out of 8 and 3 cases of bilateral reflux out of 10 resolved spontaneously.

  17. Junction-to-Case Thermal Resistance of a Silicon Carbide Bipolar Junction Transistor Measured

    NASA Technical Reports Server (NTRS)

    Niedra, Janis M.

    2006-01-01

    Junction temperature of a prototype SiC-based bipolar junction transistor (BJT) was estimated by using the base-emitter voltage (V(sub BE)) characteristic for thermometry. The V(sub BE) was measured as a function of the base current (I(sub B)) at selected temperatures (T), all at a fixed collector current (I(sub C)) and under very low duty cycle pulse conditions. Under such conditions, the average temperature of the chip was taken to be the same as that of the temperature-controlled case. At increased duty cycle such as to substantially heat the chip, but same I(sub C) pulse height, the chip temperature was identified by matching the V(sub BE) to the thermometry curves. From the measured average power, the chip-to-case thermal resistance could be estimated, giving a reasonable value. A tentative explanation for an observed bunching with increasing temperature of the calibration curves may relate to an increasing dopant atom ionization. A first-cut analysis, however, does not support this.

  18. 68Ga-PSMA-HBED Uptake on Cervicothoracic (Stellate) Ganglia, a Common Pitfall on PET/CT.

    PubMed

    Beheshti, Mohsen; Rezaee, Alireza; Langsteger, Werner

    2017-03-01

    Ga-PSMA-HBED PET/CT showed promising results in staging and restaging of prostate cancer. However, nonspecific uptake has been reported in the celiac ganglia. In this case series, we showed faint radiotracer uptake on upper thoracic region in the location of cervicothoracic (stellate) ganglia. This ganglion is located anterior to the transverse process of C7 vertebra, inferior to subclavian artery, and superior to the neck of the first rib.

  19. Single-Stage Operation for Giant Schwannoma at the Craniocervical Junction with Minimal Laminectomy: A Case Report and Literature Review

    PubMed Central

    Yoon, Sun; Park, Hunho; Lee, Kyu-Sung; Park, Seoung Woo

    2016-01-01

    Here we report a single-stage operation we performed on a patient with a large schwannoma that extended from the lower clivus to the cervico-thoracic junction caudally. A number of authors have previously performed multilevel laminectomy to remove giant schwannomas that extend for considerable length. This technique has caused cervical instability such as kyphosis or gooseneck deformity on several occasions. We removed the tumor with a left lateral suboccipital craniectomy with laminectomy only at C1 and without any subsequent surgery-related neurologic deficits. However, this technique requires meticulous preoperative evaluation on existence of Cerebrospinal fluid (CSF) cleft between the tumor and spinal cord on magnetic resonance imaging, of tumor origin located at the upper cervical root, and of detachment of tumor from the origin site. PMID:27800002

  20. Resolution of whiplash-associated allodynia following cervicothoracic thrust and non-thrust manipulation.

    PubMed

    Lowry, Carina D; O'Hearn, Michael A; Courtney, Carol A

    2011-08-01

    Whiplash injuries of the cervical spine comprise 30% of injuries reported following motor vehicle accident (MVA) and often progress to chronic painful conditions. The purpose of this case report is to describe the management of a 37-year-old female referred to physical therapy with neck and shoulder pain after whiplash injury. The patient demonstrated limited cervical and shoulder active range of motion as well as quantitative sensory testing (QST) results consistent with central nervous system sensitization. She was treated for 11 visits over a 6-week period with manual therapy and specific exercise directed to the cervicothoracic spine. Her pain decreased from 9/10 to 2/10 by the end of treatment and remained improved at 1/10 at the 6-month follow-up. Her Copenhagen Neck Functional Disability Scale decreased from 23/30 to 4/30 by the 11th visit. In addition, she demonstrated clinically significant increases in cervical active range of motion and normal somatosensation. Manual therapy of the cervicothoracic spine may be a beneficial adjunct to the standard care of patients with signs and symptoms of central sensitization after whiplash-associated disorder and primary report of neck and shoulder pain.

  1. Neurenteric cyst of the craniocervical junction--case report.

    PubMed

    Abe, K; Oyama, K; Mori, K; Ishimaru, S; Eguchi, M; Maeda, M

    1999-11-01

    A 60-year-old female presented with occipital headache and limitation of neck movement. Neurological examination showed weakness of the right sternocleidomastoid muscle. Magnetic resonance imaging revealed a cystic lesion at the craniocervical junction and posterior compression of the brain stem. The lesion was totally removed through the transcondylar approach. The histological diagnosis was neurenteric cyst. The transcondylar approach provides a direct operative view of the clivus and anterior craniovertebral junction.

  2. Utility of a 3-dimensional full-scale NaCl model for rib strut grafting for anterior fusion for cervicothoracic kyphosis

    PubMed Central

    Kobayashi, Kazuyoshi; Imagama, Shiro; Muramoto, Akio; Ito, Zenya; Ando, Kei; Yagi, Hideki; Hida, Tetsuro; Ito, Kenyu; Ishikawa, Yoshimoto; Tsushima, Mikito; Ishiguro, Naoki

    2015-01-01

    ABSTRACT In severe spinal deformity, pain and neurological disorder may be caused by spinal cord compression. Surgery for spinal reconstruction is desirable, but may be difficult in a case with severe deformity. Here, we show the utility of a 3D NaCl (salt) model in preoperative planning of anterior reconstruction using a rib strut in a 49-year-old male patient with cervicothoracic degenerative spondylosis. We performed surgery in two stages: a posterior approach with decompression and posterior instrumentation with a pedicle screw; followed by a second operation using an anterior approach, for which we created a 3D NaCl model including the cervicothoracic lesion, spinal deformity, and ribs for anterior reconstruction. The 3D NaCl model was easily scraped compared with a conventional plaster model and was useful for planning of resection and identification of a suitable rib for grafting in a preoperative simulation. Surgery was performed successfully with reference to the 3D NaCl model. We conclude that preoperative simulation with a 3D NaCl model contributes to performance of anterior reconstruction using a rib strut in a case of cervicothoracic deformity. PMID:26412901

  3. MURCS (Müllerian duct aplasia–renal agenesis–cervicothoracic somite dysplasia): a rare cause of primary amenorrhoea

    PubMed Central

    Kumar, Sunil; Sharma, Shruti

    2016-01-01

    The agenesis of the Müllerian duct is the second most common cause of primary amenorrhoea after Turner syndrome. The abnormal development of Müllerian duct often associates with the urinary tract and skeletal abnormalities. MURCS (Müllerian duct aplasia–renal agenesis–cervicothoracic somite dysplasia) association is a unique and rare developmental disorder with four common features of uterine hypoplasia or aplasia, renal agenesis or ectopy, vertebral anomalies and short stature. We report a case of young female with primary amenorrhoea. She had well-developed secondary sexual characteristics along with multiple congenital developmental abnormalities such as the absence of uterus, ectopic kidney, cervical vertebral fusion, hemivertebrae, scoliosis, cervical rib, facial asymmetry and growth retardation. Our case highlights the rarity and clinical importance of this syndrome. For the evaluation of primary amenorrhoea in a female with well-developed secondary sexual characteristics, congenital anomalies should be ruled out before hormone and karyotype analyses. PMID:27099773

  4. Traumatic closed index extensor tendon rupture at the musclotendinous junction: a report of two cases.

    PubMed

    Komura, Shingo; Yokoi, Tatsuo; Nonomura, Hidehiko

    2011-03-01

    This report describes two cases of traumatic closed index extensor tendon rupture at the musclotendinous junction. Both patients were injured when their work gloves were caught in the revolving parts of machines, and both were treated surgically. One of the patients completely ruptured the index extensor digitorum communis (EDC) and the extensor indicis proprius (EIP) tendons at the musclotendinous junction of dorsal forearm. In this patient, the distal stump of the index EDC tendon was sutured to the middle EDC tendon in an end-to-side juncture. The other patient completely ruptured the EIP tendon and partially ruptured the index EDC tendon at the musclotendinous junction. In this patient, tendon transfer of the extensor digiti minimi (EDM) to the EIP tendon and plication of the index EDC tendon were performed. In both cases, surgical intervention enabled the patients to extend their index fingers almost normally; however, the former complained of inability to extend his index finger independently. Tendon transfer of the EDM in cases of index extensor tendon rupture at the musclotendinous junction is a good method to restore ability to independently extend the index finger. However, consideration should be given to anatomical variation in the little finger. The EDC tendon is sometimes absent leaving the EDM tendon as the only extensor tendon to the little finger.

  5. Retrospective analysis of a case series of patients with traumatic injuries to the craniocervical junction

    PubMed Central

    Esteves, Luiz Adriano; Joaquim, Andrei Fernandes; Tedeschi, Helder

    2016-01-01

    ABSTRACT Objective To evaluate the correlation between the treatment, the characteristics of the lesions and the clinical outcome of patients with traumatic injuries to the craniocervical junction. Methods This was a retrospective study of patients treated conservatively or surgically between 2010 and 2013 with complete data sets. Results We analyzed 37 patients, 73% were men with mean age of 41.7 years. Of these, 32% were submitted to initial surgical treatment and 68% received conservative treatment. Seven (29%) underwent surgery subsequently. In the surgical group, there were seven cases of odontoid type II fractures, two cases of fracture of posterior elements of the axis, one case of C1-C2 dislocation with associated fractured C2, one case of occipitocervical dislocation, and one case of combined C1 and C2 fractures, and facet dislocation. Only one patient had neurological déficit that improved after treatment. Two surgical complications were seen: a liquoric fistula and one surgical wound infection (reaproached). In the group treated conservatively, odontoid fractures (eight cases) and fractures of the posterior elements of C2 (five cases) were more frequent. In two cases, in addition to the injuries of the craniocervical junction, there were fractures in other segments of the spine. None of the patients who underwent conservative treatment presented neurological deterioration. Conclusion Although injuries of craniocervical junction are relatively rare, they usually involve fractures of the odontoid and the posterior elements of the axis. Our results recommend early surgical treatment for type II odontoid fractures and ligament injuries, the conservative treatment for other injuries. PMID:28076601

  6. Circuit theory of multiple Andreev reflections in diffusive SNS junctions: The incoherent case

    NASA Astrophysics Data System (ADS)

    Bezuglyi, E. V.; Bratus', E. N.; Shumeiko, V. S.; Wendin, G.; Takayanagi, H.

    2000-12-01

    The incoherent regime of multiple Andreev reflections (MAR) is studied in long diffusive SNS junctions at applied voltages larger than the Thouless energy. Incoherent MAR are treated as a transport problem in energy space by means of a circuit theory for an equivalent electrical network. The current through NS interfaces is explained in terms of diffusion flows of electrons and holes through ``tunnel'' and ``Andreev'' resistors. These resistors in diffusive junctions play roles analogous to the normal and Andreev reflection coefficients in Octavio-Tinkham-Blonder-Klapwijk theory for ballistic junctions. The theory is applied to the subharmonic gap structure (SGS); simple analytical results are obtained for the distribution function and current spectral density for the limiting cases of resistive and transparent NS interfaces. In the general case, the exact solution is found in terms of chain fractions, and the current is calculated numerically. SGS shows qualitatively different behavior for even and odd subharmonic numbers n=2Δ/eV, and the maximum slopes of the differential resistance correspond to the gap subharmonics, eV=2Δ/n. The influence of inelastic scattering on the subgap anomalies of the differential resistance is analyzed.

  7. A randomized, comparative trial: does pillow type alter cervico-thoracic spinal posture when side lying?

    PubMed Central

    Gordon, Susan J; Grimmer-Somers, Karen A; Trott, Patricia H

    2011-01-01

    Background Many patients ask for advice about choosing a pillow. This research was undertaken to determine if pillow type alters cervico-thoracic spine position when resting in the side-lying position. Aim To investigate the effect of different pillow shape and content on the slope of cervico-thoracic spine segments when side lying. Materials and methods The study was a randomized blinded comparative trial set in a laboratory that replicated a bedroom. The subjects were side sleepers aged over 18 years. Exclusion criteria were history of surgery to the cervico-thoracic spine, an injury or accident to the cervico-thoracic spine in the preceding year, or currently receiving treatment for neck symptoms. Each participant rested in a standardized side-lying position for 10 minutes on each of the trial pillows: regular shaped polyester, foam, feather, and latex pillows, and a contour shaped foam pillow. Reflective markers were placed on external occipital protuberance (EOP), C2, C4, C7, and T3, and digital images were recorded of subjects at 0 and 10 minutes on each pillow. Images were digitized using each reflective marker and the slope of each spinal segment calculated. Univariate analysis of variance models were used to investigate slope differences between pillows at 0 and 10 minutes. Significance was established at P < 0.01 to take account of chance effects from repeated measures and multiple comparisons. Results At 0 and 10 minutes, the EOP-C2, C2-C4, and C4-C7 segmental slopes were significantly different across all pillows. Significant differences were identified when comparing the feather pillow with the latex, regular and contour foam pillows, and when comparing the polyester and foam contour pillows. The regular and contour foam pillows produced similar slopes at all spinal segments. Conclusion Cervico-thoracic spinal segment slope alters significantly when people change from a foam, latex, or polyester pillow to a feather pillow and vice versa. The shape of a

  8. Remodeling Brain Activity by Repetitive Cervicothoracic Transspinal Stimulation after Human Spinal Cord Injury

    PubMed Central

    Murray, Lynda M.; Knikou, Maria

    2017-01-01

    Interventions that can produce targeted brain plasticity after human spinal cord injury (SCI) are needed for restoration of impaired movement in these patients. In this study, we tested the effects of repetitive cervicothoracic transspinal stimulation in one person with cervical motor incomplete SCI on cortical and corticospinal excitability, which were assessed via transcranial magnetic stimulation with paired and single pulses, respectively. We found that repetitive cervicothoracic transspinal stimulation potentiated intracortical facilitation in flexor and extensor wrist muscles, recovered intracortical inhibition in the more impaired wrist flexor muscle, increased corticospinal excitability bilaterally, and improved voluntary muscle strength. These effects may have been mediated by improvements in cortical integration of ascending sensory inputs and strengthening of corticospinal connections. Our novel therapeutic intervention opens new avenues for targeted brain neuromodulation protocols in individuals with cervical motor incomplete SCI. PMID:28265259

  9. The Effect of Different Pillow Heights on the Parameters of Cervicothoracic Spine Segments

    PubMed Central

    Kim, Hyung Cheol; Jun, Hyo Sub; Kim, Ji Hee; Ahn, Jun Hyong; Chang, In Bok; Song, Joon Ho

    2015-01-01

    Objective To investigate the effect of different pillow heights on the slope of the cervicothoracic spine segments. Methods A prospective analysis of data from 16 asymptomatic adults (aged 20 to 30 years) was carried out. Exclusion criteria were history of injury or accident to the cervicothoracic spine, cervicothoracic spine surgery, or treatment for neck symptoms. We used three different pillow heights: flat (0 cm), 10-cm, and 20-cm pillows. Cervical sagittal parameters, measured with radiography, included; C2-7 Cobb's angle, T1 slope (T1S), thoracic inlet angle (TIA), and neck tilt (NT). Statistical analyses were performed using Spearman correlation coefficients. Results As the height of the pillow increased, the T1S & C2-7 Cobb's angle increased while the NT values tended to decrease. The TIA values, however, remained constant. Additionally, there was a statistically significant sex difference in T1S with the 0-cm pillow (p=0.01), and in NT with the 20-cm pillow (p=0.01). Conclusion From the data obtained in this study, we recommend that the most suitable pillow height is 10 cm, considering the normal cervical lordosis. PMID:26512267

  10. Functional outcome of pyeloplasty for ureteropelvic junction obstruction: Prospective study in 30 consecutive cases

    SciTech Connect

    O'Reilly, P.H.

    1989-08-01

    In a prospective study of 50 consecutive patients with urographic renal pelvic dilatation, 30 with genuine ureteropelvic junction obstruction identified by 123-iodine-hippurate diuretic renal scanning (renography) were treated by dismembered pyeloplasty. One patient with reduced preoperative function required secondary nephrectomy. Three patients with normal function in solitary kidneys had unchanged postoperative function. In the remaining 26 patients preoperative function measured by diuretic renal scanning was compared to 6-month postoperative values. If split function changes of less than 5 per cent were considered insignificant, to allow for inherent statistical errors of renal scanning, preoperative function was decreased in 18 patients, improved postoperatively in 10 and remained the same in 8. In 8 patients preoperative function was normal and remained so postoperatively. Drainage improved in 22 of the 26 patients and was unchanged in 4. Analysis of functional change by Student's t test and the Wilcoxon paired sums test showed significant improvement in mean and median function (p less than 0.001), with the degree of improvement being greatest in patients with the most severely depressed preoperative levels. In addition to producing significant improvement in drainage in ureteropelvic junction obstruction, pyeloplasty arrests functional deterioration in almost every case and improves function significantly in the majority.

  11. Dorsal midline hemivertebra at the lumbosacral junction: report of 2 cases.

    PubMed

    Ansari, Shaheryar F; Rodgers, Richard B; Fulkerson, Daniel H

    2015-01-01

    Congenital scoliosis from laterally located hemivertebrae at the lumbosacral junction has been described previously. However, dorsally located midline hemivertebrae at this location have not been reported. The authors describe the presentation, treatment, and outcomes of 2 patients (1 male and 1 female) with this rare malformation. All clinical and radiographic records were reviewed. Outcomes were recorded using survey instruments (Oswestry Disability Index and the 36-Item Short Form Health Survey). Radiographic assessment of bony fusion was performed using CT scanning 1 year after surgery. Both patients presented with back and leg pain, urinary hesitancy/incontinence, difficulty sitting and lying down, waddling gait, and restriction of movement. Imaging showed a wedge-shaped dorsal deformity that stretched the nerve roots and compressed the canal. Both patients underwent resection of the hemivertebra with posterolateral instrumented fusion from L-2 to the pelvis. The female patient had a low-lying conus and underwent sectioning of the filum terminale. Both patients showed improvement in the ability to sit and lie flat and in bowel and bladder function after surgery. The authors describe their experience with 2 patients with similar, rare congenital bony deformities at the lumbosacral junction. To their knowledge, similar cases have not been previously reported.

  12. Trombone tongue: a new clinical sign for significant medullary compression at the craniovertebral junction. Case report.

    PubMed

    Lee, Cheong H; Casey, Adrian T H; Allibone, James B; Chelvarajah, Ramesh

    2006-12-01

    The authors describe a previously unreported clinical sign that may indicate the onset of significant compression of the medulla oblongata in cases of craniovertebral junction abnormalities. This 17-year-old boy presented with mild bilateral leg weakness. Imaging studies revealed severe basilar invagination and a marked Chiari malformation. While awaiting surgery, his tongue developed an involuntary constant protrusion-intrusion repetitive motion. The onset of this so-named "trombone tongue" sign was followed shortly afterward by rapidly progressive spastic tetraparesis. After the authors performed a transmaxillary clivectomy, foramen magnum decompression, and occipitocervical fusion, they noted that the abnormal tongue motion promptly resolved and the tetraparesis gradually improved. The authors discuss their current understanding of the central control of tongue movements and present a hypothesis on the pathogenesis of trombone tongue based on the neuroanatomical basis of another abnormal tongue movement sign, lingual myoclonus.

  13. Singular layers for transmission problems in thin shallow shell theory: Elastic junction case

    NASA Astrophysics Data System (ADS)

    Merabet, Ismail; Chacha, D. A.; Nicaise, Serge

    2010-05-01

    In this Note we study two-dimensional transmission problems for the linear Koiter's model of an elastic multi-structure composed of two thin shallow shells with the same thickness ɛ≪1, in the elastic junction case. We suppose that the loading is singular, that the elastic coefficients are of different order on each part ( O(ɛ) and O(1) respectively) and that the elastic stiffness coefficient of the hinge is k=O(ɛ). The formal limit problem fails to give a solution satisfying all boundary and transmission conditions; it gives only the outer solution. We derive the inner limit problem which allows us to describe the transmission layer.

  14. Standard test case for a low-speed, turbulent junction vortex flow

    NASA Technical Reports Server (NTRS)

    Pierce, F. J.

    1991-01-01

    The mean flow structure upstream, around within, and in the near wake of a turbulent junction or horseshoe vortex is reported for an incompressible subsonic flow. Measurements of the primitive variables of velocity and pressure are reported on all surfaces bounding the region of the vortex flow and on three transverse and one streamwise plane within the flowfield itself for comparisons between the measured and any calculated flow variables. Detailed surface flow visualizations and some direct force measurements of surface shear stress are also available. The data is a highly detailed, coherent, self-consistent set offered to the computational fluid mechanics community as a standard test case for the evaluation of the capability of numerical solvers intended for predicting the flowfield in such a complex, separated, three-dimensional turbulent flow. This data base is available for copying to user supplied tapes or for transmission via BITNET, as well as in two National Technical Information Service (NTIS) reports.

  15. Wideband rotating junctions

    NASA Astrophysics Data System (ADS)

    Pochernyaev, V. N.

    1993-06-01

    Rotating junctions of coaxial-waveguide and waveguide type with a traveling wave coefficient exceeding 0.8 in a wide frequency range are considered. The design of these junctions is based on a method of the theory of electrodynamic circuits. Numerical results are obtained for rotating junctions of partially filled rectangular waveguide type and their particular cases.

  16. Traumatic Tear of the Latissimus Dorsi Myotendinous Junction: Case Report of a CrossFit-Related Injury.

    PubMed

    Friedman, Michael V; Stensby, J Derek; Hillen, Travis J; Demertzis, Jennifer L; Keener, Jay D

    2015-01-01

    A case of a latissimus dorsi myotendinous junction strain in an avid CrossFit athlete is presented. The patient developed acute onset right axillary burning and swelling and subsequent palpable pop with weakness while performing a "muscle up." Magnetic resonance imaging examination demonstrated a high-grade tear of the right latissimus dorsi myotendinous junction approximately 9 cm proximal to its intact humeral insertion. There were no other injuries to the adjacent shoulder girdle structures. Isolated strain of the latissimus dorsi myotendinous junction is a very rare injury with a scarcity of information available regarding its imaging appearance and preferred treatment. This patient was treated conservatively and was able to resume active CrossFit training within 3 months. At 6 months postinjury, he had only a mild residual functional deficit compared with his preinjury level.

  17. Cervicothoracic Subcutaneous Emphysema and Pneumomediastinum After Third Molar Extraction.

    PubMed

    Picard, Maxime; Pham Dang, Nathalie; Mondie, Jean Michel; Barthelemy, Isabelle

    2015-12-01

    Third molar extraction is one of the most common interventions in dental and maxillofacial surgery. Complications are frequent and well documented, with swelling, pain, bleeding, infection, and lingual or alveolar nerve injury being the most common. This report describes a case of subcutaneous extensive emphysema and pneumomediastinum that occurred 4 days after extraction of an impacted right mandibular third molar. The management and etiology of this case and those reported in the literature are discussed.

  18. Role of laparoscopy in ureteropelvic junction obstruction with concomitant pathology: a case series study

    PubMed Central

    El-Fayoumi, Abdel-Rahman; Gakis, Georgios; Amend, Bastian; Khairul-Asri, Mohd Ghani; Stenzl, Arnulf; Schwentner, Christian

    2015-01-01

    Introduction Laparoscopic pyeloplasty is considered a standard treatment for ureteropelvic junction obstruction (UPJO). However, the presence of another pathology makes it a more challenging operation and guides the surgeon towards open conversion. In this study, we present our experience in difficult pyeloplasty cases managed by laparoscopy. Material and methods Six patients (4 females and 2 males) with an average age of 44 and a range of 27 to 60 years old, were diagnosed for UPJO. Three were on the left side and 3 on the right side. In addition to UPJO, 2 patients had renal stones, one patient had both renal ptosis and an umbilical hernia, 3 patients had a para-pelvic cyst, hepatomegaly and malrotated kidney, respectively. All patients had a preoperative ultrasound, CT or IVU, and a renal isotope scan. Laparoscopic pyeloplasty was performed according to the dismembered Anderson-Hynes technique with auxiliary maneuver, according to the pathology. Results All patients were treated successfully for UPJO and the concomitant pathologies, except hepatomegaly and malrotation. Mean operative time was 125 minutes and estimated blood loss was <50 ml. Conclusions Laparoscopic pyeloplasty can be performed in difficult situations provided that the surgeon has enough experience with laparoscopy. PMID:26855804

  19. Spontaneous epidural hematoma due to cervico-thoracic angiolipoma.

    PubMed

    Eap, C; Bannwarth, M; Jazeron, J-F; Kleber, J-C; Theret, É; Duntze, J; Litre, C-F

    2015-12-01

    Epidural angiolipomas are uncommon benign tumors of the spine. Their clinical presentation is usually a progressive spinal cord compression. We report the case of a 22-year-old patient who presented with an acute paraparesis and a spontaneous epidural hematoma, which revealed a epidural angiolipoma which extended from C7 to T3. The patient underwent a C7-T3 laminectomy, in emergency, with evacuation of the hematoma and extradural complete resection of a fibrous epidural tumor bleeding. The postoperative course was favorable with regression of neurological symptoms. Epidural angiolipomas can be revealed by spontaneous intratumoral hemorrhage without traumatism. The standard treatment is total removal by surgery.

  20. Neonatal Airway Compromise by a Giant Cervicothoracic Venous Haemangioma

    PubMed Central

    Shenoy, Janardhan; Coutinho, Anita; Pai, Suresh; Rai, Santosh PV

    2017-01-01

    Haemangiomas are most common non-malignant vascular tumours of infancy. Here, we describe an antenatally detected mass over the neck causing compressive respiratory compromise at birth requiring resuscitative measures at birth. The mass showed increased vascularity on Contrast Enhanced Computed Tomography (CECT) with extension upto superior mediastinum. Surgical excision was required following failure to medical measures with steroids and propranolol. Histopathology confirmed it to be a venous haemangioma. This case highlights that these benign lesions may reach large sizes and antenatal detection may help in planning effective delivery and resuscitative measures. PMID:28384953

  1. Technology Solutions Case Study: New Insights for Improving the Designs of Flexible Duct Junction Boxes

    SciTech Connect

    2014-01-01

    In this project, IBACOS explored the relationships between pressure and physical configurations of flexible duct junction boxes by using computational fluid dynamics simulations to predict individual box parameters and total system pressure, thereby ensuring improved HVAC performance.

  2. True Cervicothoracic Meningocele: A Rare and Benign Condition

    PubMed Central

    Pessoa, Bruno L.; Lima, Yara

    2015-01-01

    Cervical meningoceles are rare spinal dysraphism, accounting for approximately 7% of all cystic spinal dysraphism. In spite of the rarity, the clinical course is most of the times benign. The surgical treatment includes resection of the lesion and untethering, when presented. We present a 14-day-old female child with true meningoceles who underwent to surgical excision and dura-mater repair. Retrospect analysis of the literature concerning true cervical meningocele is performed. By reporting this illustrative case, we focus on its classification and its differentiation from other types of cervical spinal dysraphism, such as myelocystocele and myelomeningocele. Although its course is benign, it is mandatory a continuum follow up with periodic magnetic resonance imaging of spinal cord, since late neurological deterioration has been described. PMID:26788266

  3. Laser etching causing fatigue fracture at the neck-shoulder junction of an uncemented femoral stem: A case report.

    PubMed

    Jang, Bob; Kanawati, Andrew; Brazil, Declan; Bruce, Warwick

    2013-01-01

    Fatigue fracture of a femoral component in total hip arthroplasty is a rare occurrence but well documented in the literature. It is understood that proximal loosing of a femoral stem with a well fixed stem distally will result in cantilever bending and eventual fatigue fracture of the stem. Other factors which may potentiate a fatigue fracture are material design, implant positioning, and patient characteristics. More recently, laser etching on the femoral neck of an implant has resulted in fatigue fracture. We report a case of a fatigue fracture at the neck-shoulder junction in a well fixed, uncemented, femoral component due to laser etching in the region of high tensile stress.

  4. Traumatic dissecting aneurysm at the vertebrobasilar junction in a 3-month-old infant: evaluation and treatment strategies. Case report.

    PubMed

    Wang, Huan; Orbach, Darren B

    2008-05-01

    Intracranial aneurysms in young infants are extremely rare, with few published reports on the etiology, evaluation, treatment strategies, and follow-up of this condition in this population. The authors report the case of a traumatic dissecting aneurysm at the vertebrobasilar junction (VBJ) in a 3-month-old infant caused by nonaccidental trauma. Therapeutic occlusion of the VBJ was contemplated, but coil embolization of the main aneurysm sac proved feasible, and anticoagulation and antiplatelet agents were initiated. The patient made a full neurological recovery, and follow-up studies demonstrated stable aneurysm occlusion. Management and follow-up strategies for this challenging condition are discussed.

  5. Model of stacked long Josephson junctions: Parallel algorithm and numerical results in case of weak coupling

    NASA Astrophysics Data System (ADS)

    Zemlyanaya, E. V.; Bashashin, M. V.; Rahmonov, I. R.; Shukrinov, Yu. M.; Atanasova, P. Kh.; Volokhova, A. V.

    2016-10-01

    We consider a model of system of long Josephson junctions (LJJ) with inductive and capacitive coupling. Corresponding system of nonlinear partial differential equations is solved by means of the standard three-point finite-difference approximation in the spatial coordinate and utilizing the Runge-Kutta method for solution of the resulting Cauchy problem. A parallel algorithm is developed and implemented on a basis of the MPI (Message Passing Interface) technology. Effect of the coupling between the JJs on the properties of LJJ system is demonstrated. Numerical results are discussed from the viewpoint of effectiveness of parallel implementation.

  6. Nanotube junctions

    DOEpatents

    Crespi, Vincent Henry; Cohen, Marvin Lou; Louie, Steven Gwon Sheng; Zettl, Alexander Karlwalter

    2003-01-01

    The present invention comprises a new nanoscale metal-semiconductor, semiconductor-semiconductor, or metal-metal junction, designed by introducing topological or chemical defects in the atomic structure of the nanotube. Nanotubes comprising adjacent sections having differing electrical properties are described. These nanotubes can be constructed from combinations of carbon, boron, nitrogen and other elements. The nanotube can be designed having different indices on either side of a junction point in a continuous tube so that the electrical properties on either side of the junction vary in a useful fashion. For example, the inventive nanotube may be electrically conducting on one side of a junction and semiconducting on the other side. An example of a semiconductor-metal junction is a Schottky barrier. Alternatively, the nanotube may exhibit different semiconductor properties on either side of the junction. Nanotubes containing heterojunctions, Schottky barriers, and metal-metal junctions are useful for microcircuitry.

  7. Nanotube junctions

    DOEpatents

    Crespi, Vincent Henry; Cohen, Marvin Lou; Louie, Steven Gwon; Zettl, Alexander Karlwalte

    2004-12-28

    The present invention comprises a new nanoscale metal-semiconductor, semiconductor-semiconductor, or metal-metal junction, designed by introducing topological or chemical defects in the atomic structure of the nanotube. Nanotubes comprising adjacent sections having differing electrical properties are described. These nanotubes can be constructed from combinations of carbon, boron, nitrogen and other elements. The nanotube can be designed having different indices on either side of a junction point in a continuous tube so that the electrical properties on either side of the junction vary in a useful fashion. For example, the inventive nanotube may be electrically conducting on one side of a junction and semiconducting on the other side. An example of a semiconductor-metal junction is a Schottky barrier. Alternatively, the nanotube may exhibit different semiconductor properties on either side of the junction. Nanotubes containing heterojunctions, Schottky barriers, and metal-metal junctions are useful for microcircuitry.

  8. Assessment of environmental benefits of flyover construction over signalized junctions: a case study.

    PubMed

    Goyal, S K; Goel, Sangita; Tamhane, S M

    2009-01-01

    In the present study, the impact of the flyover construction to curb traffic congestion problem has been assessed in terms of traffic decongestion, time saving, fuel saving and emission reduction. A flyover has also been constructed over four signalized junctions in the main commercial area in Nagpur city, India. It was found that about 35% of the total traffic is diverted to the flyover, which results in a reduction of about 32% in the total emission generation. Travel on the flyover resulted in as much as 60-70% saving in time, compared to the travel on the main road, particularly when all the four signals are found to be in the red phase. The loss of fuel for combustion and the associated cost resulting from waiting for the signal to change are also estimated, and these are found to be significant.

  9. Occult Congenital Ureteropelvic Junction Obstruction in Two Adults Presenting with Collecting System Rupture After Blunt Renal Trauma: A Case Report Series

    PubMed Central

    Hoffner, Haley E.; Dagrosa, Lawrence M.; Pais, Vernon M.

    2015-01-01

    Abstract We report two adult cases of congenital ureteropelvic junction obstruction detected incidentally in the setting of blunt abdominal trauma. CT images are provided to describe the presentation, while review of the literature and management of renal trauma are discussed. PMID:27579396

  10. [Adenocarcinoma of the gastro-esophagus junction associated to endobrachyesophagus. Two case reports. Review of the literature].

    PubMed

    Kreiker, Joseph; Daou, Robert

    2004-01-01

    Barrett esophagus (BE) is intestinal metaplasia (MI) within the distal tubular esophagus. The BE results in replacement of the normal squamous-lined epithelium with a columnar type epithelium. This metaplastic lesion is a clearly defined risk factor for the development of esophageal adenocarcinoma (ADC). In the western countries the incidence of adenocarcinoma of the lower esophagus and the gastro-esophagus junction have rapidly increased during the past twenty years. The 5-year survival is very poor. Although the relative risk of individuals in the United States with BE developing esophageal adenocarcinoma is very high, the absolute risk is extremely low due to the small number of cases. This lesion is caused by a persistent gastro-esophageal reflux. The nature of the reflux liquid is mixed acid and alkaline in the big majority of cases. A familial aggregation of BE and esophageal adenocarcinoma are present in 14% of patients with BE and esophageal adenocarcinoma. The diagnosis, the surveillance, the new tools of characterization of BE and the therapy remain an actual problem. We present 2 cases of endobrachyesophagus associated to an adenocarcinoma of the lower esophagus and a review of the main actual problem.

  11. Josephson junction

    DOEpatents

    Wendt, J.R.; Plut, T.A.; Martens, J.S.

    1995-05-02

    A novel method for fabricating nanometer geometry electronic devices is described. Such Josephson junctions can be accurately and reproducibly manufactured employing photolithographic and direct write electron beam lithography techniques in combination with aqueous etchants. In particular, a method is described for manufacturing planar Josephson junctions from high temperature superconducting material. 10 figs.

  12. Josephson junction

    DOEpatents

    Wendt, Joel R.; Plut, Thomas A.; Martens, Jon S.

    1995-01-01

    A novel method for fabricating nanometer geometry electronic devices is described. Such Josephson junctions can be accurately and reproducibly manufactured employing photolithographic and direct write electron beam lithography techniques in combination with aqueous etchants. In particular, a method is described for manufacturing planar Josephson junctions from high temperature superconducting material.

  13. Gap junctions.

    PubMed

    Goodenough, Daniel A; Paul, David L

    2009-07-01

    Gap junctions are aggregates of intercellular channels that permit direct cell-cell transfer of ions and small molecules. Initially described as low-resistance ion pathways joining excitable cells (nerve and muscle), gap junctions are found joining virtually all cells in solid tissues. Their long evolutionary history has permitted adaptation of gap-junctional intercellular communication to a variety of functions, with multiple regulatory mechanisms. Gap-junctional channels are composed of hexamers of medium-sized families of integral proteins: connexins in chordates and innexins in precordates. The functions of gap junctions have been explored by studying mutations in flies, worms, and humans, and targeted gene disruption in mice. These studies have revealed a wide diversity of function in tissue and organ biology.

  14. Gap Junctions

    PubMed Central

    Goodenough, Daniel A.; Paul, David L.

    2009-01-01

    Gap junctions are aggregates of intercellular channels that permit direct cell–cell transfer of ions and small molecules. Initially described as low-resistance ion pathways joining excitable cells (nerve and muscle), gap junctions are found joining virtually all cells in solid tissues. Their long evolutionary history has permitted adaptation of gap-junctional intercellular communication to a variety of functions, with multiple regulatory mechanisms. Gap-junctional channels are composed of hexamers of medium-sized families of integral proteins: connexins in chordates and innexins in precordates. The functions of gap junctions have been explored by studying mutations in flies, worms, and humans, and targeted gene disruption in mice. These studies have revealed a wide diversity of function in tissue and organ biology. PMID:20066080

  15. Giant prolactinoma causing cranio-cervical junction instability: a case report.

    PubMed

    Zaben, Malik J A; Harrisson, Stuart E; Mathad, N V

    2011-12-01

    Prolactinomas are common secretory pituitary tumours, usually managed with dopamine agonists. There have previously been case reports of rarer giant prolactinomas causing invasion of surrounding structures. We describe a case report of an exceptionally aggressive giant prolactinoma that eroded the occipital condyles causing cranio-cervical joint instability mandating surgical fixation.

  16. Gap Junctions

    PubMed Central

    Nielsen, Morten Schak; Axelsen, Lene Nygaard; Sorgen, Paul L.; Verma, Vandana; Delmar, Mario; Holstein-Rathlou, Niels-Henrik

    2013-01-01

    Gap junctions are essential to the function of multicellular animals, which require a high degree of coordination between cells. In vertebrates, gap junctions comprise connexins and currently 21 connexins are known in humans. The functions of gap junctions are highly diverse and include exchange of metabolites and electrical signals between cells, as well as functions, which are apparently unrelated to intercellular communication. Given the diversity of gap junction physiology, regulation of gap junction activity is complex. The structure of the various connexins is known to some extent; and structural rearrangements and intramolecular interactions are important for regulation of channel function. Intercellular coupling is further regulated by the number and activity of channels present in gap junctional plaques. The number of connexins in cell-cell channels is regulated by controlling transcription, translation, trafficking, and degradation; and all of these processes are under strict control. Once in the membrane, channel activity is determined by the conductive properties of the connexin involved, which can be regulated by voltage and chemical gating, as well as a large number of posttranslational modifications. The aim of the present article is to review our current knowledge on the structure, regulation, function, and pharmacology of gap junctions. This will be supported by examples of how different connexins and their regulation act in concert to achieve appropriate physiological control, and how disturbances of connexin function can lead to disease. © 2012 American Physiological Society. Compr Physiol 2:1981-2035, 2012. PMID:23723031

  17. Giant pseudomeningocele after spinal surgery: A case report

    PubMed Central

    Srilomsak, Prepram; Okuno, Kazuma; Sakakibara, Toshihiko; Wang, Zhuo; Kasai, Yuichi

    2012-01-01

    Very few reports have described giant pseudomeningoceles ≥ 8 cm in diameter. We report this case of the biggest giant pseudomeningocele at the unusual cervicothoracic level. A 59 year old man who underwent cervicothoracic laminectomy had a giant pseudomeningocele detected and the lesion gradually grew to about 15 cm in diameter by 2 years postoperatively. Cerebrospinal fluid leak closure was performed and the postoperative course was favorable. We present this case, review the literature and discuss the size and portion, mechanism of formation, symptoms and treatments of giant pseudomeningocele. PMID:22816066

  18. Singular layers for transmission problems in thin shallow shell theory: Rigid junction case

    NASA Astrophysics Data System (ADS)

    Merabet, Ismail; Chacha, D. A.; Nicaise, S.

    2010-02-01

    In this Note we study two-dimensional transmission problems for the linear Koiter's model of an elastic multi-structure composed of two thin shallow shells. This work enters in the framework of singular perturbation of problems depending on a small parameter ɛ. The formal limit problem fails to give a solution satisfying all boundary and transmission conditions; it gives only the outer solution. Both in the case of regular or singular loadings, we derive a limit problem which allows us to determine the inner solution explicitly.

  19. Craniovertebral junction realignment for the treatment of basilar invagination with syringomyelia: preliminary report of 12 cases.

    PubMed

    Goel, Atul; Sharma, Praveen

    2005-10-01

    Twelve selected patients, eight males and four females aged 14 to 50 years, with syringomyelia associated with congenital craniovertebral bony anomalies including basilar invagination and fixed atlantoaxial dislocation, and associated Chiari I malformation in eight, were treated by atlantoaxial joint manipulation and restoration of the craniovertebral region alignment between October 2002 and March 2004. Three patients had a history of trauma prior to the onset of symptoms. Spastic quadriparesis and ataxia were the most prominent symptoms. The mean duration of symptoms was 11 months. The atlantoaxial dislocation and basilar invagination were reduced by manual distraction of the facets of the atlas and axis, stabilization by placement of bone graft and metal spacers within the joint, and direct atlantoaxial fixation using an inter-articular plate and screw method technique. Following surgery all patients showed symptomatic improvement and restoration of craniovertebral alignment during follow up from 3 to 20 months (mean 7 months). Radiological improvement of the syrinx could not be evaluated as stainless steel metal plates, screws, and spacers were used for fixation. Manipulation of the atlantoaxial joints and restoring the anatomical craniovertebral alignments in selected cases of syringomyelia leads to remarkable and sustained clinical recovery, and is probably the optimum surgical treatment.

  20. Cervicothoracic Manual Therapy Plus Exercise Therapy Versus Exercise Therapy Alone in the Management of Individuals With Shoulder Pain: A Multicenter Randomized Controlled Trial.

    PubMed

    Mintken, Paul E; McDevitt, Amy W; Cleland, Joshua A; Boyles, Robert E; Beardslee, Amber R; Burns, Scott A; Haberl, Matthew D; Hinrichs, Lauren A; Michener, Lori A

    2016-08-01

    Study Design Multicenter randomized controlled trial. Background Cervicothoracic manual therapy has been shown to improve pain and disability in individuals with shoulder pain, but the incremental effects of manual therapy in addition to exercise therapy have not been investigated in a randomized controlled trial. Objectives To compare the effects of cervicothoracic manual therapy and exercise therapy to those of exercise therapy alone in individuals with shoulder pain. Methods Individuals (n = 140) with shoulder pain were randomly assigned to receive 2 sessions of cervicothoracic range-of-motion exercises plus 6 sessions of exercise therapy, or 2 sessions of high-dose cervicothoracic manual therapy and range-of-motion exercises plus 6 sessions of exercise therapy (manual therapy plus exercise). Pain and disability were assessed at baseline, 1 week, 4 weeks, and 6 months. The primary aim (treatment group by time) was examined using linear mixed-model analyses and the repeated measure of time for the Shoulder Pain and Disability Index (SPADI), the numeric pain-rating scale, and the shortened version of the Disabilities of the Arm, Shoulder and Hand questionnaire (QuickDASH). Patient-perceived success was assessed and analyzed using the global rating of change (GROC) and the Patient Acceptable Symptom State (PASS), using chi-square tests of independence. Results There were no significant 2-way interactions of group by time or main effects by group for pain or disability. Both groups improved significantly on the SPADI, numeric pain-rating scale, and QuickDASH. Secondary outcomes of success on the GROC and PASS significantly favored the manual therapy-plus-exercise group at 4 weeks (P = .03 and P<.01, respectively) and on the GROC at 6 months (P = .04). Conclusion Adding 2 sessions of high-dose cervicothoracic manual therapy to an exercise program did not improve pain or disability in patients with shoulder pain, but did improve patient-perceived success at 4 weeks

  1. Proximal junctional vertebral fracture-subluxation after adult spine deformity surgery. Does vertebral augmentation avoid this complication? A case report

    PubMed Central

    2012-01-01

    Background To report to the orthopedic community a case of vertebral fracture and adjacent vertebral subluxation through the upper instrumented vertebra after thoracolumbar fusion with augmentation of the cranial level. Methods This report reviewed the patient`s medical record, her imaging studies and related literature. The possible factors contributing to this fracture are hypothesized. Results A 70-year-old woman underwent decompressive surgery and posterolateral fusion for adult lumbar scoliosis. We used pedicular screws from T10 to S1 and iliac screw at the right side, augmented with cement at T10, T11, L1, L5 and S1; and prophylactic vertebroplasty at T9 to avoid the "topping-off syndrome". Thirty days after discharge, without recognizable inciting trauma, the patient complained of pain in the lower thoracic area. The exam revealed overall neurological deficit below the level of fracture. CT scan and MRI demonstrated a T10 vertebral collapse and T9 vertebral subluxation with morphologic features of flexion-distraction fracture through the upper edge of the screw. At this point, the authors performed posterior decompression at T9 to T10 and extended posterolateral arthrodesis from T2 to T10. To our knowledge, this is an unreported fracture. Conclusions Augmentation of the cranial level in a long thoracolumbar fusion has been developed to avoid the junctional kyphosis and compression fractures at that level. We alert the orthopedic community that this augmentation may lead to further and more severe fractures, although this opinion requires investigation for confirmation. PMID:22947422

  2. Fractional order junctions

    NASA Astrophysics Data System (ADS)

    Machado, J. Tenreiro

    2015-01-01

    Gottfried Leibniz generalized the derivation and integration, extending the operators from integer up to real, or even complex, orders. It is presently recognized that the resulting models capture long term memory effects difficult to describe by classical tools. Leon Chua generalized the set of lumped electrical elements that provide the building blocks in mathematical models. His proposal of the memristor and of higher order elements broadened the scope of variables and relationships embedded in the development of models. This paper follows the two directions and proposes a new logical step, by generalizing the concept of junction. Classical junctions interconnect system elements using simple algebraic restrictions. Nevertheless, this simplistic approach may be misleading in the presence of unexpected dynamical phenomena and requires including additional "parasitic" elements. The novel γ -junction includes, as special cases, the standard series and parallel connections and allows a new degree of freedom when building models. The proposal motivates the search for experimental and real world manifestations of the abstract conjectures.

  3. Association of Craniovertebral Junction Anomalies, Klippel-Feil Syndrome, Ruptured Dermoid Cyst and Mirror Movement in One Patient: A Unique Case and Literature Review.

    PubMed

    Zhang, Yu-Kun; Geng, Su-Min; Liu, Pi-Nan; Lv, Gang

    2016-01-01

    The Klippel-Feil syndrome (KFS) has been reported to be associated with intracranial neoplasms, most frequently epidermoid or dermoid cysts. To our knowledge, however, patients who present with a posterior fossa dermoid cyst (DC) and KFS are extremely rare with only 24 previously reported cases in the English literature worldwide. Therefore, we present the first report of a patient with a craniocervical ruptured DC accompanied by craniovertebral junction (CVJ) anomalies, KFS and mirror movement. Meanwhile, a literature review of KFS accompanying with posterior fossa DC discusses these conditions from the embryological, anatomical, clinical and therapeutic perspectives. Additionally, the combination of CVJ anomalies, KFS and DC may represent a new syndrome that has previously gone unnoticed.

  4. [Long-term evolution of esophago-gastric junctions surgically treated to correct gastro-esophageal reflux. 111 cases].

    PubMed

    Vaysse, P; Baunin, C; Guitard, J; Moscovici, J; Visentin, M; Chansou, A; Fedacou, F; Juskiewenski, S

    1989-01-01

    One hundred eleven patients underwent a surgical procedure for correction of intractable gastroesophageal reflux. Twenty children were severely mentally retarded. The range of follow up was 6 months to 15 years. Upper gastro-intestinal series was realised at tenth post-operative day for 111 children, then during the first year for 97 children, between the first and fifth year for 62 children and after the fifth year for 25 children. The first upper gastro-intestinal control (at tenth day) was normal for 111 patients. Next controls revealed, usually during the first post-operative year, an esophago-gastric junction anomaly for 49 patients (44%). Most of them are light (41/111 = 37%): occasional reflux (9 children; more frequent without pyloroplasty) of little paraesophageal hernia (32 children; more frequent with closure of esophageal hiatus by two suture lines, with esophageal fixation on median arcuatum ligament or without esophageal fixation on esophageal hiatus); these light anomalies are symptom free and sometimes transitories. Rarely, anomalies are important (8/111 = 7%): big paraesophageal hernia of recurrence (more frequent with partial posterior fundoplication and in children severely mentally retarded); five patients were symptomatic and had to be reoperated. Also now, we don't use partial posterior fundoplication and in mentally retarded children we prefer a Collis procedure.

  5. Epithelial adhesive junctions

    PubMed Central

    Capaldo, Christopher T.; Farkas, Attila E.

    2014-01-01

    Epithelial adhesive cell-to-cell contacts contain large, plasma membrane-spanning multiprotein aggregates that perform vital structural and signaling functions. Three prominent adhesive contacts are the tight junction, adherens junction, and the desmosome. Each junction type has unique cellular functions and a complex molecular composition. In this review, we comment on recent and exciting advances in our understanding of junction composition and function. PMID:24592313

  6. Intraoperative somatosensory evoked potential recovery following opening of the fourth ventricle during posterior fossa decompression in Chiari malformation: case report.

    PubMed

    Grossauer, Stefan; Koeck, Katharina; Vince, Giles H

    2015-03-01

    The most appropriate surgical technique for posterior fossa decompression in Chiari malformation (CM) remains a matter of debate. Intraoperative electrophysiological studies during posterior fossa decompression of Type I CM (CM-I) aim to shed light on the entity's pathomechanism as well as on the ideal extent of decompression. The existing reports on this issue state that significant improvement in conduction occurs after craniotomy in all cases, but additional durotomy contributes a further improvement in only a minority of cases. This implies that craniotomy alone might suffice for clinical improvement without the need of duraplasty or even subarachnoid manipulation at the level of the craniocervical junction. In contrast to published data, the authors describe the case of a 32-year-old woman who underwent surgery for CM associated with extensive cervicothoracic syringomyelia and whose intraoperative somatosensory evoked potentials (SSEPs) did not notably improve after craniotomy or following durotomy; rather, they only improved after opening of the fourth ventricle and restoration of CSF flow through the foramen of Magendie. Postoperatively, the patient recovered completely from her preoperative neurological deficits. To the authors' knowledge, this is the first report of significant SSEP recovery after opening the fourth ventricle in the decompression of a CM-I. The electrophysiological and operative techniques are described in detail and the findings are discussed in the light of available literature. The authors conclude that there might be a subset of CM-I patients who require subarachnoid dissection at the level of the craniocervical junction to benefit clinically. Prospective studies with detailed electrophysiological analyses seem warranted to answer the question regarding the best surgical approach in CM-I decompression.

  7. Ballistic bipolar junctions in chemically gated graphene ribbons

    PubMed Central

    Baringhaus, Jens; Stöhr, Alexander; Forti, Stiven; Starke, Ulrich; Tegenkamp, Christoph

    2015-01-01

    The realization of ballistic graphene pn-junctions is an essential task in order to study Klein tunneling phenomena. Here we show that intercalation of Ge under the buffer layer of pre-structured SiC-samples succeeds to make truly nano-scaled pn-junctions. By means of local tunneling spectroscopy the junction width is found to be as narrow as 5 nm which is a hundred times smaller compared to electrically gated structures. The ballistic transmission across the junction is directly proven by systematic transport measurements with a 4-tip STM. Various npn- and pnp-junctions are studied with respect to the barrier length. The pn-junctions are shown to act as polarizer and analyzer with the second junction becoming transparent in case of a fully ballistic barrier. This can be attributed to the almost full suppression of electron transmission through the junction away from normal incidence. PMID:25898259

  8. [Fourth branchial cleft deformity with skin orifice: a series of 10 cases].

    PubMed

    Huang, S L; Zhang, B; Chen, L S; Liang, L; Luo, X N; Lu, Z M; Zhang, S Y

    2016-10-07

    Objective: To report rare cases of congenital neck cutaneous sinus with an orifice near the sternoclavicular joint and to investigate their origins and managements. Methods: A total of ten patients with congenital neck cutaneous sinus having an orifice near the sternoclavicular joint treated in the Guangdong General Hospital from January 2010 to June 2015 were retrospectively analyzed. Results: There four boys and six girls, aging from 11 months to 96 months with an average of 33.4 months, and they had a common feature showing a congenital cutaneous sinus with an orifice near sternoclavicular joint. Discharge of pus from the orifice or abscess formation was commonly seen soon after infection. With bacteriological study, staphylococcus aureus was positive in five cases and klebsiella pneumonia in a case. Another orifice of fistula/sinus was not depicted in pyriform with barium swallow X-ray in five cases Ultrasound studies of three cases demonstrated anechoic (i.e., nearly black) and solid-cystic lesion near sternoclavicular joint with posterior acoustic enhancement. Magnetic resonance imaging (MRI) showed isointensity of the lesion on T1 and T2 weighted images with heterogeneous enhancement and a close relationship with sternoclavicular joint. All patients underwent laryngoscopic examination, which showed no orifice of sinus in pyriform at same side. Surgical resection of fistula/sinus was performed in all cases. The lengths of the fistula varied from 5 mm to 22 mm with an average of 11 mm. Postoperative pathological examination showed all specimens were accordance with fistula. No complications were noticed. Recurrence was not observed in the cases by following-up of 6 months to 70 months (median: 33 months). Conclusion: Congenital neck cutaneous sinus with orifice near the sternoclavicular joint maybe a special clinical phenotype of the fourth branchial cleft sinus with skin orifice in cervicothoracic junction. Differential diagnoses between low cervical diseases

  9. Extended generation profile - E.B.I.C model application in the case of a PN junction

    NASA Astrophysics Data System (ADS)

    Guermazi, S.; Toureille, A.; Grill, C.; El Jani, B.

    2000-01-01

    We have developed a model for the calculation of the induced current due to an electron beam with an extended generation profile. Added to the absorbed and diffuse electrons in the depth distribution, the generation profile takes into account the lateral diffusion. The analytical expression of the electron beam induced current (EBIC) is obtained by solving the continuity equation in permanent regime by the Green function method. The induced current profile, obtained in the case of a ternary component (Ga{0.7}Al{0.3}As:N^+/Ga{0.7}Al{0.3}As:P) sulfur doped and prepared by organometallic compounds phase vapor epitaxy method, is compared to the theoretical profiles whose analytical expressions are given by Van Roosbroeck and Bresse. The experimental current profile, measured by S.E.M provided us to calculate the diffusion length of the minority carriers: L_p=1 μm in the N region and L_n=1.80 μm in the P region of the ternaire component. The theoretical curve obtained from the proposed model is in good agreement with the experimental one for a surface recombination velocity of 10^6 cm s^{-1}. Our results are found to be consistent compared to those obtained by other experimental techniques using the same samples. Nous avons développé un modèle de calcul du courant induit par un faisceau d'électrons avec un profil de génération élargi. Le profil de génération prend en compte la répartition spatiale de la diffusion et de l'absorption des électrons. L'expression analytique du courant induit (E.B.I.C) est déterminée par résolution de l'équation de continuité en régime permanent par la méthode des fonctions de Green. Le profil de courant induit obtenu dans le cas d'une jonction PN (Ga{0,7}Al{0,3}As:N^+/Ga{0,7}Al{0,3}As:P) dopée par le soufre et préparée par épitaxie à phase vapeur organo-métallique, est comparé au profil de courant théorique dont l'expression analytique est explicitée par Van Roosbroeck et Bresse. Le profil expérimental de

  10. Indian Ocean Triple Junction

    SciTech Connect

    Tapscott, C.R.; Patriat, P.; Fisher, R.L.; Sclater, J.G.; Hoskins, H.; Parsons, B.

    1980-09-10

    The boundaries of three major plates (Africa, India, and Antarctica) meet in a triple junction in the Indian Ocean near 25 /sup 0/S, 70 /sup 0/E. Using observed bathymetry and magnetic anomalies, we locate the junction to within 5 km and show that it is a ridge-ridge-ridge type. Relative plate motion is N60 /sup 0/E at 50 mm/yr (full rate) across the Central Indian Ridge, N47 /sup 0/E at 60 mm/yr across the Southeast Indian Ridge, and N3 /sup 0/W at 15 mm/yr across te Southwest Indian Ridge; the observed velocity triangle is closed. Poles of instantaneous relative plate motion are determined for all plate pairs. The data in the South Atlantic and Indian oceans are consistent with a rigid African plate without significant internal deformation. Two of the ridges at the triple junction are normal midocean spreading centers with well-defined median valleys. The Southwest Indian Ridge, however, has a peculiar morphology near the triple junction, that of an elongate triangular deep, with the triple junction at its apex. The floor of the deep represents crust formed at the Southwest Indian Ridge, and the morphology is a consequence of the evolution of the triple junction and is similar to that at the Galapagos Triple Junction. Though one cannot determine with precision the stability conditions at the triple junction, the development of the junction over the last 10 m.y. can be mapped, and the topographic expressions of the triple junction traces may be detected on the three plates.

  11. Case of Superficial Cancer Located at the Pharyngoesophageal Junction Which Was Dissected by Endoscopic Laryngopharyngeal Surgery Combined with Endoscopic Submucosal Dissection

    PubMed Central

    Kawano, Tatsuyuki; Sugimoto, Taro; Yamaguchi, Kazuya; Kawamura, Yuudai; Matsui, Toshihiro; Okuda, Masafumi; Ogo, Taichi; Kume, Yuuichiro; Nakajima, Yutaka; Mora, Andres; Okada, Takuya; Hoshino, Akihiro; Tokairin, Yutaka; Nakajima, Yasuaki; Okada, Ryuhei; Kiyokawa, Yusuke; Nomura, Fuminori; Asakage, Takahiro; Shimoda, Ryo; Ito, Takashi

    2017-01-01

    Aims. In order to determine the indications of transoral surgery for a tumor located at the pharyngoesophageal junction, the trumpet maneuver with transnasal endoscopy was used. Its efficacy is reported here. Material and Methods. An 88-year-old woman complaining of dysphagia, diagnosed with cervical esophageal cancer, and hoping to preserve her voice and swallowing function was admitted to our hospital. Conventional endoscopy showed that the tumor had invaded the hypopharynx. When inspecting the hypopharynx and the orifice of the esophagus, we asked the patient to blow hard and puff her cheeks with her mouth closed (trumpet maneuver). After the trumpet maneuver, the pharyngeal mucosa was stretched out. The pedicle of the tumor arose from the left-anterior wall of the pharyngoesophageal junction, so we decided to perform endoscopic resection. Result. Under general anesthesia, the curved laryngoscope made it possible to view the whole hypopharynx, including the apex of the piriform sinus and the orifice of the esophagus. The cervical esophageal cancer was pulled up to the hypopharynx. Under collaboration between a head and neck surgeon and an endoscopist, the tumor was resected en bloc by endoscopic laryngopharyngeal surgery combined with endoscopic submucosal dissection. Conclusion. Transnasal endoscopy using the trumpet maneuver is useful for a precise diagnosis of the pharyngoesophageal junction. Close collaboration between head and neck surgeons and endoscopists can provide good results in treating tumors of the pharyngoesophageal junction. PMID:28154766

  12. Geometrical theory of triple junctions of CSL boundaries.

    PubMed

    Gertsman, V Y

    2001-07-01

    When three grain boundaries having misorientations generating coincidence site lattices (CSLs) meet at a triple junction, a common (triple-junction) CSL is formed. A theory is developed as a set of theorems establishing the relationships between the geometrical parameters of the grain-boundary and triple-junction CSLs. Application of the theory is demonstrated in detail for the case of the cubic crystal system. It is also shown how the theory can be extended to an arbitrary crystal lattice.

  13. [A case of dural arteriovenous fistula at the craniocervical junction, which spinal MRI findings reveals increased intensity signal in Th3-medullary cone].

    PubMed

    Ueda, Masamichi; Ueda, Miki; Takeuchi, Yuko; Ochiai, Jun; Mabuchi, Chiyuki; Hattori, Shinnosuke

    2016-01-01

    A 60-year-old woman had transient weakness of the legs and urinary retention for six weeks. She presented with a gait disorder and was admitted to the hospital. She showed symptoms of paraplegia, tingling in the lower extremities, dysuria. She underwent an MRI, and T2-weighted images showed an enlargement of the thoracolumbar spinal cord and high intensity signal from Th3 to the medullary cone, and a contrast-enhanced T1-weighted image showed abnormal vessels anterior to the spine cord. Cervical and spinal angiography documented a dural arteriovenous fistula at the craniocervical junction that was fed by the right vertebral artery and the right ascending pharyngeal arteries and drained into the perimedullary veins. Surgical therapy improved her symptoms and MRI images. Craniocervical junction DAVF with thoracic-medullary cones lesion is rare.

