Case Report on Septate Uterus: An Incidental Finding in a ...

African Journals Online (AJOL)

Background: Septate uterus is caused by incomplete resorption of the Mullerian duct during embryogenesis which may alter the reproductive outcome of the patients. It is the commonest form of structural uterine anomaly and has the highest reproductive failure rate. Case Report: A 21-year-old booked G4P2. +1 woman with ...

Dual role for the O-acetyltransferase OatA in peptidoglycan modification and control of cell septation in Lactobacillus plantarum.

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Elvis Bernard

Full Text Available Until now, peptidoglycan O-acetyl transferases (Oat were only described for their peptidoglycan O-acetylating activity and for their implication in the control of peptidoglycan hydrolases. In this study, we show that a Lactobacillus plantarum mutant lacking OatA is unable to uncouple cell elongation and septation. Wild-type cells showed an elongation arrest during septation while oatA mutant cells continued to elongate at a constant rate without any observable pause during the cell division process. Remarkably, this defect does not result from a default in peptidoglycan O-acetylation, since it can be rescued by wild-type OatA as well as by a catalytic mutant or a truncated variant containing only the transmembrane domain of the protein. Consistent with a potential involvement in division, OatA preferentially localizes at mid-cell before membrane invagination and remains at this position until the end of septation. Overexpression of oatA or its inactive variants induces septation-specific aberrations, including asymmetrical and dual septum formation. Overproduction of the division inhibitors, MinC or MinD, leads to cell filamentation in the wild type while curved and branched cells are observed in the oatA mutant, suggesting that the Min system acts differently on the division process in the absence of OatA. Altogether, the results suggest that OatA plays a key role in the spatio-temporal control of septation, irrespective of its catalytic activity.

A Comparison of Therapeutic Modalities for Septated Tuberculous PleuraI Effusion on US

Energy Technology Data Exchange (ETDEWEB)

Cho, In Hwan; Kim, Kyeong Ah; Kim, Chul Joong; Kang, Eun Young; Cha, In Ho [Dae Rim St. Mary' s Hospital, Seoul (Korea, Republic of); Sim, Jae Jung [Korea University College of Medicine, Seoul (Korea, Republic of)

1995-12-15

To evaluate the utility of ultrasonography as a guide of determination of therapeutic modality an dto compare the therapeutic effects of modalities in patients with tuberculous pleural effusion. This study included 47 patients who had multiple septations on ultrasonography. We classified ultrasonographic pattern of pleural effusion into three groups according to pattern of septation : linear(n=6),moderate(n=19), honeycombing(n=22). We also classified therapeutic modalities into three groups : thoracentesis group(n=13), percutaneous catheter drainage group(n=11), intrapleural urokinase instillation group(n=23). We assessed the early and late therapeutic effects of these groups prospectively with follow-up chest radiographs. There was statistically no significant difference in therapeutic effect among the groups that had linear and moderate septa on ultrasonography(p<0.01). In patients with honeycombing septa, the therapeutic effects of catheter group and urokinase group were superior to conservative thoracentesis group(p<0.01). In urokinase group,mean duration of drainage(6.6 days) was significantly shorter than catheter group's(12.4 days) (p<0.01). Pattern of septation on ultrasonography could be an useful factor for determination of the therapeutic modality in patients with tuberculous pleural effusion. Percutaneous catheter drainage with urokinase instillation is a good therapeutic modality with shortened duration of drainage in treatment of pleural effusion with honeycombing septae

A Comparison of Therapeutic Modalities for Septated Tuberculous PleuraI Effusion on US

International Nuclear Information System (INIS)

Cho, In Hwan; Kim, Kyeong Ah; Kim, Chul Joong; Kang, Eun Young; Cha, In Ho; Sim, Jae Jung

1995-01-01

To evaluate the utility of ultrasonography as a guide of determination of therapeutic modality an dto compare the therapeutic effects of modalities in patients with tuberculous pleural effusion. This study included 47 patients who had multiple septations on ultrasonography. We classified ultrasonographic pattern of pleural effusion into three groups according to pattern of septation : linear(n=6),moderate(n=19), honeycombing(n=22). We also classified therapeutic modalities into three groups : thoracentesis group(n=13), percutaneous catheter drainage group(n=11), intrapleural urokinase instillation group(n=23). We assessed the early and late therapeutic effects of these groups prospectively with follow-up chest radiographs. There was statistically no significant difference in therapeutic effect among the groups that had linear and moderate septa on ultrasonography(p<0.01). In patients with honeycombing septa, the therapeutic effects of catheter group and urokinase group were superior to conservative thoracentesis group(p<0.01). In urokinase group,mean duration of drainage(6.6 days) was significantly shorter than catheter group's(12.4 days) (p<0.01). Pattern of septation on ultrasonography could be an useful factor for determination of the therapeutic modality in patients with tuberculous pleural effusion. Percutaneous catheter drainage with urokinase instillation is a good therapeutic modality with shortened duration of drainage in treatment of pleural effusion with honeycombing septae

A new dynamic 3D virtual methodology for teaching the mechanics of atrial septation as seen in the human heart.

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Schleich, Jean-Marc; Dillenseger, Jean-Louis; Houyel, Lucile; Almange, Claude; Anderson, Robert H

2009-01-01

Learning embryology remains difficult, since it requires understanding of many complex phenomena. The temporal evolution of developmental events has classically been illustrated using cartoons, which create difficulty in linking spatial and temporal aspects, such correlation being the keystone of descriptive embryology. We synthesized the bibliographic data from recent studies of atrial septal development. On the basis of this synthesis, consensus on the stages of atrial septation as seen in the human heart has been reached by a group of experts in cardiac embryology and pediatric cardiology. This has permitted the preparation of three-dimensional (3D) computer graphic objects for the anatomical components involved in the different stages of normal human atrial septation. We have provided a virtual guide to the process of normal atrial septation, the animation providing an appreciation of the temporal and morphologic events necessary to separate the systemic and pulmonary venous returns. We have shown that our animations of normal human atrial septation increase significantly the teaching of the complex developmental processes involved, and provide a new dynamic for the process of learning.

Value of the hypointensive internal septation on MR for the differentiation between benign and malignant breast lesions

International Nuclear Information System (INIS)

Gao Peihong; Cai Shifeng; Zhao Bin; Wang Guangbin; Peng Hongjuan; Liu Shaoling

2007-01-01

Objective: To investigate the diagnostic value of internal septation for differentiating benign from malignant breast lesions. Methods: A total of 26 patients were included in the study, in which 12 patients had 20 lesions of breast carcinoma and 14 patients had 25 lesions of fibroadenoma diagnosed either pathologically or clinically. The differential diagnoistic value of the hypointensive internal septation was analyzed. Results: The signal intensity of fibroadenomas and malignant lesions on T 2 -weighted fat-suppressed images could be classified as iso- to hyper- intensity, hypointensity and mixed intensity. According to the signal intensity classification, there were 5, 11 and 4 cases in patients with breast carcinoma respectively, while 11, 10, 4 cases in patients with fibroadenoma respectively. There was no statistical difference in the distribution between the two patient groups (χ 2 =1.764, P=0.414). The shape of fibroadenomas and malignant lesions could be classified as irregular, roundish or lobulated. According to the morphological classification, there were 12, 7 and 1 case in patients with breast carcinoma respectively, while 1, 7, 17 cases in patients with fibroadenoma respectively. There was statistical difference in the distribution between the two patient groups (χ 2 =23.262, P=0.000). The typical features of fibroadenomas were as follows: lobulated shape, hypointensive internal septations on T 2 -weighted or postcontrast images. The diagnostic sensitivity of the three imaging features for fibroadenoma was 68%(17/25), 52%(13/25), and 72%(18/25) respectively; and the diagnostic specificity was 95%(19/20), 90%(18/20), 95% (19/20) respectively. Conclusion: The internal septation is a rather specific sign for diagnosis of fibroadenomas. (authors)

Foxf genes integrate tbx5 and hedgehog pathways in the second heart field for cardiac septation.

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Andrew D Hoffmann

2014-10-01

Full Text Available The Second Heart Field (SHF has been implicated in several forms of congenital heart disease (CHD, including atrioventricular septal defects (AVSDs. Identifying the SHF gene regulatory networks required for atrioventricular septation is therefore an essential goal for understanding the molecular basis of AVSDs. We defined a SHF Hedgehog-dependent gene regulatory network using whole genome transcriptional profiling and GLI-chromatin interaction studies. The Forkhead box transcription factors Foxf1a and Foxf2 were identified as SHF Hedgehog targets. Compound haploinsufficiency for Foxf1a and Foxf2 caused atrioventricular septal defects, demonstrating the biological relevance of this regulatory network. We identified a Foxf1a cis-regulatory element that bound the Hedgehog transcriptional regulators GLI1 and GLI3 and the T-box transcription factor TBX5 in vivo. GLI1 and TBX5 synergistically activated transcription from this cis-regulatory element in vitro. This enhancer drove reproducible expression in vivo in the posterior SHF, the only region where Gli1 and Tbx5 expression overlaps. Our findings implicate Foxf genes in atrioventricular septation, describe the molecular underpinnings of the genetic interaction between Hedgehog signaling and Tbx5, and establish a molecular model for the selection of the SHF gene regulatory network for cardiac septation.

Electrical analog of a Josephson junction

International Nuclear Information System (INIS)

Goldman, A.M.

1979-01-01

It is noted that a mathematical description of the phase-coupling of two oscillators synchronized by a phase-lock-loop under the influence of thermal white noise is analogous to that of the phase coupling of two superconductors in a Josephson junction also under the influence of noise. This analogy may be useful in studying threshold instabilities of the Josephson junction in regimes not restricted to the case of large damping. This is of interest because the behavior of the mean voltage near the threshold current can be characterized by critical exponents which resemble those exhibited by an order parameter of a continuous phase transition. As it is possible to couple a collection of oscillators together in a chain, the oscillator analogy may also be useful in exploring the dynamics and statistical mechanics of coupled junctions

The potential of Dark Septate Endophytes to form root symbioses with ectomycorrhizal and ericoid mycorrhizal middle European forest plants.

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Tereza Lukešová

Full Text Available The unresolved ecophysiological significance of Dark Septate Endophytes (DSE may be in part due to existence of morphologically indistinguishable cryptic species in the most common Phialocephala fortinii s. l.--Acephala applanata species complex (PAC. We inoculated three middle European forest plants (European blueberry, Norway spruce and silver birch with 16 strains of eight PAC cryptic species and other DSE and ectomycorrhizal/ericoid mycorrhizal fungi and focused on intraradical structures possibly representing interfaces for plant-fungus nutrient transfer and on host growth response. The PAC species Acephala applanata simultaneously formed structures resembling ericoid mycorrhiza (ErM and DSE microsclerotia in blueberry. A. macrosclerotiorum, a close relative to PAC, formed ectomycorrhizae with spruce but not with birch, and structures resembling ErM in blueberry. Phialocephala glacialis, another close relative to PAC, formed structures resembling ErM in blueberry. In blueberry, six PAC strains significantly decreased dry shoot biomass compared to ErM control. In birch, one A. macrosclerotiorum strain increased root biomass and the other shoot biomass in comparison with non-inoculated control. The dual mycorrhizal ability of A. macrosclerotiorum suggested that it may form mycorrhizal links between Ericaceae and Pinaceae. However, we were unable to detect this species in Ericaceae roots growing in a forest with presence of A. macrosclerotiorum ectomycorrhizae. Nevertheless, the diversity of Ericaceae mycobionts was high (380 OTUs with individual sites often dominated by hitherto unreported helotialean and chaetothyrialean/verrucarialean species; in contrast, typical ErM fungi were either absent or low in abundance. Some DSE apparently have a potential to form mycorrhizae with typical middle European forest plants. However, except A. applanata, the tested representatives of all hitherto described PAC cryptic species formed typical DSE

Phase transition in a modified square Josephson-junction array

CERN Document Server

Han, J

1999-01-01

We study the phase transition in a modified square proximity-coupled Josephson-junction array with small superconducting islands at the center of each plaquette. We find that the modified square array undergoes a Kosterlitz-Thouless-Berezinskii-like phase transition, but at a lower temperature than the simple square array with the same single-junction critical current. The IV characteristics, as well as the phase transition, resemble qualitatively those of a disordered simple square array. The effects of the presence of the center islands in the modified square array are discussed.

Fractional Solitons in Excitonic Josephson Junctions

Science.gov (United States)

Su, Jung-Jung; Hsu, Ya-Fen

The Josephson effect is especially appealing because it reveals macroscopically the quantum order and phase. Here we study this effect in an excitonic Josephson junction: a conjunct of two exciton condensates with a relative phase ϕ0 applied. Such a junction is proposed to take place in the quantum Hall bilayer (QHB) that makes it subtler than in superconductor because of the counterflow of excitonic supercurrent and the interlayer tunneling in QHB. We treat the system theoretically by first mapping it into a pseudospin ferromagnet then describing it by the Landau-Lifshitz-Gilbert equation. In the presence of interlayer tunneling, the excitonic Josephson junction can possess a family of fractional sine-Gordon solitons that resemble the static fractional Josephson vortices in the extended superconducting Josephson junctions. Interestingly, each fractional soliton carries a topological charge Q which is not necessarily a half/full integer but can vary continuously. The resultant current-phase relation (CPR) shows that solitons with Q =ϕ0 / 2 π are the lowest energy states for small ϕ0. When ϕ0 > π , solitons with Q =ϕ0 / 2 π - 1 take place - the polarity of CPR is then switched.

A novel adhering junction in the apical ciliary apparatus of the rotifer Brachionus plicatilis (Rotifera, Monogononta).

Science.gov (United States)

Dallai, R; Lupetti, P; Lane, N J

1996-10-01

Cultures of the rotifer Brachionus plicatilis were examined with regard to their interepithelial junctions after infiltration with the extracellular tracer lanthanum, freeze-fracturing or quick-freeze deep-etching. The lateral borders between ciliated cells have an unusual apical adhering junction. This apical part of their intercellular cleft looks desmosome-like, but it is characterized by unusual intramembranous E-face clusters of particles. Deep-etching reveals that these are packed together in short rows which lie parallel to one another in orderly arrays. The true membrane surface in these areas features filaments in the form of short ribbons; these are produced by projections, possibly part of the glycocalyx, emerging from the membranes, between which the electron-dense tracer lanthanum permeates. These projections appear to overlap with each other in the centre of the intercellular cleft; this would provide a particularly flexible adaptation to maintain cell-cell contact and coordination as a consequence. The filamentous ribbons may be held in position by the intramembranous particle arrays since both have a similar size and distribution. These contacts are quite different from desmosomes and appear to represent a distinct new category of adhesive cell-cell junction. Beneath these novel structures, conventional pleated septate junctions are found, exhibiting the undulating intercellular ribbons typical of this junctional type, as well as the usual parallel alignments of intramembranous rows of EF grooves and PF particles. Below these are found gap junctions as close-packed plaques of intramembranous particles on either the P-face or E-face. After freeze-fracturing, the complementary fracture face to the particles shows pits, usually on the P-face, arrayed with a very precise hexagonal pattern.

Does facial resemblance enhance cooperation?

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Trang Giang

Full Text Available Facial self-resemblance has been proposed to serve as a kinship cue that facilitates cooperation between kin. In the present study, facial resemblance was manipulated by morphing stimulus faces with the participants' own faces or control faces (resulting in self-resemblant or other-resemblant composite faces. A norming study showed that the perceived degree of kinship was higher for the participants and the self-resemblant composite faces than for actual first-degree relatives. Effects of facial self-resemblance on trust and cooperation were tested in a paradigm that has proven to be sensitive to facial trustworthiness, facial likability, and facial expression. First, participants played a cooperation game in which the composite faces were shown. Then, likability ratings were assessed. In a source memory test, participants were required to identify old and new faces, and were asked to remember whether the faces belonged to cooperators or cheaters in the cooperation game. Old-new recognition was enhanced for self-resemblant faces in comparison to other-resemblant faces. However, facial self-resemblance had no effects on the degree of cooperation in the cooperation game, on the emotional evaluation of the faces as reflected in the likability judgments, and on the expectation that a face belonged to a cooperator rather than to a cheater. Therefore, the present results are clearly inconsistent with the assumption of an evolved kin recognition module built into the human face recognition system.

Haploinsufficiency of the Sec7 guanine nucleotide exchange factor gea1 impairs septation in fission yeast.

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Alan M Eckler

Full Text Available Membrane trafficking is essential to eukaryotic life and is controlled by a complex network of proteins that regulate movement of proteins and lipids between organelles. The GBF1/GEA family of Guanine nucleotide Exchange Factors (GEFs regulates trafficking between the endoplasmic reticulum and Golgi by catalyzing the exchange of GDP for GTP on ADP Ribosylation Factors (Arfs. Activated Arfs recruit coat protein complex 1 (COP-I to form vesicles that ferry cargo between these organelles. To further explore the function of the GBF1/GEA family, we have characterized a fission yeast mutant lacking one copy of the essential gene gea1 (gea1+/-, the Schizosaccharomyces pombe ortholog of GBF1. The haploinsufficient gea1+/- strain was shown to be sensitive to the GBF1 inhibitor brefeldin A (BFA and was rescued from BFA sensitivity by gea1p overexpression. No overt defects in localization of arf1p or arf6p were observed in gea1+/- cells, but the fission yeast homolog of the COP-I cargo sac1 was mislocalized, consistent with impaired COP-I trafficking. Although Golgi morphology appeared normal, a slight increase in vacuolar size was observed in the gea1+/- mutant strain. Importantly, gea1+/- cells exhibited dramatic cytokinesis-related defects, including disorganized contractile rings, an increased septation index, and alterations in septum morphology. Septation defects appear to result from altered secretion of enzymes required for septum dynamics, as decreased secretion of eng1p, a β-glucanase required for septum breakdown, was observed in gea1+/- cells, and overexpression of eng1p suppressed the increased septation phenotype. These observations implicate gea1 in regulation of septum breakdown and establish S. pombe as a model system to explore GBF1/GEA function in cytokinesis.

The position of the left and right ventricular outlets during septation. A comparison of chicken and rat development

NARCIS (Netherlands)

Wagenaar, J. A.; Lamers, W. H.; Los, J. A.

1986-01-01

A comparative study was made of the relative position of the outflow tracts of chicken and rat hearts with respect to the ventricles during septation. For this purpose the position of the left and right ventricular outlet including the aortic and pulmonary valve primordia and the left and right

Dark septate root endophytic fungi increase growth of Scots pine seedlings under elevated CO2 through enhanced nitrogen use efficiency.

NARCIS (Netherlands)

Alberton, O.; Kuyper, T.W.; Summerbell, R.C.