  14. Quantum junction solar cells.

    PubMed

    Tang, Jiang; Liu, Huan; Zhitomirsky, David; Hoogland, Sjoerd; Wang, Xihua; Furukawa, Melissa; Levina, Larissa; Sargent, Edward H

    2012-09-12

    Colloidal quantum dot solids combine convenient solution-processing with quantum size effect tuning, offering avenues to high-efficiency multijunction cells based on a single materials synthesis and processing platform. The highest-performing colloidal quantum dot rectifying devices reported to date have relied on a junction between a quantum-tuned absorber and a bulk material (e.g., TiO(2)); however, quantum tuning of the absorber then requires complete redesign of the bulk acceptor, compromising the benefits of facile quantum tuning. Here we report rectifying junctions constructed entirely using inherently band-aligned quantum-tuned materials. Realizing these quantum junction diodes relied upon the creation of an n-type quantum dot solid having a clean bandgap. We combine stable, chemically compatible, high-performance n-type and p-type materials to create the first quantum junction solar cells. We present a family of photovoltaic devices having widely tuned bandgaps of 0.6-1.6 eV that excel where conventional quantum-to-bulk devices fail to perform. Devices having optimal single-junction bandgaps exhibit certified AM1.5 solar power conversion efficiencies of 5.4%. Control over doping in quantum solids, and the successful integration of these materials to form stable quantum junctions, offers a powerful new degree of freedom to colloidal quantum dot optoelectronics.

  15. Towards field theory in spaces with multivolume junctions

    NASA Astrophysics Data System (ADS)

    Fomin, P. I.; Shtanov, Yu V.

    2002-06-01

    We consider a spacetime formed by several pieces with common timelike boundary which plays the role of a junction between them. We establish junction conditions for fields of various spins and derive the resulting laws of wave propagation through the junction, which turn out to be quite similar for fields of all spins. As an application, we consider the case of multivolume junctions in four-dimensional spacetime that may arise in the context of the theory of quantum creation of a closed universe on the background of a big mother universe. The theory developed can also be applied to braneworld models and to the superstring theory.

  16. Diencephalic-Mesencephalic Junction Dysplasia: A Novel Recessive Brain Malformation

    ERIC Educational Resources Information Center

    Zaki, Maha S.; Saleem, Sahar N.; Dobyns, William B.; Barkovich, A. James; Bartsch, Hauke; Dale, Anders M.; Ashtari, Manzar; Akizu, Naiara; Gleeson, Joseph G.; Grijalvo-Perez, Ana Maria

    2012-01-01

    We describe six cases from three unrelated consanguineous Egyptian families with a novel characteristic brain malformation at the level of the diencephalic-mesencephalic junction. Brain magnetic resonance imaging demonstrated a dysplasia of the diencephalic-mesencephalic junction with a characteristic "butterfly"-like contour of the…

  17. Osteopathia striata with cranial sclerosis (OSCS): review of the literature and case report demonstrating challenges of spinal fusion after trauma.

    PubMed

    Katsevman, Gennadiy A; Turner, Ryan C; Lucke-Wold, Brandon P; Sedney, Cara L; Bhatia, Sanjay

    2016-06-01

    Osteopathia striata with cranial sclerosis (OSCS) is a rare but well-described pathology characterized by abnormalities in bone deposition in the axial and cranial skeleton as well as other abnormalities and associated deficits. These skeletal abnormalities can lead to significant intra-operative challenges for the surgeon and influence outcomes for the patient. In this report, we present a case of a patient with OSCS who was involved in a traumatic motor vehicle crash and underwent posterior cervico-thoracic fusion for a T4 chance fracture. Bony abnormalities in the cervico-thoracic spine presented a significant operative challenge due to alterations in bony anatomy and bone architecture. This case serves as an example of the challenges that the spine surgeon faces when dealing with OSCS, and highlights the differences between OSCS and commoner skeletal hyperplasias such as osteopetrosis.

  18. Four-junction superconducting circuit

    NASA Astrophysics Data System (ADS)

    Qiu, Yueyin; Xiong, Wei; He, Xiao-Ling; Li, Tie-Fu; You, J. Q.

    2016-06-01

    We develop a theory for the quantum circuit consisting of a superconducting loop interrupted by four Josephson junctions and pierced by a magnetic flux (either static or time-dependent). In addition to the similarity with the typical three-junction flux qubit in the double-well regime, we demonstrate the difference of the four-junction circuit from its three-junction analogue, including its advantages over the latter. Moreover, the four-junction circuit in the single-well regime is also investigated. Our theory provides a tool to explore the physical properties of this four-junction superconducting circuit.

  19. Dot junction solar cells

    NASA Technical Reports Server (NTRS)

    Daud, T.; Crotty, G. T.

    1986-01-01

    A design of solar cells with reduced junction area on the cell surface is investigated for reduction of saturation current and increase in open-circuit voltage. Equidiameter dot junctions distributed across the surface of the cell offer an efficient alternative, with variations in dot diameter and in the spacing between dots giving the required variations in the ratio of junction area to total surface area. A simplified analysis for short-circuit current and other cell parameters, which enables cell design optimization, is presented. Experimental solar-cell performance results, as functions of different area ratios, are presented and compared with the model. It is shown that saturation current reduction is possible for achieving efficiencies as high as 18 percent in flat-plate terrestrial applications.

  20. Josephson junctions with alternating critical current density

    SciTech Connect

    Mints, R.G.; Kogan, V.G.

    1997-04-01

    The magnetic-field dependence of the critical current I{sub c}(H) is considered for a short Josephson junction with the critical current density j{sub c} alternating along the tunnel contact. Two model cases, periodic and randomly alternating j{sub c}, are treated in detail. Recent experimental data on I{sub c}(H) for grain-boundary Josephson junctions in YBa{sub 2}Cu{sub 3}O{sub x} are discussed. {copyright} {ital 1997} {ital The American Physical Society}

  1. Interplay between static and dynamic properties of semifluxons in YBa2Cu3O(7-delta) 0-pi Josephson junctions.

    PubMed

    Cedergren, K; Kirtley, J R; Bauch, T; Rotoli, G; Troeman, A; Hilgenkamp, H; Tafuri, F; Lombardi, F

    2010-04-30

    We have investigated the static and dynamic properties of long YBa2Cu3O(7-delta) 0-pi Josephson junctions and compared them with those of conventional 0 junctions. Scanning SQUID microscope imaging has revealed the presence of a semifluxon at the phase discontinuity point in 0-pi Josephson junctions. Zero field steps have been detected in the current-voltage characteristics of all junctions. Comparison with simulation allows us to attribute these steps to fluxons traveling in the junction for conventional 0 junctions and to fluxon-semifluxon interactions in the case of 0-pi Josephson junctions.

  2. Victory Junction Gang Camp

    ERIC Educational Resources Information Center

    Shell, Ryan

    2007-01-01

    This article describes the Victory Junction Gang Camp, a not-for-profit, NASCAR-themed camp for children with chronic medical conditions that serves 24 different disease groups. The mission of the camp is to give children life-changing camping experiences that are exciting, fun, and empowering in a safe and medically sound environment. While doing…

  3. Myosin-dependent remodeling of adherens junctions protects junctions from Snail-dependent disassembly

    PubMed Central

    Weng, Mo

    2016-01-01

    Although Snail is essential for disassembly of adherens junctions during epithelial–mesenchymal transitions (EMTs), loss of adherens junctions in Drosophila melanogaster gastrula is delayed until mesoderm is internalized, despite the early expression of Snail in that primordium. By combining live imaging and quantitative image analysis, we track the behavior of E-cadherin–rich junction clusters, demonstrating that in the early stages of gastrulation most subapical clusters in mesoderm not only persist, but move apically and enhance in density and total intensity. All three phenomena depend on myosin II and are temporally correlated with the pulses of actomyosin accumulation that drive initial cell shape changes during gastrulation. When contractile myosin is absent, the normal Snail expression in mesoderm, or ectopic Snail expression in ectoderm, is sufficient to drive early disassembly of junctions. In both cases, junctional disassembly can be blocked by simultaneous induction of myosin contractility. Our findings provide in vivo evidence for mechanosensitivity of cell–cell junctions and imply that myosin-mediated tension can prevent Snail-driven EMT. PMID:26754645

  4. Intercellular junctions in myriapods.

    PubMed

    Dallai, R; Bigliardi, E; Lane, N J

    1990-01-01

    Tissue from the intestinal tract of myriapods, including millipedes, centipedes and pauropods were examined in tracer-impregnated sections and freeze-fracture replicas. The foregut and hindgut of all three classes exhibit pleated septate junctions; these display undulating intercellular ribbons in thin sections. In replicas they show discrete intramembranous particle (IMP) arrays aligned in rows in parallel; with one another. The tissues of the hindgut also possess scalariform junctions, characterized by cross-striated intercellular clefts in sections and IMP-enriched membranes in replicas. Gap junctions occur in all groups, but they are atypical in replicas in that their component IMPs do not always fracture onto the E face, as is characteristic of other arthropods; some IMPs cleave to the P face and others to the E face. The midgut of these organisms exhibits smooth septate junctions with conventional straight septal ribbons and occasional interseptal columns. However the intramembranous appearance in replicas is variable, particularly in centipedes, in that the rows of IMPs in chemically-unfixed propanecryofixed tissues, are prominent and adhere preferentially to the E face, with complementary P face grooves, while in fixed tissues the IMPs are much less distinct and fracture to either P face or E face. They tend not to protrude far beyond the mid-plane of the membrane bilayer and lie in rows which commonly take on the form of a network. Individual rows of the network sometimes curve to run beside a second row, over a short distance, before bending away into another part of the network. The aligned particle rows, which are much more prominent in millipedes, where they frequently lie in close parallel appositions, do not fuse into ridges as often occurs in insect tissues. The myriapod junctions, therefore, are of the same general kind as are found in the gut tract of other arthropod groups, but differ with respect to the subtleties of their intramembranous

  5. Magic-T Junction using Microstrip/Slotline Transitions

    NASA Technical Reports Server (NTRS)

    U-yen, Kongpop; Wollack, Edward J.; Doiron, Terence

    2008-01-01

    An improved broadband planar magic-T junction that incorporates microstrip/slotline transitions has been developed. In comparison with a prior broadband magic-T junction incorporating microstrip/slotline transitions, this junction offers superior broadband performance. In addition, because this junction is geometrically simpler and its performance is less affected by fabrication tolerances, the benefits of the improved design can be realized at lower fabrication cost. There are potential uses for junctions like this one in commercial microwave communication receivers, radar and polarimeter systems, and industrial microwave instrumentation. A magic-T junction is a four-port waveguide junction consisting of a combination of an H-type and an E-type junction. An E-type junction is so named because it includes a junction arm that extends from a main waveguide in the same direction as that of the electric (E) field in the waveguide. An H-type junction is so named because it includes a junction arm parallel to the magnetic (H) field in a main waveguide. A magic-T junction includes two input ports (here labeled 1 and 2, respectively) and two output ports (here labeled E and H, respectively). In an ideal case, (1) a magic-T junction is lossless, (2) the input signals add (that is, they combine in phase with each other) at port H, and (3) the input signals subtract (that is, they combine in opposite phase) at port E. The prior junction over which the present junction is an improvement affords in-phase-combining characterized by a broadband frequency response, and features a small slotline area to minimize in-band loss. However, with respect to isolation between ports 1 and 2 and return loss at port E, it exhibits narrowband frequency responses. In addition, its performance is sensitive to misalignment of microstrip and slotline components: this sensitivity is attributable to a limited number of quarter-wavelength (lambda/4) transmission-line sections for matching impedances

  6. Thermoelectricity in molecular junctions.

    PubMed

    Reddy, Pramod; Jang, Sung-Yeon; Segalman, Rachel A; Majumdar, Arun

    2007-03-16

    By trapping molecules between two gold electrodes with a temperature difference across them, the junction Seebeck coefficients of 1,4-benzenedithiol (BDT), 4,4'-dibenzenedithiol, and 4,4''-tribenzenedithiol in contact with gold were measured at room temperature to be +8.7 +/- 2.1 microvolts per kelvin (muV/K), +12.9 +/- 2.2 muV/K, and +14.2 +/- 3.2 muV/K, respectively (where the error is the full width half maximum of the statistical distributions). The positive sign unambiguously indicates p-type (hole) conduction in these heterojunctions, whereas the Au Fermi level position for Au-BDT-Au junctions was identified to be 1.2 eV above the highest occupied molecular orbital level of BDT. The ability to study thermoelectricity in molecular junctions provides the opportunity to address these fundamental unanswered questions about their electronic structure and to begin exploring molecular thermoelectric energy conversion.

  7. Notalgia paresthetica associated with cervical spinal stenosis and cervicothoracic disk disease at C4 through C7.

    PubMed

    Alai, Nili N; Skinner, Harry B; Nabili, Siamak T; Jeffes, Edward; Shahrokni, Seyed; Saemi, Arash M

    2010-02-01

    Notalgia paresthetica (NP) is a common refractory, sensory, neuropathic syndrome with the hallmark symptom of localized pruritus of the unilateral infrascapular back. It generally is a chronic noncurable condition with periodic remissions and exacerbations. While the dermatologic syndrome may be multifactorial in etiology, a possible association with underlying cervical spine disease should be evaluated for proper treatment. Collaborative multispecialty evaluation by dermatology, radiology, orthopedic surgery, and neurology may be indicated for primary management of this condition. First-line therapy for NP with associated cervical disease may include nondermatologic noninvasive treatments such as spinal manipulation, physical therapy, massage, cervical traction, cervical muscle strengthening, and oral nonsteroidal anti-inflammatory drugs and muscle relaxants. Notalgia paresthetica may in fact be a cutaneous sign of an underlying degenerative cervical spine disease. We report a case of a patient with cervical spinal stenosis that corresponded directly with the clinical findings of NP.

  8. Junction between surfaces of two topological insulators

    NASA Astrophysics Data System (ADS)

    Sen, Diptiman; Deb, Oindrila

    2012-02-01

    We study scattering from a line junction which separates the surfaces of two three-dimensional topological insulators; some aspects of this problem were recently studied in Takahashi and Murakami, Phys. Rev. Lett. 107, 166805 (2011). The velocities of the Dirac electrons on the two surfaces may be unequal and may even have opposite signs; in the latter case, we find that the electrons must, in general, go into the two-dimensional interface separating the two topological insulators. We also study what happens if the two surfaces are at an angle φ with respect to each other. We find in this case that there are bound states which propagate along the line junction with a velocity and direction of spin which depend on the bending angle φ.

  9. Signatures of topological Josephson junctions

    NASA Astrophysics Data System (ADS)

    Peng, Yang; Pientka, Falko; Berg, Erez; Oreg, Yuval; von Oppen, Felix

    2016-08-01

    Quasiparticle poisoning and diabatic transitions may significantly narrow the window for the experimental observation of the 4 π -periodic dc Josephson effect predicted for topological Josephson junctions. Here, we show that switching-current measurements provide accessible and robust signatures for topological superconductivity which persist in the presence of quasiparticle poisoning processes. Such measurements provide access to the phase-dependent subgap spectrum and Josephson currents of the topological junction when incorporating it into an asymmetric SQUID together with a conventional Josephson junction with large critical current. We also argue that pump-probe experiments with multiple current pulses can be used to measure the quasiparticle poisoning rates of the topological junction. The proposed signatures are particularly robust, even in the presence of Zeeman fields and spin-orbit coupling, when focusing on short Josephson junctions. Finally, we also consider microwave excitations of short topological Josephson junctions which may complement switching-current measurements.

  10. Large eddy simulation of a wing-body junction flow

    NASA Astrophysics Data System (ADS)

    Ryu, Sungmin; Emory, Michael; Campos, Alejandro; Duraisamy, Karthik; Iaccarino, Gianluca

    2014-11-01

    We present numerical simulations of the wing-body junction flow experimentally investigated by Devenport & Simpson (1990). Wall-junction flows are common in engineering applications but relevant flow physics close to the corner region is not well understood. Moreover, performance of turbulence models for the body-junction case is not well characterized. Motivated by the insufficient investigations, we have numerically investigated the case with Reynolds-averaged Naiver-Stokes equation (RANS) and Large Eddy Simulation (LES) approaches. The Vreman model applied for the LES and SST k- ω model for the RANS simulation are validated focusing on the ability to predict turbulence statistics near the junction region. Moreover, a sensitivity study of the form of the Vreman model will also be presented. This work is funded under NASA Cooperative Agreement NNX11AI41A (Technical Monitor Dr. Stephen Woodruff)

  11. An induced junction photovoltaic cell

    NASA Technical Reports Server (NTRS)

    Call, R. L.

    1974-01-01

    Silicon solar cells operating with induced junctions rather than diffused junctions have been fabricated and tested. Induced junctions were created by forming an inversion layer near the surface of the silicon by supplying a sheet of positive charge above the surface. Measurements of the response of the inversion layer cell to light of different wavelengths indicated it to be more sensitive to the shorter wavelengths of the sun's spectrum than conventional cells. The greater sensitivity occurs because of the shallow junction and the strong electric field at the surface.

  12. GUARD RING SEMICONDUCTOR JUNCTION

    DOEpatents

    Goulding, F.S.; Hansen, W.L.

    1963-12-01

    A semiconductor diode having a very low noise characteristic when used under reverse bias is described. Surface leakage currents, which in conventional diodes greatly contribute to noise, are prevented from mixing with the desired signal currents. A p-n junction is formed with a thin layer of heavily doped semiconductor material disposed on a lightly doped, physically thick base material. An annular groove cuts through the thin layer and into the base for a short distance, dividing the thin layer into a peripheral guard ring that encircles the central region. Noise signal currents are shunted through the guard ring, leaving the central region free from such currents. (AEC)

  13. YBCO Josephson Junction Arrays

    DTIC Science & Technology

    1993-07-14

    Also, CaRuO 3 is chemically compatible with YBa2Cu30 7 and its conductivity does not appear to be strongly dependent on doping or oxygen concentration...barrier conductivity is quite high. The first YBa2Cu30 7 layer and the SrTiO3 layer are deposited first and then patterned with ion milling (to help form...the edge junction will dominate any leakage through the SrTiO3 , thus the integrity of that dielectric will not be a concern here. The integrity of the

  14. A rare presentation of lipoma on mandibular mucogingival junction

    PubMed Central

    Sharma, Gaurav; Jain, Kanu; Nagpal, Archna; Baiju, Chandrababu Sudha

    2016-01-01

    Lipoma is the most common tumor of mesenchymal tissues of body, but its occurrence in oral cavity is infrequent. Buccal mucosa is the most common intraoral site of lipoma followed by tongue, floor of the mouth, and buccal vestibule. The involvement of mucogingival junction is rare. We present a unique case report of oral lipoma occurring on mandibular mucogingival junction with review of literature which has emphasis on differential diagnosis. PMID:27143835

  15. Quantum statistical theory of semiconductor junctions in thermal equilibrium

    NASA Technical Reports Server (NTRS)

    Von Roos, O.

    1977-01-01

    Free carrier and electric field distributions of one-dimensional semiconductor junctions are evaluated using a quantum mechanical phase-space distribution and its corresponding Boltzmann equation. Attention is given to quantum and exchange corrections in cases of high doping concentrations when carrier densities become degenerate. Quantitative differences between degenerate and classical junction characteristics, e.g., maximum electric field and built-in voltage and carrier concentration within the transition region, are evaluated numerically.

  16. Iniencephaly: Case Report

    PubMed Central

    Alvis-Miranda, Hernando R.; Bula-Anichiarico, Doris A.; Calderón-Miranda, Willem G.; Moscote-Salazar, Luis R.

    2015-01-01

    The iniencephaly involves a variable defect in the occipital bone, resulting in a large foramen magnum, partial or total absence of the cervical and thoracic vertebrae, accompanied by incomplete closure of arcs and/or vertebral bodies, significant shortening of the spinal column and hyperextension of the malformed cervicothoracic spine; the individual's face is deviated upward, the mandibular skin is directly continuous with anterior thorax due to the absence of neck. Its incidence is about 1:1000–1:2000 births, so this is a pretty rare neural tube defect. We present a case of iniencephaly in association with cardiovascular, spinal cord, and intracranial malformations that ended demonstrating the low survival of patients affected with this condition. PMID:26167231

  17. Graphene junction field-effect transistor

    NASA Astrophysics Data System (ADS)

    Ou, Tzu-Min; Borsa, Tomoko; van Zeghbroeck, Bart

    2014-03-01

    We have demonstrated for the first time a novel graphene transistor gated by a graphene/semiconductor junction rather than an insulating gate. The transistor operates much like a semiconductor junction Field Effect Transistor (jFET) where the depletion layer charge in the semiconductor modulates the mobile charge in the channel. The channel in our case is the graphene rather than another semiconductor layer. An increased reverse bias of the graphene/n-silicon junction increases the positive charge in the depletion region and thereby reduces the total charge in the graphene. We fabricated individual graphene/silicon junctions as well as graphene jFETs (GjFETs) on n-type (4.5x1015 cm-3) silicon with Cr/Au electrodes and 3 μm gate length. As a control device, we also fabricated back-gated graphene MOSFETs using a 90nm SiO2 on a p-type silicon substrate (1019 cm-3) . The graphene was grown by APCVD on copper foil and transferred with PMMA onto the silicon substrate. The GjFET exhibited an on-off ratio of 3.75, an intrinsic graphene doping of 1.75x1012 cm-2, compared to 1.17x1013 cm-2 in the MOSFET, and reached the Dirac point at 13.5V. Characteristics of the junctions and transistors were measured as a function of temperature and in response to light. Experimental data and a comparison with simulations will be presented.

  18. An unusual cause of chronic abdominal pain after laparoscopic Roux en Y gastric bypass: Case report of a penetrating fish bone causing adhesions at the biliary-digestive junction resulting in partial obstruction and chronic symptoms

    PubMed Central

    Ochieng, Vincent; Hendrickx, Leo; Valk, Jody

    2016-01-01

    Background The management of chronic abdominal pain after laparoscopic Roux-en-Y gastric bypass (LRYGP) is complex and challenging. Foreign body intestinal perforation including that caused by fish bones has previously been reported in the literature and if clinically unrecognized, can cause significant morbidity and mortality. Fish bone perforation as a cause of chronic abdominal pain after LRYGP has rarely been reported. Summary The unusual case of a 54 year old female presenting with recurrent episodes of postprandial pain 2 years after LRYGP is reported. Previous radiological and endoscopic investigations did not reveal any abnormality and after the most recent clinical presentation, a laparoscopic exploration was performed. A protruding fish bone at the biliary-digestive junction was discovered intra-operatively and successfully extracted. Dense adhesions between the involved intestinal loops were lysed in an attempt to improve intestinal transit and subsequently relieve post-prandial pain. Conclusion This case highlights the possibility of a missed fish bone perforation causing chronic postprandial abdominal pain and discomfort in a patient with a Roux-en-Y gastric bypass anatomy. Foreign body perforation is a rare cause of abdominal pain after gastric bypass that should be considered when evaluating chronic abdominal pain symptoms after LRYGP. PMID:27107305

  19. Video-Assisted Thoracoscopic Surgery and Minimal Access Spinal Surgery Compared in Anterior Thoracic or Thoracolumbar Junctional Spinal Reconstruction: A Case-Control Study and Review of the Literature

    PubMed Central

    Lee, Ching-Yu; Wu, Meng-Huang; Li, Yen-Yao; Cheng, Chin-Chang; Lee, Chien-Yin

    2016-01-01

    There are no published reports that compare the outcomes of video-assisted thoracoscopic surgery (VATS) and minimal access spinal surgery (MASS) in anterior spinal reconstruction. We conducted a retrospective case-control study in a single center and systematically reviewed the literature to compare the efficacy and safety of VATS and MASS in anterior thoracic (T) and thoracolumbar junctional (TLJ) spinal reconstruction. From 1995 to 2012, there were 111 VATS patients and 76 MASS patients treated at our hospital. VATS patients had significantly (p < 0.001) longer operating times and significantly (p < 0.022) higher thoracotomy conversion rates. We reviewed 6 VATS articles and 10 MASS articles, in which there were 625 VATS patients and 399 MASS patients. We recorded clinical complications and a thoracotomy conversion rate from our cases and the selected articles. The incidence of approach-related complications was significantly (p = 0.021) higher in VATS patients. The conversion rate was 2% in VATS patients and 0% in MASS patients (p = 0.001). In conclusion, MASS is associated with reduction in operating time, approach-related complications, and the thoracotomy conversion rate. PMID:28101511

  20. A histone octamer blocks branch migration of a Holliday junction.

    PubMed Central

    Grigoriev, M; Hsieh, P

    1997-01-01

    The Holliday junction is a key intermediate in genetic recombination. Here, we examine the effect of a nucleosome core on movement of the Holliday junction in vitro by spontaneous branch migration. Histone octamers consisting of H2A, H2B, H3, and H4 are reconstituted onto DNA duplexes containing an artificial nucleosome-positioning sequence consisting of a tandem array of an alternating AT-GC sequence motif. Characterization of the reconstituted branch migration substrates by micrococcal nuclease mapping and exonuclease III and hydroxyl radical footprinting reveal that 70% of the reconstituted octamers are positioned near the center of the substrate and the remaining 30% are located at the distal end, although in both cases some translational degeneracy is observed. Branch migration assays with the octamer-containing substrates reveal that the Holliday junction cannot migrate spontaneously through DNA organized into a nucleosomal core unless DNA-histone interactions are completely disrupted. Similar results are obtained with branch migration substrates containing an octamer positioned on a naturally occurring sequence derived from the yeast GLN3 locus. Digestion of Holliday junctions with T7 endonuclease I establishes that the junction is not trapped by the octamer but can branch migrate in regions free of histone octamers. Our findings suggest that migration of Holliday junctions during recombination and the recombinational repair of DNA damage requires proteins not only to accelerate the intrinsic rate of branch migration but also to facilitate the passage of the Holliday junction through a nucleosome. PMID:9372946

  1. Reconstruction of esophageal defects with microsurgically revascularized jejunal segments: a report of 13 cases.

    PubMed

    Chang, T S; Hwang, O L; Wang-Wei

    1980-12-01

    Experimental free transfer of a jejunal segment to a recipient bed in the neck was successfully performed in 5 mongrel dogs. This was followed by clinical application of 2 different microvascular procedures in 13 patients for repair of esophageal defects. In 7 of these patients a free jejunal transfer was used; in 6 of these patients a pedicled jejunal graft with revascularization of its distal end by microvascular anastomosis was used. The esophageal defects were located in the cervical portion in 7 cases, the cervicothoracic portion in 5 cases, and the thoracic portion in 1 case. Ten (77%) of the 13 procedures were successful.

  2. Single molecule junction conductance and binding geometry

    NASA Astrophysics Data System (ADS)

    Kamenetska, Maria

    case of pyridine-linked molecules, conductance can be reliably switched between two distinct conductance states using sub-nanometer mechanical manipulation. Using a methyl sulfide linker attached to an oligoene backbone, we are able to create a 3-nm-long molecular potentiometer, whose resistance can be tuned exponentially with Angstom-scale modulations in metal-molecule configuration. These experiments points to a new paradigm for attaining reproducible electrical characteristics of metal-organic devices which involves controlling linker-metal chemistry rather than fabricating identically structured metal-molecule interfaces. By choosing a linker group which is either insensitive to or responds reproducibly to changes in metal-molecule configuration, one can design single molecule devices with functionality more complex than a simple resistor. These ambient temperature experiments were combined with UHV conductance measurements performed in a commercial STM on amine-terminated benzene derivatives which conduct through a non-resonant tunneling mechanism, at temperatures varying from 5 to 300 Kelvin. Our results indicate that while amine-gold binding remains selective irrespective of environment, conductance is not temperature independent, in contrast to what is expected for a tunneling mechanism. Furthermore, using temperature-dependent measurements in ambient conditions we find that HOMO-conducting amines and LUMO-conducting pyridines show opposite dependence of conductance on temperature. These results indicate that energy-level alignment between the molecule and the electrodes changes as a result of varying electrode structure at different temperatures. We find that temperature can serve as a knob with which to tune transport properties of single molecule-metal junctions.

  3. Ion bipolar junction transistors

    PubMed Central

    Tybrandt, Klas; Larsson, Karin C.; Richter-Dahlfors, Agneta; Berggren, Magnus

    2010-01-01

    Dynamic control of chemical microenvironments is essential for continued development in numerous fields of life sciences. Such control could be achieved with active chemical circuits for delivery of ions and biomolecules. As the basis for such circuitry, we report a solid-state ion bipolar junction transistor (IBJT) based on conducting polymers and thin films of anion- and cation-selective membranes. The IBJT is the ionic analogue to the conventional semiconductor BJT and is manufactured using standard microfabrication techniques. Transistor characteristics along with a model describing the principle of operation, in which an anionic base current amplifies a cationic collector current, are presented. By employing the IBJT as a bioelectronic circuit element for delivery of the neurotransmitter acetylcholine, its efficacy in modulating neuronal cell signaling is demonstrated. PMID:20479274

  4. Ion bipolar junction transistors.

    PubMed

    Tybrandt, Klas; Larsson, Karin C; Richter-Dahlfors, Agneta; Berggren, Magnus

    2010-06-01

    Dynamic control of chemical microenvironments is essential for continued development in numerous fields of life sciences. Such control could be achieved with active chemical circuits for delivery of ions and biomolecules. As the basis for such circuitry, we report a solid-state ion bipolar junction transistor (IBJT) based on conducting polymers and thin films of anion- and cation-selective membranes. The IBJT is the ionic analogue to the conventional semiconductor BJT and is manufactured using standard microfabrication techniques. Transistor characteristics along with a model describing the principle of operation, in which an anionic base current amplifies a cationic collector current, are presented. By employing the IBJT as a bioelectronic circuit element for delivery of the neurotransmitter acetylcholine, its efficacy in modulating neuronal cell signaling is demonstrated.

  5. Flux Cloning Anomalities in Josephson Nano-Junctions

    NASA Astrophysics Data System (ADS)

    Hassan, Hanaa Farhan; Kusmartsev, Feo V.

    2010-12-01

    The propagation of single flux quanta in T-shaped Josephson junctions gives rise to the flux cloning phenomenon. We have studied numerically the dynamics of flux cloning in cases of extended Josephson junctions. The changing thicknesses of T-junctions lead to new and interesting effects in terms of their dynamics. We have found out that when an additional Josephson transmission line is larger than the main Josephson transmission line, numerical simulations do not show the cloning phenomenon and soliton is reflected when it approaches the T junction. This strange result may be happened because the soliton losses more energy in the sharp edge. Although the vortex is moving very highly and it has huge energy but it still does not give birth to a new vortex. We have investigated conditions at which flux cloning occurs when both widths, W and W0, are changing.

  6. Flux Cloning Anomalities in Josephson Nano-Junctions

    NASA Astrophysics Data System (ADS)

    Hassan, Hanaa Farhan; Kusmartsev, Feo V.

    The propagation of single flux quanta in T-shaped Josephson junctions gives rise to the flux cloning phenomenon. We have studied numerically the dynamics of flux cloning in cases of extended Josephson junctions. The changing thicknesses of T-junctions lead to new and interesting effects in terms of their dynamics. We have found out that when an additional Josephson transmission line is larger than the main Josephson transmission line, numerical simulations do not show the cloning phenomenon and soliton is reflected when it approaches the T junction. This strange result may be happened because the soliton losses more energy in the sharp edge. Although the vortex is moving very highly and it has huge energy but it still does not give birth to a new vortex. We have investigated conditions at which flux cloning occurs when both widths, W and W0, are changing.

  7. Effects of the environment on the switching current in graphene-based Josephson Junctions

    NASA Astrophysics Data System (ADS)

    Borzenets, Ivan; Ke, Chung-Ting; Amet, Francois; Tso Wei, Ming; Yamamoto, Michihisa; Bomze, Yuriy; Tarucha, Seigo; Finkelstein, Gleb

    The nature of the switching current and hysteresis (difference between switching and retrapping currents) in graphene-based Josephson junctions depends greatly on the interaction with the environment. Conventional devices result in underdamped Josephson junctions making the true critical current inaccessible. On the other hand, heavily isolating the Josephson junctions places them in the microscopic quantum tunneling regime even at high temperatures, also masking the critical current. We study the critical current, and the switching statistics in graphene Josephson junctions while varying the effects of the environment. Proper isolation of graphene Josephson junctions is necessary to measure the true critical current, especially so for the cases of small currents around the Dirac point. This is true for the case of conventional diffusive as well as the novel ballistic Josephson junctions.

  8. Thermopower measurements in molecular junctions.

    PubMed

    Rincón-García, Laura; Evangeli, Charalambos; Rubio-Bollinger, Gabino; Agraït, Nicolás

    2016-08-07

    The measurement of thermopower in molecular junctions offers complementary information to conductance measurements and is becoming essential for the understanding of transport processes at the nanoscale. In this review, we discuss the recent advances in the study of the thermoelectric properties of molecular junctions. After presenting the theoretical background for thermoelectricity at the nanoscale, we review the experimental techniques for measuring the thermopower in these systems and discuss the main results. Finally, we consider the challenges in the application of molecular junctions in viable thermoelectric devices.

  9. ASSEMBLY AND CHARACTERIZATION OF 8-ARM AND 12-ARM DNA BRANCHED JUNCTIONS

    PubMed Central

    Wang, Xing

    2012-01-01

    Branched DNA molecules can be assembled into objects and networks directed by sticky-ended cohesion. The connectivity of these species is limited by the number of arms flanking the branch point. To date, the only branched junctions constructed contain six or fewer arms. We report the construction of DNA branched junctions that contain either 8 or 12 double helical arms surrounding a branch point. The design of the 8-arm junction expoits the limits of a previous approach to thwart branch migration, but the design of the 12-arm junction uses a new to principle achieve this end. The 8-arm junction is stable with 16 nucleotide pairs per arm, but the 12-arm junction has been stabilized by 24 nucleotide pairs per arm. Ferguson analysis of these junctions in combination with three, four, five, and six-arm junctions indicates a linear increase in friction constant as the number of arms increases; the four-arm junction migrates anomalously at 4°C., suggesting stacking of its domains. All strands in both the 8-arm and 12-arm junctions show similar responses to hydroxyl radical autofootprinting analysis, indicating that they lack any dominant stacking structures. The stability of the 12-arm junction demonstrates that the number of arms in a junction is not limited to the case of having adjacent identical base pairs flanking the junction. The ability to construct eight-arm and twelve-arm junctions increases the number of objects, graphs and networks that can be built from branched DNA components. In principle, the stick structure corresponding to cubic close packing is now a possible target for assembly by DNA nanotechnology. PMID:17564446

  10. Josephson junction in a thin film

    SciTech Connect

    Kogan, V. G.; Dobrovitski, V. V.; Clem, J. R.; Mawatari, Yasunori; Mints, R. G.

    2001-04-01

    The phase difference {phi}(y) for a vortex at a line Josephson junction in a thin film attenuates at large distances as a power law, unlike the case of a bulk junction where it approaches exponentially the constant values at infinities. The field of a Josephson vortex is a superposition of fields of standard Pearl vortices distributed along the junction with the line density {phi}'(y)/2{pi}. We study the integral equation for {phi}(y) and show that the phase is sensitive to the ratio l/{Lambda}, where l={lambda}{sub J}{sup 2}/{lambda}{sub L}, {Lambda}=2{lambda}{sub L}{sup 2}/d, {lambda}{sub L}, and {lambda}{sub J} are the London and Josephson penetration depths, and d is the film thickness. For l<<{Lambda}, the vortex ''core'' of the size l is nearly temperature independent, while the phase ''tail'' scales as l{Lambda}/y{sup 2}={lambda}{sub J}2{lambda}{sub L}/d/y{sup 2}; i.e., it diverges as T{yields}T{sub c}. For l>>{Lambda}, both the core and the tail have nearly the same characteristic length l{Lambda}.

  11. Thermal conductance of superlattice junctions

    SciTech Connect

    Lu, Simon; McGaughey, Alan J. H.

    2015-05-15

    We use molecular dynamics simulations and the lattice-based scattering boundary method to compute the thermal conductance of finite-length Lennard-Jones superlattice junctions confined by bulk crystalline leads. The superlattice junction thermal conductance depends on the properties of the leads. For junctions with a superlattice period of four atomic monolayers at temperatures between 5 and 20 K, those with mass-mismatched leads have a greater thermal conductance than those with mass-matched leads. We attribute this lead effect to interference between and the ballistic transport of emergent junction vibrational modes. The lead effect diminishes when the temperature is increased, when the superlattice period is increased, and when interfacial disorder is introduced, but is reversed in the harmonic limit.

  12. Josephson junction Q-spoiler

    DOEpatents

    Clarke, J.; Hilbert, C.; Hahn, E.L.; Sleator, T.

    1986-03-25

    An automatic Q-spoiler comprising at least one Josephson tunnel junction connected in an LC circuit for flow of resonant current therethrough. When in use in a system for detecting the magnetic resonance of a gyromagnetic particle system, a high energy pulse of high frequency energy irradiating the particle system will cause the critical current through the Josephson tunnel junctions to be exceeded, causing the tunnel junctions to act as resistors and thereby damp the ringing of the high-Q detection circuit after the pulse. When the current has damped to below the critical current, the Josephson tunnel junctions revert to their zero-resistance state, restoring the Q of the detection circuit and enabling the low energy magnetic resonance signals to be detected.

  13. Josephson junction Q-spoiler

    DOEpatents

    Clarke, John; Hilbert, Claude; Hahn, Erwin L.; Sleator, Tycho

    1988-01-01

    An automatic Q-spoiler comprising at least one Josephson tunnel junction connected in an LC circuit for flow of resonant current therethrough. When in use in a system for detecting the magnetic resonance of a gyromagnetic particle system, a high energy pulse of high frequency energy irradiating the particle system will cause the critical current through the Josephson tunnel junctions to be exceeded, causing the tunnel junctions to act as resistors and thereby damp the ringing of the high-Q detection circuit after the pulse. When the current has damped to below the critical current, the Josephson tunnel junctions revert to their zero-resistance state, restoring the Q of the detection circuit and enabling the low energy magnetic resonance signals to be detected.

  14. Control of Junction Flow

    NASA Astrophysics Data System (ADS)

    Su, T.-C.; Bingham, C.; Kellier, L.

    2001-11-01

    Control for horseshoe vortices resulting from boundary layer separation in front of a structure has long been sought without satisfactory results. Tests were carried out in a water channel with the objective of seeking such a control. The water channel has a test section of .6m wide, .4m deep and 8m long, with an adjustable mean flow speed of up to .5m/s. Flow visualization technique was used to elucidate the flow process. To control the horseshoe vortex a long airfoil of 1cm chord was placed horizontally near the ground upstream of a 10cm thin square plate. It was found that the original horseshoe vortex moved toward and circulated around the airfoil. The junction flow immediately upstream of the obstacle was noticeably steady and free of disturbance. The process was insensitive to the streamwise location of the airfoil, horseshoe's vortical structure, stream speed and acceleration, upstream vortical influx, and magnitude/sign of airfoil's angle of attack. Experimental results with obliquely mounted square cylinder were similar, which demonstrated that controls were effective for all angles of attack.

  15. Electronic thermometry in tunable tunnel junction

    DOEpatents

    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.

  16. Octagonal Defects at Carbon Nanotube Junctions

    PubMed Central

    Jaskólski, W.; Pelc, M.; Chico, Leonor; Ayuela, A.

    2013-01-01

    We investigate knee-shaped junctions of semiconductor zigzag carbon nanotubes. Two dissimilar octagons appear at such junctions; one of them can reconstruct into a pair of pentagons. The junction with two octagons presents two degenerate localized states at Fermi energy (EF). The reconstructed junction has only one state near EF, indicating that these localized states are related to the octagonal defects. The inclusion of Coulomb interaction splits the localized states in the junction with two octagons, yielding an antiferromagnetic system. PMID:24089604

  17. Apparent AV junctional escape in Wenckebach AV block: markedly slow conduction through the slow AV pathway.

    PubMed

    Kinoshita, Shinji; Katoh, Takakazu; Hagisawa, Kohsuke; Fukushima, Tsutomu; Ikawa, Shinji

    2009-02-01

    We report here two cases of Wenckebach atrioventricular (AV) block in which apparent AV junctional escape was observed, but most likely resulted from markedly slow conduction through the slow pathway of dual AV junctional pathways. In these cases, it seems that a blocked P-wave was followed by an AV junctional escape beat. However, a blocked P-wave occasionally failed to be followed by an escape beat, and the RR interval containing the blocked P-wave was markedly longer than the above escape interval. In one case, apparent AV junctional escape beats with aberrant ventricular conduction were found, and QRS complexes of the same configuration were also found without the preceding ventricular pause. This strengthens the possibility that apparent AV junctional escape occurred because of markedly slow conduction through the slow AV pathway.

  18. Spatial inhomogeneous barrier heights at graphene/semiconductor Schottky junctions

    NASA Astrophysics Data System (ADS)

    Tomer, Dushyant

    smooth interface fails to explain such behavior, hence, we apply a modified emission theory with Gaussian distribution of Schottky barrier heights. The modified theory, applicable to inhomogeneous interfaces, explains the temperature dependent behavior of our Schottky junctions and gives a temperature independent mean barrier height. We attribute the inhomogeneous barrier height to the presence of graphene ripples and ridges in case of SiC and MoS2 while surface states and trapped charges at the interface is dominating in Si and GaAs. Additionally, we observe bias dependent current and barrier height in reverse bias regime also for all Schottky junctions. To explain such behavior, we consider two types of reverse bias conduction mechanisms; Poole-Frenkel and Schottky emission. We find that Poole-Frenkel emission explains the characteristics of graphene/SiC junctions very well. However, both the mechanism fails to interpret the behavior of graphene/Si and graphene/GaAs Schottky junctions. These findings provide insight into the fundamental physics at the interface of graphene/semiconductor junctions.

  19. dc properties of series-parallel arrays of Josephson junctions in an external magnetic field

    SciTech Connect

    Lewandowski, S.J. )

    1991-04-01

    A detailed dc theory of superconducting multijunction interferometers has previously been developed by several authors for the case of parallel junction arrays. The theory is now extended to cover the case of a loop containing several junctions connected in series. The problem is closely associated with high-{ital T}{sub {ital c}} superconductors and their clusters of intrinsic Josephson junctions. These materials exhibit spontaneous interferometric effects, and there is no reason to assume that the intrinsic junctions form only parallel arrays. A simple formalism of phase states is developed in order to express the superconducting phase differences across the junctions forming a series array as functions of the phase difference across the weakest junction of the system, and to relate the differences in critical currents of the junctions to gaps in the allowed ranges of their phase functions. This formalism is used to investigate the energy states of the array, which in the case of different junctions are split and separated by energy barriers of height depending on the phase gaps. Modifications of the washboard model of a single junction are shown. Next a superconducting inductive loop containing a series array of two junctions is considered, and this model is used to demonstrate the transitions between phase states and the associated instabilities. Finally, the critical current of a parallel connection of two series arrays is analyzed and shown to be a multivalued function of the externally applied magnetic flux. The instabilities caused by the presence of intrinsic serial junctions in granular high-{ital T}{sub {ital c}} materials are pointed out as a potential source of additional noise.

  20. Joint measurement of current-phase relations and transport properties of hybrid junctions using a three junctions superconducting quantum interference device

    SciTech Connect

    Basset, J.; Delagrange, R.; Weil, R.; Kasumov, A.; Bouchiat, H.; Deblock, R.

    2014-07-14

    We propose a scheme to measure both the current-phase relation and differential conductance dI/dV of a superconducting junction, in the normal and the superconducting states. This is done using a dc Superconducting Quantum Interference Device with two Josephson junctions in parallel with the device under investigation and three contacts. As a demonstration, we measure the current-phase relation and dI/dV of a small Josephson junction and a carbon nanotube junction. In this latter case, in a regime where the nanotube is well conducting, we show that the non-sinusoidal current phase relation we find is consistent with the theory for a weak link, using the transmission extracted from the differential conductance in the normal state. This method holds great promise for future investigations of the current-phase relation of more exotic junctions.

  1. Spontaneous Spinal Epidural Hematoma Coexisting Guillan-Barré Syndrome in a Child: A Case Report.

    PubMed

    Lee, Chi Hyung; Song, Geun Sung; Kim, Young Ha; Son, Dong Wuk; Lee, Sang Weon

    2016-09-01

    Spontaneous spinal epidural hematoma (SSEH) has been reported as a rare cause of spinal cord compression, especially in children. Clinical features are usually nonspecific, although cervicothoracic location of hematoma could be presented with progressive paraplegia. Guillian-Barré syndrome (GBS) is clinically defined as an acute peripheral neuropathy causing progressive limb weakness. Because SSEH and GBS have very similar signs and symptoms, SSEH could be misdiagnosed as GBS. Nevertheless, they can be presented together. We describe a rare case of SSEH coexisting with GBS.

  2. Spontaneous Spinal Epidural Hematoma Coexisting Guillan-Barré Syndrome in a Child: A Case Report

    PubMed Central

    Lee, Chi Hyung; Kim, Young Ha; Son, Dong Wuk; Lee, Sang Weon

    2016-01-01

    Spontaneous spinal epidural hematoma (SSEH) has been reported as a rare cause of spinal cord compression, especially in children. Clinical features are usually nonspecific, although cervicothoracic location of hematoma could be presented with progressive paraplegia. Guillian-Barré syndrome (GBS) is clinically defined as an acute peripheral neuropathy causing progressive limb weakness. Because SSEH and GBS have very similar signs and symptoms, SSEH could be misdiagnosed as GBS. Nevertheless, they can be presented together. We describe a rare case of SSEH coexisting with GBS. PMID:27800000

  3. Computer-aided design of stripline ferrite junction circulators

    NASA Technical Reports Server (NTRS)

    Uzdy, Z.

    1980-01-01

    A general design procedure is presented for stripline Y-junction circulators employing solid dielectric between ground planes. The resonator design and impedance matching are derived in a form suitable for computer evaluation. The procedure is applicable to cases where either the circulator bandwidth or the ground plane spacing is specified. An experimental S-band switching circulator design illustrates the technique.

  4. Transoral approach to the craniovertebral junction.

    PubMed

    Landeiro, José Alberto; Boechat, Sávio; Christoph, Daniel de Holanda; Gonçalves, Mariângela Barbi; Castro, Igor de; Lapenta, Mario Alberto; Ribeiro, Carlos Henrique

    2007-12-01

    The transoral approach provides a safe exposure to lesions in the midline and the ventral side of the craniovertebral junction. The advantages of the transoral approach are 1) the impinging bony pathology and granulation tissue are accessible only via the ventral route; 2) the head is placed in the extended position, thus decreasing the angulation of the brainstem during the surgery; and 3) surgery is done through the avascular median pharyngeal raphe and clivus. We analyzed the clinical effects of odontoidectomy after treating 38 patients with basilar invagination. The anterior transoral operation to treat irreducible ventral compression in patients with basilar invagination was performed in 38 patients. The patients ages ranged from 34 to 67 years. Fourteen patients had associated Chiari malformation and eight had previously undergone posterior decompressive surgery. The main indication for surgery was significant neurological deterioration. Symptoms and signs included neck pain, myelopathy, lower cranial nerve dysfunction, nystagmus and gait disturbance. Extended exposure was performed in 24 patients. The surgery was beneficial to the majority of patients. There was one death within 10 days of surgery, due to pulmonary embolism. Postoperative complications included two cases of pneumonia, three cases of oronasal fistula with regurgitation and one cerebrospinal fluid leak. In patients with marked ventral compression, the transoral approach provides direct access to the anterior face of the craniovertebral junction and effective means for odontoidectomy.

  5. Model for large arrays of Josephson junctions with unconventional superconductors

    NASA Astrophysics Data System (ADS)

    Khveshchenko, D. V.; Crooks, R.

    2011-10-01

    We study large arrays of mesoscopic junctions made out of gapless unconventional superconductors where the tunneling processes of both particle-hole and Cooper pairs give rise to a strongly retarded effective action which, contrary to the standard case, cannot be readily characterized in terms of a local Josephson energy. This action can be relevant, for example, to grain boundary and c-axis junctions in layered high-Tc superconductors. By using a particular functional representation, we describe emergent collective phenomena in this system, ascertain its phase diagram, and compute electrical conductivity.

  6. Conducting polyaniline nanowire electrode junction

    NASA Astrophysics Data System (ADS)

    Gaikwad, Sumedh; Bodkhe, Gajanan; Deshmukh, Megha; Patil, Harshada; Rushi, Arti; Shirsat, Mahendra D.; Koinkar, Pankaj; Kim, Yun-Hae; Mulchandani, Ashok

    2015-03-01

    In this paper, a synthesis of conducting polyaniline nanowires electrode junction (CPNEJ) has been reported. Conducting polyaniline nanowires electrode junction on Si/SiO2 substrate (having 3 μm gap between two gold microelectrodes) is prepared. Polyaniline nanowires with diameter (ca. 140 nm to 160 nm) were synthesized by one step electrochemical polymerization using galvanostatic (constant current) technique to bridge this gap. The surface morphology of CPNEJ was studied by scanning electron microscope (SEM). The synthesized CPNEJ is an excellent platform for biosensor applications.

  7. Transition region width of nanowire hetero- and pn-junctions grown using vapor-liquid-solid processes

    NASA Astrophysics Data System (ADS)

    Li, Na; Tan, Teh Y.; Gösele, U.

    2008-03-01

    The transition region width of nanowire heterojunctions and pn-junctions grown using vapor-liquid-solid (VLS) processes has been modeled. With two constituents or dopants I and II, the achievable width or abruptness of the junctions is attributed to the residual I atom/molecule stored in the liquid droplet at the onset of introducing II to grow the junction, and the stored I atom/molecule consumption into the subsequently grown crystal layers. The model yields satisfactory quantitative fits to a set of available Si-Ge junction data. Moreover, the model provides a satisfactory explanation to the relative junction width or abruptness differences between elemental and compound semiconductor junction cases, as well as a guideline for achieving the most desirable pn-junction widths.

  8. Length and energy gap dependences of thermoelectricity in nanostructured junctions.

    PubMed

    Asai, Yoshihiro

    2013-04-17

    The possibilities of an enhanced thermoelectric figure of merit value, ZT, in a nanostructured junction are examined for a wide range of parameter values in a theoretical model. Our research shows that the figure of merit can take a very large maximum, which depends both on the length and the energy gap values. The maximum of ZT is achieved when the Fermi level of the electrodes is aligned to the edge of the electronic transmission function of the junction, where both the conductance and the Seebeck constant are significantly enhanced. On the basis of our results, we conclude that nanowires and molecular junctions form a special class of systems where a large ZT can be expected in some cases.

  9. Traumatic Tear of the Latissimus Dorsi Myotendinous Junction

    PubMed Central

    Friedman, Michael V.; Stensby, J. Derek; Hillen, Travis J.; Demertzis, Jennifer L.; Keener, Jay D.

    2015-01-01

    A case of a latissimus dorsi myotendinous junction strain in an avid CrossFit athlete is presented. The patient developed acute onset right axillary burning and swelling and subsequent palpable pop with weakness while performing a “muscle up.” Magnetic resonance imaging examination demonstrated a high-grade tear of the right latissimus dorsi myotendinous junction approximately 9 cm proximal to its intact humeral insertion. There were no other injuries to the adjacent shoulder girdle structures. Isolated strain of the latissimus dorsi myotendinous junction is a very rare injury with a scarcity of information available regarding its imaging appearance and preferred treatment. This patient was treated conservatively and was able to resume active CrossFit training within 3 months. At 6 months postinjury, he had only a mild residual functional deficit compared with his preinjury level. PMID:26502450

  10. Work fluctuations in bosonic Josephson junctions

    NASA Astrophysics Data System (ADS)

    Lena, R. G.; Palma, G. M.; De Chiara, G.

    2016-05-01

    We calculate the first two moments and full probability distribution of the work performed on a system of bosonic particles in a two-mode Bose-Hubbard Hamiltonian when the self-interaction term is varied instantaneously or with a finite-time ramp. In the instantaneous case, we show how the irreversible work scales differently depending on whether the system is driven to the Josephson or Fock regime of the bosonic Josephson junction. In the finite-time case, we use optimal control techniques to substantially decrease the irreversible work to negligible values. Our analysis can be implemented in present-day experiments with ultracold atoms and we show how to relate the work statistics to that of the population imbalance of the two modes.

  11. Simple Electronic Analog of a Josephson Junction.

    ERIC Educational Resources Information Center

    Henry, R. W.; And Others

    1981-01-01

    Demonstrates that an electronic Josephson junction analog constructed from three integrated circuits plus an external reference oscillator can exhibit many of the circuit phenomena of a real Josephson junction. Includes computer and other applications of the analog. (Author/SK)

  12. A pediatric case of idiopathic Harlequin syndrome

    PubMed Central

    Kim, Ju Young; Lee, Moon Souk; Kim, Seung Yeon; Kim, Hyun Jung; Lee, Soo Jin; You, Chur Woo; Kim, Jon Soo

    2016-01-01

    Harlequin syndrome, which is a rare disorder caused by dysfunction of the autonomic system, manifests as asymmetric facial flushing and sweating in response to heat, exercise, or emotional factors. The syndrome may be primary (idiopathic) with a benign course, or can occur secondary to structural abnormalities or iatrogenic factors. The precise mechanism underlying idiopathic harlequin syndrome remains unclear. Here, we describe a case of a 6-year-old boy who reported left hemifacial flushing and sweating after exercise. He had an unremarkable birth history and no significant medical history. Complete ophthalmological and neurological examinations were performed, and no other abnormalities were identified. Magnetic resonance imaging was performed to exclude lesions of the cerebrum and cervicothoracic spinal cord, and no abnormalities were noted. His final diagnosis was classic idiopathic harlequin syndrome. Herein, we report the first pediatric case of idiopathic harlequin syndrome in Korea. PMID:28018464

  13. Vertical Junction Solar Cells.

    DTIC Science & Technology

    1985-12-20

    during the cure cycle. CAUTION: CV-2567 CURING AGENT MAY CAUSE SKIN AND EYE IRRITATION. IN CASE OF EYE CONTACT, IRRIGATE WITH WATER IMMEDIATELY AND GET...a diffusion pumped vacuum chamber with the pressure monitored by an ionization gauge. The heating was supplied by tungsten halogen lamps and measured...environmental protection- 93-500 space-grade encapsulant arej 24 hours at 125 C (275 F) and less low water absorption (less than useable over a wide temperature

  14. The Yolla Bolly junction revisited

    SciTech Connect

    Blake, M.C.; Jayko, A.S. ); Jones, D.L. . Dept. of Geology and Geophysics); Engebretson, D.C. . Dept. of Geology)

    1993-04-01

    West of Red Bluff, California, rocks of the northern Coast Ranges, Klamath-Sierra Nevada, and Great Valley provinces come together at what has been called the Yolla Bolly junction. Mapping of the Red Bluff and Willows 1:100,000 quadrangles has greatly clarified the enigmatic features of this complex area. Terranes of the Klamath Mountains and their Cretaceous sedimentary cover have been thrust northwestward over the Elder Creek terrane and Franciscan rocks, north of the left-lateral Cold Fork fault zone. The Condrey Mountain window (Franciscan Pickett Peak terrane) provides a measure of the magnitude of this thrusting (ca 90 km). South of the Cold Fork fault zone, the Franciscan and Elder Creek terranes were driven southeastward as tectonic wedges onto Sierran-Klamath basement. Timing of this scissor-tectonics is not constrained near the junction, but further north in southwest Oregon, Lower Eocene strata were deformed by overthrusting of the Klamath block whereas Upper Eocene strata overlap the thrust, indicating that thrusting occurred between about 52 and 60 Ma. Plate reconstructions for this time interval indicate the close proximity of the Kula-Farallon-North America triple junction and that old (ca 100 m.y.) Farallon lithosphere was being subducted north of the junction whereas to the south, very young (ca 10 m.y.) Kula plate was presumably obducted onto North America.

  15. 27 CFR 9.164 - River Junction.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2014-04-01 2014-04-01 false River Junction. 9.164... River Junction. (a) Name. The name of the viticultural area described in this section is “River Junction.” (b) Approved maps. The appropriate maps for determining the boundaries of the River...

  16. 27 CFR 9.164 - River Junction.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2011-04-01 2011-04-01 false River Junction. 9.164... River Junction. (a) Name. The name of the viticultural area described in this section is “River Junction.” (b) Approved maps. The appropriate maps for determining the boundaries of the River...

  17. Velocity selection problem in the presence of the triple junction.

    PubMed

    Brener, E A; Hüter, C; Pilipenko, D; Temkin, D E

    2007-09-07

    Melting of a bicrystal along the grain boundary is discussed. A triple junction plays a crucial role in the velocity selection problem in this case. In some range of the parameters an entirely analytical solution of this problem is given. This allows us to present a transparent picture of the structure of the selection theory. We also discuss the selection problem in the case of the growth of a "eutectoid dendrite."

  18. Ultrafast Photophysics of Organic Semiconductor Junctions

    NASA Astrophysics Data System (ADS)

    Burghardt, Irene; Bittner, Eric R.; Tamura, Hiroyuki; Pereverzev, Andrey; Ramon, John Glenn S.

    This contribution gives an overview of our recent studies of the electronic structure and ultrafast photophysics of semiconductor polymer junctions. We focus on the phonon-assisted exciton dissociation at donor-acceptor heterojunctions, using state-of-the-art electronic structure methods in conjunction with vibronic coupling models and multiconfigurational quantum dynamical techniques. The decay of the photogenerated exciton towards an interfacial charge-separated state is an ultrafast (femtosecond to picosecond scale) process which precedes photocurrent generation. We describe this process using a linear vibronic coupling model parametrized for two to three electronic states and 20-30 phonon modes. Several representative interface configurations are considered, which are shown to differ significantly in their cross-chain interactions but exhibit an efficient exciton dissociation in all cases investigated. The exciton decay depends critically on the presence of intermediate states and on the dynamical interplay between high-frequency (C=C stretch) and lowfrequency (ring-torsional) modes. The resulting molecular-level picture of exciton dissociation could contribute to the design of efficient polymer junctions.

  19. Brachioradial Pruritus as a Harbinger of Syrinx in Chronic Spinal Cord Injury: A Case Report.

    PubMed

    Skelton, Felicia; Frontera, Joel E

    2017-03-01

    This case describes a 56-year-old man with known thoracic spinal cord injury undergoing evaluation for a pruritic rash on the dorsolateral aspect of his forearms with no upper extremity neuromuscular symptoms. Common diagnoses were considered and treated with little success. The diagnosis of brachioradial pruritus (BRP) was made, and evaluation for possible causes revealed a large cervicothoracic syrinx. To our knowledge, BRP has not been described previously as the presenting sign of post-traumatic syringomelia. This patient's clinical course is delineated, as well as a brief review of BRP and its relationship to other cervical spine pathologies.

  20. Tight junction proteins: from barrier to tumorigenesis.

    PubMed

    Runkle, E Aaron; Mu, David

    2013-08-28

    The tight junction is a multi-protein complex and is the apical most junctional complex in certain epithelial and endothelial cells. A great deal of attention has been devoted to the understanding of these proteins in contributing to the barrier function - that is, regulating the paracellular flux or permeability between adjacent cells. However, tight junction proteins are now recognized as having functions beyond the barrier. The focus of this review is to discuss the barrier function of the tight junction and to summarize the literature with a focus on the role of tight junction proteins in proliferation, transformation, and metastasis.