2010-01-01

Although increasing concentrations of atmospheric CO2 are predicted to have substantial impacts on plant growth and functioning of ecosystems, there is insufficient understanding of the responses of belowground processes to such increases. We investigated the effects of different dark septate root

big bang gene modulates gut immune tolerance in Drosophila.

Science.gov (United States)

Bonnay, François; Cohen-Berros, Eva; Hoffmann, Martine; Kim, Sabrina Y; Boulianne, Gabrielle L; Hoffmann, Jules A; Matt, Nicolas; Reichhart, Jean-Marc

2013-02-19

Chronic inflammation of the intestine is detrimental to mammals. Similarly, constant activation of the immune response in the gut by the endogenous flora is suspected to be harmful to Drosophila. Therefore, the innate immune response in the gut of Drosophila melanogaster is tightly balanced to simultaneously prevent infections by pathogenic microorganisms and tolerate the endogenous flora. Here we describe the role of the big bang (bbg) gene, encoding multiple membrane-associated PDZ (PSD-95, Discs-large, ZO-1) domain-containing protein isoforms, in the modulation of the gut immune response. We show that in the adult Drosophila midgut, BBG is present at the level of the septate junctions, on the apical side of the enterocytes. In the absence of BBG, these junctions become loose, enabling the intestinal flora to trigger a constitutive activation of the anterior midgut immune response. This chronic epithelial inflammation leads to a reduced lifespan of bbg mutant flies. Clearing the commensal flora by antibiotics prevents the abnormal activation of the gut immune response and restores a normal lifespan. We now provide genetic evidence that Drosophila septate junctions are part of the gut immune barrier, a function that is evolutionarily conserved in mammals. Collectively, our data suggest that septate junctions are required to maintain the subtle balance between immune tolerance and immune response in the Drosophila gut, which represents a powerful model to study inflammatory bowel diseases.

Incidence of Septate Uterus in Reproductive-Aged Women With and Without Endometriosis.

Science.gov (United States)

LaMonica, Rachel; Pinto, Judith; Luciano, Danielle; Lyapis, Anya; Luciano, Anthony

2016-01-01

To compare the incidence of a uterine septum in women with and without endometriosis and if such incidence correlates with the stage of endometriosis Although a correlation between obstructive Mullerian anomalies and endometriosis has been well established, its link with non-obstructive anomalies remains controversial. To elucidate whether there is a correlation between endometriosis and non-obstructive Mullerian anomalies, we conducted this prospective study on all patients admitted to our Reproductive Endocrinology and Infertility surgical service from February 1, 2010 through June 30, 2012. All patients underwent both hysteroscopy and laparoscopy. Surgical indications included: infertility, pain, and/or menorrhagia. The presence or absence of endometriosis and uterine anomalies were recorded immediately after each surgery and subsequently analyzed. Endometriosis was staged according to the r-ASRM Classification and treated by resection and ablation of deep and superficial lesions, respectively. Since uterine septum is the most common Mullerian anomaly, we considered only this anomaly to test the hypothesis that uterine septum may be associated with an increased incidence of endometriosis. Prospective Study. Evidence from a well-designed case-control study (Canadian Task Force classification II-2). University-affiliated tertiary care center. Reproductive aged women admitted to our service for treatment of pelvic pain, abnormal uterine bleeding, and/or infertility. All patients underwent both hysteroscopy and laparoscopy as part of their evaluation and treatment of pelvic pain, abnormal uterine bleeding, and/or infertility. 343 patients were included in the study. The diagnosis of each patient included infertility - 52, pain - 215, both - 30 and other - 46. The diagnosis of septate uterus was made at hysteroscopy when the endometrial cavity was separated by an avascular septum that obscured visualization of both cornua when the hysteroscope was advanced to the mid

The minimally invasive endoscopic management of septated chronic subdural hematomas: surgical technique.

Science.gov (United States)

Berhouma, M; Jacquesson, T; Jouanneau, E

2014-12-01

Fibrin membranes and compartmentalization within the subdural space are a frequent cause of failure in the treatment of chronic subdural hematomas (CSH). This specific subtype of CSH classically requires craniotomy, which carries significant morbidity and mortality rates, particularly in elderly patients. In this work, we describe a minimally invasive endoscopic alternative. Under local scalp anesthesia, a rigid endoscope is inserted through a parietal burr hole in the subdural space to collapse fibrin septa and cut the internal membrane. It also allows cauterization of active bleedings and the placement of a drain under direct visualization. The endoscopic treatment of septated CSH represents a minimally invasive alternative to craniotomy especially for the internal membranectomy.

The co-occurrence and morphological continuum between ericoid mycorrhiza and dark septate endophytes in roots of six European Rhododendron species

Czech Academy of Sciences Publication Activity Database

Vohník, Martin; Albrechtová, Jana

2011-01-01

Roč. 46, č. 4 (2011), s. 373-386 ISSN 1211-9520 R&D Projects: GA ČR GP206/09/P340 Institutional research plan: CEZ:AV0Z60050516 Keywords : ericoid mycorrhiza * dark septate endophytes * rhododendrons Subject RIV: EF - Botanics Impact factor: 1.500, year: 2011

Rac1 controls epithelial tube length through the apical secretion and polarity pathways

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Kévin Sollier

2016-01-01

Full Text Available The morphometric parameters of epithelial tubes are critical to the physiology and homeostasis of most organs. In addition, many human diseases are associated with tube-size defects. Here, we show that Rac1 limits epithelial tube elongation in the developing fly trachea by promoting Rab5-dependent endocytosis of the apical determinant Crumbs. Rac1 is also involved in a positive feedback loop with the septate junction protein Coracle. Thereby, Rac1 precludes paracellular diffusion and contributes to the septate junction-dependent secretion of the chitin-modifying enzymes Vermiform and Serpentine, which restrict epithelial tube length independently of Crumbs. Thus, Rac1 is a critical component of two important pathways controlling epithelial tube morphogenesis.

Instanton glass generated by noise in a Josephson-junction array.

Science.gov (United States)

Chudnovsky, E M

2009-09-25

We compute the correlation function of a superconducting order parameter in a continuous model of a two-dimensional Josephson-junction array in the presence of a weak Gaussian noise. When the Josephson coupling is large compared to the charging energy, the correlations in the Euclidian space decay exponentially at low temperatures regardless of the strength of the noise. We interpret such a state as a collective Cooper-pair insulator and argue that it resembles properties of disordered superconducting films.

Resemblance and investment in children.

Science.gov (United States)

Dolinska, Barbara

2013-01-01

According to evolutionary explanations men hardly ever are absolutely certain about their biological fatherhood therefore they must seek various sources of information to subjectively establish whether they are the genetic fathers of the children they raise. Apicella and Marlowe (2004) showed that fathers who perceived greater similarity between their children and themselves were willing to invest more resources (e.g., time, money, care) in their offspring presumably because the perceived resemblance indicated to the fathers their genetic relatedness with their children. The present study extended the design of Apicella and Marlowe's original study and included both fathers and mothers as participants. Parents were recruited by a female confederate at the airport and at the railway station in Wroclaw (Poland). Multiple regression analyses showed that perceived resemblance predicted parental investment in the child for both men and women. The fact that mothers' declarations of investment in their children also depended on the perceived resemblance factor is not consistent with evolutionary formulations delineated by Apicella and Marlowe (2004; 2007). Future studies must resolve the issue of whether the resemblance-investment relation in fathers results from men relaying on child's resemblance to themselves as an indicator of their own biological paternity, or whether it results from the more parsimonious phenomenon that people in general are attracted more to other people who are similar to them.

Outflow tract septation and the aortic arch system in reptiles: lessons for understanding the mammalian heart.

Science.gov (United States)

Poelmann, Robert E; Gittenberger-de Groot, Adriana C; Biermans, Marcel W M; Dolfing, Anne I; Jagessar, Armand; van Hattum, Sam; Hoogenboom, Amanda; Wisse, Lambertus J; Vicente-Steijn, Rebecca; de Bakker, Merijn A G; Vonk, Freek J; Hirasawa, Tatsuya; Kuratani, Shigeru; Richardson, Michael K

2017-01-01

Cardiac outflow tract patterning and cell contribution are studied using an evo-devo approach to reveal insight into the development of aorto-pulmonary septation. We studied embryonic stages of reptile hearts (lizard, turtle and crocodile) and compared these to avian and mammalian development. Immunohistochemistry allowed us to indicate where the essential cell components in the outflow tract and aortic sac were deployed, more specifically endocardial, neural crest and second heart field cells. The neural crest-derived aorto-pulmonary septum separates the pulmonary trunk from both aortae in reptiles, presenting with a left visceral and a right systemic aorta arising from the unseptated ventricle. Second heart field-derived cells function as flow dividers between both aortae and between the two pulmonary arteries. In birds, the left visceral aorta disappears early in development, while the right systemic aorta persists. This leads to a fusion of the aorto-pulmonary septum and the aortic flow divider (second heart field population) forming an avian aorto-pulmonary septal complex. In mammals, there is also a second heart field-derived aortic flow divider, albeit at a more distal site, while the aorto-pulmonary septum separates the aortic trunk from the pulmonary trunk. As in birds there is fusion with second heart field-derived cells albeit from the pulmonary flow divider as the right 6th pharyngeal arch artery disappears, resulting in a mammalian aorto-pulmonary septal complex. In crocodiles, birds and mammals, the main septal and parietal endocardial cushions receive neural crest cells that are functional in fusion and myocardialization of the outflow tract septum. Longer-lasting septation in crocodiles demonstrates a heterochrony in development. In other reptiles with no indication of incursion of neural crest cells, there is either no myocardialized outflow tract septum (lizard) or it is vestigial (turtle). Crocodiles are unique in bearing a central shunt, the

Outflow tract septation and the aortic arch system in reptiles: lessons for understanding the mammalian heart

Directory of Open Access Journals (Sweden)

Robert E. Poelmann

2017-05-01

Full Text Available Abstract Background Cardiac outflow tract patterning and cell contribution are studied using an evo-devo approach to reveal insight into the development of aorto-pulmonary septation. Results We studied embryonic stages of reptile hearts (lizard, turtle and crocodile and compared these to avian and mammalian development. Immunohistochemistry allowed us to indicate where the essential cell components in the outflow tract and aortic sac were deployed, more specifically endocardial, neural crest and second heart field cells. The neural crest-derived aorto-pulmonary septum separates the pulmonary trunk from both aortae in reptiles, presenting with a left visceral and a right systemic aorta arising from the unseptated ventricle. Second heart field-derived cells function as flow dividers between both aortae and between the two pulmonary arteries. In birds, the left visceral aorta disappears early in development, while the right systemic aorta persists. This leads to a fusion of the aorto-pulmonary septum and the aortic flow divider (second heart field population forming an avian aorto-pulmonary septal complex. In mammals, there is also a second heart field-derived aortic flow divider, albeit at a more distal site, while the aorto-pulmonary septum separates the aortic trunk from the pulmonary trunk. As in birds there is fusion with second heart field-derived cells albeit from the pulmonary flow divider as the right 6th pharyngeal arch artery disappears, resulting in a mammalian aorto-pulmonary septal complex. In crocodiles, birds and mammals, the main septal and parietal endocardial cushions receive neural crest cells that are functional in fusion and myocardialization of the outflow tract septum. Longer-lasting septation in crocodiles demonstrates a heterochrony in development. In other reptiles with no indication of incursion of neural crest cells, there is either no myocardialized outflow tract septum (lizard or it is vestigial (turtle. Crocodiles

Ergosterol content in ericaceous hair roots correlates with dark septate endophytes but not with ericoid mycorrhizal colonization

DEFF Research Database (Denmark)

Olsrud, Maria; Michelsen, Anders; Wallander, Håkon

2007-01-01

The relationship between ergosterol content in ericaceous hair roots and ericoid mycorrhizal (ErM) colonization versus dark septate endophytic (DSE) hyphal colonization was examined in a dwarf shrub-dominated subarctic mire in Northern Sweden. Ergosterol content in hair roots did not correlate...... under natural conditions. It also suggests the possibility of using ergosterol as an estimate of DSE hyphal colonization in ericaceous dwarf shrubs. This study has implications for the interpretation of results in field studies where ergosterol was used as a sole proxy for ErM colonization....

The Drosophila blood-brain barrier: Development and function of a glial endothelium

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Stefanie eLimmer

2014-11-01

Full Text Available The efficacy of neuronal function requires a well-balanced extracellular ion homeostasis and a steady supply with nutrients and metabolites. Therefore, all organisms equipped with a complex nervous system developed a so-called blood-brain barrier, protecting it from an uncontrolled entry of solutes, metabolites or pathogens. In higher vertebrates, this diffusion barrier is established by polarized endothelial cells that form extensive tight junctions, whereas in lower vertebrates and invertebrates the blood-brain barrier is exclusively formed by glial cells. Here, we review the development and function of the glial blood-brain barrier of Drosophila melanogaster. In the Drosophila nervous system, at least seven morphologically distinct glial cell classes can be distinguished. Two of these glial classes form the blood-brain barrier. Perineurial glial cells participate in nutrient uptake and establish a first diffusion barrier. The subperineurial glial cells form septate junctions, which block paracellular diffusion and thus seal the nervous system from the hemolymph. We summarize the molecular basis of septate junction formation and address the different transport systems expressed by the blood-brain barrier forming glial cells.

The Drosophila blood-brain barrier: development and function of a glial endothelium.

Science.gov (United States)

Limmer, Stefanie; Weiler, Astrid; Volkenhoff, Anne; Babatz, Felix; Klämbt, Christian

2014-01-01

The efficacy of neuronal function requires a well-balanced extracellular ion homeostasis and a steady supply with nutrients and metabolites. Therefore, all organisms equipped with a complex nervous system developed a so-called blood-brain barrier, protecting it from an uncontrolled entry of solutes, metabolites or pathogens. In higher vertebrates, this diffusion barrier is established by polarized endothelial cells that form extensive tight junctions, whereas in lower vertebrates and invertebrates the blood-brain barrier is exclusively formed by glial cells. Here, we review the development and function of the glial blood-brain barrier of Drosophila melanogaster. In the Drosophila nervous system, at least seven morphologically distinct glial cell classes can be distinguished. Two of these glial classes form the blood-brain barrier. Perineurial glial cells participate in nutrient uptake and establish a first diffusion barrier. The subperineurial glial (SPG) cells form septate junctions, which block paracellular diffusion and thus seal the nervous system from the hemolymph. We summarize the molecular basis of septate junction formation and address the different transport systems expressed by the blood-brain barrier forming glial cells.

Linker-dependent Junction Formation Probability in Single-Molecule Junctions

Energy Technology Data Exchange (ETDEWEB)

Yoo, Pil Sun; Kim, Taekyeong [HankukUniversity of Foreign Studies, Yongin (Korea, Republic of)

2015-01-15

We compare the junction formation probabilities of single-molecule junctions with different linker molecules by using a scanning tunneling microscope-based break-junction technique. We found that the junction formation probability varies as SH > SMe > NH2 for the benzene backbone molecule with different types of anchoring groups, through quantitative statistical analysis. These results are attributed to different bonding forces according to the linker groups formed with Au atoms in the electrodes, which is consistent with previous works. Our work allows a better understanding of the contact chemistry in the metal.molecule junction for future molecular electronic devices.

[Liesegang's rings resembling helminthiasis].

Science.gov (United States)

Zámecník, M; Riedl, I

1996-12-01

So called Liesegang's rings are lamellar corpuscles which develop after periodical precipitation of oversaturated solutions in gel medium. They can occur in cysts, closed cavities, inflammatory exudates and necroses. They resemble parasitic eggs, larvae or adult forms. A case of 28-year-old woman is presented with many Liesegang's rings in a stuff from dilated renal calyx. Their preliminary evaluation considered helminths, especially Dioctophyma renale.

Gap Junctions

Science.gov (United States)

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

Inter-band and intra-band reflections in graphene–insulator–superconductor junctions with zigzag or armchair edge

Energy Technology Data Exchange (ETDEWEB)

Duque, M.F., E-mail: mfduqued@unal.edu.co; Gomez P, S., E-mail: sgomezp@unal.edu.co; Herrera, W.J., E-mail: jherreraw@unal.edu.co

2014-12-15

We analyze electron–electron and Andreev reflections (AR) for a graphene–insulator–superconductor junction for zigzag and armchair edges, where the insulator is modeled as a potential barrier characterized by a strength. We calculate the reflection probabilities and differential conductance using the Bogoliubov–de Gennes–Dirac (BdGD) equations. For low doping values and zigzag edge the reflection coefficients have the same behavior that in a graphene–superconductor junction. However for high doping values the reflection probabilities have a periodicity of πwith the strength barrier values. For high doping values and armchair edge the electron–electron reflections associated to K′ valley increase and AR associated to K valley decrease. We compare our results with the differential conductance obtained by the Green formalism. We show that the effect of barrier strength for high doping resembles the behavior when a hopping between graphene and superconductor interfaces is considered.

Four-junction superconducting circuit

Science.gov (United States)

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

2016-01-01

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. PMID:27356619

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

Science.gov (United States)

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

2016-12-02

We investigate the critical current I_{C} 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, I_{C} is found to scale as ∝exp(-k_{B}T/δE). The extracted energies δE 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 δE (or Δ) and the number of the junction's transversal modes.

Equivalent Josephson junctions

International Nuclear Information System (INIS)

Boyadzhiev, T.L.; ); Semerdzhieva, E.G.; Shukrinov, Yu.M.; Fiziko-Tekhnicheskij Inst., Dushanbe

2008-01-01

The magnetic field dependences of critical current are numerically constructed for a long Josephson junction with a shunt- or resistor-type microscopic inhomogeneities and compared to the critical curve of a junction with exponentially varying width. The numerical results show that it is possible to replace the distributed inhomogeneity of a long Josephson junction by an inhomogeneity localized at one of its ends, which has certain technological advantages. It is also shown that the critical curves of junctions with exponentially varying width and inhomogeneities localized at the ends are unaffected by the mixed fluxon-antifluxon distributions of the magnetic flux [ru

Junction and circuit fabrication

International Nuclear Information System (INIS)

Jackel, L.D.

1980-01-01

Great strides have been made in Josephson junction fabrication in the four years since the first IC SQUID meeting. Advances in lithography have allowed the production of devices with planar dimensions as small as a few hundred angstroms. Improved technology has provided ultra-high sensitivity SQUIDS, high-efficiency low-noise mixers, and complex integrated circuits. This review highlights some of the new fabrication procedures. The review consists of three parts. Part 1 is a short summary of the requirements on junctions for various applications. Part 2 reviews intergrated circuit fabrication, including tunnel junction logic circuits made at IBM and Bell Labs, and microbridge radiation sources made at SUNY at Stony Brook. Part 3 describes new junction fabrication techniques, the major emphasis of this review. This part includes a discussion of small oxide-barrier tunnel junctions, semiconductor barrier junctions, and microbridge junctions. Part 3 concludes by considering very fine lithography and limitations to miniaturization. (orig.)