  1. Tight Junction Proteins: From Barrier to Tumorigenesis

    PubMed Central

    Runkle, E. Aaron; Mu, David

    2013-01-01

    The tight junction is a multi-protein complex and is the apical most junctional complex in certain epithelial and endothelial cells. A great deal of attention has been devoted to the understanding of these proteins in contributing to the barrier function - that is, regulating the paracellular flux or permeability between adjacent cells. However, tight junction proteins are now recognized as having functions beyond the barrier. The focus of this review is to discuss the barrier function of the tight junction and to summarize the literature with a focus on the role of tight junction proteins in proliferation, transformation, and metastasis. PMID:23743355

  2. Tight Junction Proteins in Human Schwann Cell Autotypic Junctions

    PubMed Central

    Alanne, Maria H.; Pummi, Kati; Heape, Anthony M.; Grènman, Reidar; Peltonen, Juha; Peltonen, Sirkku

    2009-01-01

    Tight junctions (TJs) form physical barriers in various tissues and regulate paracellular transport of ions, water, and molecules. Myelinating Schwann cells form highly organized structures, including compact myelin, nodes of Ranvier, paranodal regions, Schmidt-Lanterman incisures, periaxonal cytoplasmic collars, and mesaxons. Autotypic TJs are formed in non-compacted myelin compartments between adjacent membrane lamellae of the same Schwann cell. Using indirect immunofluorescence and RT-PCR, we analyzed the expression of adherens junction (E-cadherin) and TJ [claudins, zonula occludens (ZO)-1, occludin] components in human peripheral nerve endoneurium, showing clear differences with published rodent profiles. Adult nerve paranodal regions contained E-cadherin, claudin-1, claudin-2, and ZO-1. Schmidt-Lanterman incisures contained E-cadherin, claudin-1, claudin-2, claudin-3, claudin-5, ZO-1, and occludin. Mesaxons contained E-cadherin, claudin-1, claudin-2, claudin-3, ZO-1, and occludin. None of the proteins studied were associated with nodal inter-Schwann cell junctions. Fetal nerve expression of claudin-1, claudin-3, ZO-1, and occludin was predominantly punctate, with a mesaxonal labeling pattern, but paranodal (ZO-1, claudin-3) and Schmidt-Lanterman incisure (claudins-1 and -3) expression profiles typical of compact myelin were visible by gestational week 37. The clear differences observed between human and published rodent nerve profiles emphasize the importance of human studies when translating the results of animal models to human diseases. (J Histochem Cytochem 57:523–529, 2009) PMID:19153196

  3. Ependymoma of the cauda equina starting with communicating hydrocephalus: a case report.

    PubMed

    Tzekov, Christo; Naydenov, Emanuil; Kalev, Ognian

    2007-01-01

    The presence of concomitant hydrocephalus in cases with spinal cord tumors is relatively rare. Here, we describe a case of myxopapillary ependymoma of the cauda equina starting with communicating hydrocephalus in a 14-year-old boy. The patient presented to the clinic without underlying causes of hydrocephalus on the neuroimaging data. After ventriculoperitoneal shunt placement, despite the numerous malfunction incidents, the patient was doing well. Eight years later, he developed progressive weakness and coldness of the lower limbs. Multiple cystic lesions in the cervicothoracic area were found on magnetic resonance imaging. Decompressive hemilaminectomy of the cervicothoracic region was performed with temporary improvement of the patient's condition. Because of persisting complaints, the sacral area of the spine was also observed and neuroimaging data for a tumoral lesion in the cauda equina region were found. The lesion was surgically removed and the histological result was myxopapillary ependymoma. Therefore, cases presenting with internal hydrocephalus without clear-cut intracranial etiology should have detailed neuroimaging of the whole central nervous system.

  4. Experiments on non-equilibrium superconductor-normal metal-superconductor Josephson junctions

    NASA Astrophysics Data System (ADS)

    Crosser, Michael S.

    By controlling the distribution function within the normal metal of a superconductor/normal metal/superconductor (SNS) Josephson junction, one can reverse the supercurrent-phase relation in the normal wire, creating a pi-junction. This manipulation is done by injecting normal quasiparticle current into the wire, via one or more leads attached at the middle of the junction. Two experiments evolve from this concept. First, in a sample of four reservoirs, two normal and two superconducting, all connected by a wire cross of normal metal, one may inject current either antisymmetrically (AS) or symmetrically (S). In the AS case, current is injected into one normal lead and extracted from the other, creating normal current flow that does not interact with the supercurrent except at the junction. In the S case, current is injected into both normal leads and extracted from the superconductors. Theory predicts that, in the absence of electron energy relaxation in the normal part of the junction, these two situations should result in identical behavior of the Josephson junction. However, due to Joule heating, the S case shows a slightly larger maximum pi-current than the AS case. The second experiment considers a more subtle effect resulting from normal current being injected symmetrically into a SNS Josephson junction. One side of the SNS junction has both normal current and supercurrent flowing in the same direction while the other side has opposing current flows. This situation creates an effective energy gradient across the SNS junction that can appear in the distribution function of the normal wire. Using superconductor/insulator/normal metal tunnelling spectroscopy, it is possible to extract these changes to the distribution function.

  5. Seebeck effect in molecular junctions.

    PubMed

    Zimbovskaya, Natalya A

    2016-05-11

    Advances in the fabrication and characterization of nanoscale systems presently allow for a better understanding of their thermoelectric properties. As is known, the building blocks of thermoelectricity are the Peltier and Seebeck effects. In the present work we review results of theoretical studies of the Seebeck effect in single-molecule junctions and similar systems. The behavior of thermovoltage and thermopower in these systems is controlled by several factors including the geometry of molecular bridges, the characteristics of contacts between the bridge and the electrodes, the strength of the Coulomb interactions between electrons on the bridge, and of electron-phonon interactions. We describe the impact of these factors on the thermopower. Also, we discuss a nonlinear Seebeck effect in molecular junctions.

  6. Seebeck effect in molecular junctions

    NASA Astrophysics Data System (ADS)

    Zimbovskaya, Natalya A.

    2016-05-01

    Advances in the fabrication and characterization of nanoscale systems presently allow for a better understanding of their thermoelectric properties. As is known, the building blocks of thermoelectricity are the Peltier and Seebeck effects. In the present work we review results of theoretical studies of the Seebeck effect in single-molecule junctions and similar systems. The behavior of thermovoltage and thermopower in these systems is controlled by several factors including the geometry of molecular bridges, the characteristics of contacts between the bridge and the electrodes, the strength of the Coulomb interactions between electrons on the bridge, and of electron-phonon interactions. We describe the impact of these factors on the thermopower. Also, we discuss a nonlinear Seebeck effect in molecular junctions.

  7. Thermocouple, multiple junction reference oven

    NASA Technical Reports Server (NTRS)

    Leblanc, L. P. (Inventor)

    1981-01-01

    An improved oven for maintaining the junctions of a plurality of reference thermocouples at a common and constant temperature is described. The oven is characterized by a cylindrical body defining a heat sink with axially extended-cylindrical cavity a singularized heating element which comprises a unitary cylindrical heating element consisting of a resistance heating coil wound about the surface of metallic spool with an axial bore defined and seated in the cavity. Other features of the oven include an annular array of radially extended bores defined in the cylindrical body and a plurality of reference thermocouple junctions seated in the bores in uniformly spaced relation with the heating element, and a temperature sensing device seated in the axial bore for detecting temperature changes as they occur in the spool and circuit to apply a voltage across the coil in response to detected drops in temperatures of the spool.

  8. Thermoelectric efficiency of molecular junctions.

    PubMed

    Perroni, C A; Ninno, D; Cataudella, V

    2016-09-21

    Focus of the review is on experimental set-ups and theoretical proposals aimed to enhance thermoelectric performances of molecular junctions. In addition to charge conductance, the thermoelectric parameter commonly measured in these systems is the thermopower, which is typically rather low. We review recent experimental outcomes relative to several junction configurations used to optimize the thermopower. On the other hand, theoretical calculations provide estimations of all the thermoelectric parameters in the linear and non-linear regime, in particular of the thermoelectric figure of merit and efficiency, completing our knowledge of molecular thermoelectricity. For this reason, the review will mainly focus on theoretical studies analyzing the role of not only electronic, but also of the vibrational degrees of freedom. Theoretical results about thermoelectric phenomena in the coherent regime are reviewed focusing on interference effects which play a significant role in enhancing the figure of merit. Moreover, we review theoretical studies including the effects of molecular many-body interactions, such as electron-vibration couplings, which typically tend to reduce the efficiency. Since a fine tuning of many parameters and coupling strengths is required to optimize the thermoelectric conversion in molecular junctions, new theoretically proposed set-ups are discussed in the conclusions.

  9. Squeezed States in Josephson Junctions.

    NASA Astrophysics Data System (ADS)

    Hu, X.; Nori, F.

    1996-03-01

    We have studied quantum fluctuation properties of Josephson junctions in the limit of large Josephson coupling energy and small charging energy, when the eigenstates of the system can be treated as being nearly localized. We have considered(X. Hu and F. Nori, preprints.) a Josephson junction in a variety of situations, e.g., coupled to one or several of the following elements: a capacitor, an inductor (in a superconducting ring), and an applied current source. By solving an effective Shrödinger equation, we have obtained squeezed vacuum (coherent) states as the ground states of a ``free-oscillating'' (linearly-driven) Josephson junction, and calculated the uncertainties of its canonical momentum, charge, and coordinate, phase. We have also shown that the excited states of the various systems we consider are similar to the number states of a simple harmonic oscillator but with different fluctuation properties. Furthermore, we have obtained the time-evolution operators for these systems. These operators can make it easier to calculate the time-dependence of the expectation values and fluctuations of various quantities starting from an arbitrary initial state.

  10. AdS and ds Entropy from String Junctions or the Function of Junction Conjunctions

    NASA Astrophysics Data System (ADS)

    Silverstein, Eva

    Flux compactifications of string theory exhibiting the possibility of discretely tuning the cosmological constant to small values have been constructed. The highly tuned vacua in this discretuum have curvature radii which scale as large powers of the flux quantum numbers, exponential in the number of cycles in the compactiflcation. By the arguments of Susskind/Witten (in the AdS case) and Gibbons/Hawking (in the dS case), we expect correspondingly large entropies associated with these vacua. If they are to provide a dual description of these vacua on their Coulomb branch, branes traded for the flux need to account for this entropy at the appropriate energy scale. In this note, we argue that simple string junctions and webs ending on the branes can account for this large entropy, obtaining a rough estimate for junction entropy that agrees with the existing rough estimates for the spacing of the discretuum. In particular, the brane entropy can account for the (A)dS entropy far away from string scale correspondence limits.

  11. Conductance spectroscopy of nontopological-topological superconductor junctions

    NASA Astrophysics Data System (ADS)

    Setiawan, F.; Cole, William S.; Sau, Jay D.; Das Sarma, S.

    2017-01-01

    We calculate the zero-temperature differential conductance d I /d V of a voltage-biased one-dimensional junction between a nontopological and a topological superconductor for arbitrary junction transparency using the scattering matrix formalism. We consider two representative models for the topological superconductors: (i) spinful p -wave and (ii) s -wave with spin-orbit coupling and spin splitting. We verify that in the tunneling limit (small junction transparencies) where only single Andreev reflections contribute to the current, the conductance for voltages below the nontopological superconductor gap Δs is zero and there are two symmetric conductance peaks appearing at e V =±Δs with the quantized value (4 -π ) 2 e2/h due to resonant Andreev reflection from the Majorana zero mode. However, when the junction transparency is not small, there is a finite conductance for e |V |< Δs arising from multiple Andreev reflections. The conductance at e V =±Δs in this case is no longer quantized. In general, the conductance is particle-hole asymmetric except for sufficiently small transparencies. We further show that, for certain values of parameters, the tunneling conductance from a zero-energy conventional Andreev bound state can be made to mimic the conductance from a true Majorana mode.

  12. Measuring the momentum of a nanomechanical oscillator using tunnel junctions

    NASA Astrophysics Data System (ADS)

    Doiron, Charles; Trauzettel, Bjoern; Bruder, Christoph

    2008-03-01

    We present a way to measure the momentum p of a nanomechanical oscillatorootnotetextC. B. Doiron, B. Trauzettel, C. Bruder. arXiv:0707.2709.. The momentum detector is based on two tunnel junctions in an Aharonov-Bohm-type setup, where one of the tunneling amplitudes depends on the motion of the oscillator and the other one does not. The coupling between the first tunnel junction and the oscillator is assumed to be linear in the position x of the oscillator t(x) = t0+ t1x. However, the presence of two junctions can, under certain conditions, lead to an effective imaginary coupling t(x) = t0+ i t1x. By calculating the equation-of-motion for the density matrix of the coupled (oscillator+tunnel junction) systemootnotetextA.A Clerk, S. Girvin. Phys. Rev. B 70, 121303 (2004)., we show that in this case the finite-frequency current noise of the detector is proportional to the momentum spectrum of the oscillator.

  13. Dynamically Active Compartments Coupled by a Stochastically Gated Gap Junction

    NASA Astrophysics Data System (ADS)

    Bressloff, Paul C.; Lawley, Sean D.

    2017-03-01

    We analyze a one-dimensional PDE-ODE system representing the diffusion of signaling molecules between two cells coupled by a stochastically gated gap junction. We assume that signaling molecules diffuse within the cytoplasm of each cell and then either bind to some active region of the cell's membrane (treated as a well-mixed compartment) or pass through the gap junction to the interior of the other cell. We treat the gap junction as a randomly fluctuating gate that switches between an open and a closed state according to a two-state Markov process. This means that the resulting PDE-ODE is stochastic due to the presence of a randomly switching boundary in the interior of the domain. It is assumed that each membrane compartment acts as a conditional oscillator, that is, it sits below a supercritical Hopf bifurcation. In the ungated case (gap junction always open), the system supports diffusion-induced oscillations, in which the concentration of signaling molecules within the two compartments is either in-phase or anti-phase. The presence of a reflection symmetry (for identical cells) means that the stochastic gate only affects the existence of anti-phase oscillations. In particular, there exist parameter choices where the gated system supports oscillations, but the ungated system does not, and vice versa. The existence of oscillations is investigated by solving a spectral problem obtained by averaging over realizations of the stochastic gate.

  14. [A case of recurrent gastroesophageal junction adenocarcinoma successfully treated with radiation plus chemotherapy (5-FU+CDDP, S-1, Paclitaxel, CPT-11) for long-term survival with good QOL].

    PubMed

    Kojima, Taiki; Matsui, Takanori; Uemura, Takanori; Fujimitsu, Yasunobu; Kure, Narihiro; Mochizuki, Yoshinari; Kojima, Hiroshi

    2008-11-01

    We report a 63-year-old man with recurrent gastroesophageal junction adenocarcinoma. He underwent esophagogastrectomy in August 2004. After curative operation with Stage III (pT3N1M0), a recurrence was found at the anastomosis site in November 2004. Chemoradiotherapy with S-1 followed by chemotherapy (S-1) was performed from January 2005 to April 2006. Lymphnode metastasis to the left side of the main bronchus appeared in May 2006, and paclitaxel was used until December 2007 when PR was indicated by CT scan and GIF. Now he is receiving CPT-11. During these 3 years and 3 months, his performance status was maintained from 0 to 1.

  15. Experimental evidence for quantum interference and vibrationally induced decoherence in single-molecule junctions.

    PubMed

    Ballmann, Stefan; Härtle, Rainer; Coto, Pedro B; Elbing, Mark; Mayor, Marcel; Bryce, Martin R; Thoss, Michael; Weber, Heiko B

    2012-08-03

    We analyze quantum interference and decoherence effects in single-molecule junctions both experimentally and theoretically by means of the mechanically controlled break junction technique and density-functional theory. We consider the case where interference is provided by overlapping quasidegenerate states. Decoherence mechanisms arising from electronic-vibrational coupling strongly affect the electrical current flowing through a single-molecule contact and can be controlled by temperature variation. Our findings underline the universal relevance of vibrations for understanding charge transport through molecular junctions.

  16. Modeling of Intrinsic Josephson Junctions in High Temperature Superconductors under External Radiation in the Breakpoint Region

    NASA Astrophysics Data System (ADS)

    Shukrinov, Yu. M.; Rahmonov, I. R.; Plecenik, A.; Streltsova, O. I.; Zuev, M. I.; Ososkov, G. A.

    2016-02-01

    The current-voltage (IV) characteristics of the intrinsic Josephson junctions in high temperature superconductors under external electromagnetic radiation are calculated numerically in the parametric resonance region. We discuss a numerical method for calculation of the Shapiro step width on the amplitude of radiation. In order to accelerate computations we used parallelization by task parameter via Simple Linux Utility for Resource Management (SLURM) arrays and tested it in the case of a single junction. An analysis of the junction transitions between rotating and oscillating states in the branching region of IV-characteristics is presented.

  17. The Dissolution of Double Holliday Junctions

    PubMed Central

    Bizard, Anna H.; Hickson, Ian D.

    2014-01-01

    Double Holliday junctions (dHJS) are important intermediates of homologous recombination. The separate junctions can each be cleaved by DNA structure-selective endonucleases known as Holliday junction resolvases. Alternatively, double Holliday junctions can be processed by a reaction known as “double Holliday junction dissolution.” This reaction requires the cooperative action of a so-called “dissolvasome” comprising a Holliday junction branch migration enzyme (Sgs1/BLM RecQ helicase) and a type IA topoisomerase (Top3/TopoIIIα) in complex with its OB (oligonucleotide/oligosaccharide binding) fold containing accessory factor (Rmi1). This review details our current knowledge of the dissolution process and the players involved in catalyzing this mechanistically complex means of completing homologous recombination reactions. PMID:24984776

  18. Physics and Applications of NIS Junctions

    SciTech Connect

    Ullom, J N

    2001-08-24

    This paper reviews the physics and applications of Normal-Insulator-Superconductor (NIS) tunnel junctions. The current-voltage properties of NIS junctions are diode-like with a strong temperature dependence. Hence, these structures can be used as sensitive thermometers at temperatures well below the energy gap, {Delta}, of the superconducting electrode. For junction voltages comparable to {Delta}/q, current flow removes energy from the normal electrode. This property has been exploited to build refrigerators capable of cooling thin-film circuits from 0.3 K to 0.1 K. Calorimeters and bolometers for the detection of X-rays and millimeter-wave radiation, respectively, have successfully been built from NIS junctions. NIS junctions have also been used to probe the superconducting state. Finally, recent ideas for the use of NIS junctions as simple circuit elements are described.

  19. In vitro formation of gap junction vesicles.

    PubMed

    Goodenough, D A

    1976-02-01

    A method is described that uses trypsin digestion combined with collagenase-hyaluronidase which produces a population of gap junction vesicles. The hexagonal lattice of subunits ("connexons") comprising the gapjunctions appears unaltered by various structural criteria and by buoyant density measurements. The gap junction vesciles are closed by either a single or a double profile of nonjunctional "membrane," which presents a smooth, particle-free fracture face. Horseradish peroxidase and cytochrome c studies have revealed that about 20% of the gap junction vesicles are impermeable to proteins 12,000 daltons or larger. The increased purity of the trypsinized junction preparation suggests that one of the disulfide reduction products of the gap-junction principal protein may be a nonjunctional contaminating peptide. The gap junction appears to be composed of a single 18,000-dalton protein, connexin, which may be reduced to a single 9,000-dalton peak. The number of peptides in this reduced peak are still unknown.

  20. Atypical traumatic craniocervical junction focal spinal subdural hematoma.

    PubMed

    Aydin, M Volkan; Sen, Orhan; Tufan, Kadir; Caner, Hakan

    2006-01-01

    Spinal subdural hematoma (SSDH) is a rare entity and post-traumatic cervical SSDH is very rare. Review of the literature revealed 8 reported cases of traumatic SSDH and only 2 were cervical. The exact mechanism and pathogenesis of SSDHs are unclear. There are still controversies about the source of bleeding and mechanisms of formation of a hematoma. Here we report a case of a unique traumatic craniocervical junction focal subdural hematoma in an 8-year-old boy and discuss the possible mechanisms of SSDHs in trauma cases.

  1. [Gap junctions and cancer: implications and perspectives].

    PubMed

    Mesnil, Marc

    2004-02-01

    Gap junctions are made of intercellular channels which permit the diffusion from cytoplasm to cytoplasm of small hydrophilic molecules (<1,200 Da) such as ions, sugars, amino acids, nucleotides, second messengers (calcium, inositol triphosphate, etc.). Since their discovery in the early sixties, several groups have described the loss of their function in cancer cells. The accumulation of such data led to the hypothesis that gap junctions are involved in the carcinogenesis process. This assumption has been confirmed by data establishing that gap junctional intercellular communication is inhibited by most of the tumor promoters and that the restoration of such a communication, by transfection of cDNAs encoding gap junction proteins (connexins), inhibits the aberrant growth rates of tumorigenic cells. Despite these important informations, several fundamental questions remain still open. First, we do not know how gap junctions mediate such a tumor suppressor effect and whether it may depend either on the cell type or on the connexin type. Moreover, most of the data concerning a possible involvement of gap junctions in carcinogenesis have been obtained from in vitro and animal models. The very few results which have been currently collected from human tumors are not sufficient to have a clear idea concerning the real involvement of gap junctions in sporadic human cancers. These points as well as other unresolved questions about the role of gap junctional intercellular communication in carcinogenesis are mentioned. To bring some answers, some prospects are proposed with the objective to use gap junctions for increasing the effect of anticancer therapies.

  2. Magnetic tunnel junction pattern technique

    NASA Astrophysics Data System (ADS)

    Chen, Eugene; Schwarz, Benjamin; Choi, Chang Ju; Kula, Witold; Wolfman, Jerome; Ounadjela, Kamel; Geha, Sam

    2003-05-01

    We have developed a magnetic tunnel junction (MTJ) pattern technique that involves transforming the magnetic layer above the tunnel barrier in unwanted areas into an insulator, thus providing insulation between different MTJ devices without suffering common tunnel barrier shorting problems. With this technique, 90%-100% yielding MTJ devices have been observed. MTJ results using this process are superior to an etching based process. Switching distribution of patterned magnetic bits is also narrower using this novel technique. Process control and the ability to stop on the tunnel barrier have been demonstrated.

  3. Thermoelectric effects in nanoscale junctions.

    PubMed

    Dubi, Yonatan; Di Ventra, Massimiliano

    2009-01-01

    Despite its intrinsic nonequilibrium origin, thermoelectricity in nanoscale systems is usually described within a static scattering approach which disregards the dynamical interaction with the thermal baths that maintain energy flow. Using the theory of open quantum systems, we show instead that unexpected properties, such as a resonant structure and large sign sensitivity, emerge if the nonequilibrium nature of this problem is considered. Our approach also allows us to define and study a local temperature, which shows hot spots and oscillations along the system according to the coupling of the latter to the electrodes. This demonstrates that Fourier's lawa paradigm of statistical mechanicsis generally violated in nanoscale junctions.

  4. Method for shallow junction formation

    DOEpatents

    Weiner, K.H.

    1996-10-29

    A doping sequence is disclosed that reduces the cost and complexity of forming source/drain regions in complementary metal oxide silicon (CMOS) integrated circuit technologies. The process combines the use of patterned excimer laser annealing, dopant-saturated spin-on glass, silicide contact structures and interference effects creates by thin dielectric layers to produce source and drain junctions that are ultrashallow in depth but exhibit low sheet and contact resistance. The process utilizes no photolithography and can be achieved without the use of expensive vacuum equipment. The process margins are wide, and yield loss due to contact of the ultrashallow dopants is eliminated. 8 figs.

  5. Method for shallow junction formation

    DOEpatents

    Weiner, Kurt H.

    1996-01-01

    A doping sequence that reduces the cost and complexity of forming source/drain regions in complementary metal oxide silicon (CMOS) integrated circuit technologies. The process combines the use of patterned excimer laser annealing, dopant-saturated spin-on glass, silicide contact structures and interference effects creates by thin dielectric layers to produce source and drain junctions that are ultrashallow in depth but exhibit low sheet and contact resistance. The process utilizes no photolithography and can be achieved without the use of expensive vacuum equipment. The process margins are wide, and yield loss due to contact of the ultrashallow dopants is eliminated.

  6. Formation and stability of ridge-ridge-ridge triple junctions in rheologically realistic lithosphere model

    NASA Astrophysics Data System (ADS)

    Gerya, Taras; Burov, Evgueni

    2015-04-01

    Triple junctions are probably the most remarkable features of plate boundaries since their presence constitutes one of the major demonstrations of plate tectonics theory. Divergent (R-R-R) triple junctions (at 120° and T junctions) are particular ones since their stability depends on the exact values of the relative velocities of plate divergence and hence is strongly affected by plate rheology and processes of crustal accretion. The mechanisms of their formation and long-term steadiness are not well understood even though it is commonly accepted, generally based on common sense, that the geometry and stability of triple junctions should be related to the intuitively acceptable geometric considerations that 3-branch configurations should be "stable" over the time on a 3D Earth surface. That said, most plate boundaries are in fact 2D in terms that they involve only two plates, while junctions with 3 and more branches, if even mechanically not excluded, are generally short-lived and hence rarely observed at tectonic scale. Indeed, it has been long-time suggested that triple junctions result from evolution of short-lived quadruple junctions, yet, without providing a consistent mechanical explanation or experimental demonstration of this process, due to the rheological complexity of the lithosphere and that of strain localization and crustal accretion processes. For example, it is supposed that R-R-R junctions form as result of axisymmetric mantle upwellings. However, impingement of buoyant fluid on a non-pre-stressed lithosphere should result in multiple radial cracks, as is well known from previous analog and numerical experiments. In case of uni-directionally pre-stressed lithosphere, it has also shown that linear 2D rift structures should be formed. Therefore, a complete 3D thermos-mechanically consistent approach is needed to understand the processes of formation of multi-branch junctions. With this goal we here reproduce and study the processes of multi

  7. [Introduction to the structure and functions of junction communications or gap junctions].

    PubMed

    Rousset, B

    1996-01-01

    Cell-to-cell communication through gap junctions (GJ) represents a direct route of exchange of informations between neighboring cells within tissues and organs. GJ are formed from the assembly of a large number of channels that differ from the other known channels because they connect the cytoplasm of adjacent cells. The GJ channel is built from two parts: the connexons. A connexon inserted into the plasma membrane of a cell interacts with another connexon belonging to an adjacent cell. Connexons are composed of proteins with four transmembrane domains that are named connexins (Cx). Six Cx form a connexon. Cx belong to a protein family with 13 known members at present. Each Cx is defined by its molecular mass in kDa (ex: Cx32, Cx43...). A given cell type expresses one or several Cx. The cell to cell transfer of molecules through GJ channels exhibit a size selectivity; only molecules with a molecular mass lower than 1000 Da such as ions and second messengers freely pass through GJ. Depending on the Cx they are made of, GJ seem to differ somewhat in their permeability properties. Cell-to-cell communication via GJ is a regulated process. GJ channels can be either open or closed. GJ mediated cell-to-cell communication or junctional coupling can be detected and quantified by visualization of the cell to cell transfer of a fluorescent probe (such as Lucifer Yellow...) previously introduced in a single cell by microinjection. The presence of GJ channels can also be identified by recording the passage of an electric current between contiguous cells. GJ are involved in numerous fundamental biological processes from the embryonic development to the homeostasis in adult tissues and organs. GJ coordinate cell activities and sometimes synchronize cell behaviour. This is the case for the propagation of the excitation wave in the cardiac muscle and smooth muscle. GJ mediate metabolic cooperation between cells; they represent a way of supply of nutrients for tissues that are

  8. Electrodeposited, Transverse Nanowire Electroluminescent Junctions.

    PubMed

    Qiao, Shaopeng; Xu, Qiang; Dutta, Rajen K; Le Thai, Mya; Li, Xiaowei; Penner, Reginald M

    2016-09-27

    The preparation by electrodeposition of transverse nanowire electroluminescent junctions (tn-ELJs) is described, and the electroluminescence (EL) properties of these devices are characterized. The lithographically patterned nanowire electrodeposition process is first used to prepare long (millimeters), linear, nanocrystalline CdSe nanowires on glass. The thickness of these nanowires along the emission axis is 60 nm, and the width, wCdSe, along the electrical axis is adjustable from 100 to 450 nm. Ten pairs of nickel-gold electrical contacts are then positioned along the axis of this nanowire using lithographically directed electrodeposition. The resulting linear array of nickel-CdSe-gold junctions produces EL with an external quantum efficiency, EQE, and threshold voltage, Vth, that depend sensitively on wCdSe. EQE increases with increasing electric field and also with increasing wCdSe, and Vth also increases with wCdSe and, therefore, the electrical resistance of the tn-ELJs. Vth down to 1.8(±0.2) V (for wCdSe ≈ 100 nm) and EQE of 5.5(±0.5) × 10(-5) (for wCdSe ≈ 450 nm) are obtained. tn-ELJs produce a broad EL emission envelope, spanning the wavelength range from 600 to 960 nm.

  9. Effect of inductive and capacitive coupling on the current-voltage characteristic and electromagnetic radiation from a system of Josephson junctions

    NASA Astrophysics Data System (ADS)

    Rahmonov, I. R.; Shukrinov, Yu. M.; Atanasova, P. Kh.; Zemlyanaya, E. V.; Bashashin, M. V.

    2017-01-01

    We have studied the current-voltage characteristic of a system of long Josephson junctions taking into account the inductive and capacitive coupling. The dependence of the average time derivative of the phase difference on the bias current and spatiotemporal dependences of the phase difference and magnetic field in each junction are considered. The possibility of branching of the current-voltage characteristic in the region of zero field step, which is associated with different numbers of fluxons in individual Josephson junctions, is demonstrated. The current-voltage characteristic of the system of Josephson junctions is compared with the case of a single junction, and it is shown that the observed branching is due to coupling between the junctions. The intensity of electromagnetic radiation associated with motion of fluxons is calculated, and the effect of coupling between junctions on the radiation power is analyzed.

  10. Extended cervico-thoracic metastasectomy for testicular non-seminomatous germ cell tumour masses through an inverse T and combined collar incision.

    PubMed

    Schweiger, Thomas; Hoetzenecker, Konrad; Taghavi, Shahrokh; Klepetko, Walter

    2015-05-01

    Non-seminomatous germ cell tumours (NSGCT) are the most common malignancy from testicular origin in young males. They are characterized by early formation of metastases along retroperitoneal and subsequent mediastinal lymph node stations. Following cisplatin-based induction chemotherapy, residual tumour masses should be removed surgically, although this implies the need for extended procedures. Such an approach can result in cure rates of over 70%. Herein, we report 2 cases of maximally extended surgery for metastatic malignant germ cell tumour of the testis. In both patients, diagnostic work-up revealed a NSGCT with retroperitoneal, mediastinal and cervical lymph node metastases. Multimodal protocols including induction chemotherapy and surgical removal of all primary and secondary tumour masses with curative intent were applied. An 'inverse T' incision in combination with a collar incision was chosen to approach the excessive supra-diaphragmatic tumour spread. This large-scaled surgical access offered an excellent exposure and allowed complete resection of all cervical and thoracic metastases in both patients. Abdominal tumour masses were resected through a standard median laparotomy. These 2 cases illustrate that complete tumour resection is feasible even in stages of NSGCT with generalized lymphatic spread. Metastasectomy should be offered to NSGCT patients despite the necessity of extended surgical approaches.

  11. Ballistic Graphene Josephson Junctions from the Short to the Long Junction Regimes

    NASA Astrophysics Data System (ADS)

    Borzenets, I. V.; Amet, F.; Ke, C. T.; Draelos, A. W.; Wei, M. T.; Seredinski, A.; Watanabe, K.; Taniguchi, T.; Bomze, Y.; Yamamoto, M.; Tarucha, S.; Finkelstein, G.

    2016-12-01

    We investigate the critical current IC of ballistic Josephson junctions made of encapsulated graphene-boron-nitride heterostructures. We observe a crossover from the short to the long junction regimes as the length of the device increases. In long ballistic junctions, IC is found to scale as ∝exp (-kBT /δ E ). The extracted energies δ E are independent of the carrier density and proportional to the level spacing of the ballistic cavity. As T →0 the critical current of a long (or short) junction saturates at a level determined by the product of δ E (or Δ ) and the number of the junction's transversal modes.

  12. Slit Diaphragms Contain Tight Junction Proteins

    PubMed Central

    Fukasawa, Hirotaka; Bornheimer, Scott; Kudlicka, Krystyna; Farquhar, Marilyn G.

    2009-01-01

    Slit diaphragms are essential components of the glomerular filtration apparatus, as changes in these junctions are the hallmark of proteinuric diseases. Slit diaphragms, considered specialized adherens junctions, contain both unique membrane proteins (e.g., nephrin, podocin, and Neph1) and typical adherens junction proteins (e.g., P-cadherin, FAT, and catenins). Whether slit diaphragms also contain tight junction proteins is unknown. Here, immunofluorescence, immunogold labeling, and cell fractionation demonstrated that rat slit diaphragms contain the tight junction proteins JAM-A (junctional adhesion molecule A), occludin, and cingulin. We found these proteins in the same protein complexes as nephrin, podocin, CD2AP, ZO-1, and Neph1 by cosedimentation, coimmunoprecipitation, and pull-down assays. PAN nephrosis increased the protein levels of JAM-A, occludin, cingulin, and ZO-1 several-fold in glomeruli and loosened their attachment to the actin cytoskeleton. These data extend current information about the molecular composition of slit diaphragms by demonstrating the presence of tight junction proteins, although slit diaphragms lack the characteristic morphologic features of tight junctions. The contribution of these proteins to the assembly of slit diaphragms and potential signaling cascades requires further investigation. PMID:19478094

  13. Dressed fluxon in a Josephson window junction

    NASA Astrophysics Data System (ADS)

    Caputo, Jean Guy; Flytzanis, Nikos; Devoret, Michel

    1994-09-01

    The static fluxon solutions of a Josephson window junction have been studied numerically. We show that the effect of the idle region surrounding the junction is to ``dress'' the fluxon causing its energy to increase. This effect can be predicted accurately by a simple model.

  14. Analysis of Tight Junction Formation and Integrity

    SciTech Connect

    Karakaya, Mahmut; Kerekes, Ryan A; Morrell-Falvey, Jennifer L; Foster, Carmen M; Retterer, Scott T

    2012-01-01

    In this paper, we study segmentation of tight junctions and analyze the formation and integrity of tight junctions in large-scale confocal image stacks, a challenging biological problem because of the low spatial resolution images and the presence of breaks in tight junction structure. We present an automated, three-step processing approach for tight junction analysis. In our approach, we first localize each individual nucleus in the image by using thresholding, morphological filters and active contours. By using each nucleus position as a seed point, we automatically segment the cell body based on the active contour. We then use an intensity-based skeletonization algorithm to generate the boundary regions for each cell, and features are extracted from tight junctions associated with each cell to assess tight junction continuity. Based on qualitative results and quantitative comparisons, we show that we are able to automatically segment tight junctions and compute relevant features that provide a quantitative measure of tight junction formation to which the permeability of the cell monolayer can ultimately be correlated.

  15. Zipper and freeway shear zone junctions

    NASA Astrophysics Data System (ADS)

    Passchier, Cees; Platt, John

    2016-04-01

    Ductile shear zones are usually presented as isolated planar high-strain domains in a less deformed wall rock, characterised by shear sense indicators such as characteristic deflected foliation traces. Many shear zones, however, form branched systems and if movement on such branches is contemporaneous, the resulting geometry can be complicated and lead to unusual fabric geometries in the wall rock. For Y-shaped shear zone junctions with three simultaneously operating branches, and with slip directions at a high angle to the branch line, eight basic types of shear zone triple junctions are possible, divided into three groups. The simplest type, called freeway junctions, have similar shear sense on all three branches. If shear sense is different on the three branches, this can lead to space problems. Some of these junctions have shear zone branches that join to form a single branch, named zipper junctions, or a single shear zone which splits to form two, known as wedge junctions. Closing zipper junctions are most unusual, since they form a non-active high-strain zone with opposite deflection of foliations. Shear zipper and shear wedge junctions have two shear zones with similar shear sense, and one with the opposite sense. All categories of shear zone junctions show characteristic flow patterns in the shear zone and its wall rock. Shear zone junctions with slip directions normal to the branch line can easily be studied, since ideal sections of shear sense indicators lie in the plane normal to the shear zone branches and the branch line. Expanding the model to allow slip oblique and parallel to the branch line in a full 3D setting gives rise to a large number of geometries in three main groups. Slip directions can be parallel on all branches but oblique to the branch line: two slip directions can be parallel and a third oblique, or all three branches can have slip in different directions. Such more complex shear zone junctions cannot be studied to advantage in a

  16. Low-high junction theory applied to solar cells

    NASA Technical Reports Server (NTRS)

    Godlewski, M. P.; Baraona, C. R.; Brandhorst, H. W., Jr.

    1974-01-01

    Recent use of alloying techniques for rear contact formation has yielded a new kind of silicon solar cell, the back surface field (BSF) cell, with abnormally high open-circuit voltage and improved radiation resistance. Several analytical models for open-circuit voltage based on the reverse saturation current are formulated to explain these observations. The zero surface recombination velocity (SRV) case of the conventional cell model, the drift field model, and the low-high junction (LHJ) model can predict the experimental trends. The LHJ model applies the theory of the low-high junction and is considered to reflect a more realistic view of cell fabrication. This model can predict the experimental trends observed for BSF cells.

  17. Low-high junction theory applied to solar cells

    NASA Technical Reports Server (NTRS)

    Godlewski, M. P.; Baraona, C. R.; Brandhorst, H. W., Jr.

    1973-01-01

    Recent use of alloying techniques for rear contact formation has yielded a new kind of silicon solar cell, the back surface field (BSF) cell, with abnormally high open circuit voltage and improved radiation resistance. Several analytical models for open circuit voltage based on the reverse saturation current are formulated to explain these observations. The zero SRV case of the conventional cell model, the drift field model, and the low-high junction (LHJ) model can predict the experimental trends. The LHJ model applies the theory of the low-high junction and is considered to reflect a more realistic view of cell fabrication. This model can predict the experimental trends observed for BSF cells. Detailed descriptions and derivations for the models are included. The correspondences between them are discussed. This modeling suggests that the meaning of minority carrier diffusion length measured in BSF cells be reexamined.

  18. Discovery of a photoresponse amplification mechanism in compensated PN junctions

    SciTech Connect

    Zhou, Yuchun; Rahman, Samia N.; Hall, David; Lo, Yu-Hwa; Liu, Yu-Hsin; Sham, L. J.

    2015-01-19

    We report the experimental evidence of uncovering a photoresponse amplification mechanism in heavily doped, partially compensated silicon p-n junctions under very low bias voltage. We show that the observed photocurrent gain occurs at a bias that is more than an order of magnitude below the threshold voltage for conventional impact ionization. Moreover, contrary to the case of avalanche detectors and p-i-n diodes, the amplified photoresponse is enhanced rather than suppressed with increasing temperature. These distinctive characteristics lead us to hypothesize that the inelastic scattering between energetic electrons (holes) and the ionized impurities in the depletion and charge neutral regions of the p-n junction in a cyclic manner plays a significant role in the amplification process. Such an internal signal amplification mechanism, which occurs at much lower bias than impact ionization and favors room temperature over cryogenic temperature, makes it promising for practical device applications.

  19. Endoscopic transoral surgery for craniovertebral junction anomalies. Technical note.

    PubMed

    Husain, Mazhar; Rastogi, Manu; Ojha, Bal Krishna; Chandra, Anil; Jha, Deepak K

    2006-10-01

    Craniovertebral junction (CVJ) anomalies continue to be challenging for neurosurgeons because of the complex anatomy of this region. To date, microsurgical decompression via a transoral route is the standard treatment for anteriorly located compressive lesions of the cervicomedullary junction (CMJ). The results obtained by minimizing surgical trauma are fewer complications, shorter hospital stays, and reduced overall psychological burden. Endoscopic surgery is becoming a leading modality in minimally invasive neurosurgical treatment. The authors performed surgery in 11 patients with irreducible osseous dislocations resulting from CVJ abnormality during a 2-year period. Anterior CMJ decompression was achieved in all patients by performing neuroendoscopically controlled transoral excision of bone and soft tissues. The surgical technique and results will be discussed. The use of the endoscope offers several advantages in cases requiring a transoral approach to the lower clivus and atlantoaxial region. The use of minimally invasive endoscopic techniques has the potential to reduce the need for a wider cranial base opening and to decrease postoperative complications.

  20. Isolated popliteus rupture at the musculo-tendinous junction.

    PubMed

    Quinlan, John F; Webb, Sandra; McDonald, Karl; Meikle, Grant; McMahon, Simon F

    2011-06-01

    We report the case of a 23-year-old professional senior international rugby union player who sustained a lateral blow to his semiflexed knee during a competitive game. Initial clinical examination was unremarkable apart from some posterolateral tenderness. A magnetic resonance imaging scan showed an isolated popliteus tendon rupture at the musculo-tendinous junction. After 5 weeks of focused rehabilitation and graduated training, he was able to resume his playing career and resumed his international playing career later that season. At the time of reporting, he has completed a full domestic and international season without any sequelae from the injury. This report highlights the rarity of such an injury, especially at the musculo-tendinous junction, and sets out a detailed rehabilitation program that has enabled the patient in question to resume his playing career.

  1. First-principles study of interface doping in ferroelectric junctions

    PubMed Central

    Wang, Pin-Zhi; Cai, Tian-Yi; Ju, Sheng; Wu, Yin-Zhong

    2016-01-01

    Effect of atomic monolayer insertion on the performance of ferroelectric tunneling junction is investigated in SrRuO3/BaTiO3/SrRuO3 heterostrucutures. Based on first-principles calculations, the atomic displacement, orbital occupancy, and ferroelectric polarization are studied. It is found that the ferroelectricity is enhanced when a (AlO2)− monolayer is inserted between the electrode SRO and the barrier BTO, where the relatively high mobility of doped holes effectively screen ferroelectric polarization. On the other hand, for the case of (LaO)+ inserted layer, the doped electrons resides at the both sides of middle ferroelectric barrier, making the ferroelectricity unfavorable. Our findings provide an alternative avenue to improve the performance of ferroelectric tunneling junctions. PMID:27063704

  2. Shear zone junctions: Of zippers and freeways

    NASA Astrophysics Data System (ADS)

    Passchier, Cees W.; Platt, John P.

    2017-02-01

    Ductile shear zones are commonly treated as straight high-strain domains with uniform shear sense and characteristic curved foliation trails, bounded by non-deforming wall rock. Many shear zones, however, are branched, and if movement on such branches is contemporaneous, the resulting shape can be complicated and lead to unusual shear sense arrangement and foliation geometries in the wall rock. For Y-shaped shear zone triple junctions with three joining branches and transport direction at a high angle to the branchline, only eight basic types of junction are thought to be stable and to produce significant displacement. The simplest type, called freeway junctions, have similar shear sense in all three branches. The other types show joining or separating behaviour of shear zone branches similar to the action of a zipper. Such junctions may have shear zone branches that join to form a single branch (closing zipper junction), or a single shear zone that splits to form two branches, (opening zipper junction). All categories of shear zone junctions show characteristic foliation patterns and deflection of markers in the wall rock. Closing zipper junctions are unusual, since they form a non-active zone with opposite deflection of foliations in the wall rock known as an extraction fault or wake. Shear zipper junctions can form domains of overprinting shear sense along their flanks. A small and large field example are given from NE Spain and Eastern Anatolia. The geometry of more complex, 3D shear zone junctions with slip parallel and oblique to the branchline is briefly discussed.

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

    SciTech Connect

    Cleland, A.N.

    1991-04-01

    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 {approx} 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.

  4. Edge mixing dynamics in graphene p-n junctions in the quantum Hall regime

    NASA Astrophysics Data System (ADS)

    Matsuo, Sadashige; Takeshita, Shunpei; Tanaka, Takahiro; Nakaharai, Shu; Tsukagoshi, Kazuhito; Moriyama, Takahiro; Ono, Teruo; Kobayashi, Kensuke

    2015-09-01

    Massless Dirac electron systems such as graphene exhibit a distinct half-integer quantum Hall effect, and in the bipolar transport regime co-propagating edge states along the p-n junction are realized. Additionally, these edge states are uniformly mixed at the junction, which makes it a unique structure to partition electrons in these edge states. Although many experimental works have addressed this issue, the microscopic dynamics of electron partition in this peculiar structure remains unclear. Here we performed shot-noise measurements on the junction in the quantum Hall regime as well as at zero magnetic field. We found that, in sharp contrast with the zero-field case, the shot noise in the quantum Hall regime is finite in the bipolar regime, but is strongly suppressed in the unipolar regime. Our observation is consistent with the theoretical prediction and gives microscopic evidence that the edge states are uniquely mixed along the p-n junction.

  5. Investigation of high-Tc superconducting tunnel junction after laser radiation processing

    NASA Astrophysics Data System (ADS)

    Broslavez, U. U.; Fomitchev, A. A.; Yakshin, Mikhail A.

    1995-03-01

    We investigate dynamic resistance (dV/dI) of high-Tc superconducting thin films and tunnel junction after laser radiation processing. The films of YBaCuO were prepared by laser and magnetron ablation on Al2O3 substrates. The tunnel junctions were made by fine silver wires attached to the processing surfaces. The resistance (dV/dI) was determined by a four-probe measurement. The YAG laser operating in Q-switched mode was used to interact with superconductors. The anomaly is observed in the current-voltage curve of the junction after radiation interaction. We observe hysteresis in the shape of V(I) curve. These effects are not observed without laser radiation interaction and in this case the behavior of tunnel junction is described for the standard BCS theory.

  6. Inhibiting Klein Tunneling in a Graphene p -n Junction without an External Magnetic Field

    NASA Astrophysics Data System (ADS)

    Oh, Hyungju; Coh, Sinisa; Son, Young-Woo; Cohen, Marvin L.

    2016-07-01

    We study by first-principles calculations a densely packed island of organic molecules (F4TCNQ ) adsorbed on graphene. We find that with electron doping the island naturally forms a p -n junction in the graphene sheet. For example, a doping level of ˜3 ×1013 electrons per cm2 results in a p -n junction with an 800 meV electrostatic potential barrier. Unlike in a conventional p -n junction in graphene, in the case of the junction formed by an adsorbed organic molecular island we expect that the Klein tunneling is inhibited, even without an applied external magnetic field. Here Klein tunneling is inhibited by the ferromagnetic order that spontaneously occurs in the molecular island upon doping. We estimate that the magnetic barrier in the graphene sheet is around 10 mT.

  7. Electrostatic control of thermoelectricity in molecular junctions.

    PubMed

    Kim, Youngsang; Jeong, Wonho; Kim, Kyeongtae; Lee, Woochul; Reddy, Pramod

    2014-11-01

    Molecular junctions hold significant promise for efficient and high-power-output thermoelectric energy conversion. Recent experiments have probed the thermoelectric properties of molecular junctions. However, electrostatic control of thermoelectric properties via a gate electrode has not been possible due to technical challenges in creating temperature differentials in three-terminal devices. Here, we show that extremely large temperature gradients (exceeding 1 × 10(9) K m(-1)) can be established in nanoscale gaps bridged by molecules, while simultaneously controlling their electronic structure via a gate electrode. Using this platform, we study prototypical Au-biphenyl-4,4'-dithiol-Au and Au-fullerene-Au junctions to demonstrate that the Seebeck coefficient and the electrical conductance of molecular junctions can be simultaneously increased by electrostatic control. Moreover, from our studies of fullerene junctions, we show that thermoelectric properties can be significantly enhanced when the dominant transport orbital is located close to the chemical potential (Fermi level) of the electrodes. These results illustrate the intimate relationship between the thermoelectric properties and charge transmission characteristics of molecular junctions and should enable systematic exploration of the recent computational predictions that promise extremely efficient thermoelectric energy conversion in molecular junctions.

  8. Microtubules regulate disassembly of epithelial apical junctions

    PubMed Central

    Ivanov, Andrei I; McCall, Ingrid C; Babbin, Brian; Samarin, Stanislav N; Nusrat, Asma; Parkos, Charles A

    2006-01-01

    Background Epithelial tight junction (TJ) and adherens junction (AJ) form the apical junctional complex (AJC) which regulates cell-cell adhesion, paracellular permeability and cell polarity. The AJC is anchored on cytoskeletal structures including actin microfilaments and microtubules. Such cytoskeletal interactions are thought to be important for the assembly and remodeling of apical junctions. In the present study, we investigated the role of microtubules in disassembly of the AJC in intestinal epithelial cells using a model of extracellular calcium depletion. Results Calcium depletion resulted in disruption and internalization of epithelial TJs and AJs along with reorganization of perijunctional F-actin into contractile rings. Microtubules reorganized into dense plaques positioned inside such F-actin rings. Depolymerization of microtubules with nocodazole prevented junctional disassembly and F-actin ring formation. Stabilization of microtubules with either docetaxel or pacitaxel blocked contraction of F-actin rings and attenuated internalization of junctional proteins into a subapical cytosolic compartment. Likewise, pharmacological inhibition of microtubule motors, kinesins, prevented contraction of F-actin rings and attenuated disassembly of apical junctions. Kinesin-1 was enriched at the AJC in cultured epithelial cells and it also accumulated at epithelial cell-cell contacts in normal human colonic mucosa. Furthermore, immunoprecipitation experiments demonstrated association of kinesin-1 with the E-cadherin-catenin complex. Conclusion Our data suggest that microtubules play a role in disassembly of the AJC during calcium depletion by regulating formation of contractile F-actin rings and internalization of AJ/TJ proteins. PMID:16509970

  9. Molecular mechanism of double Holliday junction dissolution

    PubMed Central

    2014-01-01

    Processing of homologous recombination intermediates is tightly coordinated to ensure that chromosomal integrity is maintained and tumorigenesis avoided. Decatenation of double Holliday junctions, for example, is catalysed by two enzymes that work in tight coordination and belong to the same ‘dissolvasome’ complex. Within the dissolvasome, the RecQ-like BLM helicase provides the translocase function for Holliday junction migration, while the topoisomerase III alpha-RMI1 subcomplex works as a proficient DNA decatenase, together resulting in double-Holliday-junction unlinking. Here, we review the available architectural and biochemical knowledge on the dissolvasome machinery, with a focus on the structural interplay between its components. PMID:25061510

  10. Circuit Theory of Unconventional Superconductor Junctions

    NASA Astrophysics Data System (ADS)

    Tanaka, Y.; Nazarov, Yu. V.; Kashiwaya, S.

    2003-04-01

    We extend the circuit theory of superconductivity to cover transport and proximity effect in mesoscopic systems that contain unconventional superconductor junctions. The approach fully accounts for zero-energy Andreev bound states forming at the surface of unconventional superconductors. As a simple application, we investigate the transport properties of a diffusive normal metal in series with a d-wave superconductor junction. We reveal the competition between the formation of Andreev bound states and proximity effect that depends on the crystal orientation of the junction interface.

  11. Graded junction termination extensions for electronic devices

    NASA Technical Reports Server (NTRS)

    Merrett, J. Neil (Inventor); Isaacs-Smith, Tamara (Inventor); Sheridan, David C. (Inventor); Williams, John R. (Inventor)

    2006-01-01

    A graded junction termination extension in a silicon carbide (SiC) semiconductor device and method of its fabrication using ion implementation techniques is provided for high power devices. The properties of silicon carbide (SiC) make this wide band gap semiconductor a promising material for high power devices. This potential is demonstrated in various devices such as p-n diodes, Schottky diodes, bipolar junction transistors, thyristors, etc. These devices require adequate and affordable termination techniques to reduce leakage current and increase breakdown voltage in order to maximize power handling capabilities. The graded junction termination extension disclosed is effective, self-aligned, and simplifies the implementation process.

  12. Graded junction termination extensions for electronic devices

    NASA Technical Reports Server (NTRS)

    Merrett, J. Neil (Inventor); Isaacs-Smith, Tamara (Inventor); Sheridan, David C. (Inventor); Williams, John R. (Inventor)

    2007-01-01

    A graded junction termination extension in a silicon carbide (SiC) semiconductor device and method of its fabrication using ion implementation techniques is provided for high power devices. The properties of silicon carbide (SiC) make this wide band gap semiconductor a promising material for high power devices. This potential is demonstrated in various devices such as p-n diodes, Schottky diodes, bipolar junction transistors, thyristors, etc. These devices require adequate and affordable termination techniques to reduce leakage current and increase breakdown voltage in order to maximize power handling capabilities. The graded junction termination extension disclosed is effective, self-aligned, and simplifies the implementation process.

  13. Top 50 most-cited articles on craniovertebral junction surgery

    PubMed Central

    Alan, Nima; Cohen, Jonathan Andrew; Zhou, James; Pease, Matthew; Kanter, Adam S; Okonkwo, David O; Hamilton, David Kojo

    2017-01-01

    Background: Craniovertebral junction is a complex anatomical location posing unique challenges to the surgical management of its pathologies. We aimed to identify the fifty most-cited articles that are dedicated to this field. Methods: A keyword search using the Thomson Reuters Web of Knowledge was conducted to identify articles relevant to the field of craniovertebral junction surgery. The articles were reviewed based on title, abstract, and methods, if necessary, and then ranked based on the total number of citations to identify the fifty most-cited articles. Characteristics of the articles were determined and analyzed. Results: The earliest top-cited article was published in 1948. When stratified by decade, 1990s was the most productive with 16 articles. The most-cited article was by Anderson and Dalonzo on a classification of odontoid fractures. By citation rate, the most-cited article was by Herms and Melcher who described Goel's technique of atlantoaxial fixation using C1 lateral mass screws and C2 pedicle screws with rod fixation. Atlantoaxial fixation was the most common topic. The United States, Barrow Neurological Institute, and VH Sonntag were the most represented country, institute, and author, respectively. The significant majority of articles were designed as case series providing level IV evidence. Conclusion: Using citation analysis, we have provided a list of the most-cited articles representing important contributions of various authors from many institutions across the world to the field of craniovertebral junction surgery. PMID:28250633

  14. Coherently driven, ultrafast electron-phonon dynamics in transport junctions

    SciTech Connect

    Szekely, Joshua E.; Seideman, Tamar

    2014-07-28

    Although the vast majority of studies of transport via molecular-scale heterojunctions have been conducted in the (static) energy domain, experiments are currently beginning to apply time domain approaches to the nanoscale transport problem, combining spatial with temporal resolution. It is thus an opportune time for theory to develop models to explore both new phenomena in, and new potential applications of, time-domain, coherently driven molecular electronics. In this work, we study the interaction of a molecular phonon with an electronic wavepacket transmitted via a conductance junction within a time-domain model that treats the electron and phonon on equal footing and spans the weak to strong electron-phonon coupling strengths. We explore interference between two coherent energy pathways in the electronic subspace, thus complementing previous studies of coherent phenomena in conduction junctions, where the stationary framework was used to study interference between spatial pathways. Our model provides new insights into phase decoherence and population relaxation within the electronic subspace, which have been conventionally treated by density matrix approaches that often rely on phenomenological parameters. Although the specific case of a transport junction is explored, our results are general, applying also to other instances of coupled electron-phonon systems.

  15. Chiral interface states in graphene p -n junctions

    NASA Astrophysics Data System (ADS)

    Cohnitz, Laura; De Martino, Alessandro; Häusler, Wolfgang; Egger, Reinhold

    2016-10-01

    We present a theoretical analysis of unidirectional interface states which form near p -n junctions in a graphene monolayer subject to a homogeneous magnetic field. The semiclassical limit of these states corresponds to trajectories propagating along the p -n interface by a combined skipping-snaking motion. Studying the two-dimensional Dirac equation with a magnetic field and an electrostatic potential step, we provide and discuss the exact and essentially analytical solution of the quantum-mechanical eigenproblem for both a straight and a circularly shaped junction. The spectrum consists of localized Landau-like and unidirectional snaking-skipping interface states, where we always find at least one chiral interface state. For a straight junction and at energies near the Dirac point, when increasing the potential step height, the group velocity of this state interpolates in an oscillatory manner between the classical drift velocity in a crossed electromagnetic field and the semiclassical value expected for a purely snaking motion. Away from the Dirac point, chiral interface states instead resemble the conventional skipping (edge-type) motion found also in the corresponding Schrödinger case. We also investigate the circular geometry, where chiral interface states are predicted to induce sizable equilibrium ring currents.

  16. Contributions to myometrium study in uterine-tubal junction.

    PubMed

    Neamţu, M C; Neamţu, R L; Avramescu, Elena Taina; Vrabete, Maria; Călina, Lucia Mirela; Mîndrilă, I

    2009-01-01

    Complex coordinated contractions of the tubal musculature are thought to be important for movement of the ovum from the distal end to the proximal end of the tube, while at the same time aiding in the movement of sperm from the proximal end to the distal end of the oviduct. Studies of the anatomy and the physiology of the uterine-tubal junction (UTJ), with a main concern for the muscular pattern and the secretory activity of this part of the tube, in relation with the hormonal and nervous control, can play an important role in understanding and impairment of infertility. Related to these aspects, the purpose of our research is mainly to identify the determining factors in maintaining a morphological and structural balance between contractile items and extracellular matrix items within uterine myometrium, particularly uterine-tubal junction. For this reason, the present study includes analyses of anatomical sections within uterus and uterine tubes extracted from patients during therapeutic surgeries. Thirty anatomical pieces from patients aged 23-37-year-old (uterus and tubes) were used to perform microanatomical sections, 10 pieces for each pathology identified, namely leiomyofibroma, leiomyofibroma with pregnancy, ectopic pregnancies. At the same time, the study proposes a statistic and mathematic analysis of the cases with uterine-tubal junction pathology in Oltenia region within a period of 10 years. The novelty of the study is represented by the identification of certain continuity ratios between myocyte fascicles and average tunica of arteries and arterioles, which explains the existence of "vascular units" determined by myometrial structures. Moreover, the stereo-distribution of "vascular myometrial units" explains the existence of a plexiform cavernous network, which enables many authors to describe numerous barely individualized myometrial tunicas. These units are rich in orthosympathetic vegetative innervations that might be responsible for the unfavorable

  17. High-performance DC SQUIDs with submicrometer niobium Josephson junctions

    SciTech Connect

    de Waal, V.J.; Klapwijk, T.M.; van den Hamer, P.

    1983-11-01

    We report on the fabrication and performance of low-noise, all-niobium, thin-film planar dc SQUIDs with submicrometer Josephson junctions. The junctions are evaporated obliquely through a metal shadow evaporation mask, which is made using optical lithography with 0.5 ..mu..m tolerance. The Josephson junction barrier is formed by evaporating a thin silicon film and with a subsequent oxidation in a glow discharge. The junction parameters can be reproduced within a factor of two. Typical critical currents of the SQUIDs are about 3 ..mu..A and the resistances are about 100 ..cap omega... With SQUIDs having an inductance of 1 nH the voltage modulation is a least 60 ..mu..V. An intrinsic energy resolution of 4 x 10/sup -32/ J/Hz has been reached. The SQUIDs are coupled to wire-wound input coils or with thin-film input coils. The thin-film input coil consists of a niobium spiral of 20 turns on a separate substrate. In both cases the coil is glued onto a 2-nH SQUID with a coupling efficiency of at least 0.5. Referred to the thin-film input coil, the best coupled energy resolution achieved is 1.2 x 10/sup -30/ J/Hz measured in a flux-locked loop at frequencies above 10 Hz. As far as we know, this is the best figure achieved with an all-refractory-metal thin-film SQUID. The fabrication technique used is suited for making circuits with SQUID and pickup coil on the same substrate. We describe a compact, planar, first-order gradiometer integrated with a SQUID on a single substrate. The gradient noise of this device is 3 x 10/sup -12/ Tm/sup -1/. The gradiometer has a size of 12 mm x 17 mm, is simple to fabricate, an is suitable for biomedical applications.

  18. Conductance spectra of asymmetric ferromagnet/ferromagnet/ferromagnet junctions

    NASA Astrophysics Data System (ADS)

    Pasanai, K.

    2017-01-01

    A theory of tunneling spectroscopy of ferromagnet/ferromagnet/ferromagnet junctions was studied. We applied a delta-functional approximation for the interface scattering properties under a one-dimensional system of a free electron approach. The reflection and transmission probabilities were calculated in the ballistic regime, and the conductance spectra were then calculated using the Landauer formulation. The magnetization directions were set to be either parallel (P) or anti-parallel (AP) alignments, for comparison. We found that the conductance spectra was suppressed when increasing the interfacial scattering at the interfaces. Moreover, the electron could exhibit direct transmission when the thickness was rather thin. Thus, there was no oscillation in this case. However, in the case of a thick layer the conductance spectra oscillated, and this oscillation was most prominent when the middle layer thickness increased. In the case of direct transmission, the conductance spectra of P and AP systems were definitely suppressed with increased exchange energy of the middle ferromagnet. This also refers to an increase in the magnetoresistance of the junction. In the case of oscillatory behavior, the positions of the resonance peaks were changed as the exchange energy was changed.

  19. Tunnel junction multiple wavelength light-emitting diodes

    DOEpatents

    Olson, Jerry M.; Kurtz, Sarah R.

    1992-01-01

    A multiple wavelength LED having a monolithic cascade cell structure comprising at least two p-n junctions, wherein each of said at least two p-n junctions have substantially different band gaps, and electrical connector means by which said at least two p-n junctions may be collectively energized; and wherein said diode comprises a tunnel junction or interconnect.

  20. Tunnel junction multiple wavelength light-emitting diodes

    DOEpatents

    Olson, J.M.; Kurtz, S.R.

    1992-11-24

    A multiple wavelength LED having a monolithic cascade cell structure comprising at least two p-n junctions, wherein each of said at least two p-n junctions have substantially different band gaps, and electrical connector means by which said at least two p-n junctions may be collectively energized; and wherein said diode comprises a tunnel junction or interconnect. 5 figs.

  1. Current trends in salivary gland tight junctions

    PubMed Central

    Baker, Olga J.

    2016-01-01

    ABSTRACT Tight junctions form a continuous intercellular barrier between epithelial cells that is required to separate tissue spaces and regulate selective movement of solutes across the epithelium. They are composed of strands containing integral membrane proteins (e.g., claudins, occludin and tricellulin, junctional adhesion molecules and the coxsackie adenovirus receptor). These proteins are anchored to the cytoskeleton via scaffolding proteins such as ZO-1 and ZO-2. In salivary glands, tight junctions are involved in polarized saliva secretion and barrier maintenance between the extracellular environment and the glandular lumen. This review seeks to provide an overview of what is currently known, as well as the major questions and future research directions, regarding tight junction expression, organization and function within salivary glands. PMID:27583188

  2. Presynaptic spike broadening reduces junctional potential amplitude.

    PubMed

    Spencer, A N; Przysiezniak, J; Acosta-Urquidi, J; Basarsky, T A

    1989-08-24

    Presynaptic modulation of action potential duration may regulate synaptic transmission in both vertebrates and invertebrates. Such synaptic plasticity is brought about by modifications to membrane currents at presynaptic release sites, which, in turn, lead to changes in the concentration of cytosolic calcium available for mediating transmitter release. The 'primitive' neuromuscular junction of the jellyfish Polyorchis penicillatus is a useful model of presynaptic modulation. In this study, we show that the durations of action potentials in the motor neurons of this jellyfish are negatively correlated with the amplitude of excitatory junctional potentials. We present data from in vitro voltage-clamp experiments showing that short duration voltage spikes, which elicit large excitatory junctional potentials in vivo, produce larger and briefer calcium currents than do long duration action potentials, which elicit small excitatory junctional potentials.

  3. Chirality effect in disordered graphene ribbon junctions

    NASA Astrophysics Data System (ADS)

    Long, Wen

    2012-05-01

    We investigate the influence of edge chirality on the electronic transport in clean or disordered graphene ribbon junctions. By using the tight-binding model and the Landauer-Büttiker formalism, the junction conductance is obtained. In the clean sample, the zero-magnetic-field junction conductance is strongly chirality-dependent in both unipolar and bipolar ribbons, whereas the high-magnetic-field conductance is either chirality-independent in the unipolar or chirality-dependent in the bipolar ribbon. Furthermore, we study the disordered sample in the presence of magnetic field and find that the junction conductance is always chirality-insensitive for both unipolar and bipolar ribbons with adequate disorders. In addition, the disorder-induced conductance plateaus can exist in all chiral bipolar ribbons provided the disorder strength is moderate. These results suggest that we can neglect the effect of edge chirality in fabricating electronic devices based on the magnetotransport in a disordered graphene ribbon.

  4. Adrenocortical Gap Junctions and Their Functions

    PubMed Central

    Bell, Cheryl L.; Murray, Sandra A.

    2016-01-01

    Adrenal cortical steroidogenesis and proliferation are thought to be modulated by gap junction-mediated direct cell–cell communication of regulatory molecules between cells. Such communication is regulated by the number of gap junction channels between contacting cells, the rate at which information flows between these channels, and the rate of channel turnover. Knowledge of the factors regulating gap junction-mediated communication and the turnover process are critical to an understanding of adrenal cortical cell functions, including development, hormonal response to adrenocorticotropin, and neoplastic dedifferentiation. Here, we review what is known about gap junctions in the adrenal gland, with particular attention to their role in adrenocortical cell steroidogenesis and proliferation. Information and insight gained from electrophysiological, molecular biological, and imaging (immunocytochemical, freeze fracture, transmission electron microscopic, and live cell) techniques will be provided. PMID:27445985

  5. Enhancement at the junction of silver nanorods.

    PubMed

    Gu, Geun Hoi; Suh, Jung Sang

    2008-08-19

    The enhancement of surface enhanced Raman scattering (SERS) at the junction of linearly joined silver nanorods (31 nm in diameter) deposited in the pores of anodic aluminum oxide templates was studied systematically by excitation with a 632.8 nm laser line. The single and joined silver nanorod arrays showed a similar extinction spectrum when their length was the same. Maximum enhancement was observed from the junction system of two nanorods of the same size with a total length of 62 nm. This length also corresponded to the optimum length of single nanorods for SERS by excitation with a 632.8 nm laser line. The enhancement at the junction was approximately 40 times higher than that of the 31 nm single nanorod, while it was 4 times higher than that of the 62 nm single nanorod. The enhancement factor at the junction after oxide removal was approximately 3.9 x 10 (9).

  6. UTE MRI of the Osteochondral Junction

    PubMed Central

    Biswas, Reni; Chen, Karen; Chang, Eric Y.; Chung, Christine B.

    2014-01-01

    The osteochondral junction is composed of numerous tissue components and serves important functions relating to structural stability and proper nutrition in joints such as the knee and spine. Conventional MR techniques have been inadequate at imaging the tissues of the osteochondral junction primarily because of the intrinsically short T2 nature of these tissues, rendering them “invisible” with the standard acquisitions. Ultrashort time to echo (UTE) MR techniques acquire sufficient MR signal of osteochondral tissues, thereby allowing direct evaluation. This article reviews the anatomy of the osteochondral junction of the knee and the spine, technical aspects of UTE MRI, and the application of UTE MRI for evaluation of the osteochondral junction. PMID:25061547

  7. Bias dependence of synergistic radiation effects induced by electrons and protons on silicon bipolar junction transistors

    NASA Astrophysics Data System (ADS)

    Liu, Chaoming; Li, Xingji; Yang, Jianqun; Ma, Guoliang; Xiao, Liyi

    2015-06-01

    Bias dependence on synergistic radiation effects caused by 110 keV electrons and 170 keV protons on the current gain of 3DG130 NPN bipolar junction transistors (BJTs) is studied in this paper. Experimental results indicate that the influence induced by 170 keV protons is always enhancement effect during the sequential irradiation. However, the influence induced by 110 keV electrons on the BJT under various bias cases is different during the sequential irradiation. The transition fluence of 110 keV electrons is dependent on the bias case on the emitter-base junction of BJT.

  8. [Role of postoperative chemoradiotherapy in the therapeutic management of adenocarcinomas of the stomach and oesogastric junction].

    PubMed

    Ben Salah, H; Bahri, M; Dhouib, F; Daoud, J

    2016-12-01

    The available data in the literature show that for gastric adenocarcinoma or gastroesophageal junction adenocarcinoma, postoperative chemoradiotherapy improves disease-free survival after surgery with D0 or D1 lymph node dissection (and perhaps D2) as well as in case of positive node or R1 resection. With the publications of perioperative chemotherapy trials, the role of postoperative radiotherapy in the therapeutic arsenal of gastric adenocarcinoma or gastroesophageal junction adenocarcinoma becomes difficult to define. Postoperative radiotherapy is indicated in case of R1 resection.

  9. Single Molecule Junctions: A Laboratory for Chemistry, Mechanics and Bond Rupture

    SciTech Connect

    Hybertsen M. S.

    2013-07-08

    Simultaneous measurement [1] of junction conductance and sustained force in single molecule junctions bridging metal electrodes provides a powerful tool in the quantitative study of the character of molecule-metal bonds. In this talk I will discuss three topics. First, I will describe chemical trends in link bond strength based on experiments and Density Functional Theory based calculations. Second, I will focus on the specific case of pyridine-linked junctions. Bond rupture from the high conductance junction structure shows a requires a force that exceeds the rupture force of gold point contacts and clearly indicates the role of additional forces, beyond the specific N-Au donor acceptor bond. DFT-D2 calculations with empirical addition of dispersion interactions illustrates the interplay between the donor-acceptor bonding and the non-specific van der Waals interactions between the pyridine rings and Au asperities. Third, I will describe recent efforts to characterize the diversity of junction structures realized in break-junction experiments with suitable models for the potential surfaces that are observed. [1] Venkataraman Group, Columbia University.

  10. Modeling Intrajunction Dispersion at a Well-Mixed Tidal River Junction

    DOE PAGES

    Wolfram, Phillip J.; Fringer, Oliver B.; Monsen, Nancy E.; ...

    2016-08-01

    In this paper, the relative importance of small-scale, intrajunction flow features such as shear layers, separation zones, and secondary flows on dispersion in a well-mixed tidal river junction is explored. A fully nonlinear, nonhydrostatic, and unstructured three-dimensional (3D) model is used to resolve supertidal dispersion via scalar transport at a well-mixed tidal river junction. Mass transport simulated in the junction is compared against predictions using a simple node-channel model to quantify the effects of small-scale, 3D intrajunction flow features on mixing and dispersion. The effects of three-dimensionality are demonstrated by quantifying the difference between two-dimensional (2D) and 3D model results.more » An intermediate 3D model that does not resolve the secondary circulation or the recirculating flow at the junction is also compared to the 3D model to quantify the relative sensitivity of mixing on intrajunction flow features. Resolution of complex flow features simulated by the full 3D model is not always necessary because mixing is primarily governed by bulk flow splitting due to the confluence–diffluence cycle. Finally, results in 3D are comparable to the 2D case for many flow pathways simulated, suggesting that 2D modeling may be reasonable for nonstratified and predominantly hydrostatic flows through relatively straight junctions, but not necessarily for the full junction network.« less

  11. Modeling Intrajunction Dispersion at a Well-Mixed Tidal River Junction

    SciTech Connect

    Wolfram, Phillip J.; Fringer, Oliver B.; Monsen, Nancy E.; Gleichauf, Karla T.; Fong, Derek A.; Monismith, Stephen G.

    2016-08-01

    In this paper, the relative importance of small-scale, intrajunction flow features such as shear layers, separation zones, and secondary flows on dispersion in a well-mixed tidal river junction is explored. A fully nonlinear, nonhydrostatic, and unstructured three-dimensional (3D) model is used to resolve supertidal dispersion via scalar transport at a well-mixed tidal river junction. Mass transport simulated in the junction is compared against predictions using a simple node-channel model to quantify the effects of small-scale, 3D intrajunction flow features on mixing and dispersion. The effects of three-dimensionality are demonstrated by quantifying the difference between two-dimensional (2D) and 3D model results. An intermediate 3D model that does not resolve the secondary circulation or the recirculating flow at the junction is also compared to the 3D model to quantify the relative sensitivity of mixing on intrajunction flow features. Resolution of complex flow features simulated by the full 3D model is not always necessary because mixing is primarily governed by bulk flow splitting due to the confluence–diffluence cycle. Finally, results in 3D are comparable to the 2D case for many flow pathways simulated, suggesting that 2D modeling may be reasonable for nonstratified and predominantly hydrostatic flows through relatively straight junctions, but not necessarily for the full junction network.

  12. Three-way RNA junctions with remote tertiary contacts: A recurrent and highly versatile fold

    PubMed Central

    de la Peña, Marcos; Dufour, David; Gallego, José

    2009-01-01

    Three-way junction RNAs adopt a recurrent Y shape when two of the helices form a coaxial stack and the third helix establishes one or more tertiary contacts several base pairs away from the junction. In this review, the structure, distribution, and functional relevance of these motifs are examined. Structurally, the folds exhibit conserved junction topologies, and the distal tertiary interactions play a crucial role in determining the final shape of the structures. The junctions and remote tertiary contacts behave as flexible hinge motifs that respond to changes in the other region, providing these folds with switching mechanisms that have been shown to be functionally useful in a variety of contexts. In addition, the juxtaposition of RNA domains at the junction and at the distal tertiary complexes enables the RNA helices to adopt unusual conformations that are frequently used by proteins, RNA molecules, and antibiotics as platforms for specific binding. As a consequence of these properties, Y-shaped junctions are widely distributed in all kingdoms of life, having been observed in small naked RNAs such as riboswitches and ribozymes or embedded in complex ribonucleoprotein systems like ribosomal RNAs, RNase P, or the signal recognition particle. In all cases, the folds were found to play an essential role for the functioning or assembly of the RNA or ribonucleoprotein systems that contain them. PMID:19741022

  13. Management of progressive late onset scoliosis with magnetic growth rod insertion leading to improvement of neural anomalies—a case report

    PubMed Central

    Zaveri, Amit; Pace, Valerio; Bhagawati, Dimpu; Muthukumar, Thillainayagam; Noordeen, Hilali

    2016-01-01

    Background To present the first known reported case of late onset idiopathic scoliosis with concomitant neural anomalies, treated with sequential distraction using magnetic growth rod, had significant improvement in both cranio-cervical and intraspinal anomaly. Methods A caucasian, growing female child (at the age of ten) presented with moderately progressive late onset right thoracic scoliosis. She was found to have Chiari type I malformation and a cervicothoracic syrinx on routine pre-operative MRI scanning. We treated this child by inserting magnetic growing rod (MGR) system. After 48 months of follow up with serial distractions, the metalwork (MGR) was removed due to aseptic wound breakdown and granuloma formation. Subsequently due to the progression of deformity, a definitive posterior instrumented spinal fusion was done. A repeat MRI Scan of the Spine was done prior to this definitive procedure to assess for any residual neural anomalies. Results The Chiari type I malformation appeared to have completely resolved, with no cerebellar tonsillar herniation seen, and a significant improvement in the size of the cervicothoracic syringomyelia effectively downgrading it to a prominent central canal. Conclusions This is a unique case of progressive late onset idiopathic scoliosis with associated Chiari malformation and syringomyelia, showing an improvement in these neural anomalies after gradual and protracted distractive lengthening of the spine with MGR. PMID:28097251

  14. A Model for the Behavior of Magnetic Tunnel Junctions

    SciTech Connect

    Baker, Bryan John

    2003-01-01

    of states function, and has developed an exact analytic solution for the case of an electron band of finite width. The approach taken in this thesis easily allows extension to cases where the band structure is different on either side of the barrier (known as heterojunctions) which are of greater interest in real magnetic tunnel junction devices rather than the simple, identical band structure devices.

  15. Anaesthesia management in craniovertebral junctional anomalies

    PubMed Central

    Mascarenhas, Oswald

    2016-01-01

    Craniovertebral Junctional (CVJ) anomalies are developmental disorders that affect the skeleton and enclosed neuraxis at the junction of cranium and cervical spine. The high prevalence of airway obstruction and restrictive pulmonary disease in combination with cardiovascular manifestations poses a high anaesthetic risk to these patients. This article provides a discussion of management of anaesthesia in patients with craniovertebral anomalies, the evaluation of risk factors in these patients and their management, including emergency airway issues. PMID:27891026

  16. Heat dissipation in atomic-scale junctions.

    PubMed

    Lee, Woochul; Kim, Kyeongtae; Jeong, Wonho; Zotti, Linda Angela; Pauly, Fabian; Cuevas, Juan Carlos; Reddy, Pramod

    2013-06-13

    Atomic and single-molecule junctions represent the ultimate limit to the miniaturization of electrical circuits. They are also ideal platforms for testing quantum transport theories that are required to describe charge and energy transfer in novel functional nanometre-scale devices. Recent work has successfully probed electric and thermoelectric phenomena in atomic-scale junctions. However, heat dissipation and transport in atomic-scale devices remain poorly characterized owing to experimental challenges. Here we use custom-fabricated scanning probes with integrated nanoscale thermocouples to investigate heat dissipation in the electrodes of single-molecule ('molecular') junctions. We find that if the junctions have transmission characteristics that are strongly energy dependent, this heat dissipation is asymmetric--that is, unequal between the electrodes--and also dependent on both the bias polarity and the identity of the majority charge carriers (electrons versus holes). In contrast, junctions consisting of only a few gold atoms ('atomic junctions') whose transmission characteristics show weak energy dependence do not exhibit appreciable asymmetry. Our results unambiguously relate the electronic transmission characteristics of atomic-scale junctions to their heat dissipation properties, establishing a framework for understanding heat dissipation in a range of mesoscopic systems where transport is elastic--that is, without exchange of energy in the contact region. We anticipate that the techniques established here will enable the study of Peltier effects at the atomic scale, a field that has been barely explored experimentally despite interesting theoretical predictions. Furthermore, the experimental advances described here are also expected to enable the study of heat transport in atomic and molecular junctions--an important and challenging scientific and technological goal that has remained elusive.

  17. Semiconductor tunnel junction with enhancement layer

    DOEpatents

    Klem, John F.; Zolper, John C.

    1997-01-01

    The incorporation of a pseudomorphic GaAsSb layer in a runnel diode structure affords a new degree of freedom in designing runnel junctions for p-n junction device interconnects. Previously only doping levels could be varied to control the tunneling properties. This invention uses the valence band alignment band of the GaAsSb with respect to the surrounding materials to greatly relax the doping requirements for tunneling.

  18. Semiconductor tunnel junction with enhancement layer

    DOEpatents

    Klem, J.F.; Zolper, J.C.

    1997-10-21

    The incorporation of a pseudomorphic GaAsSb layer in a runnel diode structure affords a new degree of freedom in designing runnel junctions for p-n junction device interconnects. Previously only doping levels could be varied to control the tunneling properties. This invention uses the valence band alignment band of the GaAsSb with respect to the surrounding materials to greatly relax the doping requirements for tunneling. 5 figs.

  19. Gravitational wave bursts from cosmic superstrings with Y-junctions

    SciTech Connect

    Binetruy, P.; Bohe, A.; Hertog, T.; Steer, D. A.

    2009-12-15

    Cosmic superstring loops generically contain strings of different tensions that meet at Y-junctions. These loops evolve nonperiodically in time, and have cusps and kinks that interact with the junctions. We study the effect of junctions on the gravitational wave signal emanating from cosmic string cusps and kinks. We find that earlier results on the strength of individual bursts from cusps and kinks on strings without junctions remain largely unchanged, but junctions give rise to additional contributions to the gravitational wave signal coming from strings expanding at the speed of light at a junction and kinks passing through a junction.

  20. Effect of reinforcement on the strength of junctions between cylindrical and conical shell

    SciTech Connect

    Kalnins, A.; Updike, D.P.

    1995-05-01

    Two failure modes are addressed for cylinder-cone junctions under internal or external pressure: axisymmetric yielding and low-cycle fatigue. If the junction fails to meet the failure criterion of any one of the two modes, then it must be strengthened by reinforcement. It is shown in the paper that the degree to which a junction is strengthened depends on the distribution of the reinforcement. A placement of reinforcement on the cylinder alone, leaving the actual connection between the cylinder and cone unreinforced, adds strength with regard to axisymmetric yielding, but may not strengthen the junction sufficiently with regard to low-cycle fatigue. This means that the junction may appear reinforced, but is not strengthened. It is pointed out that the design rules of Section 8, Div. 1 of the ASME B and PV Code (1992) set the need for reinforcement according to the failure criterion of low-cycle fatigue, while the distribution of the reinforcement is guided by the criterion of axisymmetric yielding. There is no assurance that the reinforced junction will meet the failure criterion of low-cycle fatigue. This means that the safety margin on the number of allowed cycles is less than that which is expected and that the junction may be unfit for cyclic service. It is also shown in the paper that a reinforcement distribution that requires minimum thicknesses for sections of both the cylinder and cone near the junction can satisfy criteria for both failure modes. This approach is already used in Code Case 2150 of Section 8, Div. 1, for half-apex cone angles from 30 to 60 deg, and required in Div. 2 for cone angles from 0 to 30 deg. Its extension to angles from 0 to 60 deg for both internal and external pressure is recommended.

  1. Effective medium theory of the space-charge region electrostatics of arrays of nanoscale junctions

    NASA Astrophysics Data System (ADS)

    Gurugubelli, Vijaya Kumar; Karmalkar, Shreepad

    2016-01-01

    We develop an Effective Medium Theory for the electrostatics of the Space-Charge Region (SCR) of Schottky and p-n junctions in arrays of nanofilms (NFs), nanowires (NWs), and nanotubes (NTs) in a dielectric ambient. The theory captures the effects of electric fields in both the semiconductor, i.e., NF/NW/NT, and the dielectric media of the array. It shows that the depletion width and the screening length characterizing the SCR tail in the array correspond to those in a bulk junction with an effective semiconductor medium, whose permittivity and doping are their weighted averages over the cross-sectional areas of the semiconductor and dielectric; the shapes of the cross-sections are immaterial. Further, the reverse bias 1 /C2 -V behavior of junctions in NF/NW/NT arrays is linear, as in bulk junctions, and is useful to extract from measurements the built-in potential, effective doping including the semiconductor-dielectric interface charge, and NF/NW/NT length. The theory is validated with numerical simulations, is useful for the experimentalist, and yields simple formulas for nano-device design which predict the following. In the limiting case of a single sheet-like NF, the junction depletion width variation with potential drop is linear rather than square-root (as in a bulk junction). In arrays of symmetric silicon p-n junctions in oxide dielectric where NF/NW thickness and separation are 5% and 100% of the bulk depletion width, respectively, the junction depletion width and the screening length are scaled up from their bulk values by the same factor of ˜2 for NF and ˜10 for NW array.

  2. Multi-junction solar cell device

    DOEpatents

    Friedman, Daniel J.; Geisz, John F.

    2007-12-18

    A multi-junction solar cell device (10) is provided. The multi-junction solar cell device (10) comprises either two or three active solar cells connected in series in a monolithic structure. The multi-junction device (10) comprises a bottom active cell (20) having a single-crystal silicon substrate base and an emitter layer (23). The multi-junction device (10) further comprises one or two subsequent active cells each having a base layer (32) and an emitter layer (23) with interconnecting tunnel junctions between each active cell. At least one layer that forms each of the top and middle active cells is composed of a single-crystal III-V semiconductor alloy that is substantially lattice-matched to the silicon substrate (22). The polarity of the active p-n junction cells is either p-on-n or n-on-p. The present invention further includes a method for substantially lattice matching single-crystal III-V semiconductor layers with the silicon substrate (22) by including boron and/or nitrogen in the chemical structure of these layers.

  3. Exercise regulation of intestinal tight junction proteins.

    PubMed

    Zuhl, Micah; Schneider, Suzanne; Lanphere, Katherine; Conn, Carole; Dokladny, Karol; Moseley, Pope

    2014-06-01

    Gastrointestinal distress, such as diarrhoea, cramping, vomiting, nausea and gastric pain are common among athletes during training and competition. The mechanisms that cause these symptoms are not fully understood. The stress of heat and oxidative damage during exercise causes disruption to intestinal epithelial cell tight junction proteins resulting in increased permeability to luminal endotoxins. The endotoxin moves into the blood stream leading to a systemic immune response. Tight junction integrity is altered by the phosphoylation state of the proteins occludin and claudins, and may be regulated by the type of exercise performed. Prolonged exercise and high-intensity exercise lead to an increase in key phosphorylation enzymes that ultimately cause tight junction dysfunction, but the mechanisms are different. The purpose of this review is to (1) explain the function and physiology of tight junction regulation, (2) discuss the effects of prolonged and high-intensity exercise on tight junction permeability leading to gastrointestinal distress and (3) review agents that may increase or decrease tight junction integrity during exercise.

  4. Predictive modelling of ferroelectric tunnel junctions

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  5. Graphene tunnel junctions with aluminum oxide barrier

    NASA Astrophysics Data System (ADS)

    Feng, Ying; Trainer, Daniel J.; Chen, Ke

    2016-10-01

    We report a development of graphene tunnel junctions made by chemical vapor deposition grown graphene and sputtered aluminum insulating by an in-situ grown aluminum oxide. The thin oxide layer formed in between the metal layer and the two-dimensional material is a crucial part of a tunnel junction. We characterized surface morphology of oxide layers and studied tunneling spectra of lead and silver tunnel junctions to estimate the quality of the aluminum oxide. The Brinkman-Rowell-Dynes model was applied to fit the conductance-voltage plots to calculate the thickness of oxide layers. Junctions with graphene both on bottom and on top were fabricated and their tunneling properties were characterized after exposure to air for weeks to test time stability. Furthermore, the resistances of graphene tunnel junctions with aluminum oxide formed naturally and in an oxygen atmosphere were studied. Our results demonstrate that in-situ aluminum oxide is an effective barrier for graphene tunnel junctions. The methods of barrier formation enable the realization of more tunnel devices and circuits based on graphene.

  6. Craniovertebral junction lesions: our experience with the transoral surgical approach.

    PubMed

    Mouchaty, Homère; Perrini, Paolo; Conti, Renato; Di Lorenzo, Nicola

    2009-06-01

    The aim of this study is to review our experience with the transoral surgical management of anterior craniovertebral junction (CVJ) lesions with particular attention to the decision making and to the indication for a consecutive stabilization. During 10 years (1998-2007), 52 consecutive patients presenting exclusively fixed anterior compression at the cervicomedullary junction underwent transoral surgery. Mean age was 55.85 years (range 17-75 years). Encountered lesions were: malformation (32 cases), rheumatoid arthritis (11 cases), tumor (5 cases) or trauma (4 cases). A total of 79% of patients presented with chronic/recurrent headache (cranial and/or high-cervical pain), 73% with varying degrees of quadrip aresis, and 29% with lower cranial nerve deficits. All of the patients but two, with posterior stabilization performed elsewhere, underwent synchronous anterior decompression and posterior occipitocervical fixation. Adjuncts to the transoral approach (Le Fort I with or without splitting of the palate), tailored to the local anatomy and to the extension of the lesions, were performed in seven cases. Follow-up ranged between 4 and 96 months. Of 35 patients with severe preoperative neurological deficits, 33 improved. The remaining 15 patients who presented with mild symptoms, healed throughout the follow-up. Perioperative mortality occurred in two cases and surgical morbidity in eight cases (dural laceration, cerebrospinal fluid leak with meningitis, malocclusion, oral wound dehiscence and occipital wound infection). Delayed instability occurred in one patient because of cranial settling of C2 vertebral body. A successful surgery achieving a stable decompression at the CVJ is an expertise demanding procedure. It requires accurate preoperative evaluation and, appropriate choice of decompression technique and stabilization instruments. Enlarged transoral approaches (despite higher morbidity) are a supportive means in cases of severe basilar invagination, cranial

  7. Charge transport in nanoscale junctions.

    PubMed

    Albrecht, Tim; Kornyshev, Alexei; Bjørnholm, Thomas

    2008-09-03

    many particle excitations, new surface states in semiconductor electrodes, various mechanisms for single molecule rectification of the current, inelastic electron spectra and SERS spectroscopy. Three terminal architectures allowing (electrochemical) gating and transistor effects. Electrochemical nanojunctions and gating: intermolecular electron transfer in multi-redox metalloproteins, contact force modulation, characteristic current-noise patterns due to conformational fluctuations, resonance effects and electrocatalysis. Novel architectures: linear coupled quantum-dot-bridged junctions, electrochemical redox mediated transfer in two center systems leading to double maxima current-voltage plots and negative differential resistance, molecular-nanoparticle hybrid junctions and unexpected mesoscopic effects in polymeric wires. Device integration: techniques for creating stable metal/molecule/metal junctions using 'nano-alligator clips' and integration with 'traditional' silicon-based technology. The Guest Editors would like to thank all of the authors and referees of this special issue for their meticulous work in making each paper a valuable contribution to this research area, the early-bird authors for their patience, and Journal of Physics: Condensed Matter editorial staff in Bristol for their continuous support.

  8. Spectrum of Lesions Affecting the Renal Pelvis and Pelviureteric Junction: A 13-Year Retrospective Analysis

    PubMed Central

    Kini, Hema; Suresh, Pooja Kundapur; Guni, Laxman Prabhu Gurupur; Bhat, Shaila; Kini, Jyoti Ramanath

    2016-01-01

    Introduction Both, the renal pelvis and the ureter, are affected by developmental, reactive and neoplastic disorders, though rare in incidence. Aim This series of cases were analysed to study the clinicopathological characteristics of the common and comparatively rare lesions involving the renal pelvis and pelviureteric junction. Materials and Methods A retrospective collection of 476 nephrectomies and pelviureteric junction resections, received over a period of 13 years from 2001 to 2013 was done. The patients’ clinical details were obtained and the histopathological findings reviewed. The lesions were classified into non-neoplastic and neoplastic categories. Results Primary involvement of the renal pelvis and pelviureteric junction was seen in 105 of 476 specimens. The mean age was 54.5 years with a male to female ratio of 2.2:1. The non-neoplastic lesions accounted for 76.2% of cases with a majority being pelviureteric junction obstruction due to inflammation induced fibromuscular hypertrophy (68.6%) causing hydronephrosis. Urothelial carcinomas were encountered in 20% of the cases. A majority of the urothelial carcinomas were infiltrative (81%) and high grade (71%) tumours. Conclusion Renal pelvis, a conduit to propel urine, can be the site for numerous disorders. Non-neoplastic lesions were more common than neoplasms. Pelviureteric junction obstruction due to inflammation induced fibromuscular hypertrophy was the commonest lesion in our study. In the neoplastic category, urothelial carcinoma was most common. However, rare lesions such as hamartomatous fibroepithelial polyp, Von Brunn’s nests, flat urothelial hyperplasia and intramuscular haemangioma of upper ureter at the pelviureteric junction were encountered along with occasional cases of tuberculosis and squamous cell carcinomas. PMID:27042468

  9. Model Building to Facilitate Understanding of Holliday Junction and Heteroduplex Formation, and Holliday Junction Resolution

    ERIC Educational Resources Information Center

    Selvarajah, Geeta; Selvarajah, Susila

    2016-01-01

    Students frequently expressed difficulty in understanding the molecular mechanisms involved in chromosomal recombination. Therefore, we explored alternative methods for presenting the two concepts of the double-strand break model: Holliday junction and heteroduplex formation, and Holliday junction resolution. In addition to a lecture and…

  10. Conductance of d-wave superconductor/normal metal/d-wave superconductor junctions

    NASA Astrophysics Data System (ADS)

    Pesin, Dmytro; Andreev, Anton; Spivak, Boris

    2008-03-01

    We develop a theory of the low-temperature conductance of superconductor/normal metal/superconductor junctions in which the superconductors have d-wave pairing symmetry. We show that at low temperatures the conductance of the junction is determined by the inelastic relaxation time of quasiparticles in the bulk of d-wave superconductors, GDND√&(d)circ;ɛ. Thus it greatly exceeds the conductance of the normal metal part of the junction, which is controlled by the elastic mean free path. This dependence of GDND on the inelastic relaxation time should be contrasted with that of the low-temperature conductance of the junction in the case of the s- wave superconductor leads, GSNS. In the latter case the conductance is proportional to the first power of the inelastic electron relaxation time in the normal metal part of the junction, GSNSτɛ^(n) [1]. [1] S. V. Lempitskii, Sov. Phys. JETP 58, 624 (1983); U. Gunsenheimer and A. D. Zaikin, Phys. Rev. B50, 6317 (1994); F. Zhou and B. Spivak, JETP Lett. 65, 369 (1997).

  11. Iniencephaly: Radiological and pathological features of a series of three cases.

    PubMed

    Chikkannaiah, Panduranga; Srinivasamurthy, V; Satish Prasad, B S; Lalyanayak, Pradeepkumar; Shivaram, Divya N

    2014-10-01

    Iniencephaly is a rare form of neural tube defect with an incidence of 0.1-10 in 10,000 pregnancies. It is characterized by the presence of occipital bone defects at foramen magnum, fixed retroflexion of head, spinal dysmorphism, and lordosis of cervicothoracic vertebrae. It is usually associated with central nervous system, gastrointestinal, and cardiovascular anomalies. We present radiological and autopsy findings in a series of 3 cases of iniencephaly (gestational ages 29.3, 23, and 24 weeks) first fetus in addition showed omphalocele, pulmonary hypoplasia, two lobes in right lung, accessory spleen, atrial septal defect, bilateral clubfoot, ambiguous genitalia, and single umbilical artery. Second fetus was a classical case of iniencephaly apertus with spina bifida. Third fetus had colpocephaly and bifid spine.

  12. Iniencephaly: Radiological and pathological features of a series of three cases

    PubMed Central

    Chikkannaiah, Panduranga; Srinivasamurthy, V.; Satish Prasad, B. S.; Lalyanayak, Pradeepkumar; Shivaram, Divya N.

    2014-01-01

    Iniencephaly is a rare form of neural tube defect with an incidence of 0.1-10 in 10,000 pregnancies. It is characterized by the presence of occipital bone defects at foramen magnum, fixed retroflexion of head, spinal dysmorphism, and lordosis of cervicothoracic vertebrae. It is usually associated with central nervous system, gastrointestinal, and cardiovascular anomalies. We present radiological and autopsy findings in a series of 3 cases of iniencephaly (gestational ages 29.3, 23, and 24 weeks) first fetus in addition showed omphalocele, pulmonary hypoplasia, two lobes in right lung, accessory spleen, atrial septal defect, bilateral clubfoot, ambiguous genitalia, and single umbilical artery. Second fetus was a classical case of iniencephaly apertus with spina bifida. Third fetus had colpocephaly and bifid spine. PMID:25288843

  13. Clathrin and Cx43 gap junction plaque endoexocytosis

    SciTech Connect

    Nickel, Beth M.; DeFranco, B. Hewa; Gay, Vernon L.; Murray, Sandra A.

    2008-10-03

    In earlier transmission electron microscopic studies, we have described pentilaminar gap junctional membrane invaginations and annular gap junction vesicles coated with short, electron-dense bristles. The similarity between these electron-dense bristles and the material surrounding clathrin-coated pits led us to suggest that the dense bristles associated with gap junction structures might be clathrin. To confirm that clathrin is indeed associated with annular gap junction vesicles and gap junction plaques, quantum dot immuno-electron microscopic techniques were used. We report here that clathrin associates with both connexin 43 (Cx43) gap junction plaques and pentilaminar gap junction vesicles. An important finding was the preferential localization of clathrin to the cytoplasmic surface of the annular or of the gap junction plaque membrane of one of the two contacting cells. This is consistent with the possibility that the direction of gap junction plaque internalization into one of two contacting cells is regulated by clathrin.

  14. Tunnel junctions, cantilevers, and potentials

    NASA Astrophysics Data System (ADS)

    Tanner, Shawn

    We have developed a process for making sub-micrometer dimensional cantilevers, clamped beams, and more complicate electro-mechanical structures that carry integrated electrical leads. Such objects are perhaps useful as test structures for connecting to and measuring the electrical properties of molecular sized objects, as high frequency electromechanical components for radio and microwave frequency applications, and as sensor components for studying the fluctuation physics of small machines. Our process uses two realigned electron-beam lithography steps, a thin film angled deposition system, and differential removal of sacrificial aluminum layers to produce freely suspended sub-micron electromechanical components. We have produced cantilevers and beams on a variety of substrates (silica, silicon, and poly-imide) and have produced insulating, conductive, and multi-layer mechanical structures. We have measured mechanical resonances in the 10 MHz range by electrostatically actuating the cantilevers while in a magnetic field (3500 gauss) and measuring the voltage that results across the front edge of the cantilever. Two structures are fabricated sharing a common ground so that a balanced detection technique can be used to eliminate background signals. Due to the square dependence of the electrostatic force on the voltage, they can be resonated by a drive voltage of 1/2 the natural frequency or at the natural frequency. Two separate attempts have been made to apply these resonators. First, a process was developed to integrate a tunnel junction with the cantilever. These devices can possibly be used for probing small-scale systems such as molecules. We have verified the exponential variation of the tunneling resistance with both substrate flex and electrostatic gating. Second, a novel gate structure was developed to create a double potential well for resonator motion. This is accomplished by placing a multilayer structure in front of the hairpin cantilever consisting two

  15. YBCO step-edge junctions with high IcRn

    NASA Astrophysics Data System (ADS)

    Mitchell, E. E.; Foley, C. P.

    2010-06-01

    Step-edge junctions represent one type of grain boundary Josephson junction employed in high-temperature superconducting junction technology. To date, the majority of results published in the literature focus on [001]-tilt grain boundary junctions (GBJs) produced using bicrystal substrates. We investigate the step morphology and YBCO (yttrium barium copper oxide) film structure of YBCO-based step-edge junctions on MgO [001] substrates which structurally resemble [100]-tilt junctions. High-resolution electron microscopy reveals a clean GBJ interface of width ~ 1 nm and a single junction at the top edge. The dependence of the transport properties on the MgO step-edge and junction morphology is examined at 4.2 K, to enable direct comparison with results for other junction studies such as [001]-tilt and [100]-tilt junctions and building on previously published 77 K data. MgO step-edge junctions show a slower reduction in critical current density with step angle compared with [001]-tilt junctions. For optimized step parameters, transport measurements revealed large critical current and normal resistance (IcRN) products (~3-5 mV), comparable with the best results obtained in other kinds of [100]-tilt GBJs in YBCO at 4.2 K. Junction-based devices such as SQUIDs (superconducting quantum interference devices) and THz imagers show excellent performance when MgO-based step-edge junctions are used.

  16. Semiconductor Lasers Containing Quantum Wells in Junctions

    NASA Technical Reports Server (NTRS)

    Yang, Rui Q.; Qiu, Yueming

    2004-01-01

    In a recent improvement upon In(x)Ga(1-x)As/InP semiconductor lasers of the bipolar cascade type, quantum wells are added to Esaki tunnel junctions, which are standard parts of such lasers. The energy depths and the geometric locations and thicknesses of the wells are tailored to exploit quantum tunneling such that, as described below, electrical resistances of junctions and concentrations of dopants can be reduced while laser performances can be improved. In(x)Ga(1-x)As/InP bipolar cascade lasers have been investigated as sources of near-infrared radiation (specifically, at wavelengths of about 980 and 1,550 nm) for photonic communication systems. The Esaki tunnel junctions in these lasers have been used to connect adjacent cascade stages and to enable transport of charge carriers between them. Typically, large concentrations of both n (electron-donor) and p (electron-acceptor) dopants have been necessary to impart low electrical resistances to Esaki tunnel junctions. Unfortunately, high doping contributes free-carrier absorption, thereby contributing to optical loss and thereby, further, degrading laser performance. In accordance with the present innovation, quantum wells are incorporated into the Esaki tunnel junctions so that the effective heights of barriers to quantum tunneling are reduced (see figure).

  17. Dislocation Multi-junctions and Strain Hardening

    SciTech Connect

    Bulatov, V; Hsiung, L; Tang, M; Arsenlis, A; Bartelt, M; Cai, W; Florando, J; Hiratani, M; Rhee, M; Hommes, G; Pierce, T; Diaz de la Rubia, T

    2006-06-20

    At the microscopic scale, the strength of a crystal derives from the motion, multiplication and interaction of distinctive line defects--dislocations. First theorized in 1934 to explain low magnitudes of crystal strength observed experimentally, the existence of dislocations was confirmed only two decades later. Much of the research in dislocation physics has since focused on dislocation interactions and their role in strain hardening: a common phenomenon in which continued deformation increases a crystal's strength. The existing theory relates strain hardening to pair-wise dislocation reactions in which two intersecting dislocations form junctions tying dislocations together. Here we report that interactions among three dislocations result in the formation of unusual elements of dislocation network topology, termed hereafter multi-junctions. The existence of multi-junctions is first predicted by Dislocation Dynamics (DD) and atomistic simulations and then confirmed by the transmission electron microscopy (TEM) experiments in single crystal molybdenum. In large-scale Dislocation Dynamics simulations, multi-junctions present very strong, nearly indestructible, obstacles to dislocation motion and furnish new sources for dislocation multiplication thereby playing an essential role in the evolution of dislocation microstructure and strength of deforming crystals. Simulation analyses conclude that multi-junctions are responsible for the strong orientation dependence of strain hardening in BCC crystals.

  18. Dislocation multi-junctions and strain hardening.

    PubMed

    Bulatov, Vasily V; Hsiung, Luke L; Tang, Meijie; Arsenlis, Athanasios; Bartelt, Maria C; Cai, Wei; Florando, Jeff N; Hiratani, Masato; Rhee, Moon; Hommes, Gregg; Pierce, Tim G; de la Rubia, Tomas Diaz

    2006-04-27

    At the microscopic scale, the strength of a crystal derives from the motion, multiplication and interaction of distinctive line defects called dislocations. First proposed theoretically in 1934 (refs 1-3) to explain low magnitudes of crystal strength observed experimentally, the existence of dislocations was confirmed two decades later. Much of the research in dislocation physics has since focused on dislocation interactions and their role in strain hardening, a common phenomenon in which continued deformation increases a crystal's strength. The existing theory relates strain hardening to pair-wise dislocation reactions in which two intersecting dislocations form junctions that tie the dislocations together. Here we report that interactions among three dislocations result in the formation of unusual elements of dislocation network topology, termed 'multi-junctions'. We first predict the existence of multi-junctions using dislocation dynamics and atomistic simulations and then confirm their existence by transmission electron microscopy experiments in single-crystal molybdenum. In large-scale dislocation dynamics simulations, multi-junctions present very strong, nearly indestructible, obstacles to dislocation motion and furnish new sources for dislocation multiplication, thereby playing an essential role in the evolution of dislocation microstructure and strength of deforming crystals. Simulation analyses conclude that multi-junctions are responsible for the strong orientation dependence of strain hardening in body-centred cubic crystals.

  19. Role of gap junctions in the propagation of the cardiac action potential.

    PubMed

    Rohr, Stephan

    2004-05-01

    Gap junctions play a pivotal role for the velocity and the safety of impulse propagation in cardiac tissue. Under physiologic conditions, the specific subcellular distribution of gap junctions together with the tight packaging of the rod-shaped cardiomyocytes underlies anisotropic conduction, which is continuous at the macroscopic scale. However, when breaking down the three-dimensional network of cells into linear single cell chains, gap junctions can be shown to limit axial current flow and to induce 'saltatory' conduction at unchanged overall conduction velocities. In two- and three-dimensional tissue, these discontinuities disappear due to lateral averaging of depolarizing current flow at the activation wavefront. During gap junctional uncoupling, discontinuities reappear and are accompanied by slowed and meandering conduction. Critical gap junctional uncoupling reduces conduction velocities to a much larger extent than does a reduction of excitability, which suggests that the safety for conduction is higher at any given conduction velocity for gap junctional uncoupling. In uniformly structured tissue, gap junctional uncoupling is accompanied by a parallel decrease in conduction velocity. However, this is not necessarily the case for non-uniform structures like tissue expansion where partial uncoupling paradoxically increases conduction velocity and has the capacity to remove unidirectional conduction blocks. Whereas the impact of gap junctions on impulse conduction is generally assessed from the point of view of cell coupling among cardiomyocytes, it is possible that other cell types within the myocardium might be coupled to cardiomyocytes as well. In this context, it has been shown that fibroblasts establish successful conduction between sheets of cardiomyocytes over distances as long as 300 microm. This might not only explain electrical synchronization of heart transplants but might be of importance for cardiac diseases involving fibrosis. Finally, the

  20. Methods for the fabrication of thermally stable magnetic tunnel junctions

    SciTech Connect

    Chang, Y. Austin; Yang, Jianhua J.; Ladwig, Peter F.

    2009-08-25

    Magnetic tunnel junctions and method for making the magnetic tunnel junctions are provided. The magnetic tunnel junctions are characterized by a tunnel barrier oxide layer sandwiched between two ferromagnetic layers. The methods used to fabricate the magnetic tunnel junctions are capable of completely and selectively oxidizing a tunnel junction precursor material using an oxidizing gas containing a mixture of gases to provide a tunnel junction oxide without oxidizing the adjacent ferromagnetic materials. In some embodiments the gas mixture is a mixture of CO and CO.sub.2 or a mixture of H.sub.2 and H.sub.2O.

  1. Thermionic refrigeration at CNT-CNT junctions

    NASA Astrophysics Data System (ADS)

    Li, C.; Pipe, K. P.

    2016-10-01

    Monte Carlo (MC) simulation is used to study carrier energy relaxation following thermionic emission at the junction of two van der Waals bonded single-walled carbon nanotubes (SWCNTs). An energy-dependent transmission probability gives rise to energy filtering at the junction, which is predicted to increase the average electron transport energy by as much as 0.115 eV, leading to an effective Seebeck coefficient of 386 μV/K. MC results predict a long energy relaxation length (˜8 μm) for hot electrons crossing the junction into the barrier SWCNT. For SWCNTs of optimal length, an analytical transport model is used to show that thermionic cooling can outweigh parasitic heat conduction due to high SWCNT thermal conductivity, leading to a significant cooling capacity (2.4 × 106 W/cm2).

  2. Junction-side illuminated silicon detector arrays

    DOEpatents

    Iwanczyk, Jan S.; Patt, Bradley E.; Tull, Carolyn

    2004-03-30

    A junction-side illuminated detector array of pixelated detectors is constructed on a silicon wafer. A junction contact on the front-side may cover the whole detector array, and may be used as an entrance window for light, x-ray, gamma ray and/or other particles. The back-side has an array of individual ohmic contact pixels. Each of the ohmic contact pixels on the back-side may be surrounded by a grid or a ring of junction separation implants. Effective pixel size may be changed by separately biasing different sections of the grid. A scintillator may be coupled directly to the entrance window while readout electronics may be coupled directly to the ohmic contact pixels. The detector array may be used as a radiation hardened detector for high-energy physics research or as avalanche imaging arrays.

  3. Studies of silicon PN junction solar cells

    NASA Technical Reports Server (NTRS)

    Lindholm, F. A.

    1975-01-01

    Silicon pn junction solar cells made with low-resistivity substrates show poorer performance than traditional theory predicts. The purpose of this research was to identify and characterize the physical mechanisms responsible for the discrepancy. Attention was concentrated on the open circuit voltage in shallow junction cells of 0.1 ohm-cm substrate resistivity. A number of possible mechanisms that can occur in silicon devices were considered. Two mechanisms which are likely to be of main importance in explaining the observed low values of open-circuit voltage were found: (1) recombination losses associated with defects introduced during junction formation, and (2) inhomogeneity of defects and impurities across the area of the cell. To explore these theoretical anticipations, various diode test structures were designed and fabricated and measurement configurations for characterizing the defect properties and the areal inhomogeneity were constructed.

  4. Electrostatic Modeling of Vacuum Insulator Triple Junctions

    SciTech Connect

    Tully, L K; Goerz, D A; Houck, T L; Javedani, J B

    2006-10-25

    Triple junctions are often initiation points for insulator flashover in pulsed power devices. The two-dimensional finite-element TriComp [1] modeling software suite was utilized for its electrostatic field modeling package to investigate electric field behavior in the anode and cathode triple junctions of a high voltage vacuum-insulator interface. TriComp enables simple extraction of values from a macroscopic solution for use as boundary conditions in a subset solution. Electric fields computed with this zoom capability correlate with theoretical analysis of the anode and cathode triple junctions within submicron distances for nominal electrode spacing of 1.0 cm. This paper will discuss the iterative zoom process with TriComp finite-element software and the corresponding theoretical verification of the results.

  5. Photocurrent Measurements of Carbon Nanotube PN Junctions

    NASA Astrophysics Data System (ADS)

    Gabor, Nathaniel; Zhong, Zhaohui; Bosnick, Ken; Park, Jiwoong; McEuen, Paul

    2007-03-01

    Gated p-n junctions in semiconducting nanotubes have recently drawn much attention for their electronic and optoelectronic characteristics [1,2,3]. We investigate the photocurrent response at a nanotube gated p-n junction using a focused laser illumination source. We find that the photocurrent at zero source-drain bias increases linearly with optical power for the component of light along the length of the nanotube. Scanned photocurrent imaging demonstrates that carrier generation occurs primarily between the p- and n- type segments of the device. Measurements in an optical cryostat down to 4K reveal large photoresponse and step-like structure in the reverse bias photocurrent. These results show that nanotube p-n junctions are highly sensitive, nanoscale photodetectors. [1] J.U. Lee et al, App. Phys. Lett. 85, 145 (2004). [2] J.U. Lee, App. Phys. Lett. 87, 073101 (2005). [3] K. Bosnick et al, App. Phys. Lett. 89, 163121 (2006).

  6. Tunnel junction based memristors as artificial synapses

    PubMed Central

    Thomas, Andy; Niehörster, Stefan; Fabretti, Savio; Shepheard, Norman; Kuschel, Olga; Küpper, Karsten; Wollschläger, Joachim; Krzysteczko, Patryk; Chicca, Elisabetta

    2015-01-01

    We prepared magnesia, tantalum oxide, and barium titanate based tunnel junction structures and investigated their memristive properties. The low amplitudes of the resistance change in these types of junctions are the major obstacle for their use. Here, we increased the amplitude of the resistance change from 10% up to 100%. Utilizing the memristive properties, we looked into the use of the junction structures as artificial synapses. We observed analogs of long-term potentiation, long-term depression and spike-time dependent plasticity in these simple two terminal devices. Finally, we suggest a possible pathway of these devices toward their integration in neuromorphic systems for storing analog synaptic weights and supporting the implementation of biologically plausible learning mechanisms. PMID:26217173

  7. Numerical Investigation of Josephson Junction Structures

    SciTech Connect

    Hristov, I.; Dimova, S.; Boyadjiev, T.

    2009-10-29

    Multilayered long Josephson Junction Structures form an interesting physical system where both nonlinearity and interaction between subsystems play an important role. Such systems allow to study physical effects that do not occur in single Josephson junction.The Sakai-Bodin-Pedersen model--a system of perturbed sine-Gordon equations--is used to study the dynamic states of stacks of inductively coupled long Josephson Junctions (LJJs). The corresponding static problem is numerically investigated as well. In order to study the stability of possible static solutions a Sturm-Liouville problem is generated and solved.The transitions from static to dynamic state and the scenario of these transitions are analyzed depending on the model parameters. Different physical characteristics--current-voltage characteristics, individual instant voltages and internal magnetic fields, are calculated and interpreted.

  8. Brownian refrigeration by hybrid tunnel junctions

    NASA Astrophysics Data System (ADS)

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

    2011-10-01

    Voltage fluctuations generated in a hot resistor can cause extraction of heat from a colder normal metal electrode of a hybrid tunnel junction between a normal metal and a superconductor. We extend the analysis presented in Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.98.210604 98, 210604 (2007) of this heat rectifying system, bearing resemblance to a Maxwell’s demon. Explicit analytic calculations show that the entropy of the total system is always increasing. We then consider a single-electron transistor configuration with two hybrid junctions in series, and show how the cooling is influenced by charging effects. We analyze also the cooling effect from nonequilibrium fluctuations instead of thermal noise, focusing on the shot noise generated in another tunnel junction. We conclude by discussing limitations for an experimental observation of the effect.

  9. Electromagnetic scattering from two-dimensional thick material junctions

    NASA Technical Reports Server (NTRS)

    Ricoy, M. A.; Volakis, John L.

    1990-01-01

    The problem of the plane wave diffraction is examined by an arbitrary symmetric two dimensional junction, where Generalized Impedance Boundary Conditions (GIBCs) and Generalized Sheet Transition Conditions (GSTCs) are employed to simulate the slabs. GIBCs and GSTCs are constructed for multilayer planar slabs of arbitrary thickness and the resulting GIBC/GSTC reflection coefficients are compared with exact counterparts to evaluate the GIBCs/GSTCs. The plane wave diffraction by a multilayer material slab recessed in a perfectly conducting ground plane is formulated and solved via the Generalized Scattering Matrix Formulation (GDMF) in conjunction with the dual integral equation approach. Various scattering patterns are computed and validated with exact results where possible. The diffraction by a material discontinuity in a thick dielectric/ferrite slab is considered by modelling the constituent slabs with GSTCs. A non-unique solution in terms of unknown constants is obtained, and these constants are evaluated for the recessed slab geometry by comparison with the solution obtained therein. Several other simplified cases are also presented and discussed. An eigenfunction expansion method is introduced to determine the unknown solution constants in the general case. This procedure is applied to the non-unique solution in terms of unknown constants; and scattering patterns are presented for various slab junctions and compared with alternative results where possible.

  10. Density Functional Theory for Steady-State Nonequilibrium Molecular Junctions

    PubMed Central

    Liu, Shuanglong; Nurbawono, Argo; Zhang, Chun

    2015-01-01

    We present a density functional theory (DFT) for steady-state nonequilibrium quantum systems such as molecular junctions under a finite bias. Based on the steady-state nonequilibrium statistics that maps nonequilibrium to an effective equilibrium, we show that ground-state DFT (GS-DFT) is not applicable in this case and two densities, the total electron density and the density of current-carrying electrons, are needed to uniquely determine the properties of the corresponding nonequilibrium system. A self-consistent mean-field approach based on two densities is then derived. The theory is implemented into SIESTA computational package and applied to study nonequilibrium electronic/transport properties of a realistic carbon-nanotube (CNT)/Benzene junction. Results obtained from our steady-state DFT (SS-DFT) are compared with those of conventional GS-DFT based transport calculations. We show that SS-DFT yields energetically more stable nonequilibrium steady state, predicts significantly lower electric current, and is able to produce correct electronic structures in local equilibrium under a limiting case. PMID:26472080

  11. Electronic Properties of Carbon Nanotubes and Junctions

    NASA Technical Reports Server (NTRS)

    Anantram, M. P.; Han, Jie; Yang, Liu; Govindan, T. R.; Jaffe, R.; Saini, Subhash (Technical Monitor)

    1998-01-01

    Metallic and semiconducting Single Wall Carbon Nanotubes (CNT) have recently been characterized using scanning tunneling microscopy (STM) and the manipulation of individual CNT has been demonstrated. These developments make the prospect of using CNT as molecular wires and possibly as electronic devices an even more interesting one. We have been modeling various electronic properties such as the density of states and the transmission coefficient of CNT wires and junctions. These studies involve first calculating the stability of junctions using molecular dynamics simulations and then calculating the electronic properties using a pi-electron tight binding Hamiltonian. We have developed the expertise to calculate the electronic properties of both finite-sized CNT and CNT systems with semi-infinite boundary conditions. In this poster, we will present an overview of some of our results. The electronic application of CNT that is most promising at this time is their use as molecular wires. The conductance can however be greatly reduced because of reflection due to defects and contacts. We have modeled the transmission through CNT in the presence of two types of defects: weak uniform disorder and strong isolated scatterers. We find that the conductance is affected in significantly different manners due to these defects Junctions of CNT have also been imaged using STM. This makes it essential to derive rules for the formation of junctions between tubes of different chirality, study their relative energies and electronic properties. We have generalized the rules for connecting two different CNT and have calculated the transmission and density of states through CNT junctions. Metallic and semiconducting CNT can be joined to form a stable junction and their current versus voltage characteristics are asymmetric. CNT are deformed by the application of external forces including interactions with a substrate or other CNT. In many experiments, these deformation are expected to

  12. Non-invasive microfluidic gap junction assay.

    PubMed

    Chen, Sisi; Lee, Luke P

    2010-03-01

    Gap junctions are protein channels between cells that allow direct electrical and metabolic coupling via the exchange of biomolecules and ions. Their expression, though ubiquitous in most mammalian cell types, is especially important for the proper functioning of cardiac and neuronal systems. Many existing methods for studying gap junction communication suffer from either unquantifiable data or difficulty of use. Here, we measure the extent of dye spread and effective diffusivities through gap junction connected cells using a quantitative microfluidic cell biology platform. After loading dye by hydrodynamic focusing of calcein/AM, dye transfer dynamics into neighboring, unexposed cells can be monitored via timelapse fluorescent microscopy. By using a selective microfluidic dye loading over a confluent layer of cells, we found that high expression of gap junctions in C6 cells transmits calcein across the monolayer with an effective diffusivity of 3.4 x 10(-13) m(2)/s, which are highly coupled by Cx43. We also found that the gap junction blocker 18alpha-GA works poorly in the presence of serum even at high concentrations (50 microM); however, it is highly effective down to 2.5 microM in the absence of serum. Furthermore, when the drug is washed out, dye spread resumes rapidly within 1 min for all doses, indicating the drug does not affect transcriptional regulation of connexins in these Cx43+ cells, in contrast to previous studies. This integrated microfluidic platform enables the in situ monitoring of gap junction communication, yielding dynamic information about intercellular molecular transfer and pharmacological inhibition and recovery.

  13. Structure and function of gap junction proteins: role of gap junction proteins in embryonic heart development.

    PubMed

    Ahir, Bhavesh K; Pratten, Margaret K

    2014-01-01

    Intercellular (cell-to-cell) communication is a crucial and complex mechanism during embryonic heart development. In the cardiovascular system, the beating of the heart is a dynamic and key regulatory process, which is functionally regulated by the coordinated spread of electrical activity through heart muscle cells. Heart tissues are composed of individual cells, each bearing specialized cell surface membrane structures called gap junctions that permit the intercellular exchange of ions and low molecular weight molecules. Gap junction channels are essential in normal heart function and they assist in the mediated spread of electrical impulses that stimulate synchronized contraction (via an electrical syncytium) of cardiac tissues. This present review describes the current knowledge of gap junction biology. In the first part, we summarise some relevant biochemical and physiological properties of gap junction proteins, including their structure and function. In the second part, we review the current evidence demonstrating the role of gap junction proteins in embryonic development with particular reference to those involved in embryonic heart development. Genetics and transgenic animal studies of gap junction protein function in embryonic heart development are considered and the alteration/disruption of gap junction intercellular communication which may lead to abnormal heart development is also discussed.

  14. Endoscopic Removal of a Nitinol Mesh Stent from the Ureteropelvic Junction after 15 Years

    PubMed Central

    Smrkolj, Tomaž; Šalinović, Domagoj

    2015-01-01

    We report a rare case of a patient with a large stone encrusted on a nitinol mesh stent in the ureteropelvic junction. The stent was inserted in the year 2000 after failure of two pyeloplasty procedures performed due to symptomatic ureteropelvic junction stenosis. By combining minimally invasive urinary stone therapies—extracorporeal shock wave lithotripsy, semirigid ureterorenoscopy with laser lithotripsy, and percutaneous nephrolithotomy—it was possible to completely remove the encrusted stone and nitinol mesh stent that was implanted for 15 years, rendering the patient symptom and obstruction free. PMID:26697258

  15. Using ion irradiation to make high-T{sub c} Josephson junctions

    SciTech Connect

    Bergeal, N.; Lesueur, J.; Sirena, M.; Faini, G.; Aprili, M.; Contour, J. P.; Leridon, B.

    2007-10-15

    In this article we describe the effect of ion irradiation on high-T{sub c} superconductor thin film and its interest for the fabrication of Josephson junctions. In particular, we show that these alternative techniques allow to go beyond most of the limitations encountered in standard junction fabrication methods, both in the case of fundamental and technological purposes. Two different geometries are presented: a planar one using a single high-T{sub c} film and a mesa one defined in a trilayer structure.

  16. Complementary junction heterostructure field-effect transistor

    DOEpatents

    Baca, A.G.; Drummond, T.J.; Robertson, P.J.; Zipperian, T.E.

    1995-12-26

    A complimentary pair of compound semiconductor junction heterostructure field-effect transistors and a method for their manufacture are disclosed. The p-channel junction heterostructure field-effect transistor uses a strained layer to split the degeneracy of the valence band for a greatly improved hole mobility and speed. The n-channel device is formed by a compatible process after removing the strained layer. In this manner, both types of transistors may be independently optimized. Ion implantation is used to form the transistor active and isolation regions for both types of complimentary devices. The invention has uses for the development of low power, high-speed digital integrated circuits. 10 figs.

  17. Complementary junction heterostructure field-effect transistor

    DOEpatents

    Baca, Albert G.; Drummond, Timothy J.; Robertson, Perry J.; Zipperian, Thomas E.

    1995-01-01

    A complimentary pair of compound semiconductor junction heterostructure field-effect transistors and a method for their manufacture are disclosed. The p-channel junction heterostructure field-effect transistor uses a strained layer to split the degeneracy of the valence band for a greatly improved hole mobility and speed. The n-channel device is formed by a compatible process after removing the strained layer. In this manner, both types of transistors may be independently optimized. Ion implantation is used to form the transistor active and isolation regions for both types of complimentary devices. The invention has uses for the development of low power, high-speed digital integrated circuits.

  18. Fluctuation of heat current in Josephson junctions

    SciTech Connect

    Virtanen, P.; Giazotto, F.

    2015-02-15

    We discuss the statistics of heat current between two superconductors at different temperatures connected by a generic weak link. As the electronic heat in superconductors is carried by Bogoliubov quasiparticles, the heat transport fluctuations follow the Levitov–Lesovik relation. We identify the energy-dependent quasiparticle transmission probabilities and discuss the resulting probability density and fluctuation relations of the heat current. We consider multichannel junctions, and find that heat transport in diffusive junctions is unique in that its statistics is independent of the phase difference between the superconductors.

  19. Resolving Atomic Connectivity in Graphene Nanostructure Junctions.

    PubMed

    Dienel, Thomas; Kawai, Shigeki; Söde, Hajo; Feng, Xinliang; Müllen, Klaus; Ruffieux, Pascal; Fasel, Roman; Gröning, Oliver

    2015-08-12

    We report on the structural characterization of junctions between atomically well-defined graphene nanoribbons (GNRs) by means of low-temperature, noncontact scanning probe microscopy. We show that the combination of simultaneously acquired frequency shift and tunneling current maps with tight binding (TB) simulations allows a comprehensive characterization of the atomic connectivity in the GNR junctions. The proposed approach can be generally applied to the investigation of graphene nanomaterials and their interconnections and is thus expected to become an important tool in the development of graphene-based circuitry.