Detecting analogical resemblance without retrieving the source analogy.

Science.gov (United States)

Kostic, Bogdan; Cleary, Anne M; Severin, Kaye; Miller, Samuel W

2010-06-01

We examined whether people can detect analogical resemblance to an earlier experimental episode without being able to recall the experimental source of the analogical resemblance. We used four-word analogies (e.g., robin-nest/beaver-dam), in a variation of the recognition-without-cued-recall method (Cleary, 2004). Participants studied word pairs (e.g., robin-nest) and were shown new word pairs at test, half of which analogically related to studied word pairs (e.g., beaver-dam) and half of which did not. For each test pair, participants first attempted to recall an analogically similar pair from the study list. Then, regardless of whether successful recall occurred, participants were prompted to rate the familiarity of the test pair, which was said to indicate the likelihood that a pair that was analogically similar to the test pair had been studied. Across three experiments, participants demonstrated an ability to detect analogical resemblance without recalling the source analogy. Findings are discussed in terms of their potential relevance to the study of analogical reasoning and insight, as well as to the study of familiarity and recognition memory.

Calcineurin Orchestrates Hyphal Growth, Septation, Drug Resistance and Pathogenesis of Aspergillus fumigatus: Where Do We Go from Here?

Directory of Open Access Journals (Sweden)

Praveen R Juvvadi

2015-12-01

Full Text Available Studies on fungal pathogens belonging to the ascomycota phylum are critical given the ubiquity and frequency with which these fungi cause infections in humans. Among these species, Aspergillus fumigatus causes invasive aspergillosis, a leading cause of death in immunocompromised patients. Fundamental to A. fumigatus pathogenesis is hyphal growth. However, the precise mechanisms underlying hyphal growth and virulence are poorly understood. Over the past 10 years, our research towards the identification of molecular targets responsible for hyphal growth, drug resistance and virulence led to the elucidation of calcineurin as a key signaling molecule governing these processes. In this review, we summarize our salient findings on the significance of calcineurin for hyphal growth and septation in A. fumigatus and propose future perspectives on exploiting this pathway for designing new fungal-specific therapeutics.

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

International Nuclear Information System (INIS)

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 ∼ 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

Josephson junction arrays

International Nuclear Information System (INIS)

Bindslev Hansen, J.; Lindelof, P.E.

1985-01-01

In this review we intend to cover recent work involving arrays of Josephson junctions. The work on such arrays falls naturally into three main areas of interest: 1. Technical applications of Josephson junction arrays for high-frequency devices. 2. Experimental studies of 2-D model systems (Kosterlitz-Thouless phase transition, commensurate-incommensurate transition in frustrated (flux) lattices). 3. Investigations of phenomena associated with non-equilibrium superconductivity in and around Josephson junctions (with high current density). (orig./BUD)

Electronic thermometry in tunable tunnel junction

Science.gov (United States)

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.

Ultrastructural characteristics of the uterine epithelium of aspidogastrean and digenean trematodes

Czech Academy of Sciences Publication Activity Database

Poddubnaya, L. G.; Levron, Céline; Gibson, D. I.

2011-01-01

Roč. 56, č. 2 (2011), 131-139 ISSN 1230-2821 R&D Projects: GA ČR GP524/07/P039; GA MŠk LC522 Institutional research plan: CEZ:AV0Z60220518 Keywords : Aspidogastrea * Digenea * Aspidogaster limacoides * Phyllodistomum angulatum * Azygia lucii * ultrastructure * uterus * septate junctions Subject RIV: GJ - Animal Vermins ; Diseases, Veterinary Medicine Impact factor: 0.789, year: 2011

Dynamics of Josephson junction arrays

International Nuclear Information System (INIS)

Hadley, P.

1989-01-01

The dynamics of Josephson junction arrays is a topic that lies at the intersection of the fields of nonlinear dynamics and Josephson junction technology. The series arrays considered here consist of several rapidly oscillating Josephson junctions where each junction is coupled equally to every other junction. The purpose of this study is to understand phaselocking and other cooperative dynamics of this system. Previously, little was known about high dimensional nonlinear systems of this sort. Numerical simulations are used to study the dynamics of these arrays. Three distinct types of periodic solutions to the array equations were observed as well as period doubled and chaotic solutions. One of the periodic solutions is the symmetric, in-phase solution where all of the junctions oscillate identically. The other two periodic solutions are symmetry-broken solutions where all of the junction do not oscillate identically. The symmetry-broken solutions are highly degenerate. As many as (N - 1) stable solutions can coexist for an array of N junctions. Understanding the stability of these several solutions and the transitions among them is vital to the design of useful devices

DNA double-strand break response factors influence end-joining features of IgH class switch and general translocation junctions.

Science.gov (United States)

Panchakshari, Rohit A; Zhang, Xuefei; Kumar, Vipul; Du, Zhou; Wei, Pei-Chi; Kao, Jennifer; Dong, Junchao; Alt, Frederick W

2018-01-23

Ig heavy chain (IgH) class switch recombination (CSR) in B lymphocytes switches IgH constant regions to change antibody functions. CSR is initiated by DNA double-strand breaks (DSBs) within a donor IgH switch (S) region and a downstream acceptor S region. CSR is completed by fusing donor and acceptor S region DSB ends by classical nonhomologous end-joining (C-NHEJ) and, in its absence, by alternative end-joining that is more biased to use longer junctional microhomologies (MHs). Deficiency for DSB response (DSBR) factors, including ataxia telangiectasia-mutated (ATM) and 53BP1, variably impair CSR end-joining, with 53BP1 deficiency having the greatest impact. However, studies of potential impact of DSBR factor deficiencies on MH-mediated CSR end-joining have been technically limited. We now use a robust DSB joining assay to elucidate impacts of deficiencies for DSBR factors on CSR and chromosomal translocation junctions in primary mouse B cells and CH12F3 B-lymphoma cells. Compared with wild-type, CSR and c-myc to S region translocation junctions in the absence of 53BP1, and, to a lesser extent, other DSBR factors, have increased MH utilization; indeed, 53BP1-deficient MH profiles resemble those associated with C-NHEJ deficiency. However, translocation junctions between c-myc DSB and general DSBs genome-wide are not MH-biased in ATM-deficient versus wild-type CH12F3 cells and are less biased in 53BP1- and C-NHEJ-deficient cells than CSR junctions or c-myc to S region translocation junctions. We discuss potential roles of DSBR factors in suppressing increased MH-mediated DSB end-joining and features of S regions that may render their DSBs prone to MH-biased end-joining in the absence of DSBR factors.

Tight junctions and human diseases.

Science.gov (United States)

Sawada, Norimasa; Murata, Masaki; Kikuchi, Keisuke; Osanai, Makoto; Tobioka, Hirotoshi; Kojima, Takashi; Chiba, Hideki

2003-09-01

Tight junctions are intercellular junctions adjacent to the apical end of the lateral membrane surface. They have two functions, the barrier (or gate) function and the fence function. The barrier function of tight junctions regulates the passage of ions, water, and various macromolecules, even of cancer cells, through paracellular spaces. The barrier function is thus relevant to edema, jaundice, diarrhea, and blood-borne metastasis. On the other hand, the fence function maintains cell polarity. In other words, tight junctions work as a fence to prevent intermixing of molecules in the apical membrane with those in the lateral membrane. This function is deeply involved in cancer cell biology, in terms of loss of cell polarity. Of the proteins comprising tight junctions, integral membrane proteins occludin, claudins, and JAMs have been recently discovered. Of these molecules, claudins are exclusively responsible for the formation of tight-junction strands and are connected with the actin cytoskeleton mediated by ZO-1. Thus, both functions of tight junctions are dependent on the integrity of the actin cytoskeleton as well as ATP. Mutations in the claudin14 and the claudin16 genes result in hereditary deafness and hereditary hypomagnesemia, respectively. Some pathogenic bacteria and viruses target and affect the tight-junction function, leading to diseases. In this review, the relationship between tight junctions and human diseases is summarized.

A single-gradient junction technique to replace multiple-junction shifts for craniospinal irradiation treatment

International Nuclear Information System (INIS)

Hadley, Austin; Ding, George X.

2014-01-01

Craniospinal irradiation (CSI) requires abutting fields at the cervical spine. Junction shifts are conventionally used to prevent setup error–induced overdosage/underdosage from occurring at the same location. This study compared the dosimetric differences at the cranial-spinal junction between a single-gradient junction technique and conventional multiple-junction shifts and evaluated the effect of setup errors on the dose distributions between both techniques for a treatment course and single fraction. Conventionally, 2 lateral brain fields and a posterior spine field(s) are used for CSI with weekly 1-cm junction shifts. We retrospectively replanned 4 CSI patients using a single-gradient junction between the lateral brain fields and the posterior spine field. The fields were extended to allow a minimum 3-cm field overlap. The dose gradient at the junction was achieved using dose painting and intensity-modulated radiation therapy planning. The effect of positioning setup errors on the dose distributions for both techniques was simulated by applying shifts of ± 3 and 5 mm. The resulting cervical spine doses across the field junction for both techniques were calculated and compared. Dose profiles were obtained for both a single fraction and entire treatment course to include the effects of the conventional weekly junction shifts. Compared with the conventional technique, the gradient-dose technique resulted in higher dose uniformity and conformity to the target volumes, lower organ at risk (OAR) mean and maximum doses, and diminished hot spots from systematic positioning errors over the course of treatment. Single-fraction hot and cold spots were improved for the gradient-dose technique. The single-gradient junction technique provides improved conformity, dose uniformity, diminished hot spots, lower OAR mean and maximum dose, and one plan for the entire treatment course, which reduces the potential human error associated with conventional 4-shifted plans

Vortex dynamics in a pipe T-junction: Recirculation and sensitivity

Science.gov (United States)

Chen, Kevin K.; Rowley, Clarence W.; Stone, Howard A.

2015-03-01

In the last few years, many researchers have noted that regions of recirculating flow often exhibit particularly high sensitivity to spatially localized feedback. We explore the flow through a T-shaped pipe bifurcation—a simple and ubiquitous, but generally poorly understood flow configuration—and provide a complex example of the relation between recirculation and sensitivity. When Re ≥ 320, a phenomenon resembling vortex breakdown occurs in four locations in the junction, with internal stagnation points appearing on vortex axes and causing flow reversal. The structure of the recirculation is similar to the traditional bubble-type breakdown. These recirculation regions are highly sensitive to spatially localized feedback in the linearized Navier-Stokes operator. The flow separation at the corners of the "T," however, does not exhibit this kind of sensitivity. We focus our analysis on the Reynolds number of 560, near the first Hopf bifurcation of the flow.

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

International Nuclear Information System (INIS)

Cleland, A.N.

1991-01-01

Experiments investigated 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 experiments on small-capacitance tunnel junctions extend the measurements on the large-area Josephson junctions from the region in which the phase variable has a fairly well-defined value, i.e. its wave function 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

Increasing gap junctional coupling: a tool for dissecting the role of gap junctions

DEFF Research Database (Denmark)

Axelsen, Lene Nygaard; Haugan, Ketil; Stahlhut, Martin

2007-01-01

Much of our current knowledge about the physiological and pathophysiological role of gap junctions is based on experiments where coupling has been reduced by either chemical agents or genetic modification. This has brought evidence that gap junctions are important in many physiological processes....... In a number of cases, gap junctions have been implicated in the initiation and progress of disease, and experimental uncoupling has been used to investigate the exact role of coupling. The inverse approach, i.e., to increase coupling, has become possible in recent years and represents a new way of testing...... the role of gap junctions. The aim of this review is to summarize the current knowledge obtained with agents that selectively increase gap junctional intercellular coupling. Two approaches will be reviewed: increasing coupling by the use of antiarrhythmic peptide and its synthetic analogs...

Junction detection and pathway selection

Science.gov (United States)

Peck, Alex N.; Lim, Willie Y.; Breul, Harry T.

1992-02-01

The ability to detect junctions and make choices among the possible pathways is important for autonomous navigation. In our script-based navigation approach where a journey is specified as a script of high-level instructions, actions are frequently referenced to junctions, e.g., `turn left at the intersection.' In order for the robot to carry out these kind of instructions, it must be able (1) to detect an intersection (i.e., an intersection of pathways), (2) know that there are several possible pathways it can take, and (3) pick the pathway consistent with the high level instruction. In this paper we describe our implementation of the ability to detect junctions in an indoor environment, such as corners, T-junctions and intersections, using sonar. Our approach uses a combination of partial scan of the local environment and recognition of sonar signatures of certain features of the junctions. In the case where the environment is known, we use additional sensor information (such as compass bearings) to help recognize the specific junction. In general, once a junction is detected and its type known, the number of possible pathways can be deduced and the correct pathway selected. Then the appropriate behavior for negotiating the junction is activated.

Supramolecular tunneling junctions

NARCIS (Netherlands)

Wimbush, K.S.

2012-01-01

In this study a variety of supramolecular tunneling junctions were created. The basis of these junctions was a self-assembled monolayer of heptathioether functionalized ß-cyclodextrin (ßCD) formed on an ultra-flat Au surface, i.e., the bottom electrode. This gave a well-defined hexagonally packed

Phase diagrams of particles with dissimilar patches: X-junctions and Y-junctions

International Nuclear Information System (INIS)

Tavares, J M; Teixeira, P I C

2012-01-01

We use Wertheim’s first-order perturbation theory to investigate the phase behaviour and the structure of coexisting fluid phases for a model of patchy particles with dissimilar patches (two patches of type A and f B patches of type B). A patch of type α = {A,B} can bond to a patch of type β = {A,B} in a volume v αβ , thereby decreasing the internal energy by ε αβ . We analyse the range of model parameters where AB bonds, or Y-junctions, are energetically disfavoured (ε AB AA /2) but entropically favoured (v AB ≫ v αα ), and BB bonds, or X-junctions, are energetically favoured (ε BB > 0). We show that, for low values of ε BB /ε AA , the phase diagram has three different regions: (i) close to the critical temperature a low-density liquid composed of long chains and rich in Y-junctions coexists with a vapour of chains; (ii) at intermediate temperatures there is coexistence between a vapour of short chains and a liquid of very long chains with X- and Y-junctions; (iii) at low temperatures an ideal gas coexists with a high-density liquid with all possible AA and BB bonds formed. It is also shown that in region (i) the liquid binodal is reentrant (its density decreases with decreasing temperature) for the lower values of ε BB /ε AA . The existence of these three regions is a consequence of the competition between the formation of X- and Y-junctions: X-junctions are energetically favoured and thus dominate at low temperatures, whereas Y-junctions are entropically favoured and dominate at higher temperatures. (paper)

Common features of a vortex structure in long exponentially shaped Josephson junctions and Josephson junctions with inhomogeneities

International Nuclear Information System (INIS)

Boyadjiev, T.L.; Semerdjieva, E.G.; Shukrinov, Yu.M.

2007-01-01

We study the vortex structure in three different models of the long Josephson junction: the exponentially shaped Josephson junction and the Josephson junctions with the resistor and the shunt inhomogeneities in the barrier layer. For these three models the critical curves 'critical current-magnetic field' are numerically constructed. We develop the idea of the equivalence of the exponentially shaped Josephson junction and the rectangular junction with the distributed inhomogeneity and demonstrate that at some parameters of the shunt and the resistor inhomogeneities in the ends of the junction the corresponding critical curves are very close to the exponentially shaped one

Behavior of tight-junction, adherens-junction and cell polarity proteins during HNF-4α-induced epithelial polarization

International Nuclear Information System (INIS)

Satohisa, Seiro; Chiba, Hideki; Osanai, Makoto; Ohno, Shigeo; Kojima, Takashi; Saito, Tsuyoshi; Sawada, Norimasa

2005-01-01

We previously reported that expression of tight-junction molecules occludin, claudin-6 and claudin-7, as well as establishment of epithelial polarity, was triggered in mouse F9 cells expressing hepatocyte nuclear factor (HNF)-4α [H. Chiba, T. Gotoh, T. Kojima, S. Satohisa, K. Kikuchi, M. Osanai, N. Sawada. Hepatocyte nuclear factor (HNF)-4α triggers formation of functional tight junctions and establishment of polarized epithelial morphology in F9 embryonal carcinoma cells, Exp. Cell Res. 286 (2003) 288-297]. Using these cells, we examined in the present study behavior of tight-junction, adherens-junction and cell polarity proteins and elucidated the molecular mechanism behind HNF-4α-initiated junction formation and epithelial polarization. We herein show that not only ZO-1 and ZO-2, but also ZO-3, junctional adhesion molecule (JAM)-B, JAM-C and cell polarity proteins PAR-3, PAR-6 and atypical protein kinase C (aPKC) accumulate at primordial adherens junctions in undifferentiated F9 cells. In contrast, CRB3, Pals1 and PATJ appeared to exhibit distinct subcellular localization in immature cells. Induced expression of HNF-4α led to translocation of these tight-junction and cell polarity proteins to beltlike tight junctions, where occludin, claudin-6 and claudin-7 were assembled, in differentiated cells. Interestingly, PAR-6, aPKC, CRB3 and Pals1, but not PAR-3 or PATJ, were also concentrated on the apical membranes in differentiated cells. These findings indicate that HNF-4α provokes not only expression of tight-junction adhesion molecules, but also modulation of subcellular distribution of junction and cell polarity proteins, resulting in junction formation and epithelial polarization

Flexible 2D layered material junctions

Science.gov (United States)

Balabai, R.; Solomenko, A.

2018-03-01

Within the framework of the methods of the electron density functional and the ab initio pseudopotential, we have obtained the valence electron density spatial distribution, the densities of electron states, the widths of band gaps, the charges on combined regions, and the Coulomb potentials for graphene-based flexible 2D layered junctions, using author program complex. It is determined that the bending of the 2D layered junctions on the angle α leads to changes in the electronic properties of these junctions. In the graphene/graphane junction, there is clear charge redistribution with different signs in the regions of junctions. The presence in the heterojunctions of charge regions with different signs leads to the formation of potential barriers. The greatest potential jump is in the graphene/fluorographene junction. The greatest value of the band gap width is in the graphene/graphane junction.