  20. A proposed route to independent measurements of tight junction conductance at discrete cell junctions

    PubMed Central

    Zhou, Lushan; Zeng, Yuhan; Baker, Lane A; Hou, Jianghui

    2015-01-01

    Direct recording of tight junction permeability is of pivotal importance to many biologic fields. Previous approaches bear an intrinsic disadvantage due to the difficulty of separating tight junction conductance from nearby membrane conductance. Here, we propose the design of Double whole-cell Voltage Clamp - Ion Conductance Microscopy (DVC-ICM) based on previously demonstrated potentiometric scanning of local conductive pathways. As proposed, DVC-ICM utilizes two coordinated whole-cell patch-clamps to neutralize the apical membrane current during potentiometric scanning, which in models described here will profoundly enhance the specificity of tight junction recording. Several potential pitfalls are considered, evaluated and addressed with alternative countermeasures. PMID:26716077

  1. Thermopower of benzenedithiol and C60 molecular junctions with Ni and Au electrodes.

    PubMed

    Lee, See Kei; Ohto, Tatsuhiko; Yamada, Ryo; Tada, Hirokazu

    2014-09-10

    We have performed thermoelectric measurements of benzenedithiol (BDT) and C60 molecules with Ni and Au electrodes using a home-built scanning tunneling microscope. The thermopower of C60 was negative for both Ni and Au electrodes, indicating the transport of carriers through the lowest unoccupied molecular orbital in both cases, as was expected from the work functions. On the other hand, the Ni-BDT-Ni junctions exhibited a negative thermopower, whereas the Au-BDT-Au junctions exhibited a positive thermopower. First-principle calculations revealed that the negative thermopower of Ni-BDT-Ni junctions is due to the spin-split hybridized states generated by the highest occupied molecular orbital of BDT coupled with s- and d-states of the Ni electrode.

  2. Molecule-lead coupling at molecular junctions: relation between the real- and state-space perspectives.

    PubMed

    Zelovich, Tamar; Kronik, Leeor; Hod, Oded

    2015-10-13

    We present insights into the lead-molecule coupling scheme in molecular electronics junctions. Using a "site-to-state" transformation that provides direct access to the coupling matrix elements between the molecular states and the eigenstate manifold of each lead, we find coupling bands whose character depends on the geometry and dimensionality of the lead. We use a standard tight-binding model to elucidate the origin of the coupling bands and explain their nature via simple "particle-in-a-box" type considerations. We further show that these coupling bands can shed light on the charge transport behavior of the junction. The picture presented in this study is not limited to the case of molecular electronics junctions and is relevant to any scenario where a finite molecular entity is coupled to a (semi)infinite system.

  3. Transition voltages of vacuum-spaced and molecular junctions with Ag and Pt electrodes

    SciTech Connect

    Wu, Kunlin; Bai, Meilin; Hou, Shimin; Sanvito, Stefano

    2014-07-07

    The transition voltage of vacuum-spaced and molecular junctions constructed with Ag and Pt electrodes is investigated by non-equilibrium Green's function formalism combined with density functional theory. Our calculations show that, similarly to the case of Au-vacuum-Au previously studied, the transition voltages of Ag and Pt metal-vacuum-metal junctions with atomic protrusions on the electrode surface are determined by the local density of states of the p-type atomic orbitals of the protrusion. Since the energy position of the Pt 6p atomic orbitals is higher than that of the 5p/6p of Ag and Au, the transition voltage of Pt-vacuum-Pt junctions is larger than that of both Ag-vacuum-Ag and Au-vacuum-Au junctions. When one moves to analyzing asymmetric molecular junctions constructed with biphenyl thiol as central molecule, then the transition voltage is found to depend on the specific bonding site for the sulfur atom in the thiol group. In particular agreement with experiments, where the largest transition voltage is found for Ag and the smallest for Pt, is obtained when one assumes S binding at the hollow-bridge site on the Ag/Au(111) surface and at the adatom site on the Pt(111) one. This demonstrates the critical role played by the linker-electrode binding geometry in determining the transition voltage of devices made of conjugated thiol molecules.

  4. Numerical study of three-dimensional separation and flow control at a wing/body junction

    NASA Technical Reports Server (NTRS)

    Ash, Robert L.; Lakshmanan, Balakrishnan

    1989-01-01

    The problem of three-dimensional separation and flow control at a wing/body junction has been investigated numerically using a three-dimensional Navier-Stokes code. The numerical code employs an algebraic grid generation technique for generating the grid for unmodified junction and an elliptic grid generation technique for filleted fin junction. The results for laminar flow past a blunt fin/flat plate junction demonstrate that after grid refinement, the computations agree with experiment and reveal a strong dependency of the number of vortices at the junction on Mach number and Reynolds number. The numerical results for pressure distribution, particle paths and limiting streamlines for turbulent flow past a swept fin show a decrease in the peak pressure and in the extent of the separated flow region compared to the laminar case. The results for a filleted juncture indicate that the streamline patterns lose much of their vortical character with proper filleting. Fillets with a radius of three and one-half times the fin leading edge diameter or two times the incoming boundary layer thickness, significantly weaken the usual necklace interaction vortex for the Mach number and Reynolds number considered in the present study.

  5. Insulator charging limits direct current across tunneling metal-insulator-semiconductor junctions

    SciTech Connect

    Vilan, Ayelet

    2016-01-07

    Molecular electronics studies how the molecular nature affects the probability of charge carriers to tunnel through the molecules. Nevertheless, transport is also critically affected by the contacts to the molecules, an aspect that is often overlooked. Specifically, the limited ability of non-metallic contacts to maintain the required charge balance across the fairly insulating molecule often have dramatic effects. This paper shows that in the case of lead/organic monolayer-silicon junctions, a charge balance is responsible for an unusual current scaling, with the junction diameter (perimeter), rather than its area. This is attributed to the balance between the 2D charging at the metal/insulator interface and the 3D charging of the semiconductor space-charge region. A derivative method is developed to quantify transport across tunneling metal-insulator-semiconductor junctions; this enables separating the tunneling barrier from the space-charge barrier for a given current-voltage curve, without complementary measurements. The paper provides practical tools to analyze specific molecular junctions compatible with existing silicon technology, and demonstrates the importance of contacts' physics in modeling charge transport across molecular junctions.

  6. Fracture of the Vomero-Premaxillary Junction in a Repaired Bilateral Cleft Lip and Palate Patient

    PubMed Central

    Zwahlen, Roger Arthur; Jayaratne, Yasas Shri Nalaka; Htun, Su Yin; Bütow, Kurt-Wilhelm

    2014-01-01

    Although dental trauma is common in bilateral cleft lip and palate (BCLP), patients' reports on bony fractures of the vomero-premaxillary junction cannot be found. The aim of this report is to illustrate clinical findings and the technique of fracture fixation in a child suffering from a fractured vomero-premaxillary junction as well as subsequent columella lengthening. A 4-year-old girl with a repaired BCLP presented with an open mucosal laceration and fractured vomero-premaxillary junction. Open reduction and fixation of the dislocated premaxilla was performed under general anesthesia. Fractured bone pieces of the vomero-premaxillary junction were removed and sharp bone edges at the vomer and the premaxilla were grinded. The repositioned premaxilla was fixed to the lateral alveolar arches with two mucoperiosteal sutures on each side. Additional columella lengthening was performed 2 years later. All family members were very happy about the new aesthetics of the girl. Although rare, fractures of the vomero-premaxillary junction present several challenges to clinicians related to anatomical, physiological, and psychological issues. Immediate and minimal invasive treatment strategies are recommended when managing such cases. PMID:25383152

  7. Chaos and related nonlinear noise phenomena in Josephson tunnel junctions

    SciTech Connect

    Miracky, R.F.

    1984-07-01

    The nonlinear dynamics of Josephson tunnel junctions shunted by a resistance with substantial self-inductance have been thoroughly investigated. The current-voltage characteristics of these devices exhibit stable regions of negative differential resistance. Very large increases in the low-frequency voltage noise with equivalent noise temperatures of 10/sup 6/ K or more, observed in the vicinity of these regions, arise from switching, or hopping, between subharmonic modes. Moderate increases in the noise, with temperatures of about 10/sup 3/ K, arise from chaotic behavior. Analog and digital simulations indicate that under somewhat rarer circumstances the same junction system can sustain a purely deterministic hopping between two unstable subharmonic modes, accompanied by excess low-frequency noise. Unlike the noise-induced case, this chaotic process occurs over a much narrower range in bias current and is destroyed by the addition of thermal noise. The differential equation describing the junction system can be reduced to a one-dimensional mapping in the vicinity of one of the unstable modes. A general analytical calculation of switching processes for a class of mappings yields the frequency dependence of the noise spectrum in terms of the parameters of the mapping. Finally, the concepts of noise-induced hopping near bifurcation thresholds are applied to the problem of the three-photon Josephson parametric amplifier. Analog simulations indicate that the noise rise observed in experimental devices arises from occasional hopping between a mode at the pump frequency ..omega../sub p/ and a mode at the half harmonic ..omega../sub p//2. The hopping is induced by thermal noise associated with the shunt resistance. 71 references.

  8. Gap junction- and hemichannel-independent actions of connexins

    PubMed Central

    Jiang, Jean X.; Gu, Sumin

    2007-01-01

    Connexins have been known to be the protein building blocks of gap junctions and mediate cell–cell communication. In contrast to the conventional dogma, recent evidence suggests that in addition to forming gap junction channels, connexins possess gap junction-independent functions. One important gap junction-independent function for connexins is to serve as the major functional component for hemichannels, the un-apposed halves of gap junctions. Hemichannels, as independent functional units, play roles that are different from that of gap junctions in the cell. The other functions of connexins appear to be gap junction- and hemichannel-independent. Published studies implicate the latter functions of connexins in cell growth, differentiation, tumorigenicity, injury, and apoptosis, although the mechanistic aspects of these actions remain largely unknown. In this review, gap junction- and hemichannel-independent functions of connexins are summarized, and the molecular mechanisms underlying these connexin functions are speculated and discussed. PMID:15955305

  9. Three-dimensional models: an emerging investigational revolution for craniovertebral junction surgery.

    PubMed

    Goel, Atul; Jankharia, Bhavin; Shah, Abhidha; Sathe, Prashant

    2016-12-01

    Complex craniovertebral junctional anomalies can be daunting to treat surgically, and preoperative information regarding the osseous abnormalities, course of the vertebral arteries, size of the pedicles, and location of the transverse foramina is invaluable to surgeons operating on these challenging cases. The authors present their experience with the emerging technology of 3D model acquisition for surgery in 11 cases of complex craniovertebral junction region anomalies. For each case, a 3D printed model was made from thin CT scans using a 64-slice CT scanner. The inclination of the joints, the presence of false articulations, the size of the pedicles, and the course of the vertebral arteries were studied preoperatively on the 3D models. The sizes of the plates and screws to be used and the angle of insertion of the screws were calculated based on the data from the models. The model was scaled to actual size and was kept beside the operating surgeon in its anatomical position during surgery. The potential uses of the models and their advantages over conventional radiological investigations are discussed. The authors conclude that 3D models can be an invaluable aid during surgery for complex craniovertebral junction anomalies. The information available from a real life-size model supersedes the information available from 3D CT reconstructions and can also be superior to virtual simulation. The models are both cost effective and easy to build and the authors suggest that they may form the basis of investigations in the near future for craniovertebral junction surgery.

  10. Endoscopic Endonasal Approaches to the Craniovertebral Junction: A Systematic Review of the Literature

    PubMed Central

    Fujii, Tatsuhiro; Platt, Andrew; Zada, Gabriel

    2015-01-01

    Background We reviewed the current literature pertaining to extended endoscopic endonasal approaches to the craniovertebral junction. Methods A systematic literature review was utilized to identify published surgical cases of endoscopic endonasal approaches to the craniovertebral junction. Full-text manuscripts were examined for various measures of surgical indications, patient characteristics, operative technique, and surgical outcomes. Results We identified 71 cases involving endoscopic endonasal approaches for surgical management of a variety of pathologies located within the craniovertebral junction. Patient ages ranged from 3 to 87 years, with 40 females and 31 males. Five patients required tracheostomy, two were reintubated, and all others experienced an average intubation duration of 0.54 days following surgery. Fifty-eight patients (81.7%) underwent an additional posterior decompression or fusion either before or after the endonasal procedure. A complete resection of the pathologic lesion was reported in 57 cases (83.8%), another five were successful biopsies, and four resulted in partial resection. The follow-up time ranged from 0.5 to 57 months. Conclusion Although the transoral approach has been the standard for anterior surgical management for the past several decades, our systematic review illustrates that the extended endoscopic endonasal approach is a safe and effective alternative for most pathologies affecting the craniovertebral junction. PMID:26682128

  11. High voltage series connected tandem junction solar battery

    DOEpatents

    Hanak, Joseph J.

    1982-01-01

    A high voltage series connected tandem junction solar battery which comprises a plurality of strips of tandem junction solar cells of hydrogenated amorphous silicon having one optical path and electrically interconnected by a tunnel junction. The layers of hydrogenated amorphous silicon, arranged in a tandem configuration, can have the same bandgap or differing bandgaps. The tandem junction strip solar cells are series connected to produce a solar battery of any desired voltage.

  12. Polyphosphonium-based ion bipolar junction transistors

    PubMed Central

    Gabrielsson, Erik O.; Berggren, Magnus

    2014-01-01

    Advancements in the field of electronics during the past few decades have inspired the use of transistors in a diversity of research fields, including biology and medicine. However, signals in living organisms are not only carried by electrons but also through fluxes of ions and biomolecules. Thus, in order to implement the transistor functionality to control biological signals, devices that can modulate currents of ions and biomolecules, i.e., ionic transistors and diodes, are needed. One successful approach for modulation of ionic currents is to use oppositely charged ion-selective membranes to form so called ion bipolar junction transistors (IBJTs). Unfortunately, overall IBJT device performance has been hindered due to the typical low mobility of ions, large geometries of the ion bipolar junction materials, and the possibility of electric field enhanced (EFE) water dissociation in the junction. Here, we introduce a novel polyphosphonium-based anion-selective material into npn-type IBJTs. The new material does not show EFE water dissociation and therefore allows for a reduction of junction length down to 2 μm, which significantly improves the switching performance of the ion transistor to 2 s. The presented improvement in speed as well the simplified design will be useful for future development of advanced iontronic circuits employing IBJTs, for example, addressable drug-delivery devices. PMID:25553192

  13. Radiation comb generation with extended Josephson junctions

    SciTech Connect

    Solinas, P.; Bosisio, R.; Giazotto, F.

    2015-09-21

    We propose the implementation of a Josephson radiation comb generator based on an extended Josephson junction subject to a time dependent magnetic field. The junction critical current shows known diffraction patterns and determines the position of the critical nodes when it vanishes. When the magnetic flux passes through one of such critical nodes, the superconducting phase must undergo a π-jump to minimize the Josephson energy. Correspondingly, a voltage pulse is generated at the extremes of the junction. Under periodic driving, this allows us to produce a comb-like voltage pulses sequence. In the frequency domain, it is possible to generate up to hundreds of harmonics of the fundamental driving frequency, thus mimicking the frequency comb used in optics and metrology. We discuss several implementations through a rectangular, cylindrical, and annular junction geometries, allowing us to generate different radiation spectra and to produce an output power up to 10 pW at 50 GHz for a driving frequency of 100 MHz.

  14. Gallium nitride junction field-effect transistor

    DOEpatents

    Zolper, John C.; Shul, Randy J.

    1999-01-01

    An all-ion implanted gallium-nitride (GaN) junction field-effect transistor (JFET) and method of making the same. Also disclosed are various ion implants, both n- and p-type, together with or without phosphorous co-implantation, in selected III-V semiconductor materials.

  15. Gallium nitride junction field-effect transistor

    DOEpatents

    Zolper, J.C.; Shul, R.J.

    1999-02-02

    An ion implanted gallium-nitride (GaN) junction field-effect transistor (JFET) and method of making the same are disclosed. Also disclosed are various ion implants, both n- and p-type, together with or without phosphorus co-implantation, in selected III-V semiconductor materials. 19 figs.

  16. Axion mass estimates from resonant Josephson junctions

    NASA Astrophysics Data System (ADS)

    Beck, Christian

    2015-03-01

    Recently it has been proposed that dark matter axions from the galactic halo can produce a small Shapiro step-like signal in Josephson junctions whose Josephson frequency resonates with the axion mass (Beck, 2013). Here we show that the axion field equations in a voltage-driven Josephson junction environment allow for a nontrivial solution where the axion-induced electrical current manifests itself as an oscillating supercurrent. The linear change of phase associated with this nontrivial solution implies the formal existence of a large magnetic field in a tiny surface area of the weak link region of the junction which makes incoming axions decay into microwave photons. We derive a condition for the design of Josephson junction experiments so that they can act as optimum axion detectors. Four independent recent experiments are discussed in this context. The observed Shapiro step anomalies of all four experiments consistently point towards an axion mass of (110±2) μeV. This mass value is compatible with the recent BICEP2 results and implies that Peccei-Quinn symmetry breaking was taking place after inflation.

  17. Polyphosphonium-based ion bipolar junction transistors.

    PubMed

    Gabrielsson, Erik O; Tybrandt, Klas; Berggren, Magnus

    2014-11-01

    Advancements in the field of electronics during the past few decades have inspired the use of transistors in a diversity of research fields, including biology and medicine. However, signals in living organisms are not only carried by electrons but also through fluxes of ions and biomolecules. Thus, in order to implement the transistor functionality to control biological signals, devices that can modulate currents of ions and biomolecules, i.e., ionic transistors and diodes, are needed. One successful approach for modulation of ionic currents is to use oppositely charged ion-selective membranes to form so called ion bipolar junction transistors (IBJTs). Unfortunately, overall IBJT device performance has been hindered due to the typical low mobility of ions, large geometries of the ion bipolar junction materials, and the possibility of electric field enhanced (EFE) water dissociation in the junction. Here, we introduce a novel polyphosphonium-based anion-selective material into npn-type IBJTs. The new material does not show EFE water dissociation and therefore allows for a reduction of junction length down to 2 μm, which significantly improves the switching performance of the ion transistor to 2 s. The presented improvement in speed as well the simplified design will be useful for future development of advanced iontronic circuits employing IBJTs, for example, addressable drug-delivery devices.

  18. Costochondral junction osteomyelitis in 3 septic foals

    PubMed Central

    Cesarini, Carla; Macieira, Susana; Girard, Christiane; Drolet, Richard; d’Anjou, Marc-André; Jean, Daniel

    2011-01-01

    The costochondral junction constitutes a potential site of infection in septic foals and it could be favored by thoracic trauma. Standard radiographs and ultrasonography are useful tools for diagnosis of this condition and ultrasound-guided needle aspiration could permit the definitive confirmation of infection. PMID:22210943

  19. Gap junctional communication during limb cartilage differentiation.

    PubMed

    Coelho, C N; Kosher, R A

    1991-03-01

    The onset of cartilage differentiation in the developing limb bud is characterized by a transient cellular condensation process in which prechondrogenic mesenchymal cells become closely apposed to one another prior to initiating cartilage matrix deposition. During this condensation process intimate cell-cell interactions occur which are necessary to trigger chondrogenic differentiation. In the present study, we demonstrate that extensive cell-cell communication via gap junctions as assayed by the intercellular transfer of lucifer yellow dye occurs during condensation and the onset of overt chondrogenesis in high density micromass cultures prepared from the homogeneous population of chondrogenic precursor cells comprising the distal subridge region of stage 25 embryonic chick wing buds. Furthermore, in heterogeneous micromass cultures prepared from the mesodermal cells of whole stage 23/24 limb buds, extensive gap junctional communication is limited to differentiating cartilage cells, while the nonchondrogenic cells of the cultures that are differentiating into the connective tissue lineage exhibit little or no intercellular communication via gap junctions. These results provide a strong incentive for considering and further investigating the possible involvement of cell-cell communication via gap junctions in the regulation of limb cartilage differentiation.

  20. All-carbon molecular tunnel junctions.

    PubMed

    Yan, Haijun; Bergren, Adam Johan; McCreery, Richard L

    2011-11-30

    This Article explores the idea of using nonmetallic contacts for molecular electronics. Metal-free, all-carbon molecular electronic junctions were fabricated by orienting a layer of organic molecules between two carbon conductors with high yield (>90%) and good reproducibility (rsd of current density at 0.5 V <30%). These all-carbon devices exhibit current density-voltage (J-V) behavior similar to those with metallic Cu top contacts. However, the all-carbon devices display enhanced stability to bias extremes and greatly improved thermal stability. Completed carbon/nitroazobenzene(NAB)/carbon junctions can sustain temperatures up to 300 °C in vacuum for 30 min and can be scanned at ±1 V for at least 1.2 × 10(9) cycles in air at 100 °C without a significant change in J-V characteristics. Furthermore, these all-carbon devices can withstand much higher voltages and current densities than can Cu-containing junctions, which fail upon oxidation and/or electromigration of the copper. The advantages of carbon contacts stem mainly from the strong covalent bonding in the disordered carbon materials, which resists electromigration or penetration into the molecular layer, and provides enhanced stability. These results highlight the significance of nonmetallic contacts for molecular electronics and the potential for integration of all-carbon molecular junctions with conventional microelectronics.

  1. Regulation of Traffic Lights at Road Junctions

    NASA Astrophysics Data System (ADS)

    Cutolo, Alfredo; Manzo, Rosanna; Rarità, Luigi

    2009-08-01

    In this work, we aim to investigate the effects of traffic lights regulation at road junctions, modelled by a fluid dynamic approach. Numerical simulations prove that it is possible to plan some optimization strategies for green and red phases for networks consisting of more nodes.

  2. The dynamic organic p-n junction.

    PubMed

    Matyba, Piotr; Maturova, Klara; Kemerink, Martijn; Robinson, Nathaniel D; Edman, Ludvig

    2009-08-01

    Static p-n junctions in inorganic semiconductors are exploited in a wide range of today's electronic appliances. Here, we demonstrate the in situ formation of a dynamic p-n junction structure within an organic semiconductor through electrochemistry. Specifically, we use scanning kelvin probe microscopy and optical probing on planar light-emitting electrochemical cells (LECs) with a mixture of a conjugated polymer and an electrolyte connecting two electrodes separated by 120 microm. We find that a significant portion of the potential drop between the electrodes coincides with the location of a thin and distinct light-emission zone positioned >30 microm away from the negative electrode. These results are relevant in the context of a long-standing scientific debate, as they prove that electrochemical doping can take place in LECs. Moreover, a study on the doping formation and dissipation kinetics provides interesting detail regarding the electronic structure and stability of the dynamic organic p-n junction, which may be useful in future dynamic p-n junction-based devices.

  3. 30 CFR 57.12007 - Junction box connection procedures.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Junction box connection procedures. 57.12007... Electricity Surface and Underground § 57.12007 Junction box connection procedures. Trailing cable and power-cable connections to junction boxes shall not be made or broken under load....

  4. Overview of the Grand Junction Office from Bluff east of ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Overview of the Grand Junction Office from Bluff east of facility. Note Buildings #35. #33 and #31A in lower left of photograph. VIEW WEST - Department of Energy, Grand Junction Office, 2597 B3/4 Road, Grand Junction, Mesa County, CO

  5. Multiphase Flow in Micro-fracture Junctions

    NASA Astrophysics Data System (ADS)

    Basagaoglu, H.; Meakin, P.; Succi, S.; Wildenschild, D.

    2005-12-01

    A two-dimensional two-phase lattice-Boltzmann model was used to simulate immiscible fluid flow in four micro-fracture geometries closely related to geological fractured systems: (1) a fracture junction with fractal surfaces embedded in a non-porous matrix; (2) a fracture junction embedded in a heterogeneous porous matrix; (3) a heterogeneous porous medium overlying a fracture with fractal surfaces; and (4) a fracture network with fractal surfaces enclosed by a non-porous medium. The spatio-temporal distributions of fluids in fracture junctions were controlled by interplays between velocity-dependent contact angle dynamics, mediated by surface roughness, and pore-scale gravitational, viscous, and capillary forces. All simulations were conducted with actual physical units. Sensitivities of lateral and vertical spreads of fluids in the fracture junctions to the orientation of fracture junctions (tilted vs. vertical) and the wetting strength of fluids were analyzed via temporal moment analyses for the first two geometries. The simulation results revealed that the receding and advancing contact angles varied strongly with the transient fluid velocity. The patterns and distributions of thin films (continuous vs. discontinuous) on rough fracture walls were largely controlled by the wetting strength of the fluids. The spatio-temporal distributions of fluids were highly sensitive to the domain size and boundary conditions (periodic, no-flow, constant density, and flux-type). Single- and two-sided wetting of fracture aperture walls and long-term entrapment of a nonwetting less-dense fluid by a wetting dense fluid were observed in the simulations. These numerical results are useful for the design of experiments and for analyzing the relative strengths of pore-scale processes in more complex and realistic fracture systems such as those encountered at the Yucca Mountain and Idaho National Laboratory sites.

  6. Gap junctional communication during human trophoblast differentiation: influence of human chorionic gonadotropin.

    PubMed

    Cronier, L; Bastide, B; Hervé, J C; Délèze, J; Malassiné, A

    1994-07-01

    During pregnancy, the trophoblast develops from the fusion of cytotrophoblastic cells into a syncytiotrophoblast. As the exchange of molecules through gap junctions is considered to play a role in the control of cell and tissue differentiation, the cell to cell diffusion of a fluorescent dye was investigated in human trophoblastic cells differentiating in culture. The fluorescence recovery after photobleaching technique was used to estimate the transfer of 6-carboxyfluorescein from contiguous cellular elements into photobleached cells. Fluorescence recovery follows a slow exponential time course when the cell to cell exchange process is rate limited by the presence of gap junctional channels between contiguous cells, contrasting with a much faster step-like course in the case of fusion of the plasma membranes. In the presence of 10% fetal calf serum, Percoll-purified cytotrophoblastic cells develop into cellular aggregates, then into a syncytium, within 24-48 h after plating. During this in vitro differentiation, fluorescence recoveries after photobleaching with a time course typical for gap junctions were observed between aggregated cytotrophoblastic cells, between cytotrophoblastic cells and syncytiotrophoblasts, and between contiguous syncytiotrophoblasts. The maximum percentage of gap junctional coupling occurs on the fourth day. This fluorescence recovery is attributed to the diffusion of dye through gap junctions, because it can be interrupted by exposure to a known junctional uncoupler (3 mM heptanol). The effects of hCG on this gap junctional communication during trophoblast differentiation were investigated. In the presence of 500 mIU/ml hCG in the culture medium, the percentage of coupled cells was increased at all stages of culture, and the highest proportion of coupled cells was observed after 2 days of culture vs. 4 days in control medium. Moreover, the diffusion rate constant k (the inverse value of the time constant measured on recovery curves) was

  7. Model building to facilitate understanding of holliday junction and heteroduplex formation, and holliday junction resolution.

    PubMed

    Selvarajah, Geeta; Selvarajah, Susila

    2016-07-08

    Students frequently expressed difficulty in understanding the molecular mechanisms involved in chromosomal recombination. Therefore, we explored alternative methods for presenting the two concepts of the double-strand break model: Holliday junction and heteroduplex formation, and Holliday junction resolution. In addition to a lecture and computer-animated video, we included a model building activity using pipe cleaners. Biotechnology undergraduates (n = 108) used the model to simulate Holliday junction and heteroduplex formation, and Holliday junction resolution. Based on student perception, an average of 12.85 and 78.35% students claimed that they completely and partially understood the two concepts, respectively. A test conducted to ascertain their understanding about the two concepts showed that 66.1% of the students provided the correct response to the three multiple choice questions. A majority of the 108 students attributed the inclusion of model building to their better understanding of Holliday junction and heteroduplex formation, and Holliday junction resolution. This underlines the importance of incorporating model building, particularly in concepts that require spatial visualization. © 2016 by The International Union of Biochemistry and Molecular Biology, 44(4):381-390, 2016.

  8. Direct detection at submillimetre wavelengths using superconducting tunnel junctions

    NASA Astrophysics Data System (ADS)

    Withington, S.; Isaak, K. G.; Kovtonyuk, S. A.; Panhuyzen, R. A.; Klapwijk, T. M.

    1995-12-01

    Superconducting tunnel-junction direct detectors are considered in some detail. For frequencies below twice that of the gap there is some bias voltage for which the input impedance is real, the responsivity quantum limited, and the dynamic range high. A susperconducting detector saturates for two reasons: intrinsic saturation due to the relative increase in two-photon tunnelling processes, and extrinsic saturation due to the input match changing with bias voltage. The responsivity of a detector with a resistive RF source is least sensitive to bias-voltage changes and has the greatest dynamic range when operating with a sloping load line. In the case of an inductive source, the dynamic range can be higher than the intrinsic saturation rate would suggest. Ideally, superconducting tunnel-junction detectors should be biased in a constant-voltage mode. If the responsivity is to be depressed by no more than a few percent, the photon step should have a height which is no more than one quarter of the total current turn-on at the gap. Superconducting direct detectors can be used to make precise and well-calibrated optical measurements at submillimetre wavelengths.

  9. Phase dynamics of low critical current density YBCO Josephson junctions

    NASA Astrophysics Data System (ADS)

    Massarotti, D.; Stornaiuolo, D.; Rotoli, G.; Carillo, F.; Galletti, L.; Longobardi, L.; Beltram, F.; Tafuri, F.

    2014-08-01

    High critical temperature superconductors (HTS) based devices can have impact in the study of the phase dynamics of Josephson junctions (JJs) thanks to the wide range of junction parameters they offer and to their unconventional properties. Measurements of current-voltage characteristics and of switching current distributions constitute a direct way to classify different regimes of the phase dynamics and of the transport, also in nontrivial case of the moderately damped regime (MDR). MDR is going to be more and more common in JJs with advances in nanopatterning superconductors and synthesizing novel hybrid systems. Distinctive signatures of macroscopic quantum tunneling and of thermal activation in presence of different tunable levels of dissipation have been detected in YBCO grain boundary JJs. Experimental data are supported by Monte Carlo simulations of the phase dynamics, in a wide range of temperatures and dissipation levels. This allows us to quantify dissipation in the MDR and partially reconstruct a phase diagram as guideline for a wide range of moderately damped systems.

  10. Pediatric bony craniovertebral junction abnormalities: Institutional experience of 10 years

    PubMed Central

    Kale, S. S.; Ailawadhi, Pankaj; Yerramneni, Vamsi Krishna; Chandra, P. S.; Kumar, Rajender; Sharma, B. S.; Mahapatra, A. K.

    2011-01-01

    Objective: To study the clinical features and treatment outcome of pediatric patients with bony craniovertebral abnormalities. Materials and Methods: The authors studied 189 consecutive cases of pediatric bony craniovertebral junction abnormalities operated between 2001 and March, 2010. Results: The pathologies were developmental (n = 162), traumatic (n = 18) and tuberculous (n = 9). Surgical procedures included transoral decompression (n = 118), occipitocervical fusion (OCF, n = 139), C 1 -C 2 fusion (n = 45), and posterior fossa decompression (n = 5). Methods for OCF included contoured stainless steel rods (n = 86), titanium lateral mass screws and plates (n = 47) and steel wires (n = 6). Constructs of all patients of posterior fixation with contoured rods and wires or lateral mass screw and rod who could be followed up were either stable/fused or were fused and stable. No implant failure was noticed among these two surgical procedures. However, 6 patients with C 1-C 2 fusion had broken wires on follow-up requiring repeat posterior fixation. Good neurological outcome was observed even in poor-grade patients. No significant effect on the curvature or growth of the spine was observed at follow-up. Conclusions: Pediatric craniovertebral junction anomalies can be managed successfully with good outcomes using a low cost contoured rod and wires. PMID:22069436

  11. Femoral head-neck junction reconstruction, after iatrogenic bone resection.

    PubMed

    Guevara-Alvarez, Alberto; Lash, Nicholas; Beck, Martin

    2015-07-01

    Arthroscopic over-resection of the head-neck junction during the treatment of a cam deformity can be a devastating complication and is difficult to treat. Large defects of the femoral head-neck junction (FHNJ) increase the risk of femoral neck fracture and can also affect hip biomechanics. We describe a case of an iatrogenic defect of the FHNJ due to excessive bone resection, and a previously non-described treatment using iliac crest autograft to restore femoral head-neck sphericity and hip joint stability. After protecting the femoral neck with an angled blade plate, the large anterior FHNJ defect was reconstructed using autogenous iliac crest bone graft; sphericity was restored by contouring the graft using spherical templates. Clinical and radiographic follow-up was performed up to 2 years. Results at 2 years showed no residual groin pain and normal range of motion. The Oxford Hip Score was 46/48, rated as excellent. Computed tomography (CT) scanning showed union of bone graft without resorption, and CT arthrogram indicating retained sphericity of the FHNJ without evidence of degenerative changes in the articular surface. This novel surgical technique can be used to restore the structural integrity and contour of the FHNJ that contains a significant anterior defect.

  12. Dynamical Coulomb blockade of tunnel junctions driven by alternating voltages

    NASA Astrophysics Data System (ADS)

    Grabert, Hermann

    2015-12-01

    The theory of the dynamical Coulomb blockade is extended to tunneling elements driven by a time-dependent voltage. It is shown that, for standard setups where an external voltage is applied to a tunnel junction via an impedance, time-dependent driving entails an excitation of the modes of the electromagnetic environment by the applied voltage. Previous approaches for ac driven circuits need to be extended to account for the driven bath modes. A unitary transformation involving also the variables of the electromagnetic environment is introduced which allows us to split off the time dependence from the Hamiltonian in the absence of tunneling. This greatly simplifies perturbation-theoretical calculations based on treating the tunneling Hamiltonian as a perturbation. In particular, the average current flowing in the leads of the tunnel junction is studied. Explicit results are given for the case of an applied voltage with a constant dc part and a sinusoidal ac part. The connection with standard dynamical Coulomb blockade theory for constant applied voltage is established. It is shown that an alternating voltage source reveals significant additional effects caused by the electromagnetic environment. The hallmark of the dynamical Coulomb blockade in ac driven devices is a suppression of higher harmonics of the current by the electromagnetic environment. The theory presented basically applies to all tunneling devices driven by alternating voltages.

  13. Transperitoneal laparoscopic pyeloplasty in the treatment of ureteropelvic junction obstruction

    PubMed Central

    Gregorio, Sergio Alonso y; Eastmond, María A. Portilla; Gómez, Angel Tabernero; Ledo, Jesús Cisneros; Togores, Luis Hidalgo; Barthel, Jesús Javier de la Peña

    2013-01-01

    Introduction Laparoscopic pyeloplasty was first described by Schuessler. During the last decade, this technique has been developed in order to achieve the same results as open surgery, with lower rates of morbidity and complications. In this study we review our experience using laparoscopic pyeloplasty as the gold standard for the treatment of the ureteropelvic junction obstruction (UPJO). Material and methods We performed a retrospective review of 62 laparoscopic pyeloplasties carried out at our center. In the last 2 years we used 3 mm and 5 mm ports in order to achieve better cosmetics results. Demographic data is described and the functionality of the affected kidney and surgical data, among others were analyzed statistically. In the case of bilateral statistical tests were considered significant as those with p values <0.05. Results The most frequent reason for consultation was ureteral pain. Patients mean age was 40 years and 94% of them had preoperative renogram showing a full or partial obstructive pattern. The right side was affected in 61% of cases and the left in the remaining 39%. The presence of stones was observed in 12 patients and crossing vessels in 58% of cases. The average stay was 3.72 days. Post–surgery complications were observed in two patients. The operative time was 178 minutes. Mean follow–up was 45 months and a success was achieved in 91%. Conclusions The transperitoneal laparoscopic pyeloplasty has become the gold standard for the treatment of ureteropelvic junction stenosis in our center because of high success rate, shorter postoperative stay, and low intra and postoperative complications. PMID:24707387

  14. Abnormal endothelial tight junctions in active lesions and normal-appearing white matter in multiple sclerosis.

    PubMed

    Plumb, Jonnie; McQuaid, Stephen; Mirakhur, Meenakshi; Kirk, John

    2002-04-01

    Blood-brain barrier (BBB) breakdown, demonstrable in vivo by enhanced MRI is characteristic of new and expanding inflammatory lesions in relapsing-remitting and chronic progressive multiple sclerosis (MS). Subtle leakage may also occur in primary progressive MS. However, the anatomical route(s) of BBB leakage have not been demonstrated. We investigated the possible involvement of interendothelial tight junctions (TJ) by examining the expression of TJ proteins (occludin and ZO-1 ) in blood vessels in active MS lesions from 8 cases of MS and in normal-appearing white (NAWM) matter from 6 cases. Blood vessels (10-50 per frozen section) were scanned using confocal laser scanning microscopy to acquire datasets for analysis. TJ abnormalities manifested as beading, interruption, absence or diffuse cytoplasmic localization of fluorescence, or separation of junctions (putative opening) were frequent (affecting 40% of vessels) in oil-red-O-positive active plaques but less frequent in NAWM (15%), and in normal (< 2%) and neurological controls (6%). Putatively "open" junctions were seen in vessels in active lesions and in microscopically inflamed vessels in NAWM. Dual fluorescence revealed abnormal TJs in vessels with pre-mortem serum protein leakage. Abnormal or open TJs, associated with inflammation may contribute to BBB leakage in enhancing MRI lesions and may also be involved in subtle leakage in non-enhancing focal and diffuse lesions in NAWM. BBB disruption due to tight junctional pathology should be regarded as a significant form of tissue injury in MS, alongside demyelination and axonopathy.

  15. Connexin26 regulates assembly and maintenance of cochlear gap junction macromolecular complex for normal hearing

    NASA Astrophysics Data System (ADS)

    Kamiya, Kazusaku; Fukunaga, Ichiro; Hatakeyama, Kaori; Ikeda, Katsuhisa

    2015-12-01

    Hereditary deafness affects about 1 in 2000 children and GJB2 gene mutation is most frequent cause for this disease in the world. GJB2 encodes connexin26 (Cx26), a component in cochlear gap junction. Recently, we found macromolecular change of gap junction plaques with two different types of Cx26 mutation as major classification of clinical case, one is a model of dominant negative type, Cx26R75W+ and the other is conditional gene deficient mouse, Cx26f/fP0Cre as a model for insufficiency of gap junction protein [6]. Gap junction composed mainly of Cx26 and Cx30 in wild type mice formed large planar gap junction plaques (GJP). In contrast, Cx26R75W+ and Cx26f/fP0Cre showed fragmented small round GJPs around the cell border. In Cx26f/fP0Cre, some of the cells with Cx26 expression due to their cellular mosaicism showed normal large GJP with Cx26 and Cx30 only at the cell junction site between two Cx26 positive cells. These indicate that bilateral Cx26 expressions from both adjacent cells are essential for the formation of the cochlear linear GJP, and it is not compensated by other cochlear Connexins such as Connexin30. In the present study, we demonstrated a new molecular pathology in most common hereditary deafness with different types of Connexin26 mutations, and this machinery can be a new target for drag design of hereditary deafness.

  16. Demonstration of an ac Josephson junction laser

    NASA Astrophysics Data System (ADS)

    Cassidy, M. C.; Bruno, A.; Rubbert, S.; Irfan, M.; Kammhuber, J.; Schouten, R. N.; Akhmerov, A. R.; Kouwenhoven, L. P.

    2017-03-01

    Superconducting electronic devices have reemerged as contenders for both classical and quantum computing due to their fast operation speeds, low dissipation, and long coherence times. An ultimate demonstration of coherence is lasing. We use one of the fundamental aspects of superconductivity, the ac Josephson effect, to demonstrate a laser made from a Josephson junction strongly coupled to a multimode superconducting cavity. A dc voltage bias applied across the junction provides a source of microwave photons, and the circuit’s nonlinearity allows for efficient down-conversion of higher-order Josephson frequencies to the cavity’s fundamental mode. The simple fabrication and operation allows for easy integration with a range of quantum devices, allowing for efficient on-chip generation of coherent microwave photons at low temperatures.

  17. String networks with junctions in competition models

    NASA Astrophysics Data System (ADS)

    Avelino, P. P.; Bazeia, D.; Losano, L.; Menezes, J.; de Oliveira, B. F.

    2017-03-01

    In this work we give specific examples of competition models, with six and eight species, whose three-dimensional dynamics naturally leads to the formation of string networks with junctions, associated with regions that have a high concentration of enemy species. We study the two- and three-dimensional evolution of such networks, both using stochastic network and mean field theory simulations. If the predation, reproduction and mobility probabilities do not vary in space and time, we find that the networks attain scaling regimes with a characteristic length roughly proportional to t 1 / 2, where t is the physical time, thus showing that the presence of junctions, on its own, does not have a significant impact on their scaling properties.

  18. Junction conditions in extended Teleparallel gravities

    SciTech Connect

    De la Cruz-Dombriz, Álvaro; Dunsby, Peter K.S.; Sáez-Gómez, Diego E-mail: peter.dunsby@uct.ac.za

    2014-12-01

    In the context of extended Teleparallel gravity theories, we address the issue of junction conditions required to guarantee the correct matching of different regions of spacetime. In the absence of shells/branes, these conditions turn out to be more restrictive than their counterparts in General Relativity as in other extended theories of gravity. In fact, the general junction conditions on the matching hypersurfaces depend on the underlying theory and a new condition on the induced tetrads in order to avoid delta-like distributions in the field equations. This result imposes strict consequences on the viability of standard solutions such as the Einstein-Straus-like construction. We find that the continuity of the scalar torsion is required in order to recover the usual General Relativity results.

  19. Current distributions in stripe Majorana junctions

    NASA Astrophysics Data System (ADS)

    Osca, Javier; Llorenç, Serra

    2017-02-01

    We calculate current and density distributions in stripe (2D planar) junctions between normal and Majorana nanowires having a finite ( y) transverse length. In presence of a magnetic field with vertical and in-plane components, the y-symmetry of the charge current distribution in the normal lead changes strongly across the Majorana phase transition: from center-symmetric if a Majorana mode is present to laterally-shifted (as expected by the Hall effect) if the field is tilted such as to destroy the Majorana mode due to the projection rule. We compare quasi-particle and charge distributions of current and density, as well as spin magnetizations. The Majorana mode causes opposite spin accumulations on the transverse sides of the junction and the emergence of a spin current.

  20. Vibrational Heat Transport in Molecular Junctions.

    PubMed

    Segal, Dvira; Agarwalla, Bijay Kumar

    2016-05-27

    We review studies of vibrational energy transfer in a molecular junction geometry, consisting of a molecule bridging two heat reservoirs, solids or large chemical compounds. This setup is of interest for applications in molecular electronics, thermoelectrics, and nanophononics, and for addressing basic questions in the theory of classical and quantum transport. Calculations show that system size, disorder, structure, dimensionality, internal anharmonicities, contact interaction, and quantum coherent effects are factors that combine to determine the predominant mechanism (ballistic/diffusive), effectiveness (poor/good), and functionality (linear/nonlinear) of thermal conduction at the nanoscale. We review recent experiments and relevant calculations of quantum heat transfer in molecular junctions. We recount the Landauer approach, appropriate for the study of elastic (harmonic) phononic transport, and outline techniques that incorporate molecular anharmonicities. Theoretical methods are described along with examples illustrating the challenge of reaching control over vibrational heat conduction in molecules.

  1. Magnetoamplification in a bipolar magnetic junction transistor.

    PubMed

    Rangaraju, N; Peters, J A; Wessels, B W

    2010-09-10

    We have demonstrated the first bipolar magnetic junction transistor using a dilute magnetic semiconductor. For an InMnAs p-n-p transistor magnetoamplification is observed at room temperature. The observed magnetoamplification is attributed to the magnetoresistance of the magnetic semiconductor InMnAs heterojunction. The magnetic field dependence of the transistor characteristics confirm that the magnetoamplification results from the junction magnetoresistance. To describe the experimentally observed transistor characteristics, we propose a modified Ebers-Moll model that includes a series magnetoresistance attributed to spin-selective conduction. The capability of magnetic field control of the amplification in an all-semiconductor transistor at room temperature potentially enables the creation of new computer logic architecture where the spin of the carriers is utilized.

  2. Excess junction current of silicon solar cells

    NASA Technical Reports Server (NTRS)

    Wang, E. Y.; Legge, R. N.; Christidis, N.

    1973-01-01

    The current-voltage characteristics of n(plus)-p silicon solar cells with 0.1, 1.0, 2.0, and 10 ohm-cm p-type base materials have been examined in detail. In addition to the usual I-V measurements, we have studied the temperature dependence of the slope of the I-V curve at the origin by the lock-in technique. The excess junction current coefficient (Iq) deduced from the slope at the origin depends on the square root of the intrinsic carrier concentration. The Iq obtained from the I-V curve fitting over the entire forward bias region at various temperatures shows the same temperature dependence. This result, in addition to the presence of an aging effect, suggest that the surface channel effect is the dominant cause of the excess junction current.

  3. Cusps on cosmic superstrings with junctions

    SciTech Connect

    Davis, Anne-Christine; Rajamanoharan, Senthooran; Nelson, William; Sakellariadou, Mairi E-mail: william.nelson@kcl.ac.uk E-mail: mairi.sakellariadou@kcl.ac.uk

    2008-11-15

    The existence of cusps on non-periodic strings ending on D-branes is demonstrated and the conditions for which such cusps are generic are derived. The dynamics of F-strings, D-strings and FD-string junctions are investigated. It is shown that pairs of FD-string junctions, such as would form after intercommutations of F-strings and D-strings, generically contain cusps. This new feature of cosmic superstrings opens up the possibility of extra channels of energy loss from a string network. The phenomenology of cusps on such cosmic superstring networks is compared to that of cusps formed on networks of their field theory analogues, the standard cosmic strings.

  4. [Paroxysmal junctional reciprocal tachycardia and fetoplacental anasarca].

    PubMed

    Maurier, F; Delisle, G; Guay, M

    1985-02-01

    Foeto-placental anasarca was diagnosed at 34 weeks gestation in a patient with acute hydramnios. Foetal tachycardia at 300 bpm was recorded. This obstetrical problem led to the birth of a premature baby with generalised oedema, for which the only apparent cause was the tachycardia. This was identified as a paroxysmal junctional reciprocating tachycardia, initiating on atrial extrasystolic echos, terminating on R waves, with lengthening of the PR interval at the onset of tachycardia, without acceleration of the sinus rate and P'R = RP'. Paroxysmal junctional reciprocating tachycardia in utero was responsible for congestive cardiac failure and foeto-placental anasarca. The cardiac failure was treated by foetal delivery, artificial respiration and digoxin. The association of digoxin-disopyramide reduces the frequency of attacks of tachycardia and treatment may be stopped after one year's follow-up.

  5. Novel tunnelling barriers for spin tunnelling junctions

    NASA Astrophysics Data System (ADS)

    Sharma, Manish

    A tunnel junction consists of two metal electrodes separated by an insulating barrier thin enough for electrons to tunnel across. With ferromagnetic electrodes, a spin-dependent tunnelling (SDT) effect, electrons of one spin tunnelling preferentially over those of the other, is observed. When the electrodes are switched from a parallel to an anti-parallel alignment, the tunnelling current changes and gives rise to tunnelling magnetoresistance (TMR). Since 1995, interest in SDT junctions has increased as TMR in excess of 15% has been achieved, making viable their use in non-volatile memory and magnetic sensors applications. In this work, two key issues of SDT junctions are addressed: spin polarization of the electrode and the tunnel barrier. Spin polarization, a measure of electron states of up and down spins, is widely believed to be an intrinsic property of the electrode. In junctions with barriers formed by plasma oxidation of composite Ta/Al films, the surprising effect of the resistance being lower with the electrodes aligned antiparallel was observed. Junctions with Ta/Al barriers and those with Al/Ta barriers behave opposite to each other and exhibit an inversion only when the Ta side of the barrier is biased positive. This demonstrates the spin polarization is also influenced by the barrier material. Half-metallic materials such as magnetite (Fe3O4) have a gap in one of the spins' states at the fermi level, thus having a theoretical spin polarization of 100%. In this work, an ultrathin Fe3O 4 layer was added between the Al2O3 barrier and the NiFe electrode. The TMR increased sharply from 4% to 16% for thicknesses less than 0.5nm. As the tunnel barrier must be thinner than 2nm, choice of the barrier material becomes critical. Presently, Al2O3 is the best known barrier. In looking for alternative materials, AlN and AlON were formed by plasma nitridation and oxy-nitridation of deposited Al films. TMR results of up to 18% and resistance-area products down to 3

  6. Spontaneous supercurrent induced by ferromagnetic pi junctions.

    PubMed

    Bauer, A; Bentner, J; Aprili, M; Della Rocca, M L; Reinwald, M; Wegscheider, W; Strunk, C

    2004-05-28

    We present magnetization measurements of mesoscopic superconducting niobium loops containing a ferromagnetic (PdNi) pi junction. The loops are prepared on top of the active area of a micro-Hall sensor based on high mobility GaAs/AlGaAs heterostructures. We observe asymmetric switching of the loop between different magnetization states when reversing the sweep direction of the magnetic field. This provides evidence for a spontaneous current induced by the intrinsic phase shift of the pi junction. In addition, the presence of the spontaneous current near zero applied field is directly revealed by an increase of the magnetic moment with decreasing temperature, which results in half integer flux quantization in the loop at low temperatures.

  7. Physiology and Function of the Tight Junction

    PubMed Central

    Anderson, James M.; Van Itallie, Christina M.

    2009-01-01

    Understanding of tight junctions has evolved from their historical perception as inert solute barriers to recognition of their physiological and biochemical complexity. Many proteins are specifically localized to tight junctions, including cytoplasmic actin-binding proteins and adhesive transmembrane proteins. Among the latter are claudins, which are critical barrier proteins. Current information suggests that the paracellular barrier is most usefully modeled as having two physiologic components: a system of charge-selective small pores, 4 Å in radius, and a second pathway created by larger discontinuities in the barrier, lacking charge or size discrimination. The first pathway is influenced by claudin expression patterns and the second is likely controlled by different proteins and signals. Recent information on claudin function and disease-causing mutations have led to a more complete understanding of their role in barrier formation, but progress is impeded by lack of high resolution structural information. PMID:20066090

  8. Vibrational Heat Transport in Molecular Junctions

    NASA Astrophysics Data System (ADS)

    Segal, Dvira; Agarwalla, Bijay Kumar

    2016-05-01

    We review studies of vibrational energy transfer in a molecular junction geometry, consisting of a molecule bridging two heat reservoirs, solids or large chemical compounds. This setup is of interest for applications in molecular electronics, thermoelectrics, and nanophononics, and for addressing basic questions in the theory of classical and quantum transport. Calculations show that system size, disorder, structure, dimensionality, internal anharmonicities, contact interaction, and quantum coherent effects are factors that combine to determine the predominant mechanism (ballistic/diffusive), effectiveness (poor/good), and functionality (linear/nonlinear) of thermal conduction at the nanoscale. We review recent experiments and relevant calculations of quantum heat transfer in molecular junctions. We recount the Landauer approach, appropriate for the study of elastic (harmonic) phononic transport, and outline techniques that incorporate molecular anharmonicities. Theoretical methods are described along with examples illustrating the challenge of reaching control over vibrational heat conduction in molecules.

  9. Quantum computing with Josephson junction circuits

    NASA Astrophysics Data System (ADS)

    Xu, Huizhong

    This work concerns the study of Josephson junction circuits in the context of their usability for quantum computing. The zero-voltage state of a current-biased Josephson junction has a set of metastable quantum energy levels. If a junction is well isolated from its environment, it will be possible to use the two lowest states as a qubit in a quantum computer. I first examine the meaning of isolation theoretically. Using a master equation, I analyzed the effect of dissipation on escape rates and suggested a simple method, population depletion technique, to measure the relaxation time (T1). Using a stochastic Bloch equation to analyze the dependence of microwave resonance peak width on current noise, I found decoherence due to current noise depends on the noise spectrum. For high frequency noise with a cutoff frequency fc much larger than 1/T1, I found decoherence due to noise can be described by a dephasing rate that is proportional to the noise spectral density. However, for low frequency noise such that its cutoff frequency fc is much smaller than 1/T 1, decoherence due to noise depends on the total rms current noise. I then analyze and test a few qubit isolation schemes, including resistive isolation, inductor-capacitor (LC) isolation, half-wavelength resonant isolation and inductor-junction (LJ) isolation. I found the resistive isolation scheme has a severe heating problem. Macroscopic quantum tunneling and energy level quantization were observed in the LC isolated Nb/AlOx/Nb and AL/ALOx/Al junction qubits at 25 mK. Relaxation times of 4--12 ns and spectroscopic coherence times of 1--3 ns were obtained for these LC isolated qubits. I found the half-wavelength isolated junction qubit has a relaxation time of about 20 ns measured by the population-depletion techniques, but no energy levels were observed in this qubit. Experimental results suggest the LJ isolated qubit has a longer relaxation and coherence times than all my previously examined samples. Using a

  10. Neuro-muscular junction block stimulator simulator.

    PubMed

    Sprick, Cyle

    2006-03-01

    Improved technology and higher fidelity are making medical simulations increasingly popular. A simulated peripheral nerve stimulator and thumb actuator has been developed for use with the SimMan Universal Patient Simulator. This device incorporates a handheld control box, a McKibben pneumatic muscle and articulated thumb, and a remote software interface for the simulation facilitator. The system simulates the action of a peripheral nerve stimulator on the ulnar nerve, and the effects of neuromuscular junction blocking agents on the thumb motion.

  11. Electronic and optical spectroscopy of molecular junctions

    NASA Astrophysics Data System (ADS)

    Preiner, Michael J.

    Electronic transport through molecules has been intensively studied in recent years, due to scientific interest in fundamental questions about charge transport and the technological promise of nanoscale circuitry. A wide range of range of experimental platforms have been developed to electronically probe both single molecules and molecular monolayers. However, it remains challenging to fabricate reliable electronic contacts to molecules, and the vast majority of molecular electronic architectures are not amenable to standard characterization techniques, such as optical spectroscopy. Thus the field of molecular electronics has been hampered with problems of reproducibility, and many fundamental questions about electronic transport remain unanswered. This thesis describes four significant contributions towards the fabrication and characterization of molecular electronic devices: (1) The development of a new method for creating robust, large area junctions where the electronic transport is through a single monolayer of molecules. This method utilizes atomic layer deposition (ALD) to grow an ultrathin oxide layer on top of a molecular monolayer, which protects the molecules against subsequent processing. (2) A new method for rapid imaging and analysis of single defects in molecular monolayers. This method also electrically passivates defects as it labels them. (3) Hot carrier spectroscopy of molecular junctions. Using optically excited hot carriers, we demonstrate the ability to probe the energy level lineup inside buried molecular junctions. (4) Efficient coupling of optical fields to metal-insulator-metal (MIM) surface plasmon modes. We show both theoretical and experimental work illustrating the ability to create very intense optical fields inside MIM systems. The intense fields generated in this manner have natural extensions to a variety of applications, such as photon assisted tunneling in molecular junctions, optical modulators, and ultrafast optoelectronic

  12. Semiconductor junction formation by directed heat

    DOEpatents

    Campbell, Robert B.

    1988-03-24

    The process of the invention includes applying precursors 6 with N- and P-type dopants therein to a silicon web 2, with the web 2 then being baked in an oven 10 to drive off excessive solvents, and the web 2 is then heated using a pulsed high intensity light in a mechanism 12 at 1100.degree.-1150.degree. C. for about 10 seconds to simultaneously form semiconductor junctions in both faces of the web.

  13. Quantum dynamics in the bosonic Josephson junction

    SciTech Connect

    Chuchem, Maya; Cohen, Doron; Smith-Mannschott, Katrina; Hiller, Moritz; Kottos, Tsampikos; Vardi, Amichay

    2010-11-15

    We employ a semiclassical picture to study dynamics in a bosonic Josephson junction with various initial conditions. Phase diffusion of coherent preparations in the Josephson regime is shown to depend on the initial relative phase between the two condensates. For initially incoherent condensates, we find a universal value for the buildup of coherence in the Josephson regime. In addition, we contrast two seemingly similar on-separatrix coherent preparations, finding striking differences in their convergence to classicality as the number of particles increases.

  14. Defect formation in long Josephson junctions

    SciTech Connect

    Gordeeva, Anna V.; Pankratov, Andrey L.

    2010-06-01

    We study numerically a mechanism of vortex formation in a long Josephson junction within the framework of the one-dimensional sine-Gordon model. This mechanism is switched on below the critical temperature. It is shown that the number of fluxons versus velocity of cooling roughly scales according to the power law with the exponent of either 0.25 or 0.5 depending on the temperature variation in the critical current density.

  15. Josephson junction microwave modulators for qubit control

    NASA Astrophysics Data System (ADS)

    Naaman, O.; Strong, J. A.; Ferguson, D. G.; Egan, J.; Bailey, N.; Hinkey, R. T.

    2017-02-01

    We demonstrate Josephson junction based double-balanced mixer and phase shifter circuits operating at 6-10 GHz and integrate these components to implement both a monolithic amplitude/phase vector modulator and an I/Q quadrature mixer. The devices are actuated by flux signals, dissipate no power on chip, exhibit input saturation powers in excess of 1 nW, and provide cryogenic microwave modulation solutions for integrated control of superconducting qubits.

  16. Effect of disorder on longitudinal resistance of a graphene p-n junction in the quantum Hall regime

    NASA Astrophysics Data System (ADS)

    Chen, Jiang-Chai; Yeung, T. C. Au; Sun, Qing-Feng

    2010-06-01

    The longitudinal resistances of a six-terminal graphene p-n junction under a perpendicular magnetic field are investigated. Because of the chirality of the Hall edge states, the longitudinal resistances on top and bottom edges of the graphene ribbon are not equal. In the presence of suitable disorder, the top-edge and bottom-edge resistances well show the plateau structures in the both unipolar and bipolar regimes, and the plateau values are determined by the Landau filling factors only. These plateau structures are in excellent agreement with the recent experiment. For the unipolar junction, the resistance plateaus emerge in the absence of impurity and they are destroyed by strong disorder. But for the bipolar junction, the resistances are very large without the plateau structures in the clean junction. The disorder can strongly reduce the resistances and leads the formation of the resistance plateaus due to the mixture of the Hall edge states in virtue of the disorder. In addition, the size effect of the junction on the resistances is studied and some extra resistance plateaus are found in the long graphene junction case. This is explained by the fact that only part of the edge states participate in the full mixing.

  17. High-performance passive microwave survey on Josephson junctions

    SciTech Connect

    Denisov, A.G.; Radzikhovsky, V.N.; Kudeliya, A.M.

    1994-12-31

    The quasi-optical generations of image of objects with their internal structure in millimeter (MM) and submillimeter (SMM) bands is one of the prime problems of modern radioelectronics. The main advantage of passive MM imaging systems in comparison with visible and infrared (IR) systems is small attenuation of signals in fog, cloud, smoke, dust and other obscurants. However at a panoramic scanning of space the observation time lengthens and thereby the information processing rate becomes restricted. So that single-channel system cannot image in real time. Therefore we must use many radiometers in parallel to reduce the observation time. Such system must contain receiving sensors as pixels in multibeam antenna. The use of Josephson Junctions (JJ) for this purpose together with the cryoelectronic devices like GaAs FET or SQUIDS for signal amplifications after JJ is of particular interest in this case.

  18. Solitary Psoas Muscle Metastasis of Gastroesphageal Junction Adenocarcinoma

    PubMed Central

    Azadeh, Payam; Yaghobi Joybari, Ali; Sarbaz, Samaneh; Ghiasi, Hosein Ali; Farasatinasab, Maryam

    2016-01-01

    Metastasis of gastroesphageal junction (GEJ) adenocarcinoma in skeletal muscle is rare and primary sites for skeletal muscle metastases are usually lung, renal and colorectal cancer. We have encountered with the first case report of solitary psoas muscle metastasis of GEJ adenocarcinoma. Here we describe a 65 years old man was diagnosed with GEJ adenocarcinoma in Gastroenterology Department, Imam Hussein Hospital, Tehran, Iran in February 2014. We were not able to use PET techniques due to lack of access. Staging CT scans demonstrated a small mass lateral to right psoas muscle. A CT-guided core needle biopsy of right psoas muscle was performed that supported a diagnosis of adenocarcinoma consistent with primary adenocarcinoma of the GEJ. Distant metastasis to skeletal muscle rarely occurs in patients with GEJ adenocarcinoma, but heightened awareness to these soft tissue lesions is warranted. CT or MR imaging could show findings suggestive of metastatic disease, although PET is preferable modality. PMID:26870148

  19. Perpendicularly magnetized exchange-biased magnetic tunnel junctions

    NASA Astrophysics Data System (ADS)

    Ney, Andreas; van Dijken, Sebastiaan; Parkin, Stuart

    2005-03-01

    Exchange biased magnetic tunnel junctions (MTJs) with perpendicular magnetic anisotropy (PMA) have been studied. The ferromagnetic electrodes were fabricated from either Co/Pt or Co/Pd multilayers and the tunnel barriers were formed from Al2O3. In some cases one of the electrodes was exchange biased with either PtMn or IrMn. We discuss the dependence of the PMA and the exchange bias on the thickness of the Co, Pt and Pd layers. The properties of the MTJs are strongly influenced by the structural morphology of the Co/Pt and the Co/Pd multilayer electrodes, which appear to give rise to rough tunnel barriers with low resistance.