Facial Resemblance Exaggerates Sex-Specific Jealousy-Based Decisions1

Directory of Open Access Journals (Sweden)

Steven M. Platek

2007-01-01

Full Text Available Sex differences in reaction to a romantic partner's infidelity are well documented and are hypothesized to be attributable to sex-specific jealousy mechanisms which are utilized to solve adaptive problems associated with risk of extra-pair copulation. Males, because of the risk of cuckoldry become more upset by sexual infidelity, while females, because of loss of resources and biparental investment tend to become more distressed by emotional infidelity. However, the degree to which these sex-specific reactions to jealousy interact with cues to kin are completely unknown. Here we investigated the interaction of facial resemblance with decisions about sex-specific jealousy scenarios. Fifty nine volunteers were asked to imagine that two different people (represented by facial composites informed them about their romantic partner's sexual or emotional infidelity. Consistent with previous research, males ranked sexual infidelity scenarios as most upsetting and females ranked emotional infidelity scenarios most upsetting. However, when information about the infidelity was provided by a face that resembled the subject, sex-specific reactions to jealousy were exaggerated. This finding highlights the use of facial resemblance as a putative self-referent phenotypic matching cue that impacts trusting behavior in sexual contexts.

The Dissolution of Double Holliday Junctions

DEFF Research Database (Denmark)

Bizard, Anna H; Hickson, Ian D

2014-01-01

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......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......) 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....

Quantum Junction Solar Cells

KAUST Repository

Tang, Jiang

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. © 2012 American Chemical Society.

Molecular electronic junction transport

DEFF Research Database (Denmark)

Solomon, Gemma C.; Herrmann, Carmen; Ratner, Mark

2012-01-01

Whenasinglemolecule,oracollectionofmolecules,isplacedbetween two electrodes and voltage is applied, one has a molecular transport junction. We discuss such junctions, their properties, their description, and some of their applications. The discussion is qualitative rather than quantitative, and f...

Gap junctions and motor behavior

DEFF Research Database (Denmark)

Kiehn, Ole; Tresch, Matthew C.

2002-01-01

The production of any motor behavior requires coordinated activity in motor neurons and premotor networks. In vertebrates, this coordination is often assumed to take place through chemical synapses. Here we review recent data suggesting that electrical gap-junction coupling plays an important role...... in coordinating and generating motor outputs in embryonic and early postnatal life. Considering the recent demonstration of a prevalent expression of gap-junction proteins and gap-junction structures in the adult mammalian spinal cord, we suggest that neuronal gap-junction coupling might also contribute...... to the production of motor behavior in adult mammals....

Ferromagnetic Josephson Junctions for Cryogenic Memory

Science.gov (United States)

Niedzielski, Bethany M.; Gingrich, Eric C.; Khasawneh, Mazin A.; Loloee, Reza; Pratt, William P., Jr.; Birge, Norman O.

2015-03-01

Josephson junctions containing ferromagnetic materials are of interest for both scientific and technological purposes. In principle, either the amplitude of the critical current or superconducting phase shift across the junction can be controlled by the relative magnetization directions of the ferromagnetic layers in the junction. Our approach concentrates on phase control utilizing two junctions in a SQUID geometry. We will report on efforts to control the phase of junctions carrying either spin-singlet or spin-triplet supercurrent for cryogenic memory applications. Supported by Northorp Grumman Corporation and by IARPA under SPAWAR Contract N66001-12-C-2017.

Electronic noise of superconducting tunnel junction detectors

International Nuclear Information System (INIS)

Jochum, J.; Kraus, H.; Gutsche, M.; Kemmather, B.; Feilitzsch, F. v.; Moessbauer, R.L.

1994-01-01

The optimal signal to noise ratio for detectors based on superconducting tunnel junctions is calculated and compared for the cases of a detector consisting of one single tunnel junction, as well as of series and of parallel connections of such tunnel junctions. The influence of 1 / f noise and its dependence on the dynamical resistance of tunnel junctions is discussed quantitatively. A single tunnel junction yields the minimum equivalent noise charge. Such a tunnel junction exhibits the best signal to noise ratio if the signal charge is independent of detector size. In case, signal charge increases with detector size, a parallel or a series connection of tunnel junctions would provide the optimum signal to noise ratio. The equivalent noise charge and the respective signal to noise ratio are deduced as functions of tunnel junction parameters such as tunneling time, quasiparticle lifetime, etc. (orig.)

Traumatic bone cyst resembling apical periodontitis.

Science.gov (United States)

Rosen, D J; Ardekian, L; Machtei, E E; Peled, M; Manor, R; Laufer, D

1997-10-01

Among the pseudocysts of the jaws, the traumatic bone cyst is known as an asymptomatic lesion often noted unintentionally during routine radiographic examinations. The lesion neither devitalizes the teeth within its borders, nor does it cause resorption of their roots. The well-demarcated traumatic bone cyst often projects into the intraradicular septa and hence has been described as having scalloped borders. The following presentation is of a traumatic bone cyst that resembled periodontal pathology in its appearance.

Atomic-scaled characterization of graphene PN junctions

Science.gov (United States)

Zhou, Xiaodong; Wang, Dennis; Dadgar, Ali; Agnihotri, Pratik; Lee, Ji Ung; Reuter, Mark C.; Ross, Frances M.; Pasupathy, Abhay N.

Graphene p-n junctions are essential devices for studying relativistic Klein tunneling and the Veselago lensing effect in graphene. We have successfully fabricated graphene p-n junctions using both lithographically pre-patterned substrates and the stacking of vertical heterostructures. We then use our 4-probe STM system to characterize the junctions. The ability to carry out scanning electron microscopy (SEM) in our STM instrument is essential for us to locate and measure the junction interface. We obtain both the topography and dI/dV spectra at the junction area, from which we track the shift of the graphene chemical potential with position across the junction interface. This allows us to directly measure the spatial width and roughness of the junction and its potential barrier height. We will compare the junction properties of devices fabricated by the aforementioned two methods and discuss their effects on the performance as a Veselago lens.

Stability of large-area molecular junctions

NARCIS (Netherlands)

Akkerman, Hylke B.; Kronemeijer, Auke J.; Harkema, Jan; van Hal, Paul A.; Smits, Edsger C. P.; de Leeuw, Dago M.; Blom, Paul W. M.

The stability of molecular junctions is crucial for any application of molecular electronics. Degradation of molecular junctions when exposed to ambient conditions is regularly observed. In this report the stability of large-area molecular junctions under ambient conditions for more than two years

Superconducting flux qubits with π-junctions

International Nuclear Information System (INIS)

Shcherbakova, Anastasia

2014-01-01

In this thesis, we present a fabrication technology of Al/AlO x /Al Josephson junctions on Nb pads. The described technology gives the possibility of combining a variety of Nb-based superconducting circuits, like pi-junction phase-shifters with sub-micron Al/AlO x /Al junctions. Using this approach, we fabricated hybrid Nb/Al flux qubits with and without the SFS-junctions and studied dispersive magnetic field response of these qubits as well as their spectroscopy characteristics.

Resonance Transport of Graphene Nanoribbon T-Shaped Junctions

International Nuclear Information System (INIS)

Xiao-Lan, Kong; Yong-Jian, Xiong

2010-01-01

We investigate the transport properties of T-shaped junctions composed of armchair graphene nanoribbons of different widths. Three types of junction geometries are considered. The junction conductance strongly depends on the atomic features of the junction geometry. When the shoulders of the junction have zigzag type edges, sharp conductance resonances usually appear in the low energy region around the Dirac point, and a conductance gap emerges. When the shoulders of the junction have armchair type edges, the conductance resonance behavior is weakened significantly, and the metal-metal-metal junction structures show semimetallic behaviors. The contact resistance also changes notably due to the various interface geometries of the junction

Arbuscular Mycorrhizal and Dark Septate Endophyte Fungal Associations in South Indian Aquatic and Wetland Macrophytes

Directory of Open Access Journals (Sweden)

Kumar Seerangan

2014-01-01

Full Text Available Investigations on the prevalence of arbuscular mycorrhizal (AM and dark septate endophyte (DSE fungal symbioses are limited for plants growing in tropical aquatic and wetland habitats compared to those growing on terrestrial moist or dry habitats. Therefore, we assessed the incidence of AM and DSE symbiosis in 8 hydrophytes and 50 wetland plants from four sites in south India. Of the 58 plant species examined, we found AM and DSE fungal symbiosis in 21 and five species, respectively. We reported for the first time AM and DSE fungal symbiosis in seven and five species, respectively. Intermediate-type AM morphology was common, and AM morphology is reported for the first time in 16 plant species. Both AM and DSE fungal colonization varied significantly across plant species and sites. Intact and identifiable AM fungal spores occurred in root zones of nine plant species, but AM fungal species richness was low. Though no clear relationship between AM and DSE fungal colonization was recognized, a significant negative correlation between AM colonization and spore numbers was established. Our study suggests that the occurrence of AM and DSE fungal symbiosis in plants growing in hydrophytic and wetland habitats is not as common as in terrestrial habitats.

Josephson junctions with ferromagnetic interlayer

International Nuclear Information System (INIS)

Wild, Georg Hermann

2012-01-01

We report on the fabrication of superconductor/insulator/ferromagnetic metal/superconductor (Nb/AlO x /Pd 0.82 Ni 0.18 /Nb) Josephson junctions (SIFS JJs) with high critical current densities, large normal resistance times area products, and high quality factors. For these junctions, a transition from 0- to π-coupling is observed for a thickness d F =6 nm of the ferromagnetic Pd 0.82 Ni 0.18 interlayer. The magnetic field dependence of the critical current of the junctions demonstrates good spatial homogeneity of the tunneling barrier and ferromagnetic interlayer. Magnetic characterization shows that the Pd 0.82 Ni 0.18 has an out-of-plane anisotropy and large saturation magnetization indicating negligible dead layers at the interfaces. A careful analysis of Fiske modes up to about 400 GHz provides valuable information on the junction quality factor and the relevant damping mechanisms. Whereas losses due to quasiparticle tunneling dominate at low frequencies, at high frequencies the damping is explained by the finite surface resistance of the junction electrodes. High quality factors of up to 30 around 200 GHz have been achieved. They allow to study the junction dynamics, in particular the switching probability from the zero-voltage into the voltage state with and without microwave irradiation. The experiments with microwave irradiation are well explained within semi-classical models and numerical simulations. In contrast, at mK temperature the switching dynamics without applied microwaves clearly shows secondary quantum effects. Here, we could observe for the first time macroscopic quantum tunneling in Josephson junctions with a ferromagnetic interlayer. This observation excludes fluctuations of the critical current as a consequence of an unstable magnetic domain structure of the ferromagnetic interlayer and affirms the suitability of SIFS Josephson junctions for quantum information processing.

Josephson junctions with ferromagnetic interlayer

Energy Technology Data Exchange (ETDEWEB)

Wild, Georg Hermann

2012-03-04

We report on the fabrication of superconductor/insulator/ferromagnetic metal/superconductor (Nb/AlO{sub x}/Pd{sub 0.82}Ni{sub 0.18}/Nb) Josephson junctions (SIFS JJs) with high critical current densities, large normal resistance times area products, and high quality factors. For these junctions, a transition from 0- to {pi}-coupling is observed for a thickness d{sub F}=6 nm of the ferromagnetic Pd{sub 0.82}Ni{sub 0.18} interlayer. The magnetic field dependence of the critical current of the junctions demonstrates good spatial homogeneity of the tunneling barrier and ferromagnetic interlayer. Magnetic characterization shows that the Pd{sub 0.82}Ni{sub 0.18} has an out-of-plane anisotropy and large saturation magnetization indicating negligible dead layers at the interfaces. A careful analysis of Fiske modes up to about 400 GHz provides valuable information on the junction quality factor and the relevant damping mechanisms. Whereas losses due to quasiparticle tunneling dominate at low frequencies, at high frequencies the damping is explained by the finite surface resistance of the junction electrodes. High quality factors of up to 30 around 200 GHz have been achieved. They allow to study the junction dynamics, in particular the switching probability from the zero-voltage into the voltage state with and without microwave irradiation. The experiments with microwave irradiation are well explained within semi-classical models and numerical simulations. In contrast, at mK temperature the switching dynamics without applied microwaves clearly shows secondary quantum effects. Here, we could observe for the first time macroscopic quantum tunneling in Josephson junctions with a ferromagnetic interlayer. This observation excludes fluctuations of the critical current as a consequence of an unstable magnetic domain structure of the ferromagnetic interlayer and affirms the suitability of SIFS Josephson junctions for quantum information processing.

Pareidolia in Neuroendocrinology: A Pituitary Macroadenoma Resembling "Big Bird".

Science.gov (United States)

de Herder, Wouter W

2016-04-01

The MRI picture of a pituitary macroadenoma with supra- and perisellar expansion resembled a famous character from a children's television series demonstrating that pareidolia is also observed in neuro-endocrinology and -radiology.

Electron optics with ballistic graphene junctions

Science.gov (United States)

Chen, Shaowen

Electrons transmitted across a ballistic semiconductor junction undergo refraction, analogous to light rays across an optical boundary. A pn junction theoretically provides the equivalent of a negative index medium, enabling novel electron optics such as negative refraction and perfect (Veselago) lensing. In graphene, the linear dispersion and zero-gap bandstructure admit highly transparent pn junctions by simple electrostatic gating, which cannot be achieved in conventional semiconductors. Robust demonstration of these effects, however, has not been forthcoming. Here we employ transverse magnetic focusing to probe propagation across an electrostatically defined graphene junction. We find perfect agreement with the predicted Snell's law for electrons, including observation of both positive and negative refraction. Resonant transmission across the pn junction provides a direct measurement of the angle dependent transmission coefficient, and we demonstrate good agreement with theory. Comparing experimental data with simulation reveals the crucial role played by the effective junction width, providing guidance for future device design. Efforts toward sharper pn junction and possibility of zero field Veselago lensing will also be discussed. This work is supported by the Semiconductor Research Corporations NRI Center for Institute for Nanoelectronics Discovery and Exploration (INDEX).

Peltier cooling in molecular junctions

Science.gov (United States)

Cui, Longji; Miao, Ruijiao; Wang, Kun; Thompson, Dakotah; Zotti, Linda Angela; Cuevas, Juan Carlos; Meyhofer, Edgar; Reddy, Pramod

2018-02-01

The study of thermoelectricity in molecular junctions is of fundamental interest for the development of various technologies including cooling (refrigeration) and heat-to-electricity conversion1-4. Recent experimental progress in probing the thermopower (Seebeck effect) of molecular junctions5-9 has enabled studies of the relationship between thermoelectricity and molecular structure10,11. However, observations of Peltier cooling in molecular junctions—a critical step for establishing molecular-based refrigeration—have remained inaccessible. Here, we report direct experimental observations of Peltier cooling in molecular junctions. By integrating conducting-probe atomic force microscopy12,13 with custom-fabricated picowatt-resolution calorimetric microdevices, we created an experimental platform that enables the unified characterization of electrical, thermoelectric and energy dissipation characteristics of molecular junctions. Using this platform, we studied gold junctions with prototypical molecules (Au-biphenyl-4,4'-dithiol-Au, Au-terphenyl-4,4''-dithiol-Au and Au-4,4'-bipyridine-Au) and revealed the relationship between heating or cooling and charge transmission characteristics. Our experimental conclusions are supported by self-energy-corrected density functional theory calculations. We expect these advances to stimulate studies of both thermal and thermoelectric transport in molecular junctions where the possibility of extraordinarily efficient energy conversion has been theoretically predicted2-4,14.

Dynamics of pi-junction interferometer circuits

DEFF Research Database (Denmark)

Kornkev, V.K.; Mozhaev, P.B.; Borisenko, I.V.

2002-01-01

The pi-junction superconducting circuit dynamics was studied by means of numerical simulation technique. Parallel arrays consisting of Josephson junctions of both 0- and pi-type were studied as a model of high-T-c grain-boundary Josephson junction. The array dynamics and the critical current depe...

Geodynamical simulation of the RRF triple junction

Science.gov (United States)

Wang, Z.; Wei, D.; Liu, M.; Shi, Y.; Wang, S.

2017-12-01

Triple junction is the point at which three plate boundaries meet. Three plates at the triple junction form a complex geological tectonics, which is a natural laboratory to study the interactions of plates. This work studies a special triple junction, the oceanic transform fault intersects the collinear ridges with different-spreading rates, which is free of influence of ridge-transform faults and nearby hotspots. First, we build 3-D numerical model of this triple junction used to calculate the stead-state velocity and temperature fields resulting from advective and conductive heat transfer. We discuss in detail the influence of the velocity and temperature fields of the triple junction from viscosity, spreading rate of the ridge. The two sides of the oceanic transform fault are different sensitivities to the two factors. And, the influence of the velocity mainly occurs within 200km of the triple junction. Then, we modify the model by adding a ridge-transform fault to above model and directly use the velocity structure of the Macquarie triple junction. The simulation results show that the temperature at both sides of the oceanic transform fault decreases gradually from the triple junction, but the temperature difference between the two sides is a constant about 200°. And, there is little effect of upwelling velocity away from the triple junction 100km. The model results are compared with observational data. The heat flux and thermal topography along the oceanic transform fault of this model are consistent with the observed data of the Macquarie triple junction. The earthquakes are strike slip distributed along the oceanic transform fault. Their depths are also consistent with the zone of maximum shear stress. This work can help us to understand the interactions of plates of triple junctions and help us with the foundation for the future study of triple junctions.

Loss models for long Josephson junctions

DEFF Research Database (Denmark)

Olsen, O. H.; Samuelsen, Mogens Rugholm

1984-01-01

A general model for loss mechanisms in long Josephson junctions is presented. An expression for the zero-field step is found for a junction of overlap type by means of a perturbation method. Comparison between analytic solution and perturbation result shows good agreement.......A general model for loss mechanisms in long Josephson junctions is presented. An expression for the zero-field step is found for a junction of overlap type by means of a perturbation method. Comparison between analytic solution and perturbation result shows good agreement....

Dynamics of the Josephson multi-junction system with junctions characterized by non-sinusoidal current - phase relationship

International Nuclear Information System (INIS)

Abal'osheva, I.; Lewandowski, S.J.

2004-01-01

It is shown that the inclusion of junctions characterized by non-sinusoidal current - phase relationship in the systems composed of multiple Josephson junctions - results in the appearance of additional system phase states. Numerical simulations and stability considerations confirm that those phase states can be realized in practice. Moreover, spontaneous formation of the grain boundary junctions in high-T c superconductors with non-trivial current-phase relations due to the d-wave symmetry of the order parameter is probable. Switching between the phase states of multiple grain boundary junction systems can lead to additional 1/f noise in high-T c superconductors. (author)

Theoretical and experimental investigations on synchronization in many-junction arrays of HTSC Josephson junctions. Final report

International Nuclear Information System (INIS)

Seidel, P.; Heinz, E.; Pfuch, A.; Machalett, F.; Krech, W.; Basler, M.

1996-06-01

Different many-junction arrays of Josephson junctions were studied theoretically to analyse the mechanisms of synchronization, the influence of internal and external parameters and the maximal allowed spread of parameters for the single junctions. Concepts to realize arrays using standard high-T c superconductor technology were created, e.g. the new arrangement of multijunction superconducting loops (MSL). First experimental results show the relevance of this concept. Intrinsic one-dimensional arrays in thin film technology were prepared as mesas out of Bi or Tl 2212 films. to characterize HTSC Josephson junctions methods based on the analysis of microwave-induced steps were developed. (orig.) [de

Single P-N junction tandem photovoltaic device

Science.gov (United States)

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

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%.

Fathers see stronger family resemblances than non-fathers in unrelated children's faces.

Science.gov (United States)

Bressan, Paola; Dal Pos, Stefania

2012-12-01

Even after they have taken all reasonable measures to decrease the probability that their spouses cheat on them, men still face paternal uncertainty. Such uncertainty can lead to paternal disinvestment, which reduces the children's probability to survive and reproduce, and thus the reproductive success of the fathers themselves. A theoretical model shows that, other things being equal, men who feel confident that they have fathered their spouses' offspring tend to enjoy greater fitness (i.e., leave a larger number of surviving progeny) than men who do not. This implies that fathers should benefit from exaggerating paternal resemblance. We argue that the self-deceiving component of this bias could be concealed by generalizing this resemblance estimation boost to (1) family pairs other than father-child and (2) strangers. Here, we tested the prediction that fathers may see, in unrelated children's faces, stronger family resemblances than non-fathers. In Study 1, 70 men and 70 women estimated facial resemblances between children paired, at three different ages (as infants, children, and adolescents), either to themselves or to their parents. In Study 2, 70 men and 70 women guessed the true parents of the same children among a set of adults. Men who were fathers reported stronger similarities between faces than non-fathers, mothers, and non-mothers did, but were no better at identifying childrens' real parents. We suggest that, in fathers, processing of facial resemblances is biased in a manner that reflects their (adaptive) wishful thinking that fathers and children are related.

The anatomical locus of T-junction processing.

Science.gov (United States)

Schirillo, James A

2009-07-01

Inhomogeneous surrounds can produce either asymmetrical or symmetrical increment/decrement induction by orienting T-junctions to selectively group a test patch with surrounding regions [Melfi, T., & Schirillo, J. (2000). T-junctions in inhomogeneous surrounds. Vision Research, 40, 3735-3741]. The current experiments aimed to determine where T-junctions are processed by presenting each eye with a different image so that T-junctions exist only in the fused percept. Only minor differences were found between retinal and cortical versus cortical-only conditions, indicating that T-junctions are processed cortically.

Mixing in T-junctions

NARCIS (Netherlands)

Kok, Jacobus B.W.; van der Wal, S.

1996-01-01

The transport processes that are involved in the mixing of two gases in a T-junction mixer are investigated. The turbulent flow field is calculated for the T-junction with the k- turbulence model by FLOW3D. In the mathematical model the transport of species is described with a mixture fraction

Effect of junction configurations on microdroplet formation in a T-junction microchannel

Science.gov (United States)

Lih, F. L.; Miao, J. M.

2015-03-01

This study investigates the dynamic formation process of water microdroplets in a silicon oil flow in a T-junction microchannel. Segmented water microdroplets are formed at the junction when the water flow is perpendicularly injected into the silicon oil flow in a straight rectangular microchannel. This study further presents the effects of the water flow inlet geometry on hydrodynamic characteristics of water microdroplet formation. A numerical multiphase volume of fluid (VOF) scheme is coupled to solve the unsteady three-dimensional laminar Navier-Stokes equations to depict the droplet formation phenomena at the junction. Predicted results on the length and generated frequency of the microdroplets agree well with experimental results in a T-junction microchannel with straight and flat inlets (the base model) for both fluid flows. Empirical correlations are reported between the volumetric flow ratio and the dimensionless microdroplet length or dimensionless frequency of droplet generation at a fixed capillary number of 4.7 · 10-3. The results of this study indicate a reduction in the droplet length of approximately 21% if the straight inlet for the water flow is modified to a downstream sudden contraction inlet for the water flow.

Delivery of double singleton pregnancies in a woman with a double uterus, double cervix, and complete septate vagina

Directory of Open Access Journals (Sweden)

Ming-Jie Yang

2015-12-01

Full Text Available Uterine anomalies involving a double uterus, double cervix, also known as didelphys uterus, and complete septate vagina are rarely seen and have an associated fertility problem. However, artificial reproductive technology with embryo transfers can help solve this fertility challenge. Conception in the uterus in just one side is commonly seen for embryos, which are always transferred through the usually used (dilated vagina. We here present a patient with the above uterine anomaly who conceived with the aid of in vitro fertilization and embryo transfer to both uterine cavities under general anesthesia, which resulted in successful double singleton pregnancies with one fetus in each uterus. With intensive prenatal care, the pregnancy course for each fetus was rather uneventful. Although both fetuses were in cephalic presentation, cesarean section was performed at the 39th week of gestation with good outcomes in order to preclude anticipated difficulties if the baby had been delivered through the rarely dilated vagina. However, order of birth between the two fetuses was a crucial decision during the operation.

Poster - Thur Eve - 57: Craniospinal irradiation with jagged-junction IMRT approach without beam edge matching for field junctions.

Science.gov (United States)

Cao, F; Ramaseshan, R; Corns, R; Harrop, S; Nuraney, N; Steiner, P; Aldridge, S; Liu, M; Carolan, H; Agranovich, A; Karva, A

2012-07-01

Craniospinal irradiation were traditionally treated the central nervous system using two or three adjacent field sets. A intensity-modulated radiotherapy (IMRT) plan (Jagged-Junction IMRT) which overcomes problems associated with field junctions and beam edge matching, improves planning and treatment setup efficiencies with homogenous target dose distribution was developed. Jagged-Junction IMRT was retrospectively planned on three patients with prescription of 36 Gy in 20 fractions and compared to conventional treatment plans. Planning target volume (PTV) included the whole brain and spinal canal to the S3 vertebral level. The plan employed three field sets, each with a unique isocentre. One field set with seven fields treated the cranium. Two field sets treated the spine, each set using three fields. Fields from adjacent sets were overlapped and the optimization process smoothly integrated the dose inside the overlapped junction. For the Jagged-Junction IMRT plans vs conventional technique, average homogeneity index equaled 0.08±0.01 vs 0.12±0.02, and conformity number equaled 0.79±0.01 vs 0.47±0.12. The 95% isodose surface covered (99.5±0.3)% of the PTV vs (98.1±2.0)%. Both Jagged-Junction IMRT plans and the conventional plans had good sparing of the organs at risk. Jagged-Junction IMRT planning provided good dose homogeneity and conformity to the target while maintaining a low dose to the organs at risk. Jagged-Junction IMRT optimization smoothly distributed dose in the junction between field sets. Since there was no beam matching, this treatment technique is less likely to produce hot or cold spots at the junction in contrast to conventional techniques. © 2012 American Association of Physicists in Medicine.

Valley dependent transport in graphene L junction

Science.gov (United States)

Chan, K. S.

2018-05-01

We studied the valley dependent transport in graphene L junctions connecting an armchair lead and a zigzag lead. The junction can be used in valleytronic devices and circuits. Electrons injected from the armchair lead into the junction is not valley polarized, but they can become valley polarized in the zigzag lead. There are Fermi energies, where the current in the zigzag lead is highly valley polarized and the junction is an efficient generator of valley polarized current. The features of the valley polarized current depend sensitively on the widths of the two leads, as well as the number of dimers in the armchair lead, because this number has a sensitive effect on the band structure of the armchair lead. When an external potential is applied to the junction, the energy range with high valley polarization is enlarged enhancing its function as a generator of highly valley polarized current. The scaling behavior found in other graphene devices is also found in L junctions, which means that the results presented here can be extended to junctions with larger dimensions after appropriate scaling of the energy.

Method of manufacturing Josephson junction integrated circuits

International Nuclear Information System (INIS)

Jillie, D.W. Jr.; Smith, L.N.

1985-01-01

Josephson junction integrated circuits of the current injection type and magnetically controlled type utilize a superconductive layer that forms both Josephson junction electrode for the Josephson junction devices on the integrated circuit as well as a ground plane for the integrated circuit. Large area Josephson junctions are utilized for effecting contact to lower superconductive layers and islands are formed in superconductive layers to provide isolation between the groudplane function and the Josephson junction electrode function as well as to effect crossovers. A superconductor-barrier-superconductor trilayer patterned by local anodization is also utilized with additional layers formed thereover. Methods of manufacturing the embodiments of the invention are disclosed

delta-biased Josephson tunnel junctions

DEFF Research Database (Denmark)

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

2010-01-01

Abstract: The behavior of a long Josephson tunnel junction drastically depends on the distribution of the dc bias current. We investigate the case in which the bias current is fed in the central point of a one-dimensional junction. Such junction configuration has been recently used to detect...... the persistent currents circulating in a superconducting loop. Analytical and numerical results indicate that the presence of fractional vortices leads to remarkable differences from the conventional case of uniformly distributed dc bias current. The theoretical findings are supported by detailed measurements...

Junction depth measurement using carrier illumination

International Nuclear Information System (INIS)

Borden, Peter

2001-01-01

Carrier Illumination [trade mark] (CI) is a new method recently developed to meet the need for a non-destructive, high throughput junction depth measurement on patterned wafers. A laser beam creates a quasi-static excess carrier profile in the semiconductor underlying the activated junction. The excess carrier profile is fairly constant below the junction, and drops rapidly in the junction, creating a steep index of refraction gradient at the junction edge. Interference with light reflected from this index gradient provides a signal that is analyzed to determine the junction depth. The paper summarizes evaluation of performance in full NMOS and PMOS process flows, on both bare and patterned wafers. The aims have been to validate (1) performance in the presence of underlying layers typically found at the source/drain (S/D) process steps and (2) measurement on patterned wafers. Correlation of CI measurements to SIMS and transistor drive current are shown. The data were obtained from NMOS structures using As S/D and LDD implants. Correlations to SRP, SIMS and sheet resistance are shown for PMOS structures using B 11 LDD implants. Gage capability measurements are also presented

NbN tunnel junctions

International Nuclear Information System (INIS)

Villegier, J.C.; Vieux-Rochaz, L.; Goniche, M.; Renard, P.; Vabre, M.

1984-09-01

All-niobium nitride Josephon junctions have been prepared successfully using a new processing called SNOP: Selective Niobium (nitride) Overlap Process. Such a process involves the ''trilayer'' deposition on the whole wafer before selective patterning of the electrodes by optically controlled dry reactive ion etching. Only two photomask levels are need to define an ''overlap'' or a ''cross-type'' junction with a good accuracy. The properties of the niobium nitride films deposited by DC-magnetron sputtering and the surface oxide growth are analysed. The most critical point to obtain high quality and high gap value junctions resides in the early stage of the NbN counterelectrode growth. Some possibilities to overcome such a handicap exist even if the fabrication needs substrate temperatures below 250 0 C

Comparative genomics provides insights into the lifestyle and reveals functional heterogeneity of dark septate endophytic fungi.

Science.gov (United States)

Knapp, Dániel G; Németh, Julianna B; Barry, Kerrie; Hainaut, Matthieu; Henrissat, Bernard; Johnson, Jenifer; Kuo, Alan; Lim, Joanne Hui Ping; Lipzen, Anna; Nolan, Matt; Ohm, Robin A; Tamás, László; Grigoriev, Igor V; Spatafora, Joseph W; Nagy, László G; Kovács, Gábor M

2018-04-20

Dark septate endophytes (DSE) are a form-group of root endophytic fungi with elusive functions. Here, the genomes of two common DSE of semiarid areas, Cadophora sp. and Periconia macrospinosa were sequenced and analyzed with another 32 ascomycetes of different lifestyles. Cadophora sp. (Helotiales) and P. macrospinosa (Pleosporales) have genomes of 70.46 Mb and 54.99 Mb with 22,766 and 18,750 gene models, respectively. The majority of DSE-specific protein clusters lack functional annotation with no similarity to characterized proteins, implying that they have evolved unique genetic innovations. Both DSE possess an expanded number of carbohydrate active enzymes (CAZymes), including plant cell wall degrading enzymes (PCWDEs). Those were similar in three other DSE, and contributed a signal for the separation of root endophytes in principal component analyses of CAZymes, indicating shared genomic traits of DSE fungi. Number of secreted proteases and lipases, aquaporins, and genes linked to melanin synthesis were also relatively high in our fungi. In spite of certain similarities between our two DSE, we observed low levels of convergence in their gene family evolution. This suggests that, despite originating from the same habitat, these two fungi evolved along different evolutionary trajectories and display considerable functional differences within the endophytic lifestyle.

Hysteresis development in superconducting Josephson junctions

International Nuclear Information System (INIS)

Refai, T.F.; Shehata, L.N.

1988-09-01

The resistively and capacitive shunted junction model is used to investigate hysteresis development in superconducting Josephson junctions. Two empirical formulas that relate the hysteresis width and the quasi-particle diffusion length in terms of the junctions electrical parameters, temperature and frequency are obtained. The obtained formulas provide a simple tool to investigate the full potentials of the hysteresis phenomena. (author). 9 refs, 3 figs

Fabrication of Josephson Junction without shadow evaporation

Science.gov (United States)

Wu, Xian; Ku, Hsiangsheng; Long, Junling; Pappas, David

We developed a new method of fabricating Josephson Junction (Al/AlOX/Al) without shadow evaporation. Statistics from room temperature junction resistance and measurement of qubits are presented. Unlike the traditional ``Dolan Bridge'' technique, this method requires two individual lithographies and straight evaporations of Al. Argon RF plasma is used to remove native AlOX after the first evaporation, followed by oxidation and second Al evaporation. Junction resistance measured at room temperature shows linear dependence on Pox (oxidation pressure), √{tox} (oxidation time), and inverse proportional to junction area. We have seen 100% yield of qubits made with this method. This method is promising because it eliminates angle dependence during Junction fabrication, facilitates large scale qubits fabrication.

Quantum synchronization effects in intrinsic Josephson junctions

International Nuclear Information System (INIS)

Machida, M.; Kano, T.; Yamada, S.; Okumura, M.; Imamura, T.; Koyama, T.

2008-01-01

We investigate quantum dynamics of the superconducting phase in intrinsic Josephson junctions of layered high-T c superconductors motivated by a recent experimental observation for the switching rate enhancement in the low temperature quantum regime. We pay attention to only the capacitive coupling between neighboring junctions and perform large-scale simulations for the Schroedinger equation derived from the Hamiltonian considering the capacitive coupling alone. The simulation focuses on an issue whether the switching of a junction induces those of the other junctions or not. The results reveal that the superconducting phase dynamics show synchronous behavior with increasing the quantum character, e.g., decreasing the junction plane area and effectively the temperature. This is qualitatively consistent with the experimental result

Entropy Flow Through Near-Critical Quantum Junctions

Science.gov (United States)

Friedan, Daniel

2017-05-01

This is the continuation of Friedan (J Stat Phys, 2017. doi: 10.1007/s10955-017-1752-8). Elementary formulas are derived for the flow of entropy through a circuit junction in a near-critical quantum circuit close to equilibrium, based on the structure of the energy-momentum tensor at the junction. The entropic admittance of a near-critical junction in a bulk-critical circuit is expressed in terms of commutators of the chiral entropy currents. The entropic admittance at low frequency, divided by the frequency, gives the change of the junction entropy with temperature—the entropic "capacitance". As an example, and as a check on the formalism, the entropic admittance is calculated explicitly for junctions in bulk-critical quantum Ising circuits (free fermions, massless in the bulk), in terms of the reflection matrix of the junction. The half-bit of information capacity per end of critical Ising wire is re-derived by integrating the entropic "capacitance" with respect to temperature, from T=0 to T=∞.

Ballistic Josephson junctions based on CVD graphene

Science.gov (United States)

Li, Tianyi; Gallop, John; Hao, Ling; Romans, Edward

2018-04-01

Josephson junctions with graphene as the weak link between superconductors have been intensely studied in recent years, with respect to both fundamental physics and potential applications. However, most of the previous work was based on mechanically exfoliated graphene, which is not compatible with wafer-scale production. To overcome this limitation, we have used graphene grown by chemical vapour deposition (CVD) as the weak link of Josephson junctions. We demonstrate that very short, wide CVD-graphene-based Josephson junctions with Nb electrodes can work without any undesirable hysteresis in their electrical characteristics from 1.5 K down to a base temperature of 320 mK, and their gate-tuneable critical current shows an ideal Fraunhofer-like interference pattern in a perpendicular magnetic field. Furthermore, for our shortest junctions (50 nm in length), we find that the normal state resistance oscillates with the gate voltage, consistent with the junctions being in the ballistic regime, a feature not previously observed in CVD-graphene-based Josephson junctions.

Overlap junctions for high coherence superconducting qubits

Science.gov (United States)

Wu, X.; Long, J. L.; Ku, H. S.; Lake, R. E.; Bal, M.; Pappas, D. P.

2017-07-01

Fabrication of sub-micron Josephson junctions is demonstrated using standard processing techniques for high-coherence, superconducting qubits. These junctions are made in two separate lithography steps with normal-angle evaporation. Most significantly, this work demonstrates that it is possible to achieve high coherence with junctions formed on aluminum surfaces cleaned in situ by Ar plasma before junction oxidation. This method eliminates the angle-dependent shadow masks typically used for small junctions. Therefore, this is conducive to the implementation of typical methods for improving margins and yield using conventional CMOS processing. The current method uses electron-beam lithography and an additive process to define the top and bottom electrodes. Extension of this work to optical lithography and subtractive processes is discussed.

Surface-Enhanced Raman Scattering in Molecular Junctions.

Science.gov (United States)

Iwane, Madoka; Fujii, Shintaro; Kiguchi, Manabu

2017-08-18

Surface-enhanced Raman scattering (SERS) is a surface-sensitive vibrational spectroscopy that allows Raman spectroscopy on a single molecular scale. Here, we present a review of SERS from molecular junctions, in which a single molecule or molecules are made to have contact from the top to the bottom of metal surfaces. The molecular junctions are nice platforms for SERS as well as transport measurement. Electronic characterization based on the transport measurements of molecular junctions has been extensively studied for the development of miniaturized electronic devices. Simultaneous SERS and transport measurement of the molecular junctions allow both structural (geometrical) and electronic information on the single molecule scale. The improvement of SERS measurement on molecular junctions open the door toward new nanoscience and nanotechnology in molecular electronics.