  20. High-performance passive microwave survey on Josephson Junctions

    NASA Technical Reports Server (NTRS)

    Denisov, A. G.; Radzikhovsky, V. N.; Kudeliya, A. M.

    1995-01-01

    The quasi-optical generations of images of objects with their internal structure in millimeter (MM) and submillimeter (SMM) bands is one of prime problems of modern radioelectronics. The main advantage of passive MM imaging systems in comparison with visible and infrared (IR) systems is small attenuation of signals in fog, cloud, smoke, dust and other obscurants. However, at a panoramic scanning of space the observation time lengthens and thereby the information processing rate becomes restricted so that single-channel system cannot image in real time. Therefore we must use many radiometers in parallel to reduce the observation time. Such system must contain receiving sensors as pixels in multibeam antenna. The use of Josephson Junctions (JJ) for this purpose together with the cryoelectronic devices like GaAs FET (field effect transistors) or SQUIDS for signal amplifications after JJ is of particular interest in this case.

  1. Comparative analysis of the gap junction protein from rat heart and liver: is there a tissue specificity of gap junctions?

    PubMed

    Gros, D B; Nicholson, B J; Revel, J P

    1983-12-01

    Gap junctions have been isolated from both rat heart and liver, tissues where junctions are typical in appearance and physiology. The purity of the fractions obtained was monitored by electron microscopy (thin-sectioning and negative staining) and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The myocardial gap junctions are comprised of a single polypeptide of Mr 28,000, apparently derived from a protein of Mr 30,000. Hepatic gap junctions are also comprised of a single native protein of Mr 28,000 as previously reported. Exhaustive trypsin digestion of the isolated junctions cleaves both of these proteins similarly, while leaving their characteristic junctional lattice structures intact. However, comparison of heart and liver junctional proteins by two-dimensional peptide mapping of tryptic and alpha-chymotryptic fragments, followed by high pressure liquid chromatography, reveals no homology between these proteins.

  2. Hemichannel and junctional properties of connexin 50.

    PubMed Central

    Beahm, Derek L; Hall, James E

    2002-01-01

    Lens fiber connexins, cx50 and cx46 (alpha3 and alpha8), belong to a small subset of connexins that can form functional hemichannels in nonjunctional membranes. Knockout of either cx50 or cx46 results in a cataract, so the properties of both connexins are likely essential for proper physiological functioning of the lens. Although portions of the sequences of these two connexins are nearly identical, their hemichannel properties are quite different. Cx50 hemichannels are much more sensitive to extracellular acidification than cx46 hemichannels and differ from cx46 hemichannels both in steady-state and kinetic properties. Comparison of the two branches of the cx50 hemichannel G-V curve with the junctional G-V curve suggests that cx50 gap junctions gate with positive relative polarity. The histidine-modifying reagent, diethyl pyrocarbonate, reversibly blocks cx50 hemichannel currents but not cx46 hemichannel currents. Because cx46 and cx50 have very similar amino acid sequences, one might expect that replacing the two histidines unique to the third transmembrane region of cx50 with the corresponding cx46 residues would produce mutants more closely resembling cx46. In fact this does not happen. Instead the mutant cx50H161N does not form detectable hemichannels but forms gap junctions indistinguishable from wild type. Cx50H176Q is oocyte lethal, and the double mutant, cx50H61N/H176Q, neither forms hemichannels nor kills oocytes. PMID:11916859

  3. Josephson effect in a Weyl SNS junction

    NASA Astrophysics Data System (ADS)

    Madsen, Kevin A.; Bergholtz, Emil J.; Brouwer, Piet W.

    2017-02-01

    We calculate the Josephson current density j (ϕ ) for a Weyl superconductor-normal-metal-superconductor junction for which the outer terminals are superconducting Weyl metals and the normal layer is a Weyl (semi)metal. We describe the Weyl (semi)metal using a simple model with two Weyl points. The model has broken time-reversal symmetry, but inversion symmetry is present. We calculate the Josephson current for both zero and finite temperature for the two pairing mechanisms inside the superconductors that have been proposed in the literature, zero-momentum BCS-like pairing and finite-momentum FFLO-like pairing, and assuming the short-junction limit. For both pairing types we find that the current is proportional to the normal-state junction conductivity, with a proportionality coefficient that shows quantitative differences between the two pairing mechanisms. The current for the BCS-like pairing is found to be independent of the chemical potential, whereas the current for the FFLO-like pairing is not.

  4. Primary thermometry with nanoscale tunnel junctions

    SciTech Connect

    Hirvi, K.P.; Kauppinen, J.P.; Paalanen, M.A.; Pekola, J.P.

    1995-10-01

    We have found current-voltage (I-V) and conductance (dI/dV) characteristics of arrays of nanoscale tunnel junctions between normal metal electrodes to exhibit suitable features for primary thermometry. The current through a uniform array depends on the ratio of the thermal energy k{sub B}T and the electrostatic charging energy E{sub c} of the islands between the junctions and is completely blocked by Coulomb repulsion at T=0 and at small voltages eV/2 {<=} Ec. In the opposite limit, k{sub B}T {much_gt} E{sub c}, the width of the conductance minimum scales linearly and universally with T and N, the number of tunnel junctions, and qualifies as a primary thermometer. The zero bias drop in the conductance is proportional to T{sup -1} and can be used as a secondary thermometer. We will show with Monte Carlo simulations how background charge and nonuniformities of the array will affect the thermometer.

  5. Molecular Diffusion through Cyanobacterial Septal Junctions.

    PubMed

    Nieves-Morión, Mercedes; Mullineaux, Conrad W; Flores, Enrique

    2017-01-03

    Heterocyst-forming cyanobacteria grow as filaments in which intercellular molecular exchange takes place. During the differentiation of N2-fixing heterocysts, regulators are transferred between cells. In the diazotrophic filament, vegetative cells that fix CO2 through oxygenic photosynthesis provide the heterocysts with reduced carbon and heterocysts provide the vegetative cells with fixed nitrogen. Intercellular molecular transfer has been traced with fluorescent markers, including calcein, 5-carboxyfluorescein, and the sucrose analogue esculin, which are observed to move down their concentration gradient. In this work, we used fluorescence recovery after photobleaching (FRAP) assays in the model heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120 to measure the temperature dependence of intercellular transfer of fluorescent markers. We find that the transfer rate constants are directly proportional to the absolute temperature. This indicates that the "septal junctions" (formerly known as "microplasmodesmata") linking the cells in the filament allow molecular exchange by simple diffusion, without any activated intermediate state. This constitutes a novel mechanism for molecular transfer across the bacterial cytoplasmic membrane, in addition to previously characterized mechanisms for active transport and facilitated diffusion. Cyanobacterial septal junctions are functionally analogous to the gap junctions of metazoans.

  6. Junction point on partially singular trajectories

    NASA Astrophysics Data System (ADS)

    Odia, Ameze; Bell, David J.

    2012-12-01

    In recent times, several works have been performed on the design of fuel optimal trajectories for space navigation. These works show the possibility of the existence of partially singular trajectories for systems that are linear analytic (Park et al. 2010). Linear analytic systems may show the existence of partially singular subarcs, and the point where these subarcs meet is called a junction point. Thus, knowledge about junction conditions became necessary when solving the optimal control problem for such systems. This led to the development of two 'theorems' on junction conditions, given by McDanell and Powers (McDanell, J.P. and Powers W.F. (1971), 'Necessary Conditions for Joining Optimal Singular and Nonsingular Sub Arcs', SIAM Journal of Control, 9, 161-173). However, the second 'theorem', which is now known as a conjecture, could not satisfy all classes of linear analytic system. Therefore, the aim of this study was to detect and correct the errors in the derivation of the McDanell and Powers conjecture. The error in their derivations was corrected and then tested on two newly mathematically constructed systems. The results of these tests were found to be satisfactory. This implies that by making the necessary corrections, the conjecture can still be useful in generating a general theorem for all classes of systems.

  7. STUDIES ON AN EPITHELIAL (GLAND) CELL JUNCTION

    PubMed Central

    Loewenstein, Werner R.; Kanno, Yoshinobu

    1964-01-01

    Membrane permeability of an epithelial cell junction (Drosophila salivary gland) was examined with intracellular microelectrodes and with fluorescent tracers. In contrast to the non-junctional cell membrane surface, which has a low permeability to ions (10-4 mho/cm2), the junctional membrane surface is highly permeable. In fact, it introduces no substantial restriction to ion flow beyond that in the cytoplasm; the resistance through a chain of cells (150 Ω cm) is only slightly greater than in extruded cytoplasm (100 Ω cm). The diffusion resistance along the intercellular space to the exterior, on the other hand, is very high. Here, there exists an ion barrier of, at least, 104Ω cm2. As a result, small ions and fluorescein move rather freely from one cell to the next, but do not leak appreciably through the intercellular space to the exterior. The organ here, rather than the single cell, appears to be the unit of ion environment. The possible underlying structural aspects are discussed. PMID:14206423

  8. Molecular beam epitaxy growth of germanium junctions for multi-junction solar cell applications

    NASA Astrophysics Data System (ADS)

    Masuda, T.; Faucher, J.; Lee, M. L.

    2016-11-01

    We report on the molecular beam epitaxy (MBE) growth and device characteristics of Ge solar cells. Integrating a Ge bottom cell beneath a lattice-matched triple junction stack grown by MBE could enable ultra-high efficiencies without metamorphic growth or wafer bonding. However, a diffused junction cannot be readily formed in Ge by MBE due to the low sticking coefficient of group-V molecules on Ge surfaces. We therefore realized Ge junctions by growth of homo-epitaxial n-Ge on p-Ge wafers within a standard III-V MBE system. We then fabricated Ge solar cells, finding growth temperature and post-growth annealing to be key factors for achieving high efficiency. Open-circuit voltage and fill factor values of ~0.175 V and ~0.59 without a window layer were obtained, both of which are comparable to diffused Ge junctions formed by metal-organic vapor phase epitaxy. We also demonstrate growth of high-quality, single-domain GaAs on the Ge junction, as needed for subsequent growth of III-V subcells, and that the surface passivation afforded by the GaAs layer slightly improves the Ge cell performance.

  9. Gap junctions in several tissues share antigenic determinants with liver gap junctions.

    PubMed Central

    Dermietzel, R; Leibstein, A; Frixen, U; Janssen-Timmen, U; Traub, O; Willecke, K

    1984-01-01

    Using affinity-purified antibodies against mouse liver gap junction protein (26 K), discrete fluorescent spots were seen by indirect immunofluorescence labelling on apposed membranes of contiguous cells in several mouse and rat tissues: pancreas (exocrine part), kidney, small intestine (epithelium and circular smooth muscle), Fallopian tube, endometrium, and myometrium of delivering rats. No reaction was seen on sections of myocardium, ovaries and lens. Specific labelling of gap junction plaques was demonstrated by immunoelectron microscopy on ultrathin frozen sections through liver and the exocrine part of pancreas after treatment with gold protein A. Weak immunoreactivity was found on the endocrine part of the pancreas (i.e., Langerhans islets) after glibenclamide treatment of mice and rats, which causes an increase of insulin secretion and of the size as well as the number of gap junction plaques in cells of Langerhans islets. Furthermore, the affinity purified anti-liver 26 K antibodies were shown by immunoblot to react with proteins of similar mol. wt. in pancreas and kidney membranes. Taken together these results suggest that gap junctions from several, morphogenetically different tissues have specific antigenic sites in common. The different extent of specific immunoreactivity of anti-liver 26 K antibodies with different tissues is likely due to differences in size and number of gap junctions although structural differences cannot be excluded. Images Fig. 1. Fig. 2. Fig. 3. Fig. 4. Fig. 5. Fig. 6. PMID:6209130

  10. Computational Fluid Dynamics Analysis of Flexible Duct Junction Box Design

    SciTech Connect

    Beach, R.; Prahl, D.; Lange, R.

    2013-12-01

    IBACOS explored the relationships between pressure and physical configurations of flexible duct junction boxes by using computational fluid dynamics (CFD) simulations to predict individual box parameters and total system pressure, thereby ensuring improved HVAC performance. Current Air Conditioning Contractors of America (ACCA) guidance (Group 11, Appendix 3, ACCA Manual D, Rutkowski 2009) allows for unconstrained variation in the number of takeoffs, box sizes, and takeoff locations. The only variables currently used in selecting an equivalent length (EL) are velocity of air in the duct and friction rate, given the first takeoff is located at least twice its diameter away from the inlet. This condition does not account for other factors impacting pressure loss across these types of fittings. For each simulation, the IBACOS team converted pressure loss within a box to an EL to compare variation in ACCA Manual D guidance to the simulated variation. IBACOS chose cases to represent flows reasonably correlating to flows typically encountered in the field and analyzed differences in total pressure due to increases in number and location of takeoffs, box dimensions, and velocity of air, and whether an entrance fitting is included. The team also calculated additional balancing losses for all cases due to discrepancies between intended outlet flows and natural flow splits created by the fitting. In certain asymmetrical cases, the balancing losses were significantly higher than symmetrical cases where the natural splits were close to the targets. Thus, IBACOS has shown additional design constraints that can ensure better system performance.

  11. On the structural organization of isolated bovine lens fiber junctions.

    PubMed

    Zampighi, G; Simon, S A; Robertson, J D; McIntosh, T J; Costello, M J

    1982-04-01

    Junctions between fiber cells of bovine lenses have been isolated in milligram quantities, without using detergents or proteases. The structure of the isolated junctions has been studied by thin-section, negative-stain, and freeze-fracture electron microscopy and by x-ray diffraction. The junctions are large and most often have an undulating surface topology as determined by thin sectioning and freeze-fracture. These undulations resemble the tongue-and-groove interdigitations between lens fiber cells previously seen by others (D. H. Dickson and G. W. Crock, 1972, Invest. Ophthalmol. 11:809-815). In sections, the isolated junctions display a pentalamellar structure approximately 13-14 nm in overall thickness, which is significantly thinner than liver gap junctions. Each junctional membrane contains in the plane of the lipid bilayers distinct units arranged in a square lattice with a center-to-center spacing of 6.6 nm. Freeze-fracture replicas of the junctions fractured transversely show that the repeating units extend across the entire thickness of each membrane. Each unit is probably constructed from four identical subunits, with each subunit containing a protein of an apparent molecular weight of 27,000. We conclude that the lens junctions are structurally and chemically, different from gap junctions and could represent a new kind of intercellular contact, not simply another crystalline state of the gap junction protein.

  12. Cancer of the oesophagus and gastroesophageal junction – a difficult clinical problem

    PubMed Central

    Kot, Marta; Kotucha, Bartłomiej; Stępień, Renata; Kozieł, Dorota

    2014-01-01

    Introduction Cancer located in the oesophagus and gastroesophageal junction is a complex clinical problem and the results of its treatment still remain unsatisfactory. The objective of the study was the clinical analysis of a group of patients with cancer of the oesophagus or gastroesophageal junction, who received combined medical and surgical treatment. Material and methods The analysis was performed on a group of 128 patients with the diagnosis of oesophageal cancer or cancer of the gastroesophageal junction. Analysis of medical records and follow-up examinations were used in the research procedure. Results From among 128 patients with a diagnosis of oesophageal or gastroesophageal junction cancer, 50 (38.5%) received surgical resections. The surgery most frequently performed (n = 15) was sub-total oesophageal resection according to Akiyama procedure by right-sided thoracotomy (oesophageal anastomosis in the neck). The largest group were patients (n = 26) with stage T3N1M0 of advancement of the disease. In all cases of cancer located in the lower third of the oesophagus, an adenocarcinoma pattern was diagnosed in the histopathological examination, whereas in the case of cancers located in the middle third and upper third of the thoracic oesophagus a carcinoma planoepitheliale pattern was seen. Anastomotic leaks occurred in seven patients (14%). Six patients died during the post-operative period (12%). The mean survival time in the group of analysed patients was two years. Conclusions Cancer of the oesophagus or gastroesophageal junction is associated with low resectability, high risk of complications after surgery, and poor oncologic outcome. It is necessary to seek new methods of treatment. PMID:25477759

  13. HPV type 16 in conjunctival and junctional papilloma, dysplasia, and squamous cell carcinoma.

    PubMed Central

    Saegusa, M; Takano, Y; Hashimura, M; Okayasu, I; Shiga, J

    1995-01-01

    AIMS--To clarify the role of human papillomavirus (HPV) infection in the development of papilloma, dysplasia, squamous cell carcinoma, and basal cell epithelioma arising from the eyelids, including the tunica conjunctiva palpebrum (conjunctiva), its junction to epidemis of eyelid skin (junction), and eyelid skin. METHODS--Sixteen cases of papilloma, four of dysplasia, four of squamous cell carcinoma, and 12 of basal cell epithelioma were examined using formalin fixed and paraffin embedded samples. Detection of HPV-DNA was performed by PCR-RFLP and in situ hybridisation (ISH) methods. RESULTS--HPV-16 was detected in 12/16 papillomas (75%), 2/4 dysplasias (50%), and 1/4 squamous cell carcinomas (25%) but in none of the basal cell epitheliomas. No other HPV subtypes were found. ISH assay showed positive signals in only two cases of dysplasia and squamous cell carcinoma. The mean age of HPV-16 positive dysplasia and squamous cell carcinoma cases (81.7 years) was significantly higher than that of HPV-16 positive papilloma cases (p < 0.01). CONCLUSIONS--Based on the presence of HPV-16 in both benign and malignant lesions and the age distribution, it seems likely that HPV-16 alone may be incapable of causing development of conjunctival and junctional dysplasia and squamous cell carcinoma, and that any correlation between the papilloma-squamous cell carcinoma sequence and HPV infection may be due to rare events. Images PMID:8567996

  14. The structural organization and protein composition of lens fiber junctions

    PubMed Central

    1989-01-01

    The structural organization and protein composition of lens fiber junctions isolated from adult bovine and calf lenses were studied using combined electron microscopy, immunolocalization with monoclonal and polyclonal anti-MIP and anti-MP70 (two putative gap junction-forming proteins), and freeze-fracture and label-fracture methods. The major intrinsic protein of lens plasma membranes (MIP) was localized in single membranes and in an extensive network of junctions having flat and undulating surface topologies. In wavy junctions, polyclonal and monoclonal anti-MIPs labeled only the cytoplasmic surface of the convex membrane of the junction. Label-fracture experiments demonstrated that the convex membrane contained MIP arranged in tetragonal arrays 6-7 nm in unit cell dimension. The apposing concave membrane of the junction displayed fracture faces without intramembrane particles or pits. Therefore, wavy junctions are asymmetric structures composed of MIP crystals abutted against particle-free membranes. In thin junctions, anti-MIP labeled the cytoplasmic surfaces of both apposing membranes with varying degrees of asymmetry. In thin junctions, MIP was found organized in both small clusters and single membranes. These small clusters also abut against particle-free apposing membranes, probably in a staggered or checkerboard pattern. Thus, the structure of thin and wavy junctions differed only in the extent of crystallization of MIP, a property that can explain why this protein can produce two different antibody-labeling patterns. A conclusion of this study is that wavy and thin junctions do not contain coaxially aligned channels, and, in these junctions, MIP is unlikely to form gap junction-like channels. We suggest MIP may behave as an intercellular adhesion protein which can also act as a volume-regulating channel to collapse the lens extracellular space. Junctions constructed of MP70 have a wider overall thickness (18-20 nm) and are abundant in the cortical regions

  15. Beyond the Lorentzian Model in Quantum Transport: Energy-Dependent Resonance Broadening in Molecular Junctions

    NASA Astrophysics Data System (ADS)

    Liu, Zhenfei; Neaton, Jeffrey B.

    In quantum transport calculations, transmission functions of molecular junctions, as well as spectral functions of metal-organic interfaces, often feature peaks originating from molecular resonances. These resonance peaks are often assumed to be Lorentzian, with an energy-independent broadening function Γ. However, in the general case, the wide-band-limit breaks down, and the Lorentzian approximation is no longer valid. Here, we develop a new energy-dependent broadening function Γ (E) , based on diagonalization of non-Hermitian matrices within a non-equilbrium Green's function (NEGF) formalism. As defined, Γ (E) can describe resonances of non-Lorentzian nature and can be decomposed into components associated with the left and right leads, respectively; and it is particularly useful in understanding transport properties in terms of molecular orbitals in asymmetric junctions. We compute this quantity via an ab initio NEGF approach based on density functional theory and illustrate its utility with several junctions of experimental relevance, including recent work on rectification in Au-graphite junctions. This work is supported by the DOE, and computational resources are provided by NERSC.

  16. Massive Dirac fermion transport in a gapped graphene-based magnetic tunnel junction

    NASA Astrophysics Data System (ADS)

    Soodchomshom, Bumned; Tang, I.-Ming; Hoonsawat, Rassmidara

    2009-08-01

    The spin transport in a graphene-based magnetic (NG/ferromagnetic barrier (FB)/NG) tunnel junction with the graphene sheet being grown on a SiC substrate is investigated. Zhou et al. [Nat. Mater. 6 (2007) 770] has shown that in these epitaxial grown graphene sheets, the electrons behave like massive relativistic particles with an energy gap of 2 Δ∼260 meV opening up in the energy spectrum of the massive relativistic electron. Basing on assumption that gap in graphene can occur under the influence of the magnetic field, we find that in the case of thick ferromagnetic graphene barriers, the electronic gap causes the barrier to behave as a strong insulator when the gate potential is in the range 400-130 meV< V G<400+130 meV (and the energy level Ef∼400 meV above Dirac point). For these values of V G, the spin polarization of the junction is P(%)∼100% except for V G= E f, where it is P(%)=0%. The current of the junction, for thick FB, can be rapidly switched from a 100% spin up current to a 100% spin down current by small variation of V G from V G< E f to V G> E f , the features of a perfect spin filtering electronic junction.

  17. Electron Transport through Polyene Junctions in between Carbon Nanotubes: an Ab Initio Realization

    NASA Astrophysics Data System (ADS)

    Chen, Yiing-Rei; Chen, Kai-Yu; Dou, Kun-Peng; Tai, Jung-Shen; Lee, Hsin-Han; Kaun, Chao-Cheng

    With both ab initio and tight-binding model calculations, we study a system of polyene bridged armchair carbon nanotube electrodes, considering one-polyene and two-polyene cases, to address aspects of quantum transport through junctions with multiple conjugated molecules. The ab initio results of the two-polyene cases not only show the interference effect in transmission, but also the sensitive dependence of such effect on the combination of relative contact sites, which agrees nicely with the tight-binding model. Moreover, we show that the discrepancy mainly brought by ab initio relaxation provides an insight into the influence upon transmission spectra, from the junction's geometry, bonding and effective potential. This work was supported by the Ministry of Science and Technology of the Republic of China under Grant Nos. 99-2112-M-003-012-MY2 and 103-2622-E-002-031, and the National Center for Theoretical Sciences of Taiwan.

  18. Bilateral spontaneous pneumothorax secondary to aspiration pneumonia induced by a wristwatch lodged at the pharyngoesophageal junction.

    PubMed

    Kawai, Chihiro; Miyao, Masashi; Kotani, Hirokazu; Tamaki, Keiji

    2015-06-01

    Bilateral spontaneous pneumothorax secondary to disease is rare and seldom encountered in forensic autopsies; however, traumatic bilateral pneumothorax occurs often. Herein, we present a forensic case involving a 50-year-old woman who died 4 days after ingesting a wristwatch. Postmortem computed tomography and autopsy findings demonstrated that the wristwatch was lodged at the pharyngoesophageal junction, that she had a bilateral pneumothorax unaccompanied by any thoracic wound, and that macular hemorrhagic lesions on the lung surfaces were responsible for the pneumothorax. A histological examination of the macular lesions revealed that they were aspiration pneumonia foci with many birefringent foreign materials. Furthermore, a necrotic process secondary to aspiration pneumonia with a one way check-valve hyperinflation caused by foreign materials in the bronchioles was the most probable pathogenesis of her pneumothorax. To our knowledge, this is the first reported case of a bilateral secondary spontaneous pneumothorax caused by a large foreign body at the pharyngoesophageal junction leading to death.

  19. Electron Transport through Porphyrin Molecular Junctions

    NASA Astrophysics Data System (ADS)

    Zhou, Qi

    The goal of this work is to study the properties that would affect the electron transport through a porphyrin molecular junction. This work contributes to the field of electron transport in molecular junctions in the following 3 aspects. First of all, by carrying out experiments comparing the conductance of the iron (III) porphyrin (protected) and the free base porphyrin (protected), it is confirmed that the molecular energy level broadening and shifting occurs for porphyrin molecules when coupled with the metal electrodes, and this level broadening and shifting plays an important role in the electron transport through molecular junctions. Secondly, by carrying out an in-situ deprotection of the acetyl-protected free base porphyrin molecules, it is found out that the presence of acetyl groups reduces the conductance. Thirdly, by incorporating the Matrix-assisted laser desorption/ionization (MALDI) spectrum and the in-situ deprotection prior to formation of molecular junctions, it allows a more precise understanding of the molecules involved in the formation of molecular junctions, and therefore allows an accurate analysis of the conductance histogram. The molecules are prepared by self-assembly and the junctions are formed using a Scanning Tunneling Microscopy (STM) molecular break junction technique. The porphyrin molecules are characterized by MALDI in solution before self-assembly to a gold/mica substrate. The self-assembled monolayers (SAMs) of porphyrins on gold are characterized by Ultraviolet-visible (UV-Vis) reflection spectroscopy to confirm that the molecules are attached to the substrate. The SAMs are then characterized by Angle-Resolved X-ray photoelectron spectroscopy (ARXPS) to determine the thickness and the average molecular orientation of the molecular layer. The electron transport is measured by conductance-displacement (G-S) experiments under a given bias (-0.4V). The conductance value of a single molecule is identified by a statistical analysis

  20. The critical power to maintain thermally stable molecular junctions.

    PubMed

    Wang, Yanlei; Xu, Zhiping

    2014-07-09

    With the rise of atomic-scale devices such as molecular electronics and scanning probe microscopies, energy transport processes through molecular junctions have attracted notable research interest recently. In this work, heat dissipation and transport across diamond/benzene/diamond molecular junctions are explored by performing atomistic simulations. We identify the critical power Pcr to maintain thermal stability of the junction through efficient dissipation of local heat. We also find that the molecule-probe contact features a power-dependent interfacial thermal resistance RK in the order of 10(9) kW(-1). Moreover, both Pcr and RK display explicit dependence on atomic structures of the junction, force and temperature. For instance, Pcr can be elevated in multiple-molecule junctions, and streching the junction enhances RK by a factor of 2. The applications of these findings in molecular electronics and scanning probing measurements are discussed, providing practical guidelines in their rational design.

  1. The critical power to maintain thermally stable molecular junctions

    NASA Astrophysics Data System (ADS)

    Wang, Yanlei; Xu, Zhiping

    2014-07-01

    With the rise of atomic-scale devices such as molecular electronics and scanning probe microscopies, energy transport processes through molecular junctions have attracted notable research interest recently. In this work, heat dissipation and transport across diamond/benzene/diamond molecular junctions are explored by performing atomistic simulations. We identify the critical power Pcr to maintain thermal stability of the junction through efficient dissipation of local heat. We also find that the molecule-probe contact features a power-dependent interfacial thermal resistance RK in the order of 109 kW-1. Moreover, both Pcr and RK display explicit dependence on atomic structures of the junction, force and temperature. For instance, Pcr can be elevated in multiple-molecule junctions, and streching the junction enhances RK by a factor of 2. The applications of these findings in molecular electronics and scanning probing measurements are discussed, providing practical guidelines in their rational design.

  2. Single P-N junction tandem photovoltaic device

    DOEpatents

    Walukiewicz, Wladyslaw; Ager, III, Joel W.; Yu, Kin Man

    2011-10-18

    A single P-N junction solar cell is provided having two depletion regions for charge separation while allowing the electrons and holes to recombine such that the voltages associated with both depletion regions of the solar cell will add together. The single p-n junction solar cell includes an alloy of either InGaN or InAlN formed on one side of the P-N junction with Si formed on the other side in order to produce characteristics of a two junction (2J) tandem solar cell through only a single P-N junction. A single P-N junction solar cell having tandem solar cell characteristics will achieve power conversion efficiencies exceeding 30%.

  3. Single P-N junction tandem photovoltaic device

    DOEpatents

    Walukiewicz, Wladyslaw [Kensington, CA; Ager, III, Joel W.; Yu, Kin Man [Lafayette, CA

    2012-03-06

    A single P-N junction solar cell is provided having two depletion regions for charge separation while allowing the electrons and holes to recombine such that the voltages associated with both depletion regions of the solar cell will add together. The single p-n junction solar cell includes an alloy of either InGaN or InAlN formed on one side of the P-N junction with Si formed on the other side in order to produce characteristics of a two junction (2J) tandem solar cell through only a single P-N junction. A single P-N junction solar cell having tandem solar cell characteristics will achieve power conversion efficiencies exceeding 30%.

  4. Structure, regulation and function of gap junctions in liver

    PubMed Central

    Maes, Michaël; Decrock, Elke; Wang, Nan; Leybaert, Luc; da Silva, Tereza Cristina; Veloso Alves Pereira, Isabel; Jaeschke, Hartmut; Cogliati, Bruno; Vinken, Mathieu

    2016-01-01

    Gap junctions are a specialized group of cell-to-cell junctions that mediate direct intercellular communication between cells. They arise from the interaction of 2 hemichannels of adjacent cells, which in turn are composed of 6 connexin proteins. In liver, gap junctions are predominantly found in hepatocytes and play critical roles in virtually all phases of the hepatic life cycle, including cell growth, differentiation, liver-specific functionality and cell death. Liver gap junctions are directed through a broad variety of mechanisms ranging from epigenetic control of connexin expression to posttranslational regulation of gap junction activity. This paper reviews established and novel aspects regarding the architecture, control and functional relevance of liver gap junctions. PMID:27001459

  5. Electron optics with p-n junctions in ballistic graphene

    NASA Astrophysics Data System (ADS)

    Chen, Shaowen; Han, Zheng; Elahi, Mirza M.; Habib, K. M. Masum; Wang, Lei; Wen, Bo; Gao, Yuanda; Taniguchi, Takashi; Watanabe, Kenji; Hone, James; Ghosh, Avik W.; Dean, Cory R.

    2016-09-01

    Electrons transmitted across a ballistic semiconductor junction are expected to undergo refraction, analogous to light rays across an optical boundary. In graphene, the linear dispersion and zero-gap band structure admit highly transparent p-n junctions by simple electrostatic gating. Here, we employ transverse magnetic focusing to probe the propagation of carriers across an electrostatically defined graphene junction. We find agreement with the predicted Snell’s law for electrons, including the observation of both positive and negative refraction. Resonant transmission across the p-n junction provides a direct measurement of the angle-dependent transmission coefficient. Comparing experimental data with simulations reveals the crucial role played by the effective junction width, providing guidance for future device design. Our results pave the way for realizing electron optics based on graphene p-n junctions.

  6. Coherent diffraction of thermal currents in long Josephson tunnel junctions

    NASA Astrophysics Data System (ADS)

    Guarcello, Claudio; Giazotto, Francesco; Solinas, Paolo

    2016-08-01

    We discuss heat transport in thermally-biased long Josephson tunnel junctions in the presence of an in-plane magnetic field. In full analogy with the Josephson critical current, the phase-dependent component of the heat current through the junction displays coherent diffraction. Thermal transport is analyzed as a function of both the length and the damping of the junction, highlighting deviations from the standard "Fraunhofer" pattern characteristic of short junctions. The heat current diffraction patterns show features strongly related to the formation and penetration of Josephson vortices, i.e., solitons. We show that a dynamical treatment of the system is crucial for the realistic description of the Josephson junction, and it leads to peculiar results. In fact, hysteretic behaviors in the diffraction patterns when the field is swept up and down are observed, corresponding to the trapping of vortices in the junction.

  7. Concomitant achondroplasia and Chiari II malformation: A double-hit at the cervicomedullary junction

    PubMed Central

    Awad, Al-Wala; Aleck, Kyrieckos A; Bhardwaj, Ratan D

    2014-01-01

    We report the first case of a neonate with concurrent Chiari II malformation and achondroplasia. Although rare, both these conditions contribute to several deleterious anatomical changes at the cervicomedullary junction and thus predispose to acute hydrocephalus. Although our patient was initially asymptomatic, hydrocephalus ensued several weeks after birth and required cerebral spinal fluid diversion. We discuss the potential links between the two conditions, the pathophysiology, and the important clinical implications for the management of the increased risk of hydrocephalus. PMID:25405196

  8. Asymmetry in the normal-metal to high-T/sub c/ superconductor tunnel junction

    SciTech Connect

    Flensberg, K.; Hedega-circlerd, P.; Brix, M.

    1988-07-01

    We show that the observed asymmetry in the I-V characteristics of high-T/sub c/ material to normal-metal junctions can be explained within the resonating-valence-bond model. For a bias current with electrons moving from the superconductor to the normal metal, the current is quadratic in the bias voltage, and in the opposite case, with electrons moving from the normal metal to the superconductor, the current is linear in V.

  9. Gallstone impacted in the rectosigmoid junction causing a biliary ileus and a sigmoid perforation.

    PubMed

    Van Kerschaver, O; Van Maele, V; Vereecken, L; Kint, M

    2009-01-01

    A gallstone ileus is an unusual form of bowel obstruction. Colonic gallstone ileus is rare, difficult to diagnose, and still has a high mortality rate. We present a case of biliary ileus caused by an impacted gallstone, causing necrosis and perforation of the rectosigmoid junction. A Hartmann's procedure was performed to treat the perforation and the obstruction. Cholecystectomy and closure of the cholecysto-colonic fistula were delayed until restoration of the intestinal continuity.

  10. Incessant junctional reciprocating tachycardia caused by dual atrioventricular nodal pathways and atrio-nodal bypass tract.

    PubMed Central

    Santarelli, P; Sosa, E; Denes, P

    1982-01-01

    A case is described with clinical and electrocardiographic findings of incessant junctional reciprocating tachycardia. Electrophysiological study showed that longitudinal dissociation of the atrioventricular node into two pathways was responsible for the maintenance of the arrhythmia. The two intranodal pathways had different refractory periods but reciprocally related and overlapping conduction times (anterograde fast, retrograde slow, and vice versa). Induction and termination of the arrhythmia was related to the presence of a partial atrio-nodal bypass tract. Images PMID:7082510

  11. Junction conditions in quadratic gravity: thin shells and double layers

    NASA Astrophysics Data System (ADS)

    Reina, Borja; Senovilla, José M. M.; Vera, Raül

    2016-05-01

    The junction conditions for the most general gravitational theory with a Lagrangian containing terms quadratic in the curvature are derived. We include the cases with a possible concentration of matter on the joining hypersurface—termed as thin shells, domain walls or braneworlds in the literature—as well as the proper matching conditions where only finite jumps of the energy-momentum tensor are allowed. In the latter case we prove that the matching conditions are more demanding than in general relativity. In the former case, we show that generically the shells/domain walls are of a new kind because they possess, in addition to the standard energy-momentum tensor, a double layer energy-momentum contribution which actually induces an external energy flux vector and an external scalar pressure/tension on the shell. We prove that all these contributions are necessary to make the entire energy-momentum tensor divergence-free, and we present the field equations satisfied by these energy-momentum quantities. The consequences of all these results are briefly analyzed.

  12. Observing Holliday junction branch migration one step at a time

    NASA Astrophysics Data System (ADS)

    Ha, Taekjip

    2004-03-01

    During genetic recombination, two homologous DNA molecules undergo strand exchange to form a four-way DNA (Holliday) junction and the recognition and processing of this species by branch migration and junction resolving enzymes determine the outcome. We have used single molecule fluorescence techniques to study two intrinsic structural dynamics of the Holliday junction, stacking conformer transitions and spontaneous branch migration. Our studies show that the dynamics of branch migration, resolved with one base pair resolution, is determined by the stability of conformers which in turn depends on the local DNA sequences. Therefore, the energy landscape of Holliday junction branch migation is not uniform, but is rugged.

  13. Craniovertebral Junction Instability: A Review of Facts about Facets

    PubMed Central

    2015-01-01

    Craniovertebral junction surgery involves an appropriate philosophical, biomechanical and anatomical understanding apart from high degree of technical skill and ability of controlling venous and arterial bleeding. The author presents his 30-year experience with treating complex craniovertebral junction instability related surgical issues. The facets of atlas and axis form the primary site of movements at the craniovertebral junction. All craniovertebral junction instability is essentially localized to the atlantoaxial facet joint. Direct manipulation and fixation of the facets forms the basis of treatment for instability. PMID:26240728

  14. Imaging snake orbits at graphene n -p junctions

    NASA Astrophysics Data System (ADS)

    Kolasiński, K.; Mreńca-Kolasińska, A.; Szafran, B.

    2017-01-01

    We consider conductance mapping of the snake orbits confined along the n -p junction defined in graphene by the electrostatic doping in the quantum Hall regime. We explain the periodicity of conductance oscillations at the magnetic field and the Fermi energy scales by the properties of the n -p junction as a conducting channel. We evaluate the conductance maps for a floating gate scanning the surface of the device. In the quantum Hall conditions the currents flow near the edges of the sample and along the n -p junction. The conductance mapping resolves only the n -p junction and not the edges. The conductance oscillations along the junction are found in the maps with periodicity related to the cyclotron orbits of the scattering current. Stronger probe potentials provide support to localized resonances at one of the sides of the junction with current loops that interfere with the n -p junction currents. The interference results in a series of narrow lines parallel to the junction with positions that strongly depend on the magnetic field through the Aharonov-Bohm effect. The consequences of a limited transparency of finite-width n -p junctions are also discussed.

  15. Photoresponse in arrays of thermoelectric nanowire junctions

    NASA Astrophysics Data System (ADS)

    Huber, T. E.; Scott, R.; Johnson, S.; Brower, T.; Belk, J. H.; Hunt, J. H.

    2013-07-01

    We report the first demonstration of optical detection by thermoelectric nanowire junctions. We employed devices composed of bismuth nanowire arrays which are capped with a transparent indium tin oxide electrode. The incident surface features very low optical reflectivity and enhanced light trapping. The unique attributes of the thermoelectric arrays are the combination of strong temporal and optical wavelength dependences of the photocurrent. Under infrared illumination, the signal can be completely described by thermoelectric effects considering cooling rates given by heat diffusion through the array. In addition, under visible illumination, we observe a photovoltaic response.

  16. Plasmon Enhanced Hetero-Junction Solar Cell

    NASA Astrophysics Data System (ADS)

    Long, Gen; Ching, Levine; Sadoqi, Mostafa; Xu, Huizhong

    2015-03-01

    Here we report a systematic study of plasmon-enhanced hetero-junction solar cells made of colloidal quantum dots (PbS) and nanowires (ZnO), with/without metal nanoparticles (Au). The structure of solar cell devices was characterized by AFM, SEM and profilometer, etc. The power conversion efficiencies of solar cell devices were characterized by solar simulator (OAI TriSOL, AM1.5G Class AAA). The enhancement in the photocurrent due to introduction of metal nanoparticles was obvious. We believe this is due to the plasmonic effect from the metal nanoparticles. The correlation between surface roughness, film uniformity and device performance was also studied.

  17. Collisions of Strings with Y Junctions

    SciTech Connect

    Copeland, E. J.; Kibble, T. W. B.; Steer, D. A.

    2006-07-14

    We study the dynamics of Nambu-Goto strings with junctions at which three strings meet. In particular, we exhibit one simple exact solution and examine the process of intercommuting of two straight strings in which they exchange partners but become joined by a third string. We show that there are important kinematical constraints on this process. The exchange cannot occur if the strings meet with very large relative velocity. This may have important implications for the evolution of cosmic superstring networks and non-Abelian string networks.

  18. Charge Transport Processes in Molecular Junctions

    NASA Astrophysics Data System (ADS)

    Smith, Christopher Eugene

    Molecular electronics (ME) has evolved into a rich area of exploration that combines the fields of chemistry, materials, electronic engineering and computational modeling to explore the physics behind electronic conduction at the molecular level. Through studying charge transport properties of single molecules and nanoscale molecular materials the field has gained the potential to bring about new avenues for the miniaturization of electrical components where quantum phenomena are utilized to achieve solid state molecular device functionality. Molecular junctions are platforms that enable these studies and consist of a single molecule or a small group of molecules directly connected to electrodes. The work presented in this thesis has built upon the current understanding of the mechanisms of charge transport in ordered junctions using self-assembled monolayer (SAM) molecular thin films. Donor and acceptor compounds were synthesized and incorporated into SAMs grown on metal substrates then the transport properties were measured with conducting probe atomic force microscopy (CP-AFM). In addition to experimentally measured current-voltage (I-V) curves, the transport properties were addressed computationally and modeled theoretically. The key objectives of this project were to 1) investigate the impact of molecular structure on hole and electron charge transport, 2) understand the nature of the charge carriers and their structure-transport properties through long (<4 nm) conjugated molecular wires, and 3) quantitatively extract interfacial properties characteristic to macroscopic junctions, such as energy level alignment and molecule-contact electronic coupling from experimental I-V curves. Here, we lay ground work for creating a more complete picture of charge transport in macroscopically ordered molecular junctions of controlled architecture, length and charge carrier. The polaronic nature of hopping transport has been predicted in long, conjugated molecular wires

  19. Anatomy and biomechanics of the craniovertebral junction.

    PubMed

    Lopez, Alejandro J; Scheer, Justin K; Leibl, Kayla E; Smith, Zachary A; Dlouhy, Brian J; Dahdaleh, Nader S

    2015-04-01

    The craniovertebral junction (CVJ) has unique anatomical structures that separate it from the subaxial cervical spine. In addition to housing vital neural and vascular structures, the majority of cranial flexion, extension, and axial rotation is accomplished at the CVJ. A complex combination of osseous and ligamentous supports allow for stability despite a large degree of motion. An understanding of anatomy and biomechanics is essential to effectively evaluate and address the various pathological processes that may affect this region. Therefore, the authors present an up-to-date narrative review of CVJ anatomy, normal and pathological biomechanics, and fixation techniques.

  20. Nonintrusive Measurement Of Temperature Of LED Junction

    NASA Technical Reports Server (NTRS)

    Leidecker, Henning; Powers, Charles

    1991-01-01

    Temperature inferred from spectrum of emitted light. Method of determining temperature of junction based on two relevant characteristics of LED. Gap between valence and conduction electron-energy bands in LED material decreases with increasing temperature, causing wavelength of emitted photon to increase with temperature. Other, as temperature increases, non-radiative processes dissipate more of input electrical energy as heat and less as photons in band-gap wavelenth region; optical and quantum efficiencies decrease with increasing temperature. In principal, either characteristic alone used to determine temperature. However, desirable to use both to obtain indication of uncertainty.

  1. Ferromagnetic-Insulator-Based Superconducting Junctions as Sensitive Electron Thermometers

    NASA Astrophysics Data System (ADS)

    Giazotto, F.; Solinas, P.; Braggio, A.; Bergeret, F. S.

    2015-10-01

    We present an exhaustive theoretical analysis of charge and thermoelectric transport in a normal-metal-ferromagnetic-insulator-superconductor junction and explore the possibility of its use as a sensitive thermometer. We investigate the transfer functions and the intrinsic noise performance for different measurement configurations. A common feature of all configurations is that the best temperature-noise performance is obtained in the nonlinear temperature regime for a structure based on an Europium chalcogenide ferromagnetic insulator in contact with a superconducting Al film structure. For an open-circuit configuration, although the maximal intrinsic temperature sensitivity can achieve 10 nK Hz-1 /2 , a realistic amplifying chain will reduce the sensitivity up to 10 μ K Hz-1 /2 . To overcome this limitation, we propose a measurement scheme in a closed-circuit configuration based on state-of-the-art superconducting-quantum-interference-device detection technology in an inductive setup. In such a case, we show that temperature-noise can be as low as 35 nK Hz-1 /2 . We also discuss a temperature-to-frequency converter where the obtained thermovoltage developed over a Josephson junction operated in the dissipative regime is converted into a high-frequency signal. We predict that the structure can generate frequencies up to approximately 120 GHz and transfer functions up to 200 GHz /K at around 1 K. If operated as an electron thermometer, the device may provide temperature-noise lower than 35 nK Hz-1 /2 thereby being potentially attractive for radiation-sensing applications.

  2. Full potential of radial junction Si thin film solar cells with advanced junction materials and design

    NASA Astrophysics Data System (ADS)

    Qian, Shengyi; Misra, Soumyadeep; Lu, Jiawen; Yu, Zhongwei; Yu, Linwei; Xu, Jun; Wang, Junzhuan; Xu, Ling; Shi, Yi; Chen, Kunji; Roca i Cabarrocas, Pere

    2015-07-01

    Combining advanced materials and junction design in nanowire-based thin film solar cells requires a different thinking of the optimization strategy, which is critical to fulfill the potential of nano-structured photovoltaics. Based on a comprehensive knowledge of the junction materials involved in the multilayer stack, we demonstrate here, in both experimental and theoretical manners, the potential of hydrogenated amorphous Si (a-Si:H) thin film solar cells in a radial junction (RJ) configuration. Resting upon a solid experimental basis, we also assess a more advanced tandem RJ structure with radially stacking a-Si:H/nanocrystalline Si (nc-Si:H) PIN junctions, and show that a balanced photo-current generation with a short circuit current density of Jsc = 14.2 mA/cm2 can be achieved in a tandem RJ cell, while reducing the expensive nc-Si:H absorber thickness from 1-3 μ m (in planar tandem cells) to only 120 nm. These results provide a clearly charted route towards a high performance Si thin film photovoltaics.

  3. Optimal design of high-efficiency single-junction and tandem concentrator space cells at 80 deg C and 100 SUNS

    NASA Technical Reports Server (NTRS)

    Fan, J. C. C.; Palm, B. J.

    1984-01-01

    Computer analysis was used to determine the AMO conversion efficiency of single-junction crystalline cells, two-cell and three-cell crystalline tandem structures operating under 100 suns and at 80 C. For optimally designed devices, the calculated efficiencies are 24% for single-junction cells, 33 to 35% for two-cell tandem structures, and 37 to 39% for three-cell tandem structures. Practical efficiencies are expected to be about 15 relative percentage points lower in each case.

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

    DOEpatents

    Chang, Y. Austin; Yang, Jianhua Joshua

    2008-11-11

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

  5. Rabies virus binding at neuromuscular junctions.

    PubMed

    Burrage, T G; Tignor, G H; Smith, A L

    1985-04-01

    Morphological, immunocytochemical, biochemical, and immunological techniques have been used to describe rabies virus binding to a sub-cellular unit and molecular complex at the neuromuscular junction (NMJ). Early after infection in vivo, virus antigen and virus particles were found by immunofluorescence, electron microscopy and immunoelectron microscopy in regions of high density acetylcholine receptors (AChR) at NMJs. One monoclonal antibody (alpha-Mab) to the alpha subunit of the AChR blocked attachment of radio-labeled rabies virus to cultured muscle cells bearing high density patches of AChR. A sub-cellular structure, resembling an array of AChR monomers, bound both rabies virus antigens and alpha-Mab. By immunoblotting with electrophoretically transferred motor endplate proteins, rabies virus proteins and alpha-Mab bound to two proteins of 43 000 and 110 000 daltons. A rabies virus glycoprotein antibody detected virus antigen bound to the 110 000 dalton protein. An auto-immune (anti-idiotypic) response followed immunization of mice with rabies virus glycoprotein antigen; the antibody was directed to the 110 000 dalton protein. This auto-antibody altered the kinetics of neutralization by rabies virus antibody and induced the formation of rabies virus antibody after inoculation of mice. These results define, at the neuromuscular junction, a rabies virus receptor which may be part of the acetylcholine receptor complex.

  6. Edge currents in frustrated Josephson junction ladders

    NASA Astrophysics Data System (ADS)

    Marques, A. M.; Santos, F. D. R.; Dias, R. G.

    2016-09-01

    We present a numerical study of quasi-1D frustrated Josephson junction ladders with diagonal couplings and open boundary conditions, in the large capacitance limit. We derive a correspondence between the energy of this Josephson junction ladder and the expectation value of the Hamiltonian of an analogous tight-binding model, and show how the overall superconducting state of the chain is equivalent to the minimum energy state of the tight-binding model in the subspace of one-particle states with uniform density. To satisfy the constraint of uniform density, the superconducting state of the ladder is written as a linear combination of the allowed k-states of the tight-binding model with open boundaries. Above a critical value of the parameter t (ratio between the intra-rung and inter-rung Josephson couplings) the ladder spontaneously develops currents at the edges, which spread to the bulk as t is increased until complete coverage is reached. Above a certain value of t, which varies with ladder size (t = 1 for an infinite-sized ladder), the edge currents are destroyed. The value t = 1 corresponds, in the tight-binding model, to the opening of a gap between two bands. We argue that the disappearance of the edge currents with this gap opening is not coincidental, and that this points to a topological origin for these edge current states.

  7. Virus interaction with the apical junctional complex.

    PubMed

    Gonzalez-Mariscal, Lorenza; Garay, Erika; Lechuga, Susana

    2009-01-01

    In order to infect pathogens must breach the epithelial barriers that separate the organism from the external environment or that cover the internal cavities and ducts of the body. Epithelia seal the passage through the paracellular pathway with the apical junctional complex integrated by tight and adherens junctions. In this review we describe how viruses like coxsackie, swine vesicular disease virus, adenovirus, reovirus, feline calcivirus, herpes viruses 1 and 2, pseudorabies, bovine herpes virus 1, poliovirus and hepatitis C use as cellular receptors integral proteins present at the AJC of epithelial cells. Interaction with these proteins contributes in a significant manner in defining the particular tropism of each virus. Besides these proteins, viruses exhibit a wide range of cellular co-receptors among which proteins present in the basolateral cell surface like integrins are often found. Therefore targeting proteins of the AJC constitutes a strategy that might allow viruses to bypass the physical barrier that blocks their access to receptors expressed on the basolateral surface of epithelial cells.

  8. Functional ferroelectric tunnel junctions on silicon

    NASA Astrophysics Data System (ADS)

    Guo, Rui; Wang, Zhe; Zeng, Shengwei; Han, Kun; Huang, Lisen; Schlom, Darrell G.; Venkatesan, T.; Ariando; Chen, Jingsheng

    2015-07-01

    The quest for solid state non-volatility memory devices on silicon with high storage density, high speed, low power consumption has attracted intense research on new materials and novel device architectures. Although flash memory dominates in the non-volatile memory market currently, it has drawbacks, such as low operation speed, and limited cycle endurance, which prevents it from becoming the “universal memory”. In this report, we demonstrate ferroelectric tunnel junctions (Pt/BaTiO3/La0.67Sr0.33MnO3) epitaxially grown on silicon substrates. X-ray diffraction spectra and high resolution transmission electron microscope images prove the high epitaxial quality of the single crystal perovskite films grown on silicon. Furthermore, the write speed, data retention and fatigue properties of the device compare favorably with flash memories. The results prove that the silicon-based ferroelectric tunnel junction is a very promising candidate for application in future non-volatile memories.

  9. Angular craniometry in craniocervical junction malformation.

    PubMed

    Botelho, Ricardo Vieira; Ferreira, Edson Dener Zandonadi

    2013-10-01

    The craniometric linear dimensions of the posterior fossa have been relatively well studied, but angular craniometry has been poorly studied and may reveal differences in the several types of craniocervical junction malformation. The objectives of this study were to evaluate craniometric angles compared with normal subjects and elucidate the main angular differences among the types of craniocervical junction malformation and the correlation between craniocervical and cervical angles. Angular craniometries were studied using primary cranial angles (basal and Boogard's) and secondary craniocervical angles (clivus canal and cervical spine lordosis). Patients with basilar invagination had significantly wider basal angles, sharper clivus canal angles, larger Boogard's angles, and greater cervical lordosis than the Chiari malformation and control groups. The Chiari malformation group does not show significant differences when compared with normal controls. Platybasia occurred only in basilar invagination and is suggested to be more prevalent in type II than in type I. Platybasic patients have a more acute clivus canal angle and show greater cervical lordosis than non-platybasics. The Chiari group does not show significant differences when compared with the control, but the basilar invagination groups had craniometric variables significantly different from normal controls. Hyperlordosis observed in the basilar inavagination group was associated with craniocervical kyphosis conditioned by acute clivus canal angles.

  10. Molecular Diffusion through Cyanobacterial Septal Junctions

    PubMed Central

    Nieves-Morión, Mercedes

    2017-01-01

    ABSTRACT Heterocyst-forming cyanobacteria grow as filaments in which intercellular molecular exchange takes place. During the differentiation of N2-fixing heterocysts, regulators are transferred between cells. In the diazotrophic filament, vegetative cells that fix CO2 through oxygenic photosynthesis provide the heterocysts with reduced carbon and heterocysts provide the vegetative cells with fixed nitrogen. Intercellular molecular transfer has been traced with fluorescent markers, including calcein, 5-carboxyfluorescein, and the sucrose analogue esculin, which are observed to move down their concentration gradient. In this work, we used fluorescence recovery after photobleaching (FRAP) assays in the model heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120 to measure the temperature dependence of intercellular transfer of fluorescent markers. We find that the transfer rate constants are directly proportional to the absolute temperature. This indicates that the “septal junctions” (formerly known as “microplasmodesmata”) linking the cells in the filament allow molecular exchange by simple diffusion, without any activated intermediate state. This constitutes a novel mechanism for molecular transfer across the bacterial cytoplasmic membrane, in addition to previously characterized mechanisms for active transport and facilitated diffusion. Cyanobacterial septal junctions are functionally analogous to the gap junctions of metazoans. PMID:28049144

  11. Annealing free magnetic tunnel junction sensors

    NASA Astrophysics Data System (ADS)

    Knudde, S.; Leitao, D. C.; Cardoso, S.; Freitas, P. P.

    2017-04-01

    Annealing is a major step in the fabrication of magnetic tunnel junctions (MTJs). It sets the exchange bias between the pinned and antiferromagnetic layers, and helps to increase the tunnel magnetoresistance (TMR) in both amorphous and crystalline junctions. Recent research on MTJs has focused on MgO-based structures due to their high TMR. However, the strict process control and mandatory annealing step can limit the scope of the application of these structures as sensors. In this paper, we present AlOx-based MTJs that are produced by ion beam sputtering and remote plasma oxidation and show optimum transport properties with no annealing. The microfabricated devices show TMR values of up to 35% and using NiFe/CoFeB free layers provides tunable linear ranges, leading to coercivity-free linear responses with sensitivities of up to 5.5%/mT. The top-pinned synthetic antiferromagnetic reference shows a stability of about 30 mT in the microfabricated devices. Sensors with linear ranges of up to 60 mT are demonstrated. This paves the way for the integration of MTJ sensors in heat-sensitive applications such as flexible substrates, or for the design of low-footprint on-chip multiaxial sensing devices.

  12. Tricellular Tight Junctions in the Inner Ear

    PubMed Central

    2016-01-01

    Tight junctions (TJs) are structures that seal the space between the epithelial cell sheets. In the inner ear, the barrier function of TJs is indispensable for the separation of the endolymphatic and perilymphatic spaces, which is essential for the generation and maintenance of the endocochlear potential (EP). TJs are formed by the intercellular binding of membrane proteins, known as claudins, and mutations in these proteins cause deafness in humans and mice. Within the epithelial cell sheet, however, a bound structure is present at the site where the corners of three cells meet (tricellular tight junctions (tTJs)), and the maintenance of the barrier function at this location cannot be explained by the claudins alone. Tricellulin and the angulin family of proteins (angulin-1/LSR, angulin-2/ILDR1, and angulin-3/ILDR2) have been identified as tTJ-associated proteins. Tricellulin and ILDR1 are localized at the tTJ and alterations in these proteins have been reported to be involved in deafness. In this review, we will present the current state of knowledge for tTJs. PMID:27195292

  13. Conductance spectroscopy of topological superconductor wire junctions

    NASA Astrophysics Data System (ADS)

    Setiawan, F.; Brydon, Philip; Sau, Jay

    We study the zero-temperature transport properties of one-dimensional normal metal-superconductor (NS) junctions with topological superconductors across their topological transitions. Working within the Blonder-Tinkham-Klapwijk (BTK) formalism generalized for topological NS junctions, we analytically calculate the differential conductance for tunneling into two models of a topological superconductor: a spinless intrinsic p-wave superconductor and a spin-orbit-coupled s-wave superconductor in a Zeeman field. The zero-bias conductance takes nonuniversal values in the nontopological phase while it is robustly quantized at 2e2 / h in the topological regime. Despite this quantization at zero voltage, the zero-bias conductance only develops a peak (or a local maximum) as a function of voltage for sufficiently large interfacial barrier strength, or certain parameter regimes of spin-orbit coupling strength. Our calculated BTK conductance also shows that the conductance is finite inside the superconducting gap region because of the finite barrier transparency, providing a possible mechanism for the observed ``soft gap'' feature in the experimental studies. Work is done in collaboration with Sankar Das Sarma and supported by Microsoft Q, LPS-CMTC, and JQI-NSF-PFC.

  14. Thermoelectrics in an array of molecular junctions.

    PubMed

    Müller, K-H

    2008-07-28

    The room temperature thermoelectric properties of a three-dimensional array of molecular junctions are calculated. The array is composed of n-doped silicon nanoparticles where the surfaces are partially covered with polar molecules and the nanoparticles are bridged by trans-polyacetylene molecules. The role of the polar molecules is to reduce the band bending in the n-doped silicon nanoparticles and to shift the electronic resonances of the bridging molecules to the nanoparticle conduction band edges where the molecular resonances act as electron energy filters. The transmission coefficients of the bridging molecules that appear in the formulas for the Seebeck coefficient, the electrical conductance, and the electronic thermal conductance, are calculated using the nonequilibrium Green's function technique. A simple tight-binding Hamiltonian is used to describe the bridging molecules, and the self-energy term is calculated using the parabolic conduction band approximation. The dependencies of the thermoelectric properties of the molecular junctions on the silicon doping concentration and on the molecule-nanoparticle coupling are discussed. The maximal achievable thermoelectric figure of merit ZT of the array is estimated as a function of the phononic thermal conductance of the bridging molecules and the doping of the nanoparticles. The power factor of the array is also calculated. For sufficiently small phononic thermal conductances of the bridging molecules, very high ZT values are predicted.

  15. Switching and Rectification in Carbon-Nanotube Junctions

    NASA Technical Reports Server (NTRS)

    Srivastava, Deepak; Andriotis, Antonis N.; Menon, Madhu; Chernozatonskii, Leonid

    2003-01-01

    Multi-terminal carbon-nanotube junctions are under investigation as candidate components of nanoscale electronic devices and circuits. Three-terminal "Y" junctions of carbon nanotubes (see Figure 1) have proven to be especially interesting because (1) it is now possible to synthesize them in high yield in a controlled manner and (2) results of preliminary experimental and theoretical studies suggest that such junctions could exhibit switching and rectification properties. Following the preliminary studies, current-versus-voltage characteristics of a number of different "Y" junctions of single-wall carbon nanotubes connected to metal wires were computed. Both semiconducting and metallic nanotubes of various chiralities were considered. Most of the junctions considered were symmetric. These computations involved modeling of the quantum electrical conductivity of the carbon nanotubes and junctions, taking account of such complicating factors as the topological defects (pentagons, heptagons, and octagons) present in the hexagonal molecular structures at the junctions, and the effects of the nanotube/wire interfaces. A major component of the computational approach was the use of an efficient Green s function embedding scheme. The results of these computations showed that symmetric junctions could be expected to support both rectification and switching. The results also showed that rectification and switching properties of a junction could be expected to depend strongly on its symmetry and, to a lesser degree, on the chirality of the nanotubes. In particular, it was found that a zigzag nanotube branching at a symmetric "Y" junction could exhibit either perfect rectification or partial rectification (asymmetric current-versus-voltage characteristic, as in the example of Figure 2). It was also found that an asymmetric "Y" junction would not exhibit rectification.