Primary Tunnel Junction Thermometry

International Nuclear Information System (INIS)

Pekola, Jukka P.; Holmqvist, Tommy; Meschke, Matthias

2008-01-01

We describe the concept and experimental demonstration of primary thermometry based on a four-probe measurement of a single tunnel junction embedded within four arrays of junctions. We show that in this configuration random sample specific and environment-related errors can be avoided. This method relates temperature directly to Boltzmann constant, which will form the basis of the definition of temperature and realization of official temperature scales in the future

Ginzburg–Landau theory of mesoscopic multi-band Josephson junctions

Energy Technology Data Exchange (ETDEWEB)

Romeo, F.; De Luca, R., E-mail: rdeluca@unisa.it

2017-05-15

Highlights: • We generalize, in the realm of the Ginzburg–Landau theory, the de Gennes matching-matrix method for the interface order parameters to describe the superconducting properties of multi-band mesoscopic Josephson junctions. • The results are in agreement with a microscopic treatment of nanobridge junctions. • Thermal stability of the nanobridge junction is discussed in connection with recent experiments on iron-based grain-boundary junctions. - Abstract: A Ginzburg–Landau theory for multi-band mesoscopic Josephson junctions has been developed. The theory, obtained by generalizing the de Gennes matching-matrix method for the interface order parameters, allows the study of the phase dynamics of various types of mesoscopic Josephson junctions. As a relevant application, we studied mesoscopic double-band junctions also in the presence of a superconducting nanobridge interstitial layer. The results are in agreement with a microscopic treatment of the same system. Furthermore, thermal stability of the nanobridge junction is discussed in connection with recent experiments on iron-based grain-boundary junctions.

The influence of junction conformation on RNA cleavage by the hairpin ribozyme in its natural junction form.

Science.gov (United States)

Thomson, J B; Lilley, D M

1999-01-01

In the natural form of the hairpin ribozyme the two loop-carrying duplexes that comprise the majority of essential bases for activity form two adjacent helical arms of a four-way RNA junction. In the present work we have manipulated the sequence around the junction in a way known to perturb the global folding properties. We find that replacement of the junction by a different sequence that has the same conformational properties as the natural sequence gives closely similar reaction rate and Arrhenius activation energy for the substrate cleavage reaction. By comparison, rotation of the natural sequence in order to alter the three-dimensional folding of the ribozyme leads to a tenfold reduction in the kinetics of cleavage. Replacement with the U1 four-way junction that is resistant to rotation into the antiparallel structure required to allow interaction between the loops also gives a tenfold reduction in cleavage rate. The results indicate that the conformation of the junction has a major influence on the catalytic activity of the ribozyme. The results are all consistent with a role for the junction in the provision of a framework by which the loops are presented for interaction in order to create the active form of the ribozyme. PMID:10024170

Design of thin InGaAsN(Sb) n-i-p junctions for use in four-junction concentrating photovoltaic devices

Science.gov (United States)

Wilkins, Matthew M.; Gupta, James; Jaouad, Abdelatif; Bouzazi, Boussairi; Fafard, Simon; Boucherif, Abderraouf; Valdivia, Christopher E.; Arès, Richard; Aimez, Vincent; Schriemer, Henry P.; Hinzer, Karin

2017-04-01

Four-junction solar cells for space and terrestrial applications require a junction with a band gap of ˜1 eV for optimal performance. InGaAsN or InGaAsN(Sb) dilute nitride junctions have been demonstrated for this purpose, but in achieving the 14 mA/cm2 short-circuit current needed to match typical GaInP and GaAs junctions, the open-circuit voltage (VOC) and fill factor of these junctions are compromised. In multijunction devices incorporating materials with short diffusion lengths, we study the use of thin junctions to minimize sensitivity to varying material quality and ensure adequate transmission into lower junctions. An n-i-p device with 0.65-μm absorber thickness has sufficient short-circuit current, however, it relies less heavily on field-aided collection than a device with a 1-μm absorber. Our standard cell fabrication process, which includes a rapid thermal anneal of the contacts, yields a significant improvement in diffusion length and device performance. By optimizing a four-junction cell around a smaller 1-sun short-circuit current of 12.5 mA/cm2, we produced an InGaAsN(Sb) junction with open-circuit voltage of 0.44 V at 1000 suns (1 sun=100 mW/cm2), diode ideality factor of 1.4, and sufficient light transmission to allow >12.5 mA/cm2 in all four subcells.

Harmonic synchronization in resistively coupled Josephson junctions

International Nuclear Information System (INIS)

Blackburn, J.A.; Gronbech-Jensen, N.; Smith, H.J.T.

1994-01-01

The oscillations of two resistively coupled Josephson junctions biased only by a single dc current source are shown to lock harmonically in a 1:2 mode over a significant range of bias current, even when the junctions are identical. The dependence of this locking on both junction and coupling parameters is examined, and it is found that, for this particular two-junction configuration, 1:1 locking can never occur, and also that a minimum coupling coefficient is needed to support harmonic locking. Some issues related to subharmonic locking are also discussed

Allergic Contact Dermatitis to Benzoyl Peroxide Resembling Impetigo.

Science.gov (United States)

Kim, Changhyun; Craiglow, Brittany G; Watsky, Kalman L; Antaya, Richard J

2015-01-01

A 17-year-old boy presented with recurring severe dermatitis of the face of 5-months duration that resembled impetigo. He had been treated with several courses of antibiotics without improvement. Biopsy showed changes consistent with allergic contact dermatitis and patch testing later revealed sensitization to benzoyl peroxide, which the patient had been using for the treatment of acne vulgaris. © 2015 Wiley Periodicals, Inc.

Supramolecular Systems and Chemical Reactions in Single-Molecule Break Junctions.

Science.gov (United States)

Li, Xiaohui; Hu, Duan; Tan, Zhibing; Bai, Jie; Xiao, Zongyuan; Yang, Yang; Shi, Jia; Hong, Wenjing

2017-04-01

The major challenges of molecular electronics are the understanding and manipulation of the electron transport through the single-molecule junction. With the single-molecule break junction techniques, including scanning tunneling microscope break junction technique and mechanically controllable break junction technique, the charge transport through various single-molecule and supramolecular junctions has been studied during the dynamic fabrication and continuous characterization of molecular junctions. This review starts from the charge transport characterization of supramolecular junctions through a variety of noncovalent interactions, such as hydrogen bond, π-π interaction, and electrostatic force. We further review the recent progress in constructing highly conductive molecular junctions via chemical reactions, the response of molecular junctions to external stimuli, as well as the application of break junction techniques in controlling and monitoring chemical reactions in situ. We suggest that beyond the measurement of single molecular conductance, the single-molecule break junction techniques provide a promising access to study molecular assembly and chemical reactions at the single-molecule scale.

Effects of parenting quality on adolescents' personality resemblance to their parents. The TRAILS study.

Science.gov (United States)

Langenhof, M Rohaa; Komdeur, Jan; Oldehinkel, Albertine J

2016-08-01

This study considers the development of resemblance between 741 adolescents and their biological parents, across six NEO-PI-R personality traits known to be important in psychological problems: anger-hostility, impulsiveness, vulnerability, assertiveness, excitement-seeking, and self-discipline. We modelled the association between perceived parental warmth and rejection at age eleven and personality resemblance to parents at about age sixteen. Parenting experienced during early adolescence was related to the degree and direction in which adolescents resembled their parents five years later in life. Rejection, especially from fathers, significantly predicted a smaller resemblance to both the parents. Girls were more strongly affected by parental quality than boys, and there was some indication that adolescents responded in opposite ways to parenting from mothers and fathers. This study is a first step in uncovering the complex interplay between parenting, gender, and the current generation's ability to develop personality traits independent from the previous generation. Copyright © 2016 The Foundation for Professionals in Services for Adolescents. Published by Elsevier Ltd. All rights reserved.

Josephson junctions of multiple superconducting wires

Science.gov (United States)

Deb, Oindrila; Sengupta, K.; Sen, Diptiman

2018-05-01

We study the spectrum of Andreev bound states and Josephson currents across a junction of N superconducting wires which may have s - or p -wave pairing symmetries and develop a scattering matrix based formalism which allows us to address transport across such junctions. For N ≥3 , it is well known that Berry curvature terms contribute to the Josephson currents; we chart out situations where such terms can have relatively large effects. For a system of three s -wave or three p -wave superconductors, we provide analytic expressions for the Andreev bound-state energies and study the Josephson currents in response to a constant voltage applied across one of the wires; we find that the integrated transconductance at zero temperature is quantized to integer multiples of 4 e2/h , where e is the electron charge and h =2 π ℏ is Planck's constant. For a sinusoidal current with frequency ω applied across one of the wires in the junction, we find that Shapiro plateaus appear in the time-averaged voltage across that wire for any rational fractional multiple (in contrast to only integer multiples in junctions of two wires) of 2 e /(ℏ ω ) . We also use our formalism to study junctions of two p -wave and one s -wave wires. We find that the corresponding Andreev bound-state energies depend on the spin of the Bogoliubov quasiparticles; this produces a net magnetic moment in such junctions. The time variation of these magnetic moments may be controlled by an external voltage applied across the junction. We discuss experiments which may test our theory.

Molecular Diffusion through Cyanobacterial Septal Junctions.

Science.gov (United States)

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 N 2 -fixing heterocysts, regulators are transferred between cells. In the diazotrophic filament, vegetative cells that fix CO 2 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. Although bacteria are frequently considered just as unicellular organisms, there are bacteria that behave as true multicellular organisms. The heterocyst-forming cyanobacteria grow as filaments in which cells communicate. Intercellular molecular exchange is thought to be mediated by septal junctions. Here, we show that intercellular transfer of fluorescent markers in the cyanobacterial filament has the physical properties of simple diffusion. Thus, cyanobacterial septal junctions are functionally analogous to metazoan gap junctions

Josephson tunnel junctions in niobium films

International Nuclear Information System (INIS)

Wiik, Tapio.

1976-12-01

A method of fabricating stable Josephson tunnel junctions with reproducible characteristics is described. The junctions have a sandwich structure consisting of a vacuum evaporated niobium film, a niobium oxide layer produced by the glow discharge method and a lead film deposited by vacuum evaporation. Difficulties in producing thin-film Josephson junctions are discussed. Experimental results suggest that the lower critical field of the niobium film is the most essential parameter when evaluating the quality of these junctions. The dependence of the lower critical field on the film thickness and on the Ginzburg-Landau parameter of the film is studied analytically. Comparison with the properties of the evaporated films and with the previous calculations for bulk specimens shows that the presented model is applicable for most of the prepared samples. (author)

Josephson junctions with ferromagnetic alloy interlayer

Energy Technology Data Exchange (ETDEWEB)

Himmel, Nico

2015-07-23

Josephson junctions are used as active devices in superconducting electronics and quantum information technology. Outstanding properties are their distinct non-linear electrical characteristics and a usually sinusoidal relation between the current and the superconducting phase difference across the junction. In general the insertion of ferromagnetic material in the barrier of a Josephson junction is associated with a suppression of superconducting correlations. But also new phenomena can arise which may allow new circuit layouts and enhance the performance of applications. This thesis presents a systematic investigation for two concepts to fabricate Josephson junctions with a rather uncommon negative critical current. Such devices exhibit an intrinsic phase slip of π between the electrodes, so they are also known as π junctions. Both studies go well beyond existing experiments and in one system a π junction is shown for the first time. All the thin film junctions are based on superconducting Nb electrodes. In a first approach, barriers made from Si and Fe were investigated with respect to the realisation of π junctions by spin-flip processes. The distribution of Fe in the Si matrix was varied from pure layers to disperse compounds. The systematic fabrication of alloy barriers was facilitated by the development of a novel timing-based combinatorial sputtering technique for planetary deposition systems. An orthogonal gradient approach allowed to create binary layer libraries with independent variations of thickness and composition. Second, Nb vertical stroke AlO{sub x} vertical stroke Nb vertical stroke Ni{sub 60}Cu{sub 40} vertical stroke Nb (SIsFS) double barrier junctions were experimentally studied for the occurrence of proximity effect induced order parameter oscillations. Detailed dependencies of the critical current density on the thickness of s-layer and F-layer were acquired and show a remarkable agreement to existing theoretical predictions. Especially

Josephson junctions with ferromagnetic alloy interlayer

International Nuclear Information System (INIS)

Himmel, Nico

2015-01-01

Josephson junctions are used as active devices in superconducting electronics and quantum information technology. Outstanding properties are their distinct non-linear electrical characteristics and a usually sinusoidal relation between the current and the superconducting phase difference across the junction. In general the insertion of ferromagnetic material in the barrier of a Josephson junction is associated with a suppression of superconducting correlations. But also new phenomena can arise which may allow new circuit layouts and enhance the performance of applications. This thesis presents a systematic investigation for two concepts to fabricate Josephson junctions with a rather uncommon negative critical current. Such devices exhibit an intrinsic phase slip of π between the electrodes, so they are also known as π junctions. Both studies go well beyond existing experiments and in one system a π junction is shown for the first time. All the thin film junctions are based on superconducting Nb electrodes. In a first approach, barriers made from Si and Fe were investigated with respect to the realisation of π junctions by spin-flip processes. The distribution of Fe in the Si matrix was varied from pure layers to disperse compounds. The systematic fabrication of alloy barriers was facilitated by the development of a novel timing-based combinatorial sputtering technique for planetary deposition systems. An orthogonal gradient approach allowed to create binary layer libraries with independent variations of thickness and composition. Second, Nb vertical stroke AlO x vertical stroke Nb vertical stroke Ni 60 Cu 40 vertical stroke Nb (SIsFS) double barrier junctions were experimentally studied for the occurrence of proximity effect induced order parameter oscillations. Detailed dependencies of the critical current density on the thickness of s-layer and F-layer were acquired and show a remarkable agreement to existing theoretical predictions. Especially a variation of

Molecular series-tunneling junctions.

Science.gov (United States)

Liao, Kung-Ching; Hsu, Liang-Yan; Bowers, Carleen M; Rabitz, Herschel; Whitesides, George M

2015-05-13

Charge transport through junctions consisting of insulating molecular units is a quantum phenomenon that cannot be described adequately by classical circuit laws. This paper explores tunneling current densities in self-assembled monolayer (SAM)-based junctions with the structure Ag(TS)/O2C-R1-R2-H//Ga2O3/EGaIn, where Ag(TS) is template-stripped silver and EGaIn is the eutectic alloy of gallium and indium; R1 and R2 refer to two classes of insulating molecular units-(CH2)n and (C6H4)m-that are connected in series and have different tunneling decay constants in the Simmons equation. These junctions can be analyzed as a form of series-tunneling junctions based on the observation that permuting the order of R1 and R2 in the junction does not alter the overall rate of charge transport. By using the Ag/O2C interface, this system decouples the highest occupied molecular orbital (HOMO, which is localized on the carboxylate group) from strong interactions with the R1 and R2 units. The differences in rates of tunneling are thus determined by the electronic structure of the groups R1 and R2; these differences are not influenced by the order of R1 and R2 in the SAM. In an electrical potential model that rationalizes this observation, R1 and R2 contribute independently to the height of the barrier. This model explicitly assumes that contributions to rates of tunneling from the Ag(TS)/O2C and H//Ga2O3 interfaces are constant across the series examined. The current density of these series-tunneling junctions can be described by J(V) = J0(V) exp(-β1d1 - β2d2), where J(V) is the current density (A/cm(2)) at applied voltage V and βi and di are the parameters describing the attenuation of the tunneling current through a rectangular tunneling barrier, with width d and a height related to the attenuation factor β.

Performance of single-junction and dual-junction InGaP/GaAs solar cells under low concentration ratios

International Nuclear Information System (INIS)

Khan, Aurangzeb; Yamaguchi, Masafumi; Takamoto, Tatsuya

2004-01-01

A study of the performance of single-junction InGaP/GaAs and dual-junction InGaP/GaAs tandem cells under low concentration ratios (up to 15 suns), before and after 1 MeV electron irradiation is presented. Analysis of the tunnel junction parameters under different concentrated light illuminations reveals that the peak current (J P ) and valley current (J V ) densities should be greater than the short-circuit current density (J sc ) for better performance. The tunnel junction behavior against light intensity improved after irradiation. This led to the suggestion that the peak current density (J P ) and valley current density (J V ) of the tunnel junction were enhanced after irradiation or the peak current was shifted to higher concentration. The recovery of the radiation damage under concentrated light illumination conditions suggests that the performance of the InGaP/GaAs tandem solar cell can be enhanced even under low concentration ratios

Current noise in tunnel junctions

Energy Technology Data Exchange (ETDEWEB)

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

2017-06-15

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

Septation of infectious hyphae is critical for appressoria formation and virulence in the smut fungus Ustilago maydis.

Directory of Open Access Journals (Sweden)

Johannes Freitag

2011-05-01

Full Text Available Differentiation of hyphae into specialized infection structures, known as appressoria, is a common feature of plant pathogenic fungi that penetrate the plant cuticle. Appressorium formation in U. maydis is triggered by environmental signals but the molecular mechanism of this hyphal differentiation is largely unknown. Infectious hyphae grow on the leaf surface by inserting regularly spaced retraction septa at the distal end of the tip cell leaving empty sections of collapsed hyphae behind. Here we show that formation of retraction septa is critical for appressorium formation and virulence in U. maydis. We demonstrate that the diaphanous-related formin Drf1 is necessary for actomyosin ring formation during septation of infectious hyphae. Drf1 acts as an effector of a Cdc42 GTPase signaling module, which also consists of the Cdc42-specific guanine nucleotide exchange factor Don1 and the Ste20-like kinase Don3. Deletion of drf1, don1 or don3 abolished formation of retraction septa resulting in reduced virulence. Appressorium formation in these mutants was not completely blocked but infection structures were found only at the tip of short filaments indicating that retraction septa are necessary for appressorium formation in extended infectious hyphae. In addition, appressoria of drf1 mutants penetrated the plant tissue less frequently.

Septation of infectious hyphae is critical for appressoria formation and virulence in the smut fungus Ustilago maydis.

Science.gov (United States)

Freitag, Johannes; Lanver, Daniel; Böhmer, Christian; Schink, Kay Oliver; Bölker, Michael; Sandrock, Björn

2011-05-01

Differentiation of hyphae into specialized infection structures, known as appressoria, is a common feature of plant pathogenic fungi that penetrate the plant cuticle. Appressorium formation in U. maydis is triggered by environmental signals but the molecular mechanism of this hyphal differentiation is largely unknown. Infectious hyphae grow on the leaf surface by inserting regularly spaced retraction septa at the distal end of the tip cell leaving empty sections of collapsed hyphae behind. Here we show that formation of retraction septa is critical for appressorium formation and virulence in U. maydis. We demonstrate that the diaphanous-related formin Drf1 is necessary for actomyosin ring formation during septation of infectious hyphae. Drf1 acts as an effector of a Cdc42 GTPase signaling module, which also consists of the Cdc42-specific guanine nucleotide exchange factor Don1 and the Ste20-like kinase Don3. Deletion of drf1, don1 or don3 abolished formation of retraction septa resulting in reduced virulence. Appressorium formation in these mutants was not completely blocked but infection structures were found only at the tip of short filaments indicating that retraction septa are necessary for appressorium formation in extended infectious hyphae. In addition, appressoria of drf1 mutants penetrated the plant tissue less frequently.

Curved Josephson junction

International Nuclear Information System (INIS)

Dobrowolski, Tomasz

2012-01-01

The constant curvature one and quasi-one dimensional Josephson junction is considered. On the base of Maxwell equations, the sine–Gordon equation that describes an influence of curvature on the kink motion was obtained. It is showed that the method of geometrical reduction of the sine–Gordon model from three to lower dimensional manifold leads to an identical form of the sine–Gordon equation. - Highlights: ► The research on dynamics of the phase in a curved Josephson junction is performed. ► The geometrical reduction is applied to the sine–Gordon model. ► The results of geometrical reduction and the fundamental research are compared.

Josephson tunnel junctions with ferromagnetic interlayer

International Nuclear Information System (INIS)

Weides, M.P.

2006-01-01

Superconductivity and ferromagnetism are well-known physical properties of solid states that have been widely studied and long thought about as antagonistic phenomena due to difference in spin ordering. It turns out that the combination of both superconductor and ferromagnet leads to a very rich and interesting physics. One particular example, the phase oscillations of the superconducting order parameter inside the ferromagnet, will play a major role for the devices discussed in this work. In this thesis, I present Josephson junctions with a thin Al 2 O 3 tunnel barrier and a ferromagnetic interlayer, i.e. superconductor-insulator-ferromagnet-superconductor (SIFS) stacks. The fabrication of junctions was optimized regarding the insulation of electrodes and the homogeneity of the current transport. The junctions were either in the 0 or π coupled ground state, depending on the thickness of the ferromagnetic layer and on temperature. The influence of ferromagnetic layer thickness on the transport properties and the coupling (0, π) of SIFS tunnel junctions was studied. Furthermore, using a stepped ferromagnetic layer with well-chosen thicknesses, I obtained the so-called 0-π Josephson junction. At a certain temperature this 0-π junction can be made perfectly symmetric. In this case the ground state corresponds to a vortex of supercurrent creating a magnetic flux which is a fraction of the magnetic flux quantum Φ 0 . Such structures allow to study the physics of fractional vortices and to build various electronic circuits based on them. The SIFS junctions presented here have an exponentially vanishing damping at T → 0. The SIFS technology developed within the framework of this work may be used to construct classical and quantum devices such as oscillators, memory cells and qubits. (orig.)

Josephson tunnel junctions with ferromagnetic interlayer

Energy Technology Data Exchange (ETDEWEB)

Weides, M.P.

2006-07-01

Superconductivity and ferromagnetism are well-known physical properties of solid states that have been widely studied and long thought about as antagonistic phenomena due to difference in spin ordering. It turns out that the combination of both superconductor and ferromagnet leads to a very rich and interesting physics. One particular example, the phase oscillations of the superconducting order parameter inside the ferromagnet, will play a major role for the devices discussed in this work. In this thesis, I present Josephson junctions with a thin Al{sub 2}O{sub 3} tunnel barrier and a ferromagnetic interlayer, i.e. superconductor-insulator-ferromagnet-superconductor (SIFS) stacks. The fabrication of junctions was optimized regarding the insulation of electrodes and the homogeneity of the current transport. The junctions were either in the 0 or {pi} coupled ground state, depending on the thickness of the ferromagnetic layer and on temperature. The influence of ferromagnetic layer thickness on the transport properties and the coupling (0, {pi}) of SIFS tunnel junctions was studied. Furthermore, using a stepped ferromagnetic layer with well-chosen thicknesses, I obtained the so-called 0-{pi} Josephson junction. At a certain temperature this 0-{pi} junction can be made perfectly symmetric. In this case the ground state corresponds to a vortex of supercurrent creating a magnetic flux which is a fraction of the magnetic flux quantum {phi}{sub 0}. Such structures allow to study the physics of fractional vortices and to build various electronic circuits based on them. The SIFS junctions presented here have an exponentially vanishing damping at T {yields} 0. The SIFS technology developed within the framework of this work may be used to construct classical and quantum devices such as oscillators, memory cells and qubits. (orig.)

Mechanically Stacked Dual-Junction and Triple-Junction III-V/Si-IBC Cells with Efficiencies Exceeding 31.5% and 35.4%: Preprint

Energy Technology Data Exchange (ETDEWEB)

Schnabel, Manuel [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Tamboli, Adele C [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Warren, Emily L [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Schulte-Huxel, Henning [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Klein, Talysa [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Van Hest, Marinus F [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Geisz, John F [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Stradins, Paul [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Steiner, Myles A [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Rienaecker, Michael [Institute for Solar Energy Research Hamelin (ISFH); Merkle, Agnes [Institute for Solar Energy Research Hamelin (ISFH); Kajari-Schroeder, S. [Institute for Solar Energy Research Hamelin (ISFH); Niepelt, Raphael [Institute for Solar Energy Research Hamelin (ISFH); Schmidt, Jan [Institute for Solar Energy Research Hamelin (ISFH); Leibniz Universitat Hannover; Brendel, Rolf [Institute for Solar Energy Research Hamelin (ISFH); Leibniz Universitat Hannover; Peibst, Robby [Institute for Solar Energy Research Hamelin (ISFH); Leibniz Universitat Hannover

2017-10-02

Despite steady advancements in the efficiency of crystalline Silicon (c-Si) photovoltaics (PV) within the last decades, the theoretical efficiency limit of 29.4 percent depicts an insurmountable barrier for silicon-based single-junction solar cells. Combining the Si cell with a second absorber material on top in a dual junction tandem or triple junction solar cell is an attractive option to surpass this limit significantly. We demonstrate a mechanically stacked GaInP/Si dual-junction cell with an in-house measured efficiency of 31.5 percent and a GaInP/GaAs/Si triple-junction cell with a certified efficiency of 35.4 percent.

Familial Resemblance in Dietary Intakes of Children, Adolescents, and Parents

DEFF Research Database (Denmark)

Bogl, Leonie H.; Silventoinen, Karri; Hebestreit, Antje

2017-01-01

Information on familial resemblance is important for the design of effective family-based interventions. We aimed to quantify familial correlations and estimate the proportion of variation attributable to genetic and shared environmental effects (i.e., familiality) for dietary intake variables an...

Electromagnetic waves in single- and multi-Josephson junctions

International Nuclear Information System (INIS)

Matsumoto, Hideki; Koyama, Tomio; Machida, Masahiko

2008-01-01

The terahertz wave emission from the intrinsic Josephson junctions is one of recent topics in high T c superconductors. We investigate, by numerical simulation, properties of the electromagnetic waves excited by a constant bias current in the single- and multi-Josephson junctions. Nonlinear equations of phase-differences are solved numerically by treating the effects of the outside electromagnetic fields as dynamical boundary conditions. It is shown that the emitted power of the electromagnetic wave can become large near certain retrapping points of the I-V characteristics. An instability of the inside phase oscillation is related to large amplitude of the oscillatory waves. In the single- (or homogeneous mutli-) Josephson junctions, electromagnetic oscillations can occur either in a form of standing waves (shorter junctions) or by formation of vortex-antivortex pairs (longer junctions). How these two effects affects the behavior of electromagnetic waves in the intrinsic Josephson junctions is discussed

Tunable Nitride Josephson Junctions.

Energy Technology Data Exchange (ETDEWEB)

Missert, Nancy A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Henry, Michael David [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lewis, Rupert M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Howell, Stephen W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Wolfley, Steven L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Brunke, Lyle Brent [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Wolak, Matthaeus [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2017-12-01

We have developed an ambient temperature, SiO₂/Si wafer - scale process for Josephson junctions based on Nb electrodes and Ta x N barriers with tunable electronic properties. The films are fabricated by magnetron sputtering. The electronic properties of the Ta_xN barriers are controlled by adjusting the nitrogen flow during sputtering. This technology offers a scalable alternative to the more traditional junctions based on AlO_x barriers for low - power, high - performance computing.

Scattering theory of superconductive tunneling in quantum junctions

International Nuclear Information System (INIS)

Shumeiko, V.S.; Bratus', E.N.

1997-01-01

A consistent theory of superconductive tunneling in single-mode junctions within a scattering formulation of Bogolyubov-de Gennes quantum mechanics is presented. The dc Josephson effect and dc quasiparticle transport in the voltage-biased junctions are considered. Elastic quasiparticle scattering by the junction determines the equilibrium Josephson current. The origin of Andreev bound states in tunnel junctions and their role in equilibrium Josephson transport are discussed. In contrast, quasiparticle tunneling in voltage-biased junctions is determined by inelastic scattering. A general expression for inelastic scattering amplitudes is derived and the quasiparticle current is calculated at all voltages with emphasis on a discussion of the properties of sub gap tunnel current and the nature of subharmonic gap structure

Archaic artifacts resembling celestial spheres

Science.gov (United States)

Dimitrakoudis, S.; Papaspyrou, P.; Petoussis, V.; Moussas, X.

We present several bronze artifacts from the Archaic Age in Greece (750-480 BC) that resemble celestial spheres or forms of other astronomical significance. They are studied in the context of the Dark Age transition from Mycenaean Age astronomical themes to the philosophical and practical revival of astronomy in the Classical Age with its plethora of astronomical devices. These artifacts, mostly votive in nature are spherical in shape and appear in a variety of forms their most striking characteristic being the depiction of meridians and/or an equator. Most of those artifacts come from Thessaly, and more specifically from the temple of Itonia Athena at Philia, a religious center of pan-Hellenic significance. Celestial spheres, similar in form to the small artifacts presented in this study, could be used to measure latitudes, or estimate the time at a known place, and were thus very useful in navigation.

Partners in health? Exploring resemblance in health between partners in married and cohabiting couples.

Science.gov (United States)

Monden, Christiaan

2007-04-01

Sociological theories on family formation and families and health suggest that married and cohabiting partners will resemble each other in health status, positively or negatively. The family is often seen as a health-enhancing agent for individuals. However, there are large health differences among families. This study aims to answer the question whether it is the case that the healthy live with the healthy and individuals with poor health have partners who are also in poor health. Moreover, it examines whether resemblance in health is a consequence of partner choice--educational homogamy in particular--behaviour or shared circumstances. Younger and older couples are compared to investigate whether health resemblance increases over the lifecourse. Analyses of a nationally representative sample of almost 12,000 Dutch couples show that partners are indeed significantly alike with regard to several health indicators. Respondents whose partner reports poor health are almost three times more likely to report poor health than respondents whose partner is in good health. There is a strong accumulation of health problems within households. Partner selection with regard to education causes part of the partner resemblance in health. Less support is found for the hypotheses that risk behaviour, mutual influence or the effects of shared circumstances cause similarity between partners' health status. Surprisingly, partners in older couples, who have been together for a longer time, do not resemble each other significantly more than partners in younger couples. The implications of these findings for sociological theory and social inequalities in health are discussed.

The Texas Adoption Project: adopted children and their intellectual resemblance to biological and adoptive parents.

Science.gov (United States)

Horn, J M

1983-04-01

Intelligence test scores were obtained from parents and children in 300 adoptive families and compared with similar measures available for the biological mothers of the same adopted children. Results supported the hypothesis that genetic variability is an important influence in the development of individual differences for intelligence. The most salient finding was that adopted children resemble their biological mothers more than they resemble the adoptive parents who reared them from birth. A small subset of the oldest adopted children did not resemble their biological mothers. The suggestion that the influence of genes declines with age is treated with caution since other adoption studies report a trend in the opposite direction.

Short chain molecular junctions: Charge transport versus dipole moment

International Nuclear Information System (INIS)

Ikram, I. Mohamed; Rabinal, M.K.

2015-01-01

Graphical abstract: - Highlights: • The role of dipole moment of organic molecules on molecular junctions has been studied. • Molecular junctions constituted using propargyl molecules of different dipole moments. • The electronic properties of the molecules were calculated using Gaussian software. • Junctions show varying rectification due to their varying dipole moment and orientation. - Abstract: The investigation of the influence of dipole moment of short chain organic molecules having three carbon atoms varying in end group on silicon surface was carried on. Here, we use three different molecules of propargyl series varying in dipole moment and its orientation to constitute molecular junctions. The charge transport mechanism in metal–molecules–semiconductor (MMS) junction obtained from current–voltage (I–V) characteristics shows the rectification behavior for two junctions whereas the other junction shows a weak rectification. The electronic properties of the molecules were calculated using Gaussian software package. The observed rectification behavior of these junctions is examined and found to be accounted to the orientation of dipole moment and electron cloud density distribution inside the molecules

The challenge of unravelling family resemblance related to illness behaviour.

NARCIS (Netherlands)

Cardol, M.; Groenewegen, P.P.; Spreeuwenberg, P.; Dijk, L. van; Bosch, W. van den; Bakker, D.H. de

2005-01-01

Background: Efforts to promote health or prevent disease may conflict with patients’ habits at home. Irrespective of the national setting, families are important social contexts in which illness occurs and resolves. Family members resemble each other in their illness behaviour, even across

Some chaotic features of intrinsically coupled Josephson junctions

International Nuclear Information System (INIS)

Kolahchi, M.R.; Shukrinov, Yu.M.; Hamdipour, M.; Botha, A.E.; Suzuki, M.

2013-01-01

Highlights: ► Intrinsically coupled Josephson junctions model a high-T c superconductor. ► Intrinsically coupled Josephson junctions can act as a chaotic nonlinear system. ► Chaos could be due to resonance overlap. ► Avoiding parameters that lead to chaos is important for the design of resonators. -- Abstract: We look for chaos in an intrinsically coupled system of Josephson junctions. This study has direct applications for the high-T c resonators which require coherence amongst the junctions

Gap junctions and connexin-interacting proteins

NARCIS (Netherlands)

Giepmans, Ben N G

2004-01-01

Gap junctions form channels between adjacent cells. The core proteins of these channels are the connexins. Regulation of gap junction communication (GJC) can be modulated by connexin-associating proteins, such as regulatory protein phosphatases and protein kinases, of which c-Src is the

Planar Josephson tunnel junctions in a transverse magnetic field

DEFF Research Database (Denmark)

Monacoa, R.; Aarøe, Morten; Mygind, Jesper

2007-01-01

demagnetization effects imposed by the tunnel barrier and electrodes geometry are important. Measurements of the junction critical current versus magnetic field in planar Nb-based high-quality junctions with different geometry, size, and critical current density show that it is advantageous to use a transverse......Traditionally, since the discovery of the Josephson effect in 1962, the magnetic diffraction pattern of planar Josephson tunnel junctions has been recorded with the field applied in the plane of the junction. Here we discuss the static junction properties in a transverse magnetic field where...

Traumatic funicular phlebitis of the thoracic wall resembling Mondor's disease: a case report

Directory of Open Access Journals (Sweden)

Kondo Takeshi

2011-03-01

Full Text Available Abstract Introduction Mondor's disease is a peculiar form of thrombophlebitis, involving a superficial vein in the subcutaneous fat of the breast or anterior chest wall. Case presentation The author presents a case of a 35-year-old male Japanese patient with cord-like induration in the right lateral thoracic wall. This lesion was diagnosed as traumatic funicular phlebitis, resembling Mondor's disease. Conclusion Traumatic funicular phlebitis, resembling Mondor's disease, is a clinical entity which may give suggestive insight to the etiology of Mondor's disease itself.

Particle detection with superconducting tunnel junctions

International Nuclear Information System (INIS)

Jany, P.

1990-08-01

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

Photo-electrochemical solar cells with a SnO/sub 2/-liquid junction sensitized with highly concentrated dyes

Energy Technology Data Exchange (ETDEWEB)

Shimura, Michiko; Shakushiro, Kiyoaki; Shimura, Yukio

1986-09-01

The sensitization of a SnO/sub 2/-liquid junction cell with highly concentrated dyes was investigated. The dyes used were Crystal Violet, Methyl Violet B, Malachite Green, Pararosaniline, and Rhodamine B. Anomalous or positive photovoltages were obtained in the system when Fe(CN)/sub 6//sup 3 -/ was added. The performance of the photovoltaic cells showed an open-circuit photovoltage, Vsub(oc), of 175 mV, a short-circuit photocurrent, Isub(sc), of 12 ..mu..A, and a fill factor of 0.42. The action spectra resembled the absorption spectra of the aggregated dyes. A D-D mechanism is introduced to explain the anomaly of the photovoltage of the SnO/sub 2/ electrode sensitized with the dyes. This behaviour is relevant to the practical usage of such photo-electrochemical cells and merits further investigation.

Effect of solar-cell junction geometry on open-circuit voltage

Science.gov (United States)

Weizer, V. G.; Godlewski, M. P.

1985-01-01

Simple analytical models have been found that adequately describe the voltage behavior of both the stripe junction and dot junction grating cells as a function of junction area. While the voltage in the former case is found to be insensitive to junction area reduction, significant voltage increases are shown to be possible for the dot junction cell. With regard to cells in which the junction area has been increased in a quest for better performance, it was found that (1) texturation does not affect the average saturation current density J0, indicating that the texturation process is equivalent to a simple extension of junction area by a factor of square root of 3 and (2) the vertical junction cell geometry produces a sizable decrease in J0 that, unfortunately, is more than offset by the effects of attendant areal increases.

Advance of Mechanically Controllable Break Junction for Molecular Electronics.

Science.gov (United States)

Wang, Lu; Wang, Ling; Zhang, Lei; Xiang, Dong

2017-06-01

Molecular electronics stands for the ultimate size of functional elements, keeping up with an unstoppable trend over the past few decades. As a vital component of molecular electronics, single molecular junctions have attracted significant attention from research groups all over the world. Due to its pronounced superiority, the mechanically controllable break junctions (MCBJ) technique has been widely applied to characterize the dynamic performance of single molecular junctions. This review presents a system analysis for single-molecule junctions and offers an overview of four test-beds for single-molecule junctions, thus offering more insight into the mechanisms of electron transport. We mainly focus on the development of state-of-the-art mechanically controlled break junctions. The three-terminal gated MCBJ approaches are introduced to manipulate the electron transport of molecules, and MCBJs are combined with characterization techniques. Additionally, applications of MCBJs and remarkable properties of single molecules are addressed. Finally, the challenges and perspective for the mechanically controllable break junctions technique are provided.

Microwave phase locking of Josephson-junction fluxon oscillators

DEFF Research Database (Denmark)

Salerno, M.; Samuelsen, Mogens Rugholm; Filatrella, G.