  16. Low resistance junctions in crayfish. Structural changes with functional uncoupling

    PubMed Central

    1976-01-01

    Electrical uncoupling of crayfish septate lateral giant axons is paralleled by structural changes in the gap junctions. The changes are characterized by a tighter aggregation of the intramembrane particles and a decrease in the overall width of the junction and the thickness of the gap. Preliminary measurements indicate also a decrease in particle diameter. The uncoupling is produced by in vitro treatment of crayfish abdominal cords either with a Ca++, Mg++-free solution containing EDTA, followed by return to normal saline (Van Harreveld's solution), or with VAn Harreveld's solution containing dinitrophenol (DNP). The uncoupling is monitored by the intracellular recording of the electrical resistance at a septum between lateral giant axons. The junctions of the same septum are examined in thin sections; those of other ganglia of the same chain used for the electrical measurements are studied by freeze-fracture. In controls, most junctions contain a more or less regular array of particles repeating at a center to center distance of approximately 200 A. The overall width of the junctions is approximately 200 A and the gap thickness is 40-50 A. Vesicles (400-700 A in diameter) are closely apposed to the junctional membranes. In uncoupled axons, most junctions contain a hexagonal array of particles repeating at a center to center distance of 150-155 A. The overall width of the junctions is approximately 180 A and the gap thickness is 20-30 A. These junctions are usually curved and are rarely associated with vesicles. Isolated, PTA-stained junctions, also believed to be uncoupled, display similar structural features. There are reasons to believe that the changes in structure and permeability are triggered by an increase in the intracellular free Ca++ concentration. Most likely, the changes in permeability are caused by conformational changes in some components of the intramembrane particles at the gap junctions. PMID:820701

  17. Progress in the Development of Metamorphic Multi-Junction III-V Space-Solar Cells at Essential Research Incorporated

    NASA Technical Reports Server (NTRS)

    Sinharoy, Samar; Patton, Martin O.; Valko, Thomas M., Sr.; Weizer, Victor G.

    2002-01-01

    Theoretical calculations have shown that highest efficiency III-V multi-junction solar cells require alloy structures that cannot be grown on a lattice-matched substrate. Ever since the first demonstration of high efficiency metamorphic single junction 1.1 eV and 1.2 eV InGaAs solar cells by Essential Research Incorporated (ERI), interest has grown in the development of multi-junction cells of this type using graded buffer layer technology. ERI is currently developing a dual-junction 1.6 eV InGaP/1.1 eV InGaAs tandem cell (projected practical air-mass zero (AM0), one-sun efficiency of 28%, and 100-sun efficiency of 37.5%) under a Ballistic Missile Defense Command (BMDO) SBIR Phase II program. A second ongoing research effort at ERI involves the development of a 2.1 eV AlGaInP/1.6 eV InGaAsP/1.2 eV InGaAs triple-junction concentrator tandem cell (projected practical AM0 efficiency of 36.5% under 100 suns) under a SBIR Phase II program funded by the Air Force. We are in the process of optimizing the dual-junction cell performance. In case of the triple-junction cell, we have developed the bottom and the middle cell, and are in the process of developing the layer structures needed for the top cell. A progress report is presented in this paper.

  18. Iniencephaly. A case report.

    PubMed

    Meizner, I; Levi, A; Katz, M; Maor, E

    1992-10-01

    Prenatal ultrasound diagnosed iniencephaly apertus at 21 weeks' gestation. In this rare central nervous system (CNS) malformation the brain and neck show the main pathologies. Retroflexion of the head with exaggerated cervicothoracic lordosis is always present, and CNS malformations in the form of anencephaly, spina bifida and encephalocele are often present. The ultrasonic diagnosis should be based on the finding of extreme dorsiflexion of the head accompanied by an abnormally short and deformed spine.

  19. Delayed Presentation of Ureteropelvic Junction Obstruction and Loss of Renal Function After Initially Mild (SFU Grade 1-2) Hydronephrosis.

    PubMed

    Bowen, Diana K; Yerkes, Elizabeth B; Lindgren, Bruce W; Gong, Edward M; Faasse, Mark A

    2015-07-01

    We report 4 pediatric cases of ureteropelvic junction obstruction involving delayed progression of initially mild postnatal hydronephrosis. All 4 children became symptomatic; however, 3 already had a substantial decrement of ipsilateral kidney function by the time of diagnosis. Two of these 3 patients had previous renal scintigraphy demonstrating normal differential function. We caution that counseling regarding hydronephrosis should emphasize the importance of prompt re-evaluation for any symptoms potentially referable to delayed presentation of ureteropelvic junction obstruction, irrespective of initial hydronephrosis grade. Future studies are needed to determine the optimal follow-up regimen for conservative management of hydronephrosis.

  20. Transport spectroscopy of NS nanowire junctions with Majorana fermions

    NASA Astrophysics Data System (ADS)

    Prada, Elsa; San-Jose, Pablo; Aguado, Ramón

    2012-11-01

    We investigate transport through normal-superconductor nanowire junctions in the presence of spin-orbit coupling and magnetic field. As the Zeeman field crosses the critical bulk value Bc of the topological transition, a Majorana bound state (MBS) is formed, giving rise to a sharp zero-bias anomaly (ZBA) in the tunneling differential conductance. We identify novel features beyond this picture in wires with inhomogeneous depletion, such as the appearance of two MBSs inside a long depleted region for Bcases weakly split and may coexist with Andreev bound states near zero energy. The ZBA may appear without evidence of a topological gap closing. This latter aspect is more evident in the multiband case and stems from a smooth pinch-off barrier. Most of these features are in qualitative agreement with recent experiments [V. Mourik , ScienceSCIEAS0036-807510.1126/science.1222360 336, 1003 (2012)]. We also discuss the rich phenomenology of the problem in other regimes which remain experimentally unexplored.

  1. Claudins and the Modulation of Tight Junction Permeability

    PubMed Central

    Günzel, Dorothee

    2013-01-01

    Claudins are tight junction membrane proteins that are expressed in epithelia and endothelia and form paracellular barriers and pores that determine tight junction permeability. This review summarizes our current knowledge of this large protein family and discusses recent advances in our understanding of their structure and physiological functions. PMID:23589827

  2. Fast temporal fluctuations in single-molecule junctions.

    PubMed

    Ochs, Roif; Secker, Daniel; Elbing, Mark; Mayor, Marcel; Weber, Heiko B

    2006-01-01

    The noise within the electrical current through single-molecule junctions is studied cryogenic temperature. The organic sample molecules were contacted with the mechanically controlled break-junction technique. The noise spectra refer to a where only few Lorentzian fluctuators occur in the conductance. The frequency dependence shows qualitative variations from sample to sample.

  3. 10. VIEW UPSTREAM OF PIPELINE SECTION AT JUNCTION OF HUME ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    10. VIEW UPSTREAM OF PIPELINE SECTION AT JUNCTION OF HUME CEMENT PIPE AND CAST-IRON (460'). NOTE CYLINDRICAL COLLAR OF CEMENT SECTIONS AND BELL JUNCTIONS OF IRON PIPE. - Kalaupapa Water Supply System, Waikolu Valley to Kalaupapa Settlement, Island of Molokai, Kalaupapa, Kalawao County, HI

  4. Septal Junctions in Filamentous Heterocyst-Forming Cyanobacteria.

    PubMed

    Flores, Enrique; Herrero, Antonia; Forchhammer, Karl; Maldener, Iris

    2016-02-01

    In the filaments of heterocyst-forming cyanobacteria, septal junctions that traverse the septal peptidoglycan join adjacent cells, allowing intercellular communication. Perforations in the septal peptidoglycan have been observed, and proteins involved in the formation of such perforations and putative protein components of the septal junctions have been identified, but their relationships are debated.

  5. Conditions for synchronization in Josephson-junction arrays

    SciTech Connect

    Chernikov, A.A.; Schmidt, G.

    1995-12-31

    An effective perturbation theoretical method has been developed to study the dynamics of Josephson Junction series arrays. It is shown that the inclusion of Junction capacitances, often ignored, has a significant impact on synchronization. Comparison of analytic with computational results over a wide range of parameters shows excellent agreement.

  6. 75 FR 30756 - FM Table of Allotments, Pacific Junction, Iowa

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-02

    ... From the Federal Register Online via the Government Publishing Office FEDERAL COMMUNICATIONS COMMISSION 47 CFR Part 73 FM Table of Allotments, Pacific Junction, Iowa AGENCY: Federal Communications... Channel 299C2 at Pacific Junction, Iowa. The reference coordinates for Channel 299C2 at Pacific...

  7. 75 FR 76294 - Radio Broadcasting Services: Pacific Junction, IA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-08

    ... COMMISSION 47 CFR Part 73 Radio Broadcasting Services: Pacific Junction, IA AGENCY: Federal Communications Commission. ACTION: Final rule. SUMMARY: The staff deletes FM Channel 299C2 at Pacific Junction, Iowa... landing system configurations and the Commission's spacing requirements Further, there are no other...

  8. Processing of Superconductor-Normal-Superconductor Josephson Edge Junctions

    NASA Technical Reports Server (NTRS)

    Kleinsasser, A. W.; Barner, J. B.

    1997-01-01

    The electrical behavior of epitaxial superconductor-normal-superconductor (SNS) Josephson edge junctions is strongly affected by processing conditions. Ex-situ processes, utilizing photoresist and polyimide/photoresist mask layers, are employed for ion milling edges for junctions with Yttrium-Barium-Copper-Oxide (YBCO) electrodes and primarily Co-doped YBCO interlayers.

  9. TEMPORAL CHANGE IN GAP JUNCTION FUNCTION IN PRIMARY HEPATOCYTES

    EPA Science Inventory

    TEMPORAL CHANGES IN GAP JUNCTION FUNCTION IN PRIMARY *

    The objective of this study was to examine the reduction in gap junction communication (GJC) in primary hepatocytes due to coincident melatonin and magnetic field treatments to determine if these conditions could prov...

  10. Josephson junctions in high-T/sub c/ superconductors

    DOEpatents

    Falco, C.M.; Lee, T.W.

    1981-01-14

    The invention includes a high T/sub c/ Josephson sperconducting junction as well as the method and apparatus which provides the junction by application of a closely controlled and monitored electrical discharge to a microbridge region connecting two portions of a superconducting film.

  11. Sensitivity of gap junctional conductance to H ions in amphibian embryonic cells is independent of voltage sensitivity.

    PubMed Central

    Spray, D C; Campos de Carvalho, A; Bennett, M V

    1986-01-01

    In vertebrate embryos gap junctional conductance (gj) is reduced by transjunctional voltage (Vj) and by cytoplasmic acidification; in each case sensitivity is comparable to those of other channels gated by voltage and ligand-receptor binding. We show here that the mechanisms by which Vj and intracellular pH (pHi) gate gj are apparently independent. Partial reduction of gj by lowering pHi neither attenuates nor enhances further reduction by Vj. Certain drugs irreversibly (glutaraldehyde, 1-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline) or reversibly (retinoic acid) abolish dependence of gj on pHi without appreciably affecting kinetic properties of voltage dependence or the shape of the steady-state Vj-gj relation. These findings suggest that the mechanisms by which pHi and Vj act on the gap junction are at least partially distinct and presumably involve separate regions of the junctional macromolecules. PMID:3085092

  12. Photodetection in p-n junctions formed by electrolyte-gated transistors of two-dimensional crystals

    NASA Astrophysics Data System (ADS)

    Kozawa, Daichi; Pu, Jiang; Shimizu, Ryo; Kimura, Shota; Chiu, Ming-Hui; Matsuki, Keiichiro; Wada, Yoshifumi; Sakanoue, Tomo; Iwasa, Yoshihiro; Li, Lain-Jong; Takenobu, Taishi

    2016-11-01

    Transition metal dichalcogenide monolayers have attracted much attention due to their strong light absorption and excellent electronic properties. These advantages make this type of two-dimensional crystal a promising one for optoelectronic device applications. In the case of photoelectric conversion devices such as photodetectors and photovoltaic cells, p-n junctions are one of the most important devices. Here, we demonstrate photodetection with WSe2 monolayer films. We prepare the electrolyte-gated ambipolar transistors and electrostatic p-n junctions are formed by the electrolyte-gating technique at 270 K. These p-n junctions are cooled down to fix the ion motion (and p-n junctions) and we observed the reasonable photocurrent spectra without the external bias, indicating the formation of p-n junctions. Very interestingly, two-terminal devices exhibit higher photoresponsivity than that of three-terminal ones, suggesting the formation of highly balanced anion and cation layers. The maximum photoresponsivity reaches 5 mA/W in resonance with the first excitonic peak. Our technique provides important evidence for optoelectronics in atomically thin crystals.

  13. Junctional neurulation: a unique developmental program shaping a discrete region of the spinal cord highly susceptible to neural tube defects.

    PubMed

    Dady, Alwyn; Havis, Emmanuelle; Escriou, Virginie; Catala, Martin; Duband, Jean-Loup

    2014-09-24

    In higher vertebrates, the primordium of the nervous system, the neural tube, is shaped along the rostrocaudal axis through two consecutive, radically different processes referred to as primary and secondary neurulation. Failures in neurulation lead to severe anomalies of the nervous system, called neural tube defects (NTDs), which are among the most common congenital malformations in humans. Mechanisms causing NTDs in humans remain ill-defined. Of particular interest, the thoracolumbar region, which encompasses many NTD cases in the spine, corresponds to the junction between primary and secondary neurulations. Elucidating which developmental processes operate during neurulation in this region is therefore pivotal to unraveling the etiology of NTDs. Here, using the chick embryo as a model, we show that, at the junction, the neural tube is elaborated by a unique developmental program involving concerted movements of elevation and folding combined with local cell ingression and accretion. This process ensures the topological continuity between the primary and secondary neural tubes while supplying all neural progenitors of both the junctional and secondary neural tubes. Because it is distinct from the other neurulation events, we term this phenomenon junctional neurulation. Moreover, the planar-cell-polarity member, Prickle-1, is recruited specifically during junctional neurulation and its misexpression within a limited time period suffices to cause anomalies that phenocopy lower spine NTDs in human. Our study thus provides a molecular and cellular basis for understanding the causality of NTD prevalence in humans and ascribes to Prickle-1 a critical role in lower spinal cord formation.

  14. Radiation effects on bipolar junction transistors induced by 25 MeV carbon ions

    NASA Astrophysics Data System (ADS)

    Liu, Chaoming; Li, Xingji; Geng, Hongbin; Zhao, Zhiming; Yang, Dezhuang; He, Shiyu

    2010-12-01

    The characteristic degradation in silicon NPN bipolar junction transistors (BJTs) of 3DG112 type is examined under the irradiation with 25 MeV carbon (C) ions and various bias conditions. Different electrical parameters were measured in-situ during the exposure under each bias condition. From the experimental data, larger variation of base current ( IB) is observed after irradiation at a given value of base-emitter voltage ( VBE), while the collector current is only slightly affected by irradiation at a given VBE. The gain degradation is mostly affected by the behavior of the base current. The change in the reciprocal of current gain (Δ(1/ β)) increases linearly with increasing the C ions fluence. The degradation of the NPN BJTs under various bias conditions during irradiation was studied. Compared to the case where the terminals are grounded, at a given fluence, the change in the reciprocal of current gain varies slightly less when the base-emitter junction is forward biased. On the other hand, there is no distinction for the change in the reciprocal of current gain between the case of reverse-biased base-emitter junction and that of all terminals grounded for the NPN BJTs at a given fluence.

  15. Many-body correlations and coupling in benzene-dithiol junctions

    NASA Astrophysics Data System (ADS)

    Rangel, T.; Ferretti, A.; Olevano, V.; Rignanese, G.-M.

    2017-03-01

    Most theoretical studies of nanoscale transport in molecular junctions rely on the combination of the Landauer formalism with Kohn-Sham density functional theory (DFT) using standard local and semilocal functionals to approximate exchange and correlation effects. In many cases, the resulting conductance is overestimated with respect to experiments. Recent works have demonstrated that this discrepancy may be reduced when including many-body corrections on top of DFT. Here we study benzene-dithiol (BDT) gold junctions and analyze the effect of many-body perturbation theory (MBPT) on the calculation of the conductance with respect to different bonding geometries. We find that the many-body corrections to the conductance strongly depend on the metal-molecule coupling strength. In the BDT junction with the lowest coupling, many-body corrections reduce the overestimation on the conductance to a factor 2, improving the agreement with experiments. In contrast, in the strongest coupling cases, many-body corrections on the conductance are found to be sensibly smaller and standard DFT reveals a valid approach.

  16. Junctional Internal Carotid Artery Aneurysms: The Schrödinger's Cat of Vascular Neurosurgery.

    PubMed

    Carlson, Andrew P; Loveren, Harry R van; Youssef, A Samy; Agazzi, Siviero

    2015-03-01

    Objectives Despite advances in neuroimaging, it is not always definitive whether a paraclinoid aneurysm is intradural or entirely extradural. We illustrate the potential use of surgical exploration in these aneurysms that we refer to as "junctional" aneurysms. Methods Retrospective review of eight patients with unruptured aneurysms who underwent a planned surgical exploration of a junctional aneurysm. Results Of the eight patients, three underwent exploration of the aneurysm during surgery for a different aneurysm. All three of these were found to be extradural. Five patients underwent a craniotomy for the exclusive purpose of clarifying the location of the aneurysm. Two of these cases were found to be intradural and were clipped. Two cases were found to be extradural. In one patient, the initially extradural aneurysm was converted into an intradural aneurysm during removal of the anterior clinoid process, necessitating surgical clipping. One transient third nerve palsy was observed. Discussion Until further progress in neuroimaging allows clinicians to determine unequivocally the exact anatomical location of a paraclinoid aneurysm, we advocate the use of the term junctional aneurysm to reflect the clinical uncertainty inherent in management decisions made regarding these aneurysms. We have illustrated a strategy of surgical exploration in select patients.

  17. The current-phase relation in HTS Josephson junctions

    NASA Astrophysics Data System (ADS)

    Il'ichev, E.; Zakosarenko, V.; Ijsselsteijn, R. P. J.; Schultze, V.; Meyer, H.-G.; Hoenig, H. E.

    The current-phase relation of YBa2Cu3O7-x step-edge as well as 24° and 45° grain boundary Josephson junctions has been investigated experimentally. The junctions were incorporated into a washer-shaped superconducting ring with inductance L≈80-300 pH. The ring was inductively coupled to a tank circuit with a resonance frequency 9…40 MHz. The current-phase relation was obtained from the measurement of the impedance of the phase-biased junction. It is shown, that experimentally observed deviations from harmonic behavior of the apparent current-phase relation for step-edge and 24° grain boundary junctions can be explained by the influence of thermal noise. The current-phase relation of 45° grain boundary junctions was found to be extremely non-harmonic. The reasons of this unusual behavior are discussed.

  18. Evolution of perpendicular magnetized tunnel junctions upon annealing

    NASA Astrophysics Data System (ADS)

    Devolder, Thibaut; Couet, S.; Swerts, J.; Furnemont, A.

    2016-04-01

    We study the evolution of perpendicularly magnetized tunnel junctions under 300 to 400 °C annealing. The hysteresis loops do not evolve much during annealing and they are not informative of the underlying structural evolutions. These evolutions are better revealed by the frequencies of the ferromagnetic resonance eigenmodes of the tunnel junction. Their modeling provides the exchange couplings and the layers' anisotropies within the stack which can serve as a diagnosis of the tunnel junction state after each annealing step. The anisotropies of the two CoFeB-based parts and the two Co/Pt-based parts of the tunnel junction decay at different rates during annealing. The ferromagnet exchange coupling through the texture-breaking Ta layer fails above 375 °C. The Ru spacer meant to promote a synthetic antiferromagnet behavior is also insufficiently robust to annealing. Based on these evolutions we propose optimization routes for the next generation tunnel junctions.

  19. Temperature dependence of charge transport in conjugated single molecule junctions

    NASA Astrophysics Data System (ADS)

    Huisman, Eek; Kamenetska, Masha; Venkataraman, Latha

    2011-03-01

    Over the last decade, the break junction technique using a scanning tunneling microscope geometry has proven to be an important tool to understand electron transport through single molecule junctions. Here, we use this technique to probe transport through junctions at temperatures ranging from 5K to 300K. We study three amine-terminated (-NH2) conjugated molecules: a benzene, a biphenyl and a terphenyl derivative. We find that amine groups bind selectively to undercoordinate gold atoms gold all the way down to 5K, yielding single molecule junctions with well-defined conductances. Furthermore, we find that the conductance of a single molecule junction increases with temperature and we present a mechanism for this temperature dependent transport result. Funded by a Rubicon Grant from The Netherlands Organisation for Scientific Research (NWO) and the NSEC program of NSF under grant # CHE-0641523.

  20. Quasi-optical Josephson-junction oscillator arrays

    NASA Technical Reports Server (NTRS)

    Stern, J. A.; Leduc, H. G.; Zmuidzinas, J.

    1993-01-01

    Josephson junctions are natural voltage-controlled oscillators capable of generating submillimeter-wavelength radiation, but a single junction usually can produce only 100 nW of power and often has a broad spectral linewidth. The authors are investigating 2D quasi-optical power combining arrays of 103 and 104 NbN/MgO/NbN and Nb/Al-AlO(x)/Nb junctions to overcome these limitations. The junctions are dc-biased in parallel and are distributed along interdigitated lines. The arrays couple to a resonant mode of a Fabry-Perot cavity to achieve mutual phase-locking. The array configuration has a relatively low impedance, which should allow the capacitance of the junctions to be tuned out at the oscillation frequency.

  1. Subgap conductivity in SIN-junctions of high barrier transparency

    NASA Astrophysics Data System (ADS)

    Lotkhov, S. V.; Balashov, D. V.; Khabipov, M. I.; Buchholz, F.-I.; Zorin, A. B.

    2006-11-01

    We investigate the current-voltage characteristics of high-transparency superconductor-insulator-normal metal (SIN) junctions with the specific tunnel resistance ρ ≲ 30 Ω μm2. The junctions were fabricated from different superconducting and normal conducting materials, including Nb, Al, AuPd and Cu. The subgap leakage currents were found to be appreciably larger than those given by the standard tunnelling model. We explain our results using the model of two-electron tunnelling in the coherent diffusive transport regime. We demonstrate that even in the high-transparency SIN-junctions, a noticeable reduction of the subgap current can be achieved by splitting a junction into several submicron sub-junctions. These structures can be used as nonlinear low-noise shunts in rapid-single-flux-quantum (RSFQ) circuitry for controlling Josephson qubits.

  2. Design of Steerable Wavelets to Detect Multifold Junctions.

    PubMed

    Püspöki, Zsuzsanna; Uhlmann, Virginie; Vonesch, Cédric; Unser, Michael

    2016-02-01

    We propose a framework for the detection of junctions in images. Although the detection of edges and key points is a well examined and described area, the multiscale detection of junction centers, especially for odd orders, poses a challenge in pattern analysis. The goal of this paper is to build optimal junction detectors based on 2D steerable wavelets that are polar-separable in the Fourier domain. The approaches we develop are general and can be used for the detection of arbitrary symmetric and asymmetric junctions. The backbone of our construction is a multiscale pyramid with a radial wavelet function where the directional components are represented by circular harmonics and encoded in a shaping matrix. We are able to detect M -fold junctions in different scales and orientations. We provide experimental results on both simulated and real data to demonstrate the effectiveness of the algorithm.

  3. Fixed-Gap Tunnel Junction for Reading DNA Nucleotides

    PubMed Central

    2015-01-01

    Previous measurements of the electronic conductance of DNA nucleotides or amino acids have used tunnel junctions in which the gap is mechanically adjusted, such as scanning tunneling microscopes or mechanically controllable break junctions. Fixed-junction devices have, at best, detected the passage of whole DNA molecules without yielding chemical information. Here, we report on a layered tunnel junction in which the tunnel gap is defined by a dielectric layer, deposited by atomic layer deposition. Reactive ion etching is used to drill a hole through the layers so that the tunnel junction can be exposed to molecules in solution. When the metal electrodes are functionalized with recognition molecules that capture DNA nucleotides via hydrogen bonds, the identities of the individual nucleotides are revealed by characteristic features of the fluctuating tunnel current associated with single-molecule binding events. PMID:25380505

  4. Effect of sound on gap-junction-based intercellular signaling: Calcium waves under acoustic irradiation

    NASA Astrophysics Data System (ADS)

    Deymier, P. A.; Swinteck, N.; Runge, K.; Deymier-Black, A.; Hoying, J. B.

    2015-11-01

    We present a previously unrecognized effect of sound waves on gap-junction-based intercellular signaling such as in biological tissues composed of endothelial cells. We suggest that sound irradiation may, through temporal and spatial modulation of cell-to-cell conductance, create intercellular calcium waves with unidirectional signal propagation associated with nonconventional topologies. Nonreciprocity in calcium wave propagation induced by sound wave irradiation is demonstrated in the case of a linear and a nonlinear reaction-diffusion model. This demonstration should be applicable to other types of gap-junction-based intercellular signals, and it is thought that it should be of help in interpreting a broad range of biological phenomena associated with the beneficial therapeutic effects of sound irradiation and possibly the harmful effects of sound waves on health.

  5. First-principles study of the critical thickness in asymmetric ferroelectric tunnel junctions

    SciTech Connect

    Cai Mengqiu; Du Yong; Huang Boyun

    2011-03-07

    The absent critical thickness of fully relaxed asymmetric ferroelectric tunnel junctions is investigated by first-principles calculations. The results show that PbTiO{sub 3} thin film between Pt and SrRuO{sub 3} electrodes can still retain a significant and stable polarization down to thicknesses as small as 0.8 nm, quite unlike the case of symmetric ferroelectric tunnel junctions. We trace this surprising result to the generation of a large electric field by the charge transfer between the electrodes caused by their different electronic environments, which acts against the depolarization field and enhances the ferroelectricity, leading to the reduction, or even complete elimination, for the critical thickness.

  6. Thermoelectric ZT enhanced by asymmetric configuration in single-molecule-magnet junctions

    NASA Astrophysics Data System (ADS)

    Niu, Pengbin; Shi, Yunlong; Sun, Zhu; Nie, Yi-Hang; Luo, Hong-Gang

    2016-02-01

    In mesoscopic devices, many factors like the Coulomb and spin interactions can enhance the thermoelectric figure of merit ZT. Here we use a system consisting of a single-molecule magnet (SMM) connected to two ferromagnetic electrodes to consider the possible enhancement effects of thermoelectric efficiency. By introducing an asymmetric configuration to the transport junction, we find that this configuration can significantly enhance the thermoelectric ZT. The optimized asymmetric thermoelectric ZT is five times that of the ZT with a symmetric configuration or non-magnetic case. Due to this asymmetry, a non-zero charge thermopower at the electron-hole symmetry point is also found. These results demonstrate that the asymmetry of the transport junction helps to enhance thermoelectric efficiency and is useful for fabricating SMM-based thermoelectric devices.

  7. Dicke-Josephson effect in a cross-typed triple-quantum-dot junction

    NASA Astrophysics Data System (ADS)

    Wang, Xiao-Qi; Yi, Guang-Yu; Gong, Wei-Jiang

    2016-12-01

    We investigate the Dicke-Josephson effect in a superconductor/triple-quantum-dot/superconductor junction in which the central dot is coupled to the superconductors. It is found that the Dicke effect can modulate the Josephson effect in a nontrivial way. In the noninteracting case, the Dicke effect induces a subpeak in the supercurrent spectrum around the energy zero point. When intradot interactions are taken into account, the role of the Dicke effect changes completely. Namely, it tends to suppress the π-phase current near the position of electron-hole symmetry. With the increase of the Coulomb strength, it has an opportunity to reverse the current direction. We thus conclude that the Dicke-Josephson effect is also an important part in describing the Josephson effect in coupled-dot junctions.

  8. Gate-tunable electron focusing across graphene p-n junction

    NASA Astrophysics Data System (ADS)

    Chen, Shaowen; Han, Zheng; Wang, Lei; Dean, Cory; Hone, James

    Electrons moving across a ballistic semiconductor junction experience a change in trajectory described by an electronic version of Snell's law. In the case of a barrier separating regions of n and ptype carriers, negative refraction is expected, which theoretically leads to a Veselago type of electron focusing. Being a ballistic bipolar 2D system, hexagonal Boron Nitride-encapsulated graphene is expected to be a model a system to realize this effect, however, robust demonstration of veselago lensing has remained limited. We describe novel methods to fabricate high quality graphene p-n junctions with atomically sharp boundaries. Using a magnetic focusing measurement scheme, we demonstrate unambiguous signatures of negative refraction in these devices. Our observations are in good agreement with simulations and shed light on future application for electronic optics in ballistic graphene.

  9. Large enhancement in thermoelectric efficiency of quantum dot junctions due to increase of level degeneracy

    NASA Astrophysics Data System (ADS)

    Kuo, David M. T.; Chen, Chih-Chieh; Chang, Yia-Chung

    2017-02-01

    It is theoretically demonstrated that the figure of merit (Z T ) of quantum dot (QD) junctions can be significantly enhanced when the degree of degeneracy of the energy levels involved in electron transport is increased. The theory is based on the the Green-function approach in the Coulomb blockade regime by including all correlation functions resulting from electron-electron interactions associated with the degenerate levels (L ). We found that electrical conductance (Ge) as well as electron thermal conductance (κe) are highly dependent on the level degeneracy (L ), whereas the Seebeck coefficient (S ) is not. Therefore, the large enhancement of Z T is mainly attributed to the increase of Ge when the phonon thermal conductance (κp h) dominates the heat transport of the QD junction system. In the serially coupled double-QD case, we also obtain a large enhancement of Z T arising from higher L . Unlike Ge and κe, S is found almost independent on electron interdot hopping strength.

  10. Effect of sound on gap-junction-based intercellular signaling: Calcium waves under acoustic irradiation.

    PubMed

    Deymier, P A; Swinteck, N; Runge, K; Deymier-Black, A; Hoying, J B

    2015-01-01

    We present a previously unrecognized effect of sound waves on gap-junction-based intercellular signaling such as in biological tissues composed of endothelial cells. We suggest that sound irradiation may, through temporal and spatial modulation of cell-to-cell conductance, create intercellular calcium waves with unidirectional signal propagation associated with nonconventional topologies. Nonreciprocity in calcium wave propagation induced by sound wave irradiation is demonstrated in the case of a linear and a nonlinear reaction-diffusion model. This demonstration should be applicable to other types of gap-junction-based intercellular signals, and it is thought that it should be of help in interpreting a broad range of biological phenomena associated with the beneficial therapeutic effects of sound irradiation and possibly the harmful effects of sound waves on health.

  11. Perpendicular magnetic tunnel junctions with double barrier and single or synthetic antiferromagnetic storage layer

    SciTech Connect

    Cuchet, Léa; Rodmacq, Bernard; Auffret, Stéphane; Sousa, Ricardo C.; Prejbeanu, Ioan L.; Dieny, Bernard

    2015-06-21

    The magnetic properties of double tunnel junctions with perpendicular anisotropy were investigated. Two synthetic antiferromagnetic references are used, while the middle storage magnetic layer can be either a single ferromagnetic or a synthetic antiferromagnetic FeCoB-based layer, with a critical thickness as large as 3.0 nm. Among the different achievable magnetic configurations in zero field, those with either antiparallel references, and single ferromagnetic storage layer, or parallel references, and synthetic antiferromagnetic storage layer, are of particular interest since they allow increasing the efficiency of spin transfer torque writing and the thermal stability of the stored information as compared to single tunnel junctions. The latter configuration can be preferred when stray fields would favour a parallel orientation of the reference layers. In this case, the synthetic antiferromagnetic storage layer is also less sensitive to residual stray fields.

  12. Altered patterns of cardiac intercellular junction distribution in hypertrophic cardiomyopathy.

    PubMed Central

    Sepp, R.; Severs, N. J.; Gourdie, R. G.

    1996-01-01

    OBJECTIVE: To examine the distribution pattern of intercellular junctions (the mechanically coupling desmosomes and the electrically coupling gap junctions) in hypertrophic cardiomyopathy (HCM) hearts showing myofibre disarray. DESIGN: Samples from six necropsied hearts were studied, representing the interventricular septum and the free walls of the left and right ventricles. Immunohistochemical labelling of desmoplakin was used as a marker for desmosomes, and of connexin43 as a marker for gap junctions, in single and double stainings. The slides were examined by confocal laser scanning microscopy. RESULTS: Marked disorganisation of intercalated discs was observed in areas featuring myofibre disarray. Besides overall derangement, localised abnormalities in desmosome organisation were evident, which included: (1) the formation of abnormally enlarged megadiscs; (2) the presence of intersecting disc structures; and (3) aberrant side to side desmosomal connections. Gap junctional abnormalities included: (1) random distribution of gap junctions over the surface of myocytes, rather than localisation to intercalated discs; (2) abundant side to side gap junction connections between adjacent myocytes; and (3) formation of abnormally shaped gap junctions. Circles of myocytes continuously interconnected by gap junctions were also observed. Regions of the diseased hearts lacking myofibre disarray, and control hearts of normal patients and patients with other cardiac diseases, did not show these alterations. CONCLUSIONS: The disorganisation of the intercellular junctions associated with myofibre disarray in HCM may play an important role in the pathophysiological manifestations of the disease. The remodelling of gap junction distribution may underlie the formation of an arrhythmogenic substrate, thereby contributing to the generation and maintenance of cardiac arrhythmias associated with HCM. Images PMID:8944586

  13. The organization of adherens junctions and desmosomes at the cardiac intercalated disc is independent of gap junctions.

    PubMed

    Gutstein, David E; Liu, Fang-Yu; Meyers, Marian B; Choo, Andrew; Fishman, Glenn I

    2003-03-01

    Adherens junctions and desmosomes are responsible for mechanically coupling myocytes in the heart and are found closely apposed to gap junction plaques at the intercalated discs of cardiomyocytes. It is not known whether loss of cardiac gap junctions, such as described in cardiac disease states, may influence the expression patterns of other intercalated disc-associated proteins. We investigated whether the major cardiac gap junction protein connexin43 (Cx43) may be responsible for regulating adherens junctions, desmosomes and their associated catenins, in terms of abundance and localization at the intercalated discs of cardiomyocytes. In order to study the effect of loss of cardiac gap junctions on the intercalated disc-associated proteins, we used a combination of immunoblotting, immunofluorescence with confocal microscopy and electron microscopy to evaluate heart tissue from mice with cardiac-specific conditional knockout of Cx43. We found that the cardiac adherens junctions, desmosomes and their associated catenins, as well as vinculin and ZO-1, maintain their normal abundance, structural appearance and localization in the absence of Cx43. We conclude from these data that Cx43 is not required for the organization of the cell adhesion junctions and their associated catenins at the intercalated disc in the adult cardiac myocyte.

  14. Metal-free molecular junctions on ITO via amino-silane binding-towards optoelectronic molecular junctions.

    PubMed

    Sergani, S; Furmansky, Y; Visoly-Fisher, I

    2013-11-15

    Light control over currents in molecular junctions is desirable as a non-contact input with high spectral and spatial resolution provided by the photonic input and the molecular electronics element, respectively. Expanding the study of molecular junctions to non-metallic transparent substrates, such as indium tin oxide (ITO), is vital for the observation of molecular optoelectronic effects. Non-metallic electrodes are expected to decrease the probability of quenching of molecular photo-excited states, light-induced plasmonic effects, or significant electrode expansion under visible light. We have developed micron-sized, metal free, optically addressable ITO molecular junctions with a conductive polymer serving as the counter-electrode. The electrical transport was shown to be dominated by the nature of the self-assembled monolayer (SAM). The use of amino-silane (APTMS) as the chemical binding scheme to ITO was found to be significant in determining the transport properties of the junctions. APTMS allows high junction yields and the formation of dense molecular layers preventing electrical short. However, polar amino-silane binding to the ITO significantly decreased the conductance compared to thiol-bound SAMs, and caused tilted geometry and disorder in the molecular layer. As the effect of the molecular structure on transport properties is clearly observed in our junctions, such metal-free junctions are suitable for characterizing the optoelectronic properties of molecular junctions.

  15. Metal-free molecular junctions on ITO via amino-silane binding—towards optoelectronic molecular junctions

    NASA Astrophysics Data System (ADS)

    Sergani, S.; Furmansky, Y.; Visoly-Fisher, I.

    2013-11-01

    Light control over currents in molecular junctions is desirable as a non-contact input with high spectral and spatial resolution provided by the photonic input and the molecular electronics element, respectively. Expanding the study of molecular junctions to non-metallic transparent substrates, such as indium tin oxide (ITO), is vital for the observation of molecular optoelectronic effects. Non-metallic electrodes are expected to decrease the probability of quenching of molecular photo-excited states, light-induced plasmonic effects, or significant electrode expansion under visible light. We have developed micron-sized, metal free, optically addressable ITO molecular junctions with a conductive polymer serving as the counter-electrode. The electrical transport was shown to be dominated by the nature of the self-assembled monolayer (SAM). The use of amino-silane (APTMS) as the chemical binding scheme to ITO was found to be significant in determining the transport properties of the junctions. APTMS allows high junction yields and the formation of dense molecular layers preventing electrical short. However, polar amino-silane binding to the ITO significantly decreased the conductance compared to thiol-bound SAMs, and caused tilted geometry and disorder in the molecular layer. As the effect of the molecular structure on transport properties is clearly observed in our junctions, such metal-free junctions are suitable for characterizing the optoelectronic properties of molecular junctions.

  16. Investigation of Photoelectrode Redox Polymer Junctions

    DTIC Science & Technology

    2007-11-02

    15, 1985 Arlington, VA 22217 13. MUMMER OF’ AGES 1C. NdONIT ORING A~jE.4CY NAME ACORISZ53II d~ifetwM( IrO ConrWfiun OttiCO) IS. 1ICLtI~TY CY-AS&5 (of...junction is exposed to selected .chemical species. DD 1472 eOInlCN o’ INOV is i’s OesoL ITZ UNCLASSIFIED e"~ A44101CrATION OF THIS P AGE (W~ign 0...configuration consisting of a platinum working electrode, a platinum counter 2 V ELTRON RESEARCH INC. electrode and a Ag / Ag + reference electrode was

  17. Ultrafast endocytosis at Caenorhabditis elegans neuromuscular junctions

    PubMed Central

    Watanabe, Shigeki; Liu, Qiang; Davis, M Wayne; Hollopeter, Gunther; Thomas, Nikita; Jorgensen, Nels B; Jorgensen, Erik M

    2013-01-01

    Synaptic vesicles can be released at extremely high rates, which places an extraordinary demand on the recycling machinery. Previous ultrastructural studies of vesicle recycling were conducted in dissected preparations using an intense stimulation to maximize the probability of release. Here, a single light stimulus was applied to motor neurons in intact Caenorhabditis elegans nematodes expressing channelrhodopsin, and the animals rapidly frozen. We found that docked vesicles fuse along a broad active zone in response to a single stimulus, and are replenished with a time constant of about 2 s. Endocytosis occurs within 50 ms adjacent to the dense projection and after 1 s adjacent to adherens junctions. These studies suggest that synaptic vesicle endocytosis may occur on a millisecond time scale following a single physiological stimulus in the intact nervous system and is unlikely to conform to current models of endocytosis. DOI: http://dx.doi.org/10.7554/eLife.00723.001 PMID:24015355

  18. Fully magnetic manganite spin filter tunnel junctions

    NASA Astrophysics Data System (ADS)

    Prasad, Bhagwati; Blamire, Mark G.

    2016-09-01

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

  19. Cascade Electronic Refrigerator Using Superconducting Tunnel Junctions

    NASA Astrophysics Data System (ADS)

    Nguyen, H. Q.; Peltonen, J. T.; Meschke, M.; Pekola, J. P.

    2016-11-01

    Microrefrigerators that operate in the subkelvin regime are key devices in quantum technology. A well-studied candidate, an electronic cooler using normal-metal-insulator-superconductor (N -I -S ) tunnel junctions, offers substantial performance and power. However, its superconducting electrodes are severely overheated due to exponential suppression of their thermal conductance towards low temperatures, and the cooler performs unsatisfactorily—especially in powerful devices needed for practical applications. We employ a second N -I -S cooling stage to thermalize the hot superconductor at the backside of the main N -I -S cooler. Not only providing a lower bath temperature, the second-stage cooler actively evacuates quasiparticles out of the hot superconductor, especially in the low-temperature limit. We demonstrate the apparent advantage of our approach. This cascade design can also be employed to manage excess heat in other cryoelectronic devices.

  20. Josephson junctions with tunable weak links.

    PubMed

    Schön, J H; Kloc, C; Hwang, H Y; Batlogg, B

    2001-04-13

    The electrical properties of organic molecular crystals, such as polyacenes or C60, can be tuned from insulating to superconducting by application of an electric field. By structuring the gate electrode of such a field-effect switch, the charge carrier density, and therefore also the superfluid density, can be modulated. Hence, weak links that behave like Josephson junctions can be fabricated between two superconducting regions. The coupling between the superconducting regions can be tuned and controlled over a wide range by the applied gate bias. Such devices might be used in superconducting circuits, and they are a useful scientific tool to study superconducting material parameters, such as the superconducting gap, as a function of carrier concentration or transition temperature.

  1. Quantum Phase Transition in Josephson Junction Arrays

    NASA Astrophysics Data System (ADS)

    Moon, K.; Girvin, S. M.

    1997-03-01

    One-dimensional Josephson junction arrays of SQUIDS exhibit a novel superconductor-insulator phase transition. The critical regime can be accessed by tuning the effective Josephson coupling energy using a weak magnetic field applied to the SQUIDS. The role of instantons induced by quantum fluctuations will be discussed. One novel feature of these systems which can be explained in terms of quantum phase slips is that in some regimes, the array resistance decreases with increasing length of the array. We calculate the finite temperature crossover function for the array resistance and compare our theoretical results with the recent experiments by D. Haviland and P. Delsing at Chalmers. This work is supported by DOE grant #DE-FG02-90ER45427 and by NSF DMR-9502555.

  2. Studies of silicon pn junction solar cells

    NASA Technical Reports Server (NTRS)

    Lindholm, F. A.; Neugroschel, A.

    1977-01-01

    Modifications of the basic Shockley equations that result from the random and nonrandom spatial variations of the chemical composition of a semiconductor were developed. These modifications underlie the existence of the extensive emitter recombination current that limits the voltage over the open circuit of solar cells. The measurement of parameters, series resistance and the base diffusion length is discussed. Two methods are presented for establishing the energy bandgap narrowing in the heavily-doped emitter region. Corrections that can be important in the application of one of these methods to small test cells are examined. Oxide-charge-induced high-low-junction emitter (OCI-HLE) test cells which exhibit considerably higher voltage over the open circuit than was previously seen in n-on-p solar cells are described.

  3. Field-effect P-N junction

    DOEpatents

    Regan, William; Zettl, Alexander

    2015-05-05

    This disclosure provides systems, methods, and apparatus related to field-effect p-n junctions. In one aspect, a device includes an ohmic contact, a semiconductor layer disposed on the ohmic contact, at least one rectifying contact disposed on the semiconductor layer, a gate including a layer disposed on the at least one rectifying contact and the semiconductor layer and a gate contact disposed on the layer. A lateral width of the rectifying contact is less than a semiconductor depletion width of the semiconductor layer. The gate contact is electrically connected to the ohmic contact to create a self-gating feedback loop that is configured to maintain a gate electric field of the gate.

  4. Controlling local currents in molecular junctions

    NASA Astrophysics Data System (ADS)

    Yadalam, Hari Kumar; Harbola, Upendra

    2016-09-01

    The effects of nonequilibrium constraints and dephasing on the circulating currents in molecular junctions are analyzed. Circulating currents are manifestations of quantum effects and can be induced either by externally applied bias or an external magnetic field through the molecular system. In a symmetric Aharonov-Bohm ring, bond currents have two contributions, bias driven and magnetic field driven. We analyze the competition between these two contributions and show that, as a consequence, current through one of the branches can be completely suppressed. We then study the effect of asymmetry (as a result of chemical substitution) on the current pathways inside the molecule and study asymmetry-induced circulating currents (without magnetic field) by tuning the coupling strength of the substituent (at finite bias).

  5. Terbinafine inhibits gap junctional intercellular communication.

    PubMed

    Lee, Ju Yeun; Yoon, Sei Mee; Choi, Eun Ju; Lee, Jinu

    2016-09-15

    Terbinafine is an antifungal agent that selectively inhibits fungal sterol synthesis by blocking squalene epoxidase. We evaluated the effect of terbinafine on gap junctional intercellular communication (GJIC). Fluorescence recovery after photobleaching (FRAP) and I-YFP GJIC assays revealed that terbinafine inhibits GJIC in a reversible and dose-dependent manner in FRT-Cx43 and LN215 cells. Treatment with terbinafine did not affect Cx43 phosphorylation status or intracellular Ca(2+) concentration, well-known action mechanisms of various GJIC blockers. While a structurally related chemical, naftifine, attenuated GJIC, epigallocatechin gallate, another potent squalene epoxidase inhibitor with a different structure, did not. These results suggest that terbinafine inhibits GJIC with a so far unknown mechanism of action.

  6. Permanent junctional reciprocating tachycardia in a dog.

    PubMed

    Santilli, Roberto A; Santos, Luis F N; Perego, Manuela

    2013-09-01

    A 5-year-old male English Bulldog was presented with a 1-year history of paroxysmal supraventricular tachycardia (SVT) partially responsive to amiodarone. At admission the surface ECG showed sustained runs of a narrow QRS complex tachycardia, with a ventricular cycle length (R-R interval) of 260 ms, alternating with periods of sinus rhythm. Endocardial mapping identified the electrogenic mechanism of the SVT as a circus movement tachycardia with retrograde and decremental conduction along a concealed postero-septal atrioventricular pathway (AP) and anterograde conduction along the atrioventricular node. These characteristics were indicative of a permanent junctional reciprocating tachycardia (PJRT). Radiofrequency catheter ablation of the AP successfully terminated the PJRT, with no recurrence of tachycardia on Holter monitoring at 12 months follow-up.

  7. Ureterocalycostomy - final resort in the management of secondary pelvi-ureteric junction obstruction: our experience.

    PubMed

    Gite, Venkat A; Siddiqui, Ayub Karam Nabi; Bote, Sachin M; Patil, Saurabh Ramesh; Kandi, Anita J; Nikose, Jayant V

    2016-01-01

    Ureterocalycostomy can be performed in patients in whom desired methods of treating secondary PUJ (Pelvi-Ureteric Junction) obstructions either failed or could not be used. In our study, one child and two adults in whom one redo-ureterocalycostomy and two ureterocalycostomies were performed for severely scarred PUJ. The causes for secondary PUJ obstruction were post-pyelolithotomy in one case, post-pyeloplasty and ureterocalycostomy for PUJ obstruction in the second patient and the third patient had long upper ureteric stricture post-ureteropyeloplasty due to tuberculosis. In all these cases ureterocalycostomy proved to be salvage/final resort for preserving functional renal unit.

  8. Stability, sub-gap current, 1/f-noise, and elemental depth profiling of annealed Al:Mn-AlOX-Al normal metal-insulator-superconducting tunnel junctions

    NASA Astrophysics Data System (ADS)

    Julin, J. K.; Chaudhuri, S.; Laitinen, M.; Sajavaara, T.; Maasilta, I. J.

    2016-12-01

    In this paper we report a study of the effect of vacuum annealing at 400°C on the properties of normal metal-insulator-superconductor (NIS) tunnel junctions, with manganese doped aluminium (Al:Mn) as the normal metal, aluminum as the superconductor and amorphous aluminum oxide as the tunneling barrier (Al:Mn-AlOx-Al). The annealing treatment improves the stability of the junctions, increases their tunneling resistance and does not have a negative impact on the low-temperature current-voltage characteristics. The measured 1/f resistance noise of the junctions also changes after annealing, in the best case decreasing by over an order of magnitude. All these observations show that annealing is a viable route to improve NIS junction devices after the sample has been fabricated.

  9. Incompressible Turbulent Wing-Body Junction Flow

    NASA Technical Reports Server (NTRS)

    Krishnamurthy, R.; Cagle, Corey D.; Chandra, S.

    1998-01-01

    The overall objective of this study is to contribute to the optimized design of fan bypass systems in advanced turbofan engines. Increasing the engine bypass ratios have provided a major boost in engine performance improvement over the last fifty years. An engine with high bypass ratio (11-16:1) such as the Advanced Ducted Propulsion (ADP) is being developed and is expected to provide an additional 25% improvement in overall efficiency over the early turbofans. Such significant improvements in overall efficiency would reduce the cost per seat mile, which is a major government and Industry challenge for the 21th century. The research is part of the Advanced Subsonic Technology (AST) program that involves a NASA, U.S. Industry and FAA partnership with the goal of a safe and highly productive global air transportation system. The immediate objective of the study is to perform numerical simulation of duct-strut interactions to elucidate the loss mechanisms associated with this configuration that is typical of advanced turbofan engines such as ADP. However, at present experimental data for a duct-strut configuration are not available. Thus, as a first step a wing-body junction flow would be studied and is the specific objective of the present study. At the outset it is to be recognized that while duct-strut interaction flow is similar to that of wing-body junction flows, there are some differences owing to the presence of a wall at both ends of the strut. Likewise, some differences are due to the sheared inflow (as opposed to a uniform inflow) velocity profile. It is however expected that some features of a wing-body junction flow would persist. Next, some of the salient aspects of the complex flow near a wing-body junction, as revealed by various studies reported in the literature will be reviewed. One of the principle characteristics of the juncture flow, is the presence of the mean flow components in a plane perpendicular to the direction of the oncoming free

  10. Proximity induced vortices and long-range triplet supercurrents in ferromagnetic Josephson junctions and spin valves

    NASA Astrophysics Data System (ADS)

    Alidoust, Mohammad; Halterman, Klaus

    2015-03-01

    Using a spin-parameterized quasiclassical Keldysh-Usadel technique, we theoretically study supercurrent transport in several types of diffusive ferromagnetic (F)/superconducting (S) configurations with differing magnetization textures. We separate out the even- and odd-frequency components of the supercurrent within the low proximity limit and identify the relative contributions from the singlet and triplet channels. We first consider inhomogeneous one-dimensional Josephson structures consisting of a uniform bilayer magnetic S/F/F/S structure and a trilayer S/F/F/F/S configuration, in which case the outer F layers can have either a uniform or conical texture relative to the central uniform F layer. Our results demonstrate that for supercurrents flowing perpendicular to the F/F interfaces, incorporating a conical texture yields the most effective way to observe the signatures of long-ranged spin-triplet supercurrents. We also consider three different types of finite-sized two-dimensional magnetic structures subjected to an applied magnetic field normal to the junction plane: a S/F/S junction with uniform magnetization texture and two S/F/F/S configurations with differing F/F bilayer arrangements. In one case, the F/F interface is parallel with the S/F junction interfaces while in the other case, the F/F junction is oriented perpendicular to the S/F interfaces. We then discuss the proximity vortices and corresponding spatial maps of currents inside the junctions. For the uniform S/F/S junction, we analytically calculate the magnetic field induced supercurrent and pair potential in both the narrow and wide junction regimes, thus providing insight into the variations in the Fraunhofer diffraction patterns and proximity vortices when transitioning from a wide junction to a narrow one. Our extensive computations demonstrate that the induced long-range spin-triplet supercurrents can deeply penetrate uniform F/F bilayers when spin-singlet supercurrents flow parallel to the

  11. Proximity induced vortices and long-range triplet supercurrents in ferromagnetic Josephson junctions and spin valves

    SciTech Connect

    Alidoust, Mohammad; Halterman, Klaus

    2015-03-28

    Using a spin-parameterized quasiclassical Keldysh-Usadel technique, we theoretically study supercurrent transport in several types of diffusive ferromagnetic (F)/superconducting (S) configurations with differing magnetization textures. We separate out the even- and odd-frequency components of the supercurrent within the low proximity limit and identify the relative contributions from the singlet and triplet channels. We first consider inhomogeneous one-dimensional Josephson structures consisting of a uniform bilayer magnetic S/F/F/S structure and a trilayer S/F/F/F/S configuration, in which case the outer F layers can have either a uniform or conical texture relative to the central uniform F layer. Our results demonstrate that for supercurrents flowing perpendicular to the F/F interfaces, incorporating a conical texture yields the most effective way to observe the signatures of long-ranged spin-triplet supercurrents. We also consider three different types of finite-sized two-dimensional magnetic structures subjected to an applied magnetic field normal to the junction plane: a S/F/S junction with uniform magnetization texture and two S/F/F/S configurations with differing F/F bilayer arrangements. In one case, the F/F interface is parallel with the S/F junction interfaces while in the other case, the F/F junction is oriented perpendicular to the S/F interfaces. We then discuss the proximity vortices and corresponding spatial maps of currents inside the junctions. For the uniform S/F/S junction, we analytically calculate the magnetic field induced supercurrent and pair potential in both the narrow and wide junction regimes, thus providing insight into the variations in the Fraunhofer diffraction patterns and proximity vortices when transitioning from a wide junction to a narrow one. Our extensive computations demonstrate that the induced long-range spin-triplet supercurrents can deeply penetrate uniform F/F bilayers when spin-singlet supercurrents flow parallel to the

  12. Mechanical deformations of boron nitride nanotubes in crossed junctions

    SciTech Connect

    Zhao, Yadong; Chen, Xiaoming; Ke, Changhong; Park, Cheol; Fay, Catharine C.; Stupkiewicz, Stanislaw

    2014-04-28

    We present a study of the mechanical deformations of boron nitride nanotubes (BNNTs) in crossed junctions. The structure and deformation of the crossed tubes in the junction are characterized by using atomic force microscopy. Our results show that the total tube heights are reduced by 20%–33% at the crossed junctions formed by double-walled BNNTs with outer diameters in the range of 2.21–4.67 nm. The measured tube height reduction is found to be in a nearly linear relationship with the summation of the outer diameters of the two tubes forming the junction. The contact force between the two tubes in the junction is estimated based on contact mechanics theories and found to be within the range of 4.2–7.6 nN. The Young's modulus of BNNTs and their binding strengths with the substrate are quantified, based on the deformation profile of the upper tube in the junction, and are found to be 1.07 ± 0.11 TPa and 0.18–0.29 nJ/m, respectively. Finally, we perform finite element simulations on the mechanical deformations of the crossed BNNT junctions. The numerical simulation results are consistent with both the experimental measurements and the analytical analysis. The results reported in this paper contribute to a better understanding of the structural and mechanical properties of BNNTs and to the pursuit of their applications.

  13. Epithelial junctions and Rho family GTPases: the zonular signalosome

    PubMed Central

    Citi, Sandra; Guerrera, Diego; Spadaro, Domenica; Shah, Jimit

    2014-01-01

    The establishment and maintenance of epithelial cell-cell junctions is crucially important to regulate adhesion, apico-basal polarity and motility of epithelial cells, and ultimately controls the architecture and physiology of epithelial organs. Junctions are supported, shaped and regulated by cytoskeletal filaments, whose dynamic organization and contractility are finely tuned by GTPases of the Rho family, primarily RhoA, Rac1 and Cdc42. Recent research has identified new molecular mechanisms underlying the cross-talk between these GTPases and epithelial junctions. Here we briefly summarize the current knowledge about the organization, molecular evolution and cytoskeletal anchoring of cell-cell junctions, and we comment on the most recent advances in the characterization of the interactions between Rho GTPases and junctional proteins, and their consequences with regards to junction assembly and regulation of cell behavior in vertebrate model systems. The concept of “zonular signalosome” is proposed, which highlights the close functional relationship between proteins of zonular junctions (zonulae occludentes and adhaerentes) and the control of cytoskeletal organization and signaling through Rho GTPases, transcription factors, and their effectors. PMID:25483301

  14. Thin-film Josephson junctions with alternating critical current density

    NASA Astrophysics Data System (ADS)

    Moshe, Maayan; Kogan, V. G.; Mints, R. G.

    2009-01-01

    We study the field dependence of the maximum current Im(H) in narrow edge-type thin-film Josephson junctions with alternating critical current density. Im(H) is evaluated within nonlocal Josephson electrodynamics taking into account the stray fields that affect the difference of the order-parameter phases across the junction and therefore the tunneling currents. We find that the phase difference along the junction is proportional to the applied field, depends on the junction geometry, but is independent of the Josephson critical current density gc , i.e., it is universal. An explicit form for this universal function is derived for small currents through junctions of the width W≪Λ , the Pearl length. The result is used to calculate Im(H) . It is shown that the maxima of Im(H)∝1/H and the zeros of Im(H) are equidistant but only in high fields. We find that the spacing between zeros is proportional to 1/W2 . The general approach is applied to calculate Im(H) for a superconducting quantum interference device with two narrow edge-type junctions. If gc changes sign periodically or randomly, as it does in grain boundaries of high- Tc materials and superconductor-ferromagnet-superconductor heterostructures, Im(H) not only acquires the major side peaks, but due to nonlocality the following peaks decay much slower than in bulk junctions.

  15. Josephson radiation from InSb-nanowire junction

    NASA Astrophysics Data System (ADS)

    van Woerkom, David; Proutski, Alexander; Krivachy, Tamas; Bouman, Daniel; van Gulik, Ruben; Gul, Onder; Cassidy, Maja; Car, Diana; Bakkers, Erik; Kouwenhoven, Leo; Geresdi, Attila

    Semiconducting nanowire Josephson junctions has recently gained interest as building blocks for Majorana circuits and gate-tuneable superconducting qubits . Here we investigate the rich physics of the Andreev bound state spectrum of InSb nanowire junctions utilizing the AC Josephson relation 2eV_bias =hf . We designed and characterized an on-chip microwave circuit coupling the nanowire junction to an Al/AlOx/Al tunnel junction. The DC response of the tunnel junction is affected by photon-assisted quasiparticle current, which gives us the possibility to measure the radiation spectrum of the nanowire junction up to several tens of GHz in frequency. Our circuit design allows for voltage or phase biasing of the Josephson junction enabling direct mapping of Andreev bound states. We discuss our fabrication methods and choice of materials to achieve radiation detection up to a magnetic field of few hundred milliTesla, compatible with Majorana states in spin-orbit coupled nanowires. This work has been supported by the Netherlands Foundations FOM, Abstract NWO and Microsoft Corporation Station Q.

  16. High electronic couplings of single mesitylene molecular junctions.

    PubMed

    Komoto, Yuki; Fujii, Shintaro; Nishino, Tomoaki; Kiguchi, Manabu

    2015-01-01

    We report on an experimental analysis of the charge transport properties of single mesitylene (1,3,5-trimethylbenzene) molecular junctions. The electronic conductance and the current-voltage characteristics of mesitylene molecules wired into Au electrodes were measured by a scanning tunnelling microscopy-based break-junction method at room temperature in a liquid environment. We found the molecular junctions exhibited two distinct conductance states with high conductance values of ca. 10(-1) G 0 and of more than 10(-3) G 0 (G 0 = 2e (2)/h) in the electronic conductance measurements. We further performed a statistical analysis of the current-voltage characteristics of the molecular junctions in the two states. Within a single channel resonant tunnelling model, we obtained electronic couplings in the molecular junctions by fitting the current-voltage characteristics to the single channel model. The origin of the high conductance was attributed to experimentally obtained large electronic couplings of the direct π-bonded molecular junctions (ca. 0.15 eV). Based on analysis of the stretch length of the molecular junctions and the large electronic couplings obtained from the I-V analysis, we proposed two structural models, in which (i) mesitylene binds to the Au electrode perpendicular to the charge transport direction and (ii) mesitylene has tilted from the perpendicular orientation.