1990-01-01

Application of the classic McLaughlin-Scott soliton perturbation theory to a Josephson-junction fluxon subjected to a microwave field that interacts with the fluxon only at the junction boundaries reduces the problem of phase locking of the fluxon oscillation to the study of a two-dimensional fun......Application of the classic McLaughlin-Scott soliton perturbation theory to a Josephson-junction fluxon subjected to a microwave field that interacts with the fluxon only at the junction boundaries reduces the problem of phase locking of the fluxon oscillation to the study of a two...

The critical current of point symmetric Josephson tunnel junctions

International Nuclear Information System (INIS)

Monaco, Roberto

2016-01-01

Highlights: • We disclose some geometrical properties of the critical current field dependence that apply to a large class of Josephson junctions characterized by a point symmetric shape. • The developed theory is valid for any orientation of the applied magnetic field, therefore it allows the determine the consequences of field misalignment in the experimental setups. • We also address that the threshold curves of Josephson tunnel junctions with complex shapes can be expressed as a linear combination of the threshold curves of junctions with simpler point symmetric shapes. - Abstract: The physics of Josephson tunnel junctions drastically depends on their geometrical configurations. The shape of the junction determines the specific form of the magnetic-field dependence of its Josephson current. Here we address the magnetic diffraction patterns of specially shaped planar Josephson tunnel junctions in the presence of an in-plane magnetic field of arbitrary orientations. We focus on a wide ensemble of junctions whose shape is invariant under point reflection. We analyze the implications of this type of isometry and derive the threshold curves of junctions whose shape is the union or the relative complement of two point symmetric plane figures.

Solar cell junction temperature measurement of PV module

KAUST Repository

Huang, B.J.

2011-02-01

The present study develops a simple non-destructive method to measure the solar cell junction temperature of PV module. The PV module was put in the environmental chamber with precise temperature control to keep the solar PV module as well as the cell junction in thermal equilibrium with the chamber. The open-circuit voltage of PV module Voc is then measured using a short pulse of solar irradiation provided by a solar simulator. Repeating the measurements at different environment temperature (40-80°C) and solar irradiation S (200-1000W/m2), the correlation between the open-circuit voltage Voc, the junction temperature Tj, and solar irradiation S is derived.The fundamental correlation of the PV module is utilized for on-site monitoring of solar cell junction temperature using the measured Voc and S at a short time instant with open circuit. The junction temperature Tj is then determined using the measured S and Voc through the fundamental correlation. The outdoor test results show that the junction temperature measured using the present method, Tjo, is more accurate. The maximum error using the average surface temperature Tave as the junction temperature is 4.8 °C underestimation; while the maximum error using the present method is 1.3 °C underestimation. © 2010 Elsevier Ltd.

Soliton excitations in Josephson tunnel junctions

DEFF Research Database (Denmark)

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

1982-01-01

A detailed numerical study of a sine-Gordon model of the Josephson tunnel junction is compared with experimental measurements on junctions with different L / λJ ratios. The soliton picture is found to apply well on both relatively long (L / λJ=6) and intermediate (L / λJ=2) junctions. We find good...... agreement for the current-voltage characteristics, power output, and for the shape and height of the zero-field steps (ZFS). Two distinct modes of soliton oscillations are observed: (i) a bunched or congealed mode giving rise to the fundamental frequency f1 on all ZFS's and (ii) a "symmetric" mode which...... on the Nth ZFS yields the frequency Nf1 Coexistence of two adjacent frequencies is found on the third ZFS of the longer junction (L / λJ=6) in a narrow range of bias current as also found in the experiments. Small asymmetries in the experimental environment, a weak magnetic field, e.g., is introduced via...

Constructing carbon nanotube junctions by Ar ion beam irradiation

International Nuclear Information System (INIS)

Ishaq, Ahmad; Ni Zhichun; Yan Long; Gong Jinlong; Zhu Dezhang

2010-01-01

Carbon nanotubes (CNTs) irradiated by Ar ion beams at elevated temperature were studied. The irradiation-induced defects in CNTs are greatly reduced by elevated temperature. Moreover, the two types of CNT junctions, the crossing junction and the parallel junction, were formed. And the CNT networks may be fabricated by the two types of CNT junctions. The formation process and the corresponding mechanism of CNT networks are discussed.

Field modulation of the critical current in magnetic Josephson junctions

International Nuclear Information System (INIS)

Blamire, M G; Smiet, C B; Banerjee, N; Robinson, J W A

2013-01-01

The dependence of the critical current of a simple Josephson junction on the applied magnetic field is well known and, for a rectangular junction, gives rise to the classic ‘Fraunhofer’ modulation with periodic zeros at the fields that introduce a flux quantum into the junction region. Much recent work has been performed on Josephson junctions that contain magnetic layers. The magnetization of such layers introduces additional flux into the junction and, for large junction areas or strong magnetic materials, can significantly distort the modulation of the critical current and strongly suppress the maximum critical current. The growing interest in junctions that induce odd-frequency triplet pairing in a ferromagnet, and the need to make quantitative comparisons with theory, mean that a full understanding of the role of magnetic barriers in controlling the critical current is necessary. This paper analyses the effect of magnetism and various magnetic configurations on Josephson critical currents; the overall treatment applies to junctions of general shape, but the specific cases of square and rectangular junctions are considered. (paper)

Shunted-Josephson-junction model. II. The nonautonomous case

DEFF Research Database (Denmark)

Belykh, V. N.; Pedersen, Niels Falsig; Sørensen, O. H.

1977-01-01

The shunted-Josephson-junction model with a monochromatic ac current drive is discussed employing the qualitative methods of the theory of nonlinear oscillations. As in the preceding paper dealing with the autonomous junction, the model includes a phase-dependent conductance and a shunt capacitance....... The mathematical discussion makes use of the phase-space representation of the solutions to the differential equation. The behavior of the trajectories in phase space is described for different characteristic regions in parameter space and the associated features of the junction IV curve to be expected are pointed...... out. The main objective is to provide a qualitative understanding of the junction behavior, to clarify which kinds of properties may be derived from the shunted-junction model, and to specify the relative arrangement of the important domains in the parameter-space decomposition....

Observation of supercurrent in graphene-based Josephson junction

Energy Technology Data Exchange (ETDEWEB)

Wang, Libin; Li, Sen; Kang, Ning [Key Laboratory for the Physics and Chemistry of Nanodevices and Department of Electronics, Peking University, Beijing 100871 (China); Xu, Chuan; Ren, Wencai [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China)

2015-07-01

Josephson junctions with a normal metal region sandwiched between two superconductors (S) are known as superconductor- normal-superconductor (SNS) structures. It has attracted significant attention especially when changing the normal metal with graphene, which allow for high tunability with the gate voltage and to study the proximity effect of the massless Dirac fermions. Here we report our work on graphene-based Josephson junction with a new two dimensional superconductor crystal, which grown directly on graphene, as superconducting electrodes. At low temperature, we observer proximity effect induced supercurrent flowing through the junction. The temperature and the magnetic field dependences of the critical current characteristics of the junction are also studied. The critical current exhibits a Fraunhofer-type diffraction pattern against magnetic field. Our experiments provided a new route of fabrication of graphene-based Josephson junction.

RESEMBLANCE OF INDIRECTNESS IN POLITENESS OF EFL LEARNERS’ REQUEST REALIZATIONS

Directory of Open Access Journals (Sweden)

Indawan Syahri

2013-07-01

Full Text Available Abstract: Politeness principles are universally utilized by the speakers of any language when realizing various speech acts. However, the speakers of particular languages relatively apply politeness due to the cultural norms embedded. The present study attempts to delineate how the Indonesian learners of English (ILE apply the politeness principles in request realizations. Specifically it devotes to the types of politeness strategies applied and resemblance of the indirectness in politeness strategies in requesting acts. The FTAs and indirectness are the theoretical bases used to trace the typologies of both politeness and request strategies. The data werere collected by means of certain elicitation techniques, i.e. DCTs and Role-plays. The analyses werere done through three stages; determining request strategies, politeness strategies, and resemblance of indirectness in politeness. The results show that the indirectness generally is parallel to politeness. Besides, some pragmatic transfers are found in terms of applying native-culture norms in realizing target speech acts.

Josephson junction arrays and superconducting wire networks

International Nuclear Information System (INIS)

Lobb, C.J.

1992-01-01

Techniques used to fabricate integrated circuits make it possible to construct superconducting networks containing as many as 10 6 wires or Josephson junctions. Such networks undergo phase transitions from resistive high-temperature states to ordered low-resistance low-temperature states. The nature of the phase transition depends strongly on controllable parameters such as the strength of the superconductivity in each wire or junction and the external magnetic field. This paper will review the physics of these phase transitions, starting with the simplest zero-magnetic field case. This leads to a Kosterlitz-Thouless transition when the junctions or wires are weak, and a simple mean-field fransition when the junctions or wires are strong. Rich behavior, resulting from frustration, occurs in the presence of a magnetic field. (orig.)

Phenomenological approach to bistable behavior of Josephson junctions

International Nuclear Information System (INIS)

Nishi, K.; Nara, S.; Hamanaka, K.

1985-01-01

The interaction of unbiased Josephson junction with external electromagnetic field in the presence of externally applied uniform magnetic field is theoretically examined by means of phenomenological treatment. It is proposed that an irradiated junction with suitably chosen parameters shows a bistable behavior of voltage across the junction as a function of the radiation intensity

Multiplication in Silicon p-n Junctions

DEFF Research Database (Denmark)

Moll, John L.

1965-01-01

Multiplication values were measured in the collector junctions of silicon p-n-p and n-p-n transistors before and after bombardment by 1016 neutrons/cm2. Within experimental error there was no change either in junction fields, as deduced from capacitance measurements, or in multiplication values i...

Anchored PKA as a gatekeeper for gap junctions.

Science.gov (United States)

Pidoux, Guillaume; Taskén, Kjetil

2015-01-01

Anchored protein kinase A (PKA) bound to A Kinase Anchoring Protein (AKAP) mediates effects of localized increases in cAMP in defined subcellular microdomains and retains the specificity in cAMP-PKA signaling to distinct extracellular stimuli. Gap junctions are pores between adjacent cells constituted by connexin proteins that provide means of communication and transfer of small molecules. While the PKA signaling is known to promote human trophoblast cell fusion, the gap junction communication through connexin 43 (Cx43) is a prerequisite for this process. We recently demonstrated that trophoblast fusion is regulated by ezrin, a known AKAP, which binds to Cx43 and delivers PKA in the vicinity gap junctions. We found that disruption of the ezrin-Cx43 interaction abolished PKA-dependent phosphorylation of Cx43 as well as gap junction communication and subsequently cell fusion. We propose that the PKA-ezrin-Cx43 macromolecular complex regulating gap junction communication constitutes a general mechanism to control opening of Cx43 gap junctions by phosphorylation in response to cAMP signaling in various cell types.

Heat Transport in Graphene Ferromagnet-Insulator-Superconductor Junctions

Institute of Scientific and Technical Information of China (English)

LI Xiao-Wei

2011-01-01

We study heat transport in a graphene ferromagnet-insulator-superconducting junction. It is found that the thermal conductance of the graphene ferromagnet-insulator-superconductor (FIS) junction is an oscillatory function of the barrier strength x in the thin-barrier limit. The gate potential U0 decreases the amplitude of thermal conductance oscillation. Both the amplitude and phase of the thermal conductance oscillation varies with the exchange energy Eh. The thermal conductance of a graphene FIS junction displays the usual exponential dependence on temperature, reflecting the s-wave symmetry of superconducting graphene.%@@ We study heat transport in a graphene ferromagnet-insulator-superconducting junction.It is found that the thermal conductance of the graphene ferromagnet-insulator-superconductor(FIS)junction is an oscillatory function of the barrier strength X in the thin-barrier limit.The gate potential Uo decreases the amplitude of thermal conductance oscillation.Both the amplitude and phase of the thermal conductance oscillation varies with the exchange energy Eh.The thermal conductance of a graphene FIS junction displays the usual exponential dependence on temperature, reflecting the s-wave symmetry of superconducting graphene.

Terahertz Responses of Intrinsic Josephson Junctions in High TC Superconductors

International Nuclear Information System (INIS)

Wang, H. B.; Wu, P. H.; Yamashita, T.

2001-01-01

High frequency responses of intrinsic Josephson junctions up to 2.5THz, including the observation of Shapiro steps under various conditions, are reported and discussed in this Letter. The sample was an array of intrinsic Josephson junctions singled out from inside a high T C superconducting Bi 2 Sr 2 CaCu 2 O 8+x single crystal, with a bow-tie antenna integrated to it. The number of junctions in the array was controllable, the junctions were homogeneous, the distribution of applied irradiation among the junctions was even, and the junctions could synchronously respond to high frequency irradiation

Long Josephson Junction Stack Coupled to a Cavity

DEFF Research Database (Denmark)

Madsen, Søren Peder; Pedersen, Niels Falsig; Groenbech-Jensen, N.

2007-01-01

A stack of inductively coupled long Josephson junctions are modeled as a system of coupled sine-Gordon equations. One boundary of the stack is coupled electrically to a resonant cavity. With one fluxon in each Josephson junction, the inter-junction fluxon forces are repulsive. We look at a possible...... transition, induced by the cavity, to a bunched state....

Structural Origins of Conductance Fluctuations in Gold–Thiolate Molecular Transport Junctions

KAUST Repository

French, William R.

2013-03-21

We report detailed atomistic simulations combined with high-fidelity conductance calculations to probe the structural origins of conductance fluctuations in thermally evolving Au-benzene-1,4-dithiolate-Au junctions. We compare the behavior of structurally ideal junctions (where the electrodes are modeled as flat surfaces) to structurally realistic, experimentally representative junctions resulting from break-junction simulations. The enhanced mobility of metal atoms in structurally realistic junctions results in significant changes to the magnitude and origin of the conductance fluctuations. Fluctuations are larger by a factor of 2-3 in realistic junctions compared to ideal junctions. Moreover, in junctions with highly deformed electrodes, the conductance fluctuations arise primarily from changes in the Au geometry, in contrast to results for junctions with nondeformed electrodes, where the conductance fluctuations are dominated by changes in the molecule geometry. These results provide important guidance to experimentalists developing strategies to control molecular conductance, and also to theoreticians invoking simplified structural models of junctions to predict their behavior. © 2013 American Chemical Society.

Structural Origins of Conductance Fluctuations in Gold–Thiolate Molecular Transport Junctions

KAUST Repository

French, William R.; Iacovella, Christopher R.; Rungger, Ivan; Souza, Amaury Melo; Sanvito, Stefano; Cummings, Peter T.

2013-01-01

We report detailed atomistic simulations combined with high-fidelity conductance calculations to probe the structural origins of conductance fluctuations in thermally evolving Au-benzene-1,4-dithiolate-Au junctions. We compare the behavior of structurally ideal junctions (where the electrodes are modeled as flat surfaces) to structurally realistic, experimentally representative junctions resulting from break-junction simulations. The enhanced mobility of metal atoms in structurally realistic junctions results in significant changes to the magnitude and origin of the conductance fluctuations. Fluctuations are larger by a factor of 2-3 in realistic junctions compared to ideal junctions. Moreover, in junctions with highly deformed electrodes, the conductance fluctuations arise primarily from changes in the Au geometry, in contrast to results for junctions with nondeformed electrodes, where the conductance fluctuations are dominated by changes in the molecule geometry. These results provide important guidance to experimentalists developing strategies to control molecular conductance, and also to theoreticians invoking simplified structural models of junctions to predict their behavior. © 2013 American Chemical Society.

Silicon fiber with p-n junction

International Nuclear Information System (INIS)

Homa, D.; Cito, A.; Pickrell, G.; Hill, C.; Scott, B.

2014-01-01

In this study, we fabricated a p-n junction in a fiber with a phosphorous doped silicon core and fused silica cladding. The fibers were fabricated via a hybrid process of the core-suction and melt-draw techniques and maintained overall diameters ranging from 200 to 900 μm and core diameters of 20–800 μm. The p-n junction was formed by doping the fiber with boron and confirmed via the current-voltage characteristic. The demonstration of a p-n junction in a melt-drawn silicon core fiber paves the way for the seamless integration of optical and electronic devices in fibers.

Quasiparticle current in superconductor-semiconductor-superconductor junctions

International Nuclear Information System (INIS)

Tartakovskij, A.V.; Fistul', M.V.

1988-01-01

It is shown that the quasiparticle current in a superconductor-semiconductor-superconductor junction may significantly increase as a result of resonant passage of the quasiparticle along particular trajectories from periodically situated localized centers. A prediction of the theory is that with increasing junction resistance there should be a change from an excessive current to a insufficient current on the current-voltage characteristics (at high voltages). The effect of transparency of the boundaries on resonance tunneling in such junctions is also investigated

Evidence for biotrophic lifestyle and biocontrol potential of dark septate endophyte Harpophora oryzae to rice blast disease.

Directory of Open Access Journals (Sweden)

Zhen-Zhu Su

Full Text Available The mutualism pattern of the dark septate endophyte (DSE Harpophora oryzae in rice roots and its biocontrol potential in rice blast disease caused by Magnaporthe oryzae were investigated. Fluorescent protein-expressing H. oryzae was used to monitor the colonization pattern. Hyphae invaded from the epidermis to the inner cortex, but not into the root stele. Fungal colonization increased with root tissue maturation, showing no colonization in the meristematic zone, slight colonization in the elongation zone, and heavy colonization in the differentiation zone. H. oryzae adopted a biotrophic lifestyle in roots accompanied by programmed cell death. Real-time PCR facilitated the accurate quantification of fungal growth and the respective plant response. The biocontrol potential of H. oryzae was visualized by inoculation with eGFP-tagged M. oryzae in rice. H. oryzae protected rice from M. oryzae root invasion by the accumulation of H2O2 and elevated antioxidative capacity. H. oryzae also induced systemic resistance against rice blast. This systemic resistance was mediated by the OsWRKY45-dependent salicylic acid (SA signaling pathway, as indicated by the strongly upregulated expression of OsWRKY45. The colonization pattern of H. oryzae was consistent with the typical characteristics of DSEs. H. oryzae enhanced local resistance by reactive oxygen species (ROS and high antioxidative level and induced OsWRKY45-dependent SA-mediated systemic resistance against rice blast.

Transport properties of molecular junctions

CERN Document Server

Zimbovskaya, Natalya A

2013-01-01

A comprehensive overview of the physical mechanisms that control electron transport and the characteristics of metal-molecule-metal (MMM) junctions is presented. As far as possible, methods and formalisms presented elsewhere to analyze electron transport through molecules are avoided. This title introduces basic concepts—a description of the electron transport through molecular junctions—and briefly describes relevant experimental methods. Theoretical methods commonly