  17. Distal gap junctions and active dendrites can tune network dynamics.

    PubMed

    Saraga, Fernanda; Ng, Leo; Skinner, Frances K

    2006-03-01

    Gap junctions allow direct electrical communication between CNS neurons. From theoretical and modeling studies, it is well known that although gap junctions can act to synchronize network output, they can also give rise to many other dynamic patterns including antiphase and other phase-locked states. The particular network pattern that arises depends on cellular, intrinsic properties that affect firing frequencies as well as the strength and location of the gap junctions. Interneurons or GABAergic neurons in hippocampus are diverse in their cellular characteristics and have been shown to have active dendrites. Furthermore, parvalbumin-positive GABAergic neurons, also known as basket cells, can contact one another via gap junctions on their distal dendrites. Using two-cell network models, we explore how distal electrical connections affect network output. We build multi-compartment models of hippocampal basket cells using NEURON and endow them with varying amounts of active dendrites. Two-cell networks of these model cells as well as reduced versions are explored. The relationship between intrinsic frequency and the level of active dendrites allows us to define three regions based on what sort of network dynamics occur with distal gap junction coupling. Weak coupling theory is used to predict the delineation of these regions as well as examination of phase response curves and distal dendritic polarization levels. We find that a nonmonotonic dependence of network dynamic characteristics (phase lags) on gap junction conductance occurs. This suggests that distal electrical coupling and active dendrite levels can control how sensitive network dynamics are to gap junction modulation. With the extended geometry, gap junctions located at more distal locations must have larger conductances for pure synchrony to occur. Furthermore, based on simulations with heterogeneous networks, it may be that one requires active dendrites if phase-locking is to occur in networks formed

  18. Thermodynamic Field Theory of the Dynamic Behavior of Bipolar Junction Transistors.

    NASA Astrophysics Data System (ADS)

    Aboulwafa, Mohamed El-Sayed

    Bipolar junction transistors play an important role in integrated-circuits, whether monolithic, or hybrid. Integrated circuit designers are obliged to use as many transistors as they can in their design, since this entails very little increase in cost. More importantly, a bipolar transistor in an integrated circuit can be connected to substitute for other components that are hard to be integrated in the same substrate. The thermodynamic field theory of generalized fields (TTGF) has had success for predicting the voltage current relationship in p-n junctions and solar cells in d-c cases. The primary object of this thesis is to apply the thermodynamic field theory to an interfacial problem which has time-varying fields. Specifically, we shall apply the concepts of TTGF to investigate the dynamic response of p-n junction devices when fed a small a-c signal. In previous applications of the TTGF, single junction devices have been considered. In this study, we apply the TTGF to a multijunction device: the bipolar transistor. In Chapter I, a brief introduction and literature review are given. In Chapter II, an introduction to the TTGF is given. Included also is a recently derived TTGF equation which governs the interaction of time varying fields in a system involving interfaces and carriers which may recombine and accumulate. Chapter III is a review for the one dimensional solution of the continuity equation. Both the d-c and a-c solutions are reviewed. In Chapter IV, the reverse biased junction is covered from the point of view of the TTGF. Force fields are identified, evaluated and the work done on the composite carrier in the respective regions is calculated. Chapter V covers the forward biased junction. Work done by force fields has been calculated. Energy due to carrier accumulation and recombination has been calculated. The law of conservation energy has been applied over the emitter-base and the emitter-base-collector loops. From the resulting equations, the input

  19. Regulation and roles for claudin-family tight junction proteins

    PubMed Central

    Findley, Mary K.; Koval, Michael

    2009-01-01

    Transmembrane proteins known as claudins play a critical role in tight junctions by regulating paracellular barrier permeability. The control of claudin assembly into tight junctions requires a complex interplay between several classes of claudins, other transmembrane proteins and scaffold proteins. Claudins are also subject to regulation by post-translational modifications including phosphorylation and palmitoylation. Several human diseases have been linked to claudin mutations, underscoring the physiologic function of these proteins. Roles for claudins in regulating cell phenotype and growth control also are beginning to emerge, suggesting a multifaceted role for claudins in regulation of cells beyond serving as a simple structural element of tight junctions. PMID:19319969

  20. Soft nanostructuring of YBCO Josephson junctions by phase separation.

    PubMed

    Gustafsson, D; Pettersson, H; Iandolo, B; Olsson, E; Bauch, T; Lombardi, F

    2010-12-08

    We have developed a new method to fabricate biepitaxial YBa2 Cu3 O7-δ (YBCO) Josephson junctions at the nanoscale, allowing junctions widths down to 100 nm and simultaneously avoiding the typical damage in grain boundary interfaces due to conventional patterning procedures. By using the competition between the superconducting YBCO and the insulating Y2 BaCuO5 phases during film growth, we formed nanometer sized grain boundary junctions in the insulating Y2 BaCuO5 matrix as confirmed by high-resolution transmission electron microscopy. Electrical transport measurements give clear indications that we are close to probing the intrinsic properties of the grain boundaries.

  1. Spin polarization of Co(0001)/graphene junctions from first principles.

    PubMed

    Sipahi, G M; Žutić, Igor; Atodiresei, N; Kawakami, R K; Lazić, P

    2014-03-12

    Junctions comprised of ferromagnets and nonmagnetic materials are one of the key building blocks in spintronics. With the recent breakthroughs of spin injection in ferromagnet/graphene junctions it is possible to consider spin-based applications that are not limited to magnetoresistive effects. However, for critical studies of such structures it is crucial to establish accurate predictive methods that would yield atomically resolved information on interfacial properties. By focusing on Co(0001)/graphene junctions and their electronic structure, we illustrate the inequivalence of different spin polarizations. We show atomically resolved spin polarization maps as a useful approach to assess the relevance of Co(0001)/graphene for different spintronics applications.

  2. Junction Temperature Measurement of IGBTs Using Short Circuit Current

    SciTech Connect

    Wang, Fei; Xu, Zhuxian; Ning, Puqi

    2012-01-01

    In this paper, a method is proposed to measure the junction temperatures of IGBT discrete devices and modules using short circuit current. Experimental results show that the short circuit current has good sensitivity, linearity and selectivity, which is suitable to be used as temperature sensitive electrical parameters (TSEP). Test circuit and hardware design are proposed for junction temperature measurement in single phase and three phase convertes. By connecting a temperature measurement unit to the converter and giving a short circuit pulse, the IGBT junction temperature can be measured.

  3. Effect of current injection into thin-film Josephson junctions

    DOE PAGES

    Kogan, V. G.; Mints, R. G.

    2014-11-11

    New thin-film Josephson junctions have recently been tested in which the current injected into one of the junction banks governs Josephson phenomena. One thus can continuously manage the phase distribution at the junction by changing the injected current. Our method of calculating the distribution of injected currents is also proposed for a half-infinite thin-film strip with source-sink points at arbitrary positions at the film edges. The strip width W is assumed small relative to Λ=2λ2/d;λ is the bulk London penetration depth of the film material and d is the film thickness.

  4. Effect of current injection into thin-film Josephson junctions

    SciTech Connect

    Kogan, V. G.; Mints, R. G.

    2014-11-11

    New thin-film Josephson junctions have recently been tested in which the current injected into one of the junction banks governs Josephson phenomena. One thus can continuously manage the phase distribution at the junction by changing the injected current. Our method of calculating the distribution of injected currents is also proposed for a half-infinite thin-film strip with source-sink points at arbitrary positions at the film edges. The strip width W is assumed small relative to Λ=2λ2/d;λ is the bulk London penetration depth of the film material and d is the film thickness.

  5. Ischemic preconditioning protects against gap junctional uncoupling in cardiac myofibroblasts.

    PubMed

    Sundset, Rune; Cooper, Marie; Mikalsen, Svein-Ole; Ytrehus, Kirsti

    2004-01-01

    Ischemic preconditioning increases the heart's tolerance to a subsequent longer ischemic period. The purpose of this study was to investigate the role of gap junction communication in simulated preconditioning in cultured neonatal rat cardiac myofibroblasts. Gap junctional intercellular communication was assessed by Lucifer yellow dye transfer. Preconditioning preserved intercellular coupling after prolonged ischemia. An initial reduction in coupling in response to the preconditioning stimulus was also observed. This may protect neighboring cells from damaging substances produced during subsequent regional ischemia in vivo, and may preserve gap junctional communication required for enhanced functional recovery during subsequent reperfusion.

  6. Unusual Presentation of Duplex Kidneys: Ureteropelvic Junction Obstruction

    PubMed Central

    Başdaş, Cemile; Özaydın, Seyithan; Karaaslan, Birgül; Alim, Elmas Reyhan; Güvenç, Ünal; Sander, Serdar

    2016-01-01

    Aim. Ureteropelvic junction obstruction (UPJO) is rarely associated with a duplex collecting system. We review this unusual anomaly in terms of presentation, diagnostic evaluation, and surgical management. Method. We retrospectively reviewed the medical records of patients diagnosed with a duplex system with UPJO. Result. Sixteen patients (6 girls, 10 boys) with 18 moieties were treated surgically and four patients were treated conservatively. The median age at surgery was two years (range, 2 months to 7 years). The lower pole and upper moiety were affected in 12 and two kidneys, respectively, and both were affected in two patients. The anomaly was right-sided in 12 moieties and left-sided in six. The duplication was incomplete in seven patients and complete in nine. The mean renal pelvis diameter at the time of surgery was 25.6 (range 11–48 mm) mm by USG. The mean renal function of the involved moiety was 28.3% before surgery. Management included pyelopyelostomy or ureteropyelostomy in six moieties, dismembered pyeloplasty in eight moieties, heminephrectomy in four cases, and simultaneous upper heminephrectomy and lower pole ureteropyelostomy in one patient. Conclusion. There is no standard approach for these patients and treatment should be individualized according to physical presentation, detailed anatomy, and severity of obstruction. PMID:27829833

  7. Nonergodic metallic and insulating phases of Josephson junction chains.

    PubMed

    Pino, Manuel; Ioffe, Lev B; Altshuler, Boris L

    2016-01-19

    Strictly speaking, the laws of the conventional statistical physics, based on the equipartition postulate [Gibbs J W (1902) Elementary Principles in Statistical Mechanics, developed with especial reference to the rational foundation of thermodynamics] and ergodicity hypothesis [Boltzmann L (1964) Lectures on Gas Theory], apply only in the presence of a heat bath. Until recently this restriction was believed to be not important for real physical systems because a weak coupling to the bath was assumed to be sufficient. However, this belief was not examined seriously until recently when the progress in both quantum gases and solid-state coherent quantum devices allowed one to study the systems with dramatically reduced coupling to the bath. To describe such systems properly one should revisit the very foundations of statistical mechanics. We examine this general problem for the case of the Josephson junction chain that can be implemented in the laboratory and show that it displays a novel high-temperature nonergodic phase with finite resistance. With further increase of the temperature the system undergoes a transition to the fully localized state characterized by infinite resistance and exponentially long relaxation.

  8. Strain effect on spin polarization in a graphene junction

    NASA Astrophysics Data System (ADS)

    Cao, Zhenzhou; Lu, Ning; Qiu, Xuejun; Wang, Guofei

    2017-04-01

    We investigate the strain effect on the spin-dependent transport in a graphene junction with spin–orbit coupling and a gate voltage. We find that uniaxial strain along the armchair direction breaks the transmission probability symmetry with respect to the incident angle, reduces the spin-flipped transmission probability, and extends the transmission gap as regard to the Fermi energy, while strain along the zig-zag direction has very little effect on transmission probabilities. We analyze the spin polarization as a function of the strain magnitude, direction, voltage, and area width. Selecting the proper strain direction and magnitude for both the Klein tunneling and classical cases, the direction of the spin-polarization vector can be controlled and its magnitude is dramatically enhanced. Strain will expand the non-zero range of the magnitude of the spin-polarization vector with respect to voltage. Increasing the strain area width over a threshold, keeps the magnitude of the spin-polarization vector stable.

  9. Nonergodic metallic and insulating phases of Josephson junction chains

    PubMed Central

    Pino, Manuel; Ioffe, Lev B.; Altshuler, Boris L.

    2016-01-01

    Strictly speaking, the laws of the conventional statistical physics, based on the equipartition postulate [Gibbs J W (1902) Elementary Principles in Statistical Mechanics, developed with especial reference to the rational foundation of thermodynamics] and ergodicity hypothesis [Boltzmann L (1964) Lectures on Gas Theory], apply only in the presence of a heat bath. Until recently this restriction was believed to be not important for real physical systems because a weak coupling to the bath was assumed to be sufficient. However, this belief was not examined seriously until recently when the progress in both quantum gases and solid-state coherent quantum devices allowed one to study the systems with dramatically reduced coupling to the bath. To describe such systems properly one should revisit the very foundations of statistical mechanics. We examine this general problem for the case of the Josephson junction chain that can be implemented in the laboratory and show that it displays a novel high-temperature nonergodic phase with finite resistance. With further increase of the temperature the system undergoes a transition to the fully localized state characterized by infinite resistance and exponentially long relaxation. PMID:26719416

  10. Fenestrated vertebrobasilar junction aneurysm: diagnostic and therapeutic considerations.

    PubMed

    Albanese, Erminia; Russo, Antonino; Ulm, Arthur J

    2009-03-01

    Vertebrobasilar junction (VBJ) aneurysms are uncommon and are often found in association with basilar artery (BA) fenestration. The complex anatomical environment of the VBJ, and the complicated geometry of the fenestration make clipping of these aneurysms difficult. Therefore, endovascular treatment of these aneurysms is now widely accepted. The authors describe the case of a 43-year-old woman with sickle cell anemia. She presented with subarachnoid hemorrhage. Digital subtraction angiography was performed and depicted multiple intracranial aneurysms. The patient had a left superior hypophysial artery aneurysm, a right superior cerebellar artery-posterior cerebral artery aneurysm, and a VBJ aneurysm associated with a fenestration of the BA. The VBJ aneurysm was not identified on the initial angiogram and was only revealed after 3D rotational angiography was performed. The 3D reconstruction was critical to the understanding of the complex geometry associated with the fenestrated BA. The VBJ was reconstructed using a combination endovascular technique. The dominant limb of the fenestration was stented and balloon-assisted coiling was performed, followed by sacrifice of the nondominant vertebral artery using coils and the embolic agent Onyx. Postoperative angiography demonstrated successful occlusion of the aneurysm with reconstruction of the VBJ. To the authors' knowledge, this is the first report of a fenestrated VBJ aneurysm treated with the combination of stenting, balloon remodeling, coiling, and vessel sacrifice. Three-dimensional angiography was critical in making the correct diagnosis of the source of the subarachnoid hemorrhage and with operative planning.

  11. RWGSCAT - RECTANGULAR WAVEGUIDE JUNCTION SCATTERING PROGRAM

    NASA Technical Reports Server (NTRS)

    Hoppe, D. J.

    1994-01-01

    In order to optimize frequency response and determine the tolerances required to meet RF specifications, accurate computer modeling of passive rectangular waveguide components is often required. Many rectangular waveguide components may be represented either exactly or approximately as a number of different size rectangular waveguides which are connected in series. RWGSCAT, Rectangular WaveGuide junction SCATtering program, solves for the scattering properties of a waveguide device. This device must consist of a number of rectangular waveguide sections of different cross sectional area which are connected in series. Devices which fall into this category include step transformers, filters, and smooth or corrugated rectangular horns. RWGSCAT will model such devices and accurately predict the reflection and transmission characteristics, taking into account higher order (other than dominant TE 10) mode excitation if it occurs, as well as multiple reflections and stored energy at each discontinuity. For devices which are large with respect to the wavelength of operation, the characteristics of the device may be required for computing a higher order mode or a number of higher order modes exciting the device. Such interactions can be represented by defining a scattering matrix for each discontinuity in the device, and then cascading the individual scattering matrices in order to determine the scattering matrix for the overall device. The individual matrices are obtained using the mode matching method. RWGSCAT is written in FORTRAN 77 for IBM PC series and compatible computers running MS-DOS. It has been successfully compiled and implemented using Lahey FORTRAN 77 under MS-DOS. A sample MS-DOS executable is provided on the distribution medium. It requires 377K of RAM for execution. Sample input data is also provided on the distribution medium. The standard distribution medium for this program is one 5.25 inch 360K MS-DOS format diskette. The contents of the diskette are

  12. Magnetic field oscillations of the critical current in long ballistic graphene Josephson junctions

    NASA Astrophysics Data System (ADS)

    Rakyta, Péter; Kormányos, Andor; Cserti, József

    2016-06-01

    We study the Josephson current in long ballistic superconductor-monolayer graphene-superconductor junctions. As a first step, we have developed an efficient computational approach to calculate the Josephson current in tight-binding systems. This approach can be particularly useful in the long-junction limit, which has hitherto attracted less theoretical interest but has recently become experimentally relevant. We use this computational approach to study the dependence of the critical current on the junction geometry, doping level, and an applied perpendicular magnetic field B . In zero magnetic field we find a good qualitative agreement with the recent experiment of M. Ben Shalom et al. [Nat. Phys. 12, 318 (2016), 10.1038/nphys3592] for the length dependence of the critical current. For highly doped samples our numerical calculations show a broad agreement with the results of the quasiclassical formalism. In this case the critical current exhibits Fraunhofer-like oscillations as a function of B . However, for lower doping levels, where the cyclotron orbit becomes comparable to the characteristic geometrical length scales of the system, deviations from the results of the quasiclassical formalism appear. We argue that due to the exceptional tunability and long mean free path of graphene systems a new regime can be explored where geometrical and dynamical effects are equally important to understand the magnetic field dependence of the critical current.

  13. Josephson current in finite-lenght nanowire SNS junctions with Majorana fermions

    NASA Astrophysics Data System (ADS)

    Aguado, Ramon; Prada, Elsa; San Jose, Pablo

    2012-02-01

    The dc Josephson effect (JE) through infinite-lenght junctions of one-dimensional topological superconductors exhibits an anomalous 4π periodic phase (φ) dependence which originates from a parity-protected level crossing of zero-energy Majorana bound states (MBS) at φ=π. This ``fractional'' JE provides an important experimental detection tool for MBS. In this talk, I will discuss the JE in more realistic SNS junctions of arbitrary transparency and when both the normal and the nanowire regions are of finite length, namely beyond the short-junction and infinite topological superconductor limits. In general, the spectrum of Andreev bound states can become rather intricate and dense as opposed to the infinite-lenght case. Moreover, the low-energy spectrum around φ=π shows always anticrossings, originated from hybridization of four MBS, which may preclude the experimental observation of the fractional JE. At finite bias voltages, Landau-Zener dynamics involving the MBS and quasi-continuum Andreev levels gives rise to a nontrivial ac Josephson current. Interestingly, the ac current phase diagram as a function of the Josephson frequency/normal transmission shows fractional JE regions which are tunable through bias/gate voltages.

  14. Adenocarcinoma of the ileocolic junction and multifocal hepatic sarcomas in an aged rhesus macaque (Macaca mulatta).

    PubMed

    Lang, Cynthia D; Daviau, Judith S; Merton, Daniel A; Caraker, Susan M

    2013-08-01

    An aged male rhesus macaque in our colony had decreased appetite and a loss of interest in behavioral testing. CBC analysis revealed a regenerative, microcytic, hypochromic anemia with thrombocytosis, consistent with iron deficiency. A fecal occult blood test was positive. Ultrasound imaging revealed numerous, vascularized focal liver lesions that suggested metastases. The macaque's appetite continued to decrease, and he became more lethargic. At this point, the investigator elected to euthanize the macaque. At necropsy, the ileocolic junction was white and abnormally thickened, and the liver was pale tan with approximately 18 discrete white masses randomly scattered throughout the hepatic parenchyma. Histologically, the mass at the ileocolic junction was identified as an intestinal adenocarcinoma, whereas the liver masses were confirmed to be undifferentiated hepatic sarcomas. This case report describes a rhesus macaque that had 2 unrelated primary neoplasms. A review of the literature indicates that this rhesus macaque is the first reported to have an adenocarcinoma of the ileocolic junction and multiple hepatic sarcomas simultaneously.

  15. Evolution in the treatment of the ureteropelvic junction obstruction syndrome. Laparoscopic versus open pyeloplasty

    PubMed Central

    Gregorio, Sergio Alonso y; Sánchez, Leslie Cuello; Portella, Pamela Fontana; Gómez, Ángel Tabernero; Ledo, Jesús Cisneros; Sebastián, Jesús Díez; Barthel, Jesús Javier de la Peña

    2015-01-01

    Introduction The treatment of ureteropelvic junction has evolved considerably over the past 20 years, resulting in new surgical techniques, but traditional open surgery remains the gold standard treatment. Currently, less invasive techniques are used for the treatment of ureteropelvic junction obstruction. The purpose of our study is to compare the surgical and functional results between laparoscopic and open pyeloplasty performed at our department during the last 12 years. Material and methods This is a retrospective review of 92 cases performed in a period of 12 years. Two groups were compared: 30 patients were treated with open surgery (OP) and 62 with a laparoscopic approach (LP). Demographics, clinical presentation, functionality of the affected kidney, presence of polar vessels, kidney stones, hospital stay, complications and functional results were statistically analyzed. Results The mean age was 42 years. The most common clinical presentation was kidney or ureteral pain: 60% (OP) vs. 52% (LP). The right side was affected in 59%; presence of crossing vessels was 47% (OP) vs. 58% (LP); presence of kidney stones was 20% (OP) vs. 19% (LP), with an average hospital stay of 5.86 days (OP) vs. 3.36 days (LP) p <0.05. Post-operative complications were observed in 3 (OP) vs. 5 (LP) patients, with a success rate comparable between groups. Conclusions In our department, we recommend LP as the standard treatment for ureteropelvic junction obstruction because of the equal success rate compared to OP and the benefits of a minimally invasive surgery. PMID:26568887

  16. Anomalous vertebral artery compression of the spinal cord at the cervicomedullary junction

    PubMed Central

    Ball, Bret Gene; Krueger, Bruce R; Piepgras, David G

    2011-01-01

    Background: Myelopathy from ectatic vertebral artery compression of the spinal cord at the cervicomedullary junction is a rare condition. Case Description: A 63-year-old female was originally diagnosed with occult hydrocephalus syndrome after presenting with symptoms of ataxia and urinary incontinence. Ventriculoperitoneal shunting induced an acute worsening of the patient′s symptoms as she immediately developed a sensory myelopathy. An MR scan demonstrated multiple congenital abnormalities including cervicomedullary stenosis with anomalous vertebral artery compression of the dorsal spinal cord at the cervicomedullary junction. The patient was taken to surgery for a suboccipital craniectomy, C1-2 laminectomy, vertebral artery decompression, duraplasty, and shunt ligation. Intraoperative findings confirmed preoperative radiography with ectactic vertebral arteries deforming the dorsal aspect of the spinal cord. There were no procedural complications and at a 6-month follow-up appointment, the patient had experienced a marked improvement in her preoperative signs and symptoms. Conclusion: Myelopathy from ectatic vertebral artery compression at the cervicomedullary junction is a rare disorder amenable to operative neurovascular decompression. PMID:21886876

  17. Assembly of the cochlear gap junction macromolecular complex requires connexin 26.

    PubMed

    Kamiya, Kazusaku; Yum, Sabrina W; Kurebayashi, Nagomi; Muraki, Miho; Ogawa, Kana; Karasawa, Keiko; Miwa, Asuka; Guo, Xueshui; Gotoh, Satoru; Sugitani, Yoshinobu; Yamanaka, Hitomi; Ito-Kawashima, Shioko; Iizuka, Takashi; Sakurai, Takashi; Noda, Tetsuo; Minowa, Osamu; Ikeda, Katsuhisa

    2014-04-01

    Hereditary deafness affects approximately 1 in 2,000 children. Mutations in the gene encoding the cochlear gap junction protein connexin 26 (CX26) cause prelingual, nonsyndromic deafness and are responsible for as many as 50% of hereditary deafness cases in certain populations. Connexin-associated deafness is thought to be the result of defective development of auditory sensory epithelium due to connexion dysfunction. Surprisingly, CX26 deficiency is not compensated for by the closely related connexin CX30, which is abundantly expressed in the same cochlear cells. Here, using two mouse models of CX26-associated deafness, we demonstrate that disruption of the CX26-dependent gap junction plaque (GJP) is the earliest observable change during embryonic development of mice with connexin-associated deafness. Loss of CX26 resulted in a drastic reduction in the GJP area and protein level and was associated with excessive endocytosis with increased expression of caveolin 1 and caveolin 2. Furthermore, expression of deafness-associated CX26 and CX30 in cell culture resulted in visible disruption of GJPs and loss of function. Our results demonstrate that deafness-associated mutations in CX26 induce the macromolecular degradation of large gap junction complexes accompanied by an increase in caveolar structures.

  18. Theory of coherent charge transport in junctions involving unconventional superconducting materials

    NASA Astrophysics Data System (ADS)

    Burmistrova, A. V.; Devyatov, I. A.

    2016-10-01

    Recent theoretical studies of coherent charge transport in junctions involving unconventional superconducting materials such as high-temperature superconducting iron-based pnictides (FeBS) and in structures with induced superconductivity which are formed of a thin metal layer with spin-orbit coupling in contact with an s-wave superconductor (SSO) are reported. The theoretical analysis is performed with our unified approach based on the tight-binding method and boundary conditions obtained for it. This approach makes it possible to take into account a complex nonparabolic and anisotropic spectrum of normal excitations in unconventional superconducting materials and their multiband character, as well as unusual types of symmetries of the superconducting order parameter in them. The possibility of a semiclassical description in the case of intraorbital superconducting pairing is demonstrated. The method of calculations and their results are presented for the conductivities of junctions between a normal metal and unconventional superconducting materials, as well as for the Josephson current. Comparison with the experiment for the junction with FeBS is performed and indicates the presence of the unusual s± symmetry of the order parameter. An experiment is proposed to test our theoretical results for SSO.

  19. An up-to-date overview of minimally invasive treatment methods in ureteropelvic junction obstruction

    PubMed Central

    Celik, Orcun; Ilbey, Yusuf Ozlem

    2015-01-01

    Introduction Over the last two decades, minimally invasive treatment options for ureteropelvic junction obstruction have been developed and are bcoming more popular. Multiple series of laparoscopic pyeloplasty have demonstrated high success rates and low perioperative morbidity in pediatric and adult populations, for both the transperitoneal and retroperitoneal approaches. In this review, we aimed to analyze the current status of minimally invasive therapy of ureteropelvic junction obstruction. Material and methods A PubMed database search was conducted to examine minimally invasive treatments of ureteropelvic junction obstruction. Results A large number of cases have been reported for adult patients, confirming that robotic pyeloplasty represents a viable option for either primary or secondary repair. Comparative studies demonstrate similar success and complication rates between minimally invasive and open pyeloplasty in both the adult and pediatric populations. A clear advantage, in terms of hospital stay, of minimally invasive over open pyeloplasty was observed only in the adult population. Conclusions Studies have shown that minimally invasive pyeloplasty techniques are a safe, effective, and feasible in adult and pediatric populations. PMID:26251754

  20. Spin supercurrent, magnetization dynamics, and φ-state in spin-textured Josephson junctions

    NASA Astrophysics Data System (ADS)

    Kulagina, Iryna; Linder, Jacob

    2014-08-01

    The prospect of combining the dissipationless nature of superconducting currents with the spin polarization of magnetic materials is interesting with respect to exploring superconducting analogs of topics in spintronics. In order to accomplish this aim, it is pivotal to understand not only how such spin supercurrents can be created, but also how they interact dynamically with magnetization textures. In this paper, we investigate the appearance of a spin supercurrent and the resulting magnetization dynamics in a textured magnetic Josephson current by using three experimentally relevant models: (i) a superconductor∣ferromagnet∣superconductor (S∣F∣S) junction with spin-active interfaces, (ii) a S∣F1∣F2∣F3∣S Josephson junction with a ferromagnetic trilayer, and (iii) a Josephson junction containing a domain wall. In all of these cases, the supercurrent is spin polarized and exerts a spin-transfer torque on the ferromagnetic interlayers which causes magnetization dynamics. Using a scattering matrix formalism in the clean limit, we compute the Andreev bound states and resulting free energy of the system which in turn is used to solve the Landau-Lifshiftz-Gilbert equation. We compute both how the inhomogeneous magnetism influences the phase dependence of the charge supercurrent and the magnetization dynamics caused by the spin polarization of the supercurrent. Using a realistic experimental parameter set, we find that the spin supercurrent can induce magnetization switching that is controlled by the superconducting phase difference. Moreover, we demonstrate that the combined effect of chiral spin symmetry breaking of the system as a whole with interface scattering causes the systems above to act as phase batteries that may supply any superconducting phase difference φ in the ground state. Such a φ-junction is accompanied by an anomalous supercurrent appearing even at zero phase difference, and we demonstrate that the flow direction of this current is

  1. Atlas Assimilation Patterns in Different Types of Adult Craniocervical Junction Malformations

    PubMed Central

    Ferreira, Edson Dener Zandonadi; Botelho, Ricardo Vieira

    2015-01-01

    Study Design. This is a cross-sectional analysis of resonance magnetic images of 111 patients with craniocervical malformations and those of normal subjects. Objective. To test the hypothesis that atlas assimilation is associated with basilar invagination (BI) and atlas's anterior arch assimilation is associated with craniocervical instability and type I BI. Summary of Background Data. Atlas assimilation is the most common malformation in the craniocervical junction. This condition has been associated with craniocervical instability and BI in isolated cases. Methods. We evaluated midline Magnetic Resonance Images (MRIs) (and/or CT scans) from patients with craniocervical junction malformation and normal subjects. The patients were separated into 3 groups: Chiari type I malformation, BI type I, and type II. The atlas assimilations were classified according to their embryological origins as follows: posterior, anterior, and both arches assimilation. Results. We studied the craniometric values of 111 subjects, 78 with craniocervical junction malformation and 33 without malformations. Of the 78 malformations, 51 patients had Chiari type I and 27 had BI, of whom 10 presented with type I and 17 with type II BI. In the Chiari group, 41 showed no assimilation of the atlas. In the type I BI group, all patients presented with anterior arch assimilation, either in isolation or associated with assimilation of the posterior arch. 63% of the patients with type II BI presented with posterior arch assimilation, either in isolation or associated with anterior arch assimilation. In the control group, no patients had atlas assimilation. Conclusion. Anterior atlas assimilation leads to type I BI. Posterior atlas assimilation more frequently leads to type II BI. Separation in terms of anterior versus posterior atlas assimilation reflects a more accurate understanding of the clinical and embryological differences in craniocervical junction malformations. Level of Evidence: N/A PMID

  2. Josephson effect in multiterminal superconductor-ferromagnet junctions coupled via triplet components

    NASA Astrophysics Data System (ADS)

    Moor, Andreas; Volkov, Anatoly F.; Efetov, Konstantin B.

    2016-03-01

    On the basis of the Usadel equation we study a multiterminal Josephson junction. This junction is composed by "magnetic" superconductors Sm, which have singlet pairing and are separated from the normal n wire by spin filters so that the Josephson coupling is caused only by fully polarized triplet components. We show that there is no interaction between triplet Cooper pairs with antiparallel total spin orientations. The presence of an additional singlet superconductor S attached to the n wire leads to a finite Josephson current IQ with an unusual current-phase relation. The density of states in the n wire for different orientations of spins of Cooper pairs is calculated. We derive a general formula for the current IQ in a multiterminal Josephson contact and apply this formula for analysis of two four-terminal Josephson junctions of different structures. It is shown in particular that both the "nematic" and the "magnetic" cases can be realized in these junctions. In a two-terminal structure with parallel filter orientations and in a three-terminal structure with antiparallel filter orientations of the "magnetic" superconductors with attached additional singlet superconductor, we find a nonmonotonic temperature dependence of the critical current. Also, in these structures, the critical current shows a Riedel peak like dependence on the exchange field in the "magnetic" superconductors. Although there is no current through the S/n interface due to orthogonality of the singlet and triplet components, the phase of the order parameter in the superconuctor S is shown to affect the Josephson current in a multiterminal structure.

  3. Backbending current-voltage characteristic for an annular Josephson junction in a magnetic field

    NASA Astrophysics Data System (ADS)

    Ustinov, Alexey V.; Malomed, Boris A.; Goldobin, Edward

    1999-07-01

    Excitation of the Josephson plasma radiation by a fluxon moving in an annular Josephson junction is studied experimentally, numerically, and using an analytical approach. An externally applied magnetic field H forms a cosinelike potential relief for the fluxon in a ring-shaped junction. The motion of the fluxon in the junction leads to an emission of plasma waves, which give rise to a resonance at a certain fluxon velocity. The experimental data agree well with numerical simulations which indicate a locking of the fluxon to the radiation frequency. The peculiar feature indicated by both experiment and numerical simulations is the shape of the resonance in the current-voltage (I-V) characteristic which shows a clear backbending, with a negative differential resistance. The analytical approach developed in this work is based on the perturbation theory for radiation emission generated by a kink in the perturbed sine-Gordon equation. To explain the observed effect, we introduce an addition to the perturbation theory, which proves to be crucial for explanation of the backbending I-V curves: We take into account the fact that the background radiation field, supported by a balance between emission from the moving kink and dissipative absorption, narrows the junction's plasma frequency gap. In the case when the emission has a resonant character, even a small change of the gap produces a strong reciprocal effect on the emission power. Following this idea, we develop a fully analytical self-consistent approximation that readily allows us to obtain the backbending I-V curves.

  4. 23. Tunnel junction, view from the lower elevator room. Lyon ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    23. Tunnel junction, view from the lower elevator room. Lyon - Whiteman Air Force Base, Oscar O-1 Minuteman Missile Alert Facility, Southeast corner of Twelfth & Vendenberg Avenues, Knob Noster, Johnson County, MO

  5. 39. Launch Control Equipment Room, seen from tunnel junction. Lyon ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    39. Launch Control Equipment Room, seen from tunnel junction. Lyon - Whiteman Air Force Base, Oscar O-1 Minuteman Missile Alert Facility, Southeast corner of Twelfth & Vendenberg Avenues, Knob Noster, Johnson County, MO

  6. Interface Structure and Transport of Complex Oxide Junctions

    SciTech Connect

    Nelson-Cheeseman, B. B.; Wong, F.; Chopdekar, R. V.; Chi, M.; Arenholz, E.; Browning, N. D.; Suzuki, Y.

    2008-02-01

    The interface structure and magnetism of hybrid magnetic tunnel junction-spin filter devices have been investigated and correlated with the transport behavior exhibited. Magnetic tunnel junctions made of theoretically predicted half-metallic electrodes (perovskite La0.7Sr0.3MnO3 and spinel Fe3O4) sandwiching a spinel NiMn2O4 tunnel barrier exhibit very high crystalline quality as observed by transmission electron microscopy. Structurally abrupt interfaces allow for the distinct magnetic switching of the electrodes as well as large junction magnetoresistance. The change in the magnetic anisotropy observed at the spinel-spinel interface supports the presence of limited interdiffusion and the creation of a magnetically soft interfacial layer, whose strong exchange coupling to the Fe3O4 electrode likely accounts for the low background magnetoresistance observed in these junctions, and the successful spin filtering when the barrier layer is ferrimagnetic.

  7. Fabrication and analysis of dot junction silicon solar cells

    NASA Technical Reports Server (NTRS)

    Crotty, G. T.; Daud, T.

    1985-01-01

    A design of solar cells with reduced junction area on the cell surface is investigated for reduction of saturation current and increase in open-circuit voltage. Equidiameter dot junctions distributed across the surface of the cell offer an efficient alternative, with variations in dot diameter and in the spacing between dots giving the required variations in the ratio of junctions area to total surface area. A simplified analysis for short-circuit current and other cell parameters, which enables cell design optimization, is presented. Efficiencies beyond 18 percent are obtainable in flat-plate terrestrial applications. Experimental solar-cell performance results, as functions of different area ratios, and bulk doping are presented. It is shown that saturation current reduction and open-circuit voltage increase is obtained by reduced junction area.

  8. View of Highway 140 and Overhang Rock. Location of junction ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View of Highway 140 and Overhang Rock. Location of junction with Old Coulterville Road behind rock. Looking north-northwest - All Year Highway, Between Arch Rock & Yosemite Valley, El Portal, Mariposa County, CA

  9. Molecular electronics: some views on transport junctions and beyond.

    PubMed

    Joachim, Christian; Ratner, Mark A

    2005-06-21

    The field of molecular electronics comprises a fundamental set of issues concerning the electronic response of molecules as parts of a mesoscopic structure and a technology-facing area of science. We will overview some important aspects of these subfields. The most advanced ideas in the field involve the use of molecules as individual logic or memory units and are broadly based on using the quantum state space of the molecule. Current work in molecular electronics usually addresses molecular junction transport, where the molecule acts as a barrier for incoming electrons: This is the fundamental Landauer idea of "conduction as scattering" generalized to molecular junction structures. Another point of view in terms of superexchange as a guiding mechanism for coherent electron transfer through the molecular bridge is discussed. Molecules generally exhibit relatively strong vibronic coupling. The last section of this overview focuses on vibronic effects, including inelastic electron tunneling spectroscopy, hysteresis in junction charge transport, and negative differential resistance in molecular transport junctions.

  10. Thermoelectricity in atom-sized junctions at room temperatures

    PubMed Central

    Tsutsui, Makusu; Morikawa, Takanori; Arima, Akihide; Taniguchi, Masateru

    2013-01-01

    Atomic and molecular junctions are an emerging class of thermoelectric materials that exploit quantum confinement effects to obtain an enhanced figure of merit. An important feature in such nanoscale systems is that the electron and heat transport become highly sensitive to the atomic configurations. Here we report the characterization of geometry-sensitive thermoelectricity in atom-sized junctions at room temperatures. We measured the electrical conductance and thermoelectric power of gold nanocontacts simultaneously down to the single atom size. We found junction conductance dependent thermoelectric voltage oscillations with period 2e2/h. We also observed quantum suppression of thermovoltage fluctuations in fully-transparent contacts. These quantum confinement effects appeared only statistically due to the geometry-sensitive nature of thermoelectricity in the atom-sized junctions. The present method can be applied to various nanomaterials including single-molecules or nanoparticles and thus may be used as a useful platform for developing low-dimensional thermoelectric building blocks. PMID:24270238

  11. High thermopower of mechanically stretched single-molecule junctions

    PubMed Central

    Tsutsui, Makusu; Morikawa, Takanori; He, Yuhui; Arima, Akihide

    2015-01-01

    Metal-molecule-metal junction is a promising candidate for thermoelectric applications that utilizes quantum confinement effects in the chemically defined zero-dimensional atomic structure to achieve enhanced dimensionless figure of merit ZT. A key issue in this new class of thermoelectric nanomaterials is to clarify the sensitivity of thermoelectricity on the molecular junction configurations. Here we report simultaneous measurements of the thermoelectric voltage and conductance on Au-1,4-benzenedithiol (BDT)-Au junctions mechanically-stretched in-situ at sub-nanoscale. We obtained the average single-molecule conductance and thermopower of 0.01 G0 and 15 μV/K, respectively, suggesting charge transport through the highest occupied molecular orbital. Meanwhile, we found the single-molecule thermoelectric transport properties extremely-sensitive to the BDT bridge configurations, whereby manifesting the importance to design the electrode-molecule contact motifs for optimizing the thermoelectric performance of molecular junctions. PMID:26112999

  12. Thermoelectricity in atom-sized junctions at room temperatures.

    PubMed

    Tsutsui, Makusu; Morikawa, Takanori; Arima, Akihide; Taniguchi, Masateru

    2013-11-25

    Atomic and molecular junctions are an emerging class of thermoelectric materials that exploit quantum confinement effects to obtain an enhanced figure of merit. An important feature in such nanoscale systems is that the electron and heat transport become highly sensitive to the atomic configurations. Here we report the characterization of geometry-sensitive thermoelectricity in atom-sized junctions at room temperatures. We measured the electrical conductance and thermoelectric power of gold nanocontacts simultaneously down to the single atom size. We found junction conductance dependent thermoelectric voltage oscillations with period 2e(2)/h. We also observed quantum suppression of thermovoltage fluctuations in fully-transparent contacts. These quantum confinement effects appeared only statistically due to the geometry-sensitive nature of thermoelectricity in the atom-sized junctions. The present method can be applied to various nanomaterials including single-molecules or nanoparticles and thus may be used as a useful platform for developing low-dimensional thermoelectric building blocks.

  13. High thermopower of mechanically stretched single-molecule junctions.

    PubMed

    Tsutsui, Makusu; Morikawa, Takanori; He, Yuhui; Arima, Akihide; Taniguchi, Masateru

    2015-06-26

    Metal-molecule-metal junction is a promising candidate for thermoelectric applications that utilizes quantum confinement effects in the chemically defined zero-dimensional atomic structure to achieve enhanced dimensionless figure of merit ZT. A key issue in this new class of thermoelectric nanomaterials is to clarify the sensitivity of thermoelectricity on the molecular junction configurations. Here we report simultaneous measurements of the thermoelectric voltage and conductance on Au-1,4-benzenedithiol (BDT)-Au junctions mechanically-stretched in-situ at sub-nanoscale. We obtained the average single-molecule conductance and thermopower of 0.01 G0 and 15 μV/K, respectively, suggesting charge transport through the highest occupied molecular orbital. Meanwhile, we found the single-molecule thermoelectric transport properties extremely-sensitive to the BDT bridge configurations, whereby manifesting the importance to design the electrode-molecule contact motifs for optimizing the thermoelectric performance of molecular junctions.

  14. Macroscopic quantum tunnelling in spin filter ferromagnetic Josephson junctions.

    PubMed

    Massarotti, D; Pal, A; Rotoli, G; Longobardi, L; Blamire, M G; Tafuri, F

    2015-06-09

    The interfacial coupling of two materials with different ordered phases, such as a superconductor (S) and a ferromagnet (F), is driving new fundamental physics and innovative applications. For example, the creation of spin-filter Josephson junctions and the demonstration of triplet supercurrents have suggested the potential of a dissipationless version of spintronics based on unconventional superconductivity. Here we demonstrate evidence for active quantum applications of S-F-S junctions, through the observation of macroscopic quantum tunnelling in Josephson junctions with GdN ferromagnetic insulator barriers. We show a clear transition from thermal to quantum regime at a crossover temperature of about 100 mK at zero magnetic field in junctions, which present clear signatures of unconventional superconductivity. Following previous demonstration of passive S-F-S phase shifters in a phase qubit, our result paves the way to the active use of spin filter Josephson systems in quantum hybrid circuits.

  15. Studies of silicon p-n junction solar cells

    NASA Technical Reports Server (NTRS)

    Neugroschel, A.; Lindholm, F. A.

    1979-01-01

    To provide theoretical support for investigating different ways to obtain high open-circuit voltages in p-n junction silicon solar cells, an analytical treatment of heavily doped transparent-emitter devices is presented that includes the effects of bandgap narrowing, Fermi-Dirac statistics, a doping concentration gradient, and a finite surface recombination velocity at the emitter surface. Topics covered include: (1) experimental determination of bandgap narrowing in the emitter of silicon p-n junction devices; (2) heavily doped transparent regions in junction solar cells, diodes, and transistors; (3) high-low-emitter solar cell; (4) determination of lifetimes and recombination currents in p-n junction solar cells; (5) MOS and oxide-charged-induced BSF solar cells; and (6) design of high efficiency solar cells for space and terrestrial applications.

  16. Manipulating Josephson junctions in thin-films by nearby vortices

    SciTech Connect

    Kogan, V G; Mints, R G

    2014-07-01

    It is shown that a vortex trapped in one of the banks of a planar edge-type Josephson junction in a narrow thin-film superconducting strip can change drastically the dependence of the junction critical current on the applied field, I-c(H). When the vortex is placed at certain discrete positions in the strip middle, the pattern I-c(H) has zero at H = 0 instead of the traditional maximum of '0-type' junctions. The number of these positions is equal to the number of vortices trapped at the same location. When the junction-vortex separation exceeds similar to W, the strip width, I-c(H) is no longer sensitive to the vortex presence. The same is true for any separation if the vortex approaches the strip edges. (C) 2014 Elsevier B.V. All rights reserved.

  17. Perspective: Thermal and thermoelectric transport in molecular junctions

    NASA Astrophysics Data System (ADS)

    Cui, Longji; Miao, Ruijiao; Jiang, Chang; Meyhofer, Edgar; Reddy, Pramod

    2017-03-01

    With the advent of molecular electronics, tremendous attention has been paid towards understanding the structure-function relationship of molecular junctions. Understanding how heat is transported, dissipated, and converted into electricity in molecular junctions is of great importance for designing thermally robust molecular circuits and high-performance energy conversion devices. Further, the study of thermal and thermoelectric phenomena in molecular junctions provides novel insights into the limits of applicability of classical laws. Here, we present a review of the computational and experimental progress made in probing thermoelectric effects, thermal conduction, heat dissipation, and local heating/cooling in self-assembled monolayer and single molecule junctions. We also discuss some outstanding challenges and potential future directions.

  18. BLACKSMITH SHOP ROOF STRUCTURE AT JUNCTION BETWEEN 60 FT. AND ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    BLACKSMITH SHOP ROOF STRUCTURE AT JUNCTION BETWEEN 60 FT. AND 90 FT. SPAN ROOF TRUSSES, LOOKING SOUTH. - Southern Pacific, Sacramento Shops, Blacksmith Shop, 111 I Street, Sacramento, Sacramento County, CA

  19. Macroscopic quantum tunnelling in spin filter ferromagnetic Josephson junctions

    PubMed Central

    Massarotti, D.; Pal, A.; Rotoli, G.; Longobardi, L.; Blamire, M. G.; Tafuri, F.

    2015-01-01

    The interfacial coupling of two materials with different ordered phases, such as a superconductor (S) and a ferromagnet (F), is driving new fundamental physics and innovative applications. For example, the creation of spin-filter Josephson junctions and the demonstration of triplet supercurrents have suggested the potential of a dissipationless version of spintronics based on unconventional superconductivity. Here we demonstrate evidence for active quantum applications of S-F-S junctions, through the observation of macroscopic quantum tunnelling in Josephson junctions with GdN ferromagnetic insulator barriers. We show a clear transition from thermal to quantum regime at a crossover temperature of about 100 mK at zero magnetic field in junctions, which present clear signatures of unconventional superconductivity. Following previous demonstration of passive S-F-S phase shifters in a phase qubit, our result paves the way to the active use of spin filter Josephson systems in quantum hybrid circuits. PMID:26054495

  20. 14. Junction of the Tempe Canal and Western Canal, looking ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    14. Junction of the Tempe Canal and Western Canal, looking north. Photographer: Mark Durben, February 1989. Source: SRPA - Tempe Canal, South Side Salt River in Tempe, Mesa & Phoenix, Tempe, Maricopa County, AZ

  1. 8. VIEW SOUTHWEST, DETAIL OF JUNCTION OF EAST AND NORTH ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    8. VIEW SOUTHWEST, DETAIL OF JUNCTION OF EAST AND NORTH ELEVATIONS AT PORCH ROOF LEVEL SHOWING GLAZED HEADERS AND BELT COURSE - David Sterrett House, State Game Lands Plot No. 169 (Upper Mifflin Township), Newville, Cumberland County, PA

  2. Memory cell operation based on small Josephson junctions arrays

    NASA Astrophysics Data System (ADS)

    Braiman, Y.; Nair, N.; Rezac, J.; Imam, N.

    2016-12-01

    In this paper we analyze a cryogenic memory cell circuit based on a small coupled array of Josephson junctions. All the basic memory operations (e.g., write, read, and reset) are implemented on the same circuit and different junctions in the array can in principle be utilized for these operations. The presented memory operation paradigm is fundamentally different from conventional single quantum flux operation logics (SFQ). As an example, we demonstrate memory operation driven by a SFQ pulse employing an inductively coupled array of three Josephson junctions. We have chosen realistic Josephson junction parameters based on state-of-the-art fabrication capabilities and have calculated access times and access energies for basic memory cell operations. We also implemented an optimization procedure based on the simulated annealing algorithm to calculate the optimized and typical values of access times and access energies.

  3. Pure valley and spin polarization current in ferromagnetic graphene junction

    NASA Astrophysics Data System (ADS)

    Wu, Qing-Ping; Liu, Zheng-Fang; Chen, Ai-Xi; Xiao, Xian-Bo; Miao, Guo-Xing

    2017-02-01

    We investigate the band structure and spin- and valley-dependent transport in ferromagnetic graphene double junctions using the transfer matrix method. The ferromagnetic double junctions include a lateral layout of normal/magnetic vector potential/normal/effective exchange field/normal graphene regions. We find that the strain combined with magnetic vector potentials breaks the valley degeneracy, and the strain combined with the effective exchange field breaks the spin degeneracy, so that there exists a spin- and valley-dependent gap in the ferromagnetic graphene double junctions, which allows only one spin species with special valley characteristics to be transported. Thus, this type of junction can achieve simultaneously pure spin- and pure valley-polarized currents and function as a perfect valley filter and a perfect spin filter. The exact nature of the valley filtering and spin filtering can be tuned by the strain, magnetic barrier, and effective exchange field strength.

  4. 10. DETAIL OF JUNCTION BETWEEN LOWER CHORD, VERTICAL LACED CHANNEL, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    10. DETAIL OF JUNCTION BETWEEN LOWER CHORD, VERTICAL LACED CHANNEL, FLOOR BEAM, EYE BAR, AND U-BOLT. WEST ABUTMENT. - River Road Bridge, Spanning Spring Creek in Spring Creek Township, Hallton, Elk County, PA

  5. PAINT SHOP, DETAIL OF FABRICATED COLUMN AT JUNCTION OF WEST ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    PAINT SHOP, DETAIL OF FABRICATED COLUMN AT JUNCTION OF WEST BAY (ORIGINAL) AND CENTER BAYS (SECOND ADDITION), LOOKING NORTHEAST. - Southern Pacific, Sacramento Shops, Paint Shop, 111 I Street, Sacramento, Sacramento County, CA

  6. 27. INTERIOR OF UTILITY ROOM SHOWING ELECTRICAL JUNCTION CABINET, HOPPER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    27. INTERIOR OF UTILITY ROOM SHOWING ELECTRICAL JUNCTION CABINET, HOPPER WINDOW, OPEN DOOR TO KITCHEN NO. 2, AND METAL SINK. VIEW TO SOUTHWEST. - Bishop Creek Hydroelectric System, Plant 6, Cashbaugh-Kilpatrick House, Bishop Creek, Bishop, Inyo County, CA

  7. Local gate effect of mechanically deformed crossed carbon nanotube junction.

    PubMed

    Qing, Quan; Nezich, Daniel A; Kong, Jing; Wu, Zhongyun; Liu, Zhongfan

    2010-11-10

    In this work, we have demonstrated that the local deformation at the crossed carbon nanotube (CNT) junctions can introduce significant tunable local gate effect under ambient environment. Atomic force microscope (AFM) manipulation of the local deformation yielded a variation in transconductance that was retained after removing the AFM tip. Application of a large source-drain voltage and pressing the CNT junction above a threshold pressure can respectively erase and recover the transconductance modulation reversibly. The local gate effect is found to be independent of the length of the crossed CNT and attributed to the charges residing at the deformed junctions due to formation of localized states. The number of localized charges is estimated to be in the range of 10(2) to 10(3). These results may find potential applications in electromechanical sensors and could have important implications for designing nonvolatile devices based on crossed CNT junctions.

  8. 55. View of junction of unlined canal and lined canal, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    55. View of junction of unlined canal and lined canal, looking southwest. Photo by Brian C. Morris, Puget Power, 1989. - Puget Sound Power & Light Company, White River Hydroelectric Project, 600 North River Avenue, Dieringer, Pierce County, WA

  9. 54. View of junction of unlined canal and lined canal, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    54. View of junction of unlined canal and lined canal, looking southwest. Photo by Brian C. Morris, Puget Power, 1989. - Puget Sound Power & Light Company, White River Hydroelectric Project, 600 North River Avenue, Dieringer, Pierce County, WA

  10. B & P Junction Substation & Interlocking Tower. Baltimore, Baltimore ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    B & P Junction Substation & Interlocking Tower. Baltimore, Baltimore City, MD. Sec. 1201, MP 95.85. - Northeast Railroad Corridor, Amtrak route between District of Columbia/Maryland state line & Maryland/Delaware state line, Baltimore, Independent City, MD

  11. High-efficiency thermal switch based on topological Josephson junctions

    NASA Astrophysics Data System (ADS)

    Sothmann, Björn; Giazotto, Francesco; Hankiewicz, Ewelina M.

    2017-02-01

    We propose theoretically a thermal switch operating by the magnetic-flux controlled diffraction of phase-coherent heat currents in a thermally biased Josephson junction based on a two-dimensional topological insulator. For short junctions, the system shows a sharp switching behavior while for long junctions the switching is smooth. Physically, the switching arises from the Doppler shift of the superconducting condensate due to screening currents induced by a magnetic flux. We suggest a possible experimental realization that exhibits a relative temperature change of 40% between the on and off state for realistic parameters. This is a factor of two larger than in recently realized thermal modulators based on conventional superconducting tunnel junctions.

  12. Chaos synchronization in gap-junction-coupled neurons

    NASA Astrophysics Data System (ADS)

    Yoshioka, Masahiko

    2005-06-01

    Depending on temperature, the modified Hodgkin-Huxley (MHH) equations exhibit a variety of dynamical behaviors, including intrinsic chaotic firing. We analyze synchronization in a large ensemble of MHH neurons that are interconnected with gap junctions. By evaluating tangential Lyapunov exponents we clarify whether the synchronous state of neurons is chaotic or periodic. Then, we evaluate transversal Lyapunov exponents to elucidate if this synchronous state is stable against infinitesimal perturbations. Our analysis elucidates that with weak gap junctions, the stability of the synchronization of MHH neurons shows rather complicated changes with temperature. We, however, find that with strong gap junctions, the synchronous state is stable over the wide range of temperature irrespective of whether synchronous state is chaotic or periodic. It turns out that strong gap junctions realize the robust synchronization mechanism, which well explains synchronization in interneurons in the real nervous system.

  13. Evidence for nonlocal electrodynamics in planar Josephson junctions.

    PubMed

    Boris, A A; Rydh, A; Golod, T; Motzkau, H; Klushin, A M; Krasnov, V M

    2013-09-13

    We study the temperature dependence of the critical current modulation I(c)(H) for two types of planar Josephson junctions: a low-Tc Nb/CuNi/Nb and a high-Tc YBa2Cu3O(7-δ) bicrystal grain-boundary junction. At low T both junctions exhibit a conventional behavior, described by the local sine-Gordon equation. However, at elevated T the behavior becomes qualitatively different: the I(c)(H) modulation field ΔH becomes almost T independent and neither ΔH nor the critical field for the penetration of Josephson vortices vanish at Tc. Such an unusual behavior is in good agreement with theoretical predictions for junctions with nonlocal electrodynamics. We extract absolute values of the London penetration depth λ from our data and show that a crossover from local to nonlocal electrodynamics occurs with increasing T when λ(T) becomes larger than the electrode thickness.

  14. Tunnel junction enhanced nanowire ultraviolet light emitting diodes

    SciTech Connect

    Sarwar, A. T. M. Golam; May, Brelon J.; Deitz, Julia I.; Grassman, Tyler J.; McComb, David W.; Myers, Roberto C.

    2015-09-07

    Polarization engineered interband tunnel junctions (TJs) are integrated in nanowire ultraviolet (UV) light emitting diodes (LEDs). A ∼6 V reduction in turn-on voltage is achieved by the integration of tunnel junction at the base of polarization doped nanowire UV LEDs. Moreover, efficient hole injection into the nanowire LEDs leads to suppressed efficiency droop in TJ integrated nanowire LEDs. The combination of both reduced bias voltage and increased hole injection increases the wall plug efficiency in these devices. More than 100 μW of UV emission at ∼310 nm is measured with external quantum efficiency in the range of 4–6 m%. The realization of tunnel junction within the nanowire LEDs opens a pathway towards the monolithic integration of cascaded multi-junction nanowire LEDs on silicon.

  15. RadNet Air Data From Grand Junction, CO

    EPA Pesticide Factsheets

    This page presents radiation air monitoring and air filter analysis data for Grand Junction, CO from EPA's RadNet system. RadNet is a nationwide network of monitoring stations that measure radiation in air, drinking water and precipitation.

  16. Homeostatic plasticity at the Drosophila neuromuscular junction.

    PubMed

    Frank, C Andrew

    2014-03-01

    In biology, homeostasis refers to how cells maintain appropriate levels of activity. This concept underlies a balancing act in the nervous system. Synapses require flexibility (i.e. plasticity) to adjust to environmental challenges. Yet there must also exist regulatory mechanisms that constrain activity within appropriate physiological ranges. An abundance of evidence suggests that homeostatic regulation is critical in this regard. In recent years, important progress has been made toward identifying molecules and signaling processes required for homeostatic forms of neuroplasticity. The Drosophila melanogaster third instar larval neuromuscular junction (NMJ) has been an important experimental system in this effort. Drosophila neuroscientists combine genetics, pharmacology, electrophysiology, imaging, and a variety of molecular techniques to understand how homeostatic signaling mechanisms take shape at the synapse. At the NMJ, homeostatic signaling mechanisms couple retrograde (muscle-to-nerve) signaling with changes in presynaptic calcium influx, changes in the dynamics of the readily releasable vesicle pool, and ultimately, changes in presynaptic neurotransmitter release. Roles in these processes have been demonstrated for several molecules and signaling systems discussed here. This review focuses primarily on electrophysiological studies or data. In particular, attention is devoted to understanding what happens when NMJ function is challenged (usually through glutamate receptor inhibition) and the resulting homeostatic responses. A significant area of study not covered in this review, for the sake of simplicity, is the homeostatic control of synapse growth, which naturally, could also impinge upon synapse function in myriad ways. This article is part of the Special Issue entitled 'Homeostatic Synaptic Plasticity'.

  17. Quantum interference in topological insulator Josephson junctions

    NASA Astrophysics Data System (ADS)

    Song, Juntao; Liu, Haiwen; Liu, Jie; Li, Yu-Xian; Joynt, Robert; Sun, Qing-feng; Xie, X. C.

    2016-05-01

    Using nonequilibrium Green's functions, we studied numerically the transport properties of a Josephson junction, superconductor-topological insulator-superconductor hybrid system. Our numerical calculation shows first that proximity-induced superconductivity is indeed observed in the edge states of a topological insulator adjoining two superconducting leads and second that the special characteristics of topological insulators endow the edge states with an enhanced proximity effect with a superconductor but do not forbid the bulk states to do the same. In a size-dependent analysis of the local current, it was found that a few residual bulk states can lead to measurable resistance, whereas because these bulk states spread over the whole sample, their contribution to the interference pattern is insignificant when the sample size is in the micrometer range. Based on these numerical results, it is concluded that the apparent disappearance of residual bulk states in the superconducting interference process as described by Hart et al. [Nat. Phys. 10, 638 (2014), 10.1038/nphys3036] is just due to the effects of size: the contribution of the topological edge states outweighs that of the residual bulk states.

  18. Gamma Radiation Tolerance of Magnetic Tunnel Junctions

    NASA Astrophysics Data System (ADS)

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

    2011-10-01

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

  19. Spin-crossover molecule based thermoelectric junction

    SciTech Connect

    Ghosh, Dibyajyoti; Parida, Prakash; Pati, Swapan K.

    2015-05-11

    Using ab-initio numerical methods, we explore the spin-dependent transport and thermoelectric properties of a spin-crossover molecule (i.e., iron complex of 2-(1H-pyrazol-1-yl)-6-(1H-tetrazole-5-yl)pyridine) based nano-junction. We demonstrate a large magnetoresistance, efficient conductance-switching, and spin-filter activity in this molecule-based two-terminal device. The spin-crossover process also modulates the thermoelectric entities. It can efficiently switch the magnitude as well as spin-polarization of the thermocurrent. We find that thermocurrent is changed by ∼4 orders of magnitude upon spin-crossover. Moreover, it also substantially affects the thermopower and consequently, the device shows extremely efficient spin-crossover magnetothermopower generation. Furthermore, by tuning the chemical potential of electrodes into a certain range, a pure spin-thermopower can be achieved for the high-spin state. Finally, the reasonably large values of figure-of-merit in the presence and absence of phonon demonstrate a large heat-to-voltage conversion efficiency of the device. We believe that our study will pave an alternative way of tuning the transport and thermoelectric properties through the spin-crossover process and can have potential applications in generation of spin-dependent current, information storage, and processing.

  20. Seebeck effect in magnetic tunnel junctions.

    PubMed

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

    2011-10-01

    Creating temperature gradients in magnetic nanostructures has resulted in a new research direction, that is, the combination of magneto- and thermoelectric effects. Here, we demonstrate the observation of one important effect of this class: the magneto-Seebeck effect. It is observed when a magnetic configuration changes the charge-based Seebeck coefficient. In particular, the Seebeck coefficient changes during the transition from a parallel to an antiparallel magnetic configuration in a tunnel junction. In this respect, it is the analogue to the tunnelling magnetoresistance. The Seebeck coefficients in parallel and antiparallel configurations are of the order of the voltages known from the charge-Seebeck effect. The size and sign of the effect can be controlled by the composition of the electrodes' atomic layers adjacent to the barrier and the temperature. The geometric centre of the electronic density of states relative to the Fermi level determines the size of the Seebeck effect. Experimentally, we realized 8.8% magneto-Seebeck effect, which results from a voltage change of about -8.7 μV K⁻¹ from the antiparallel to the parallel direction close to the predicted value of -12.1 μV K⁻¹. In contrast to the spin-Seebeck effect, it can be measured as a voltage change directly without conversion of a spin current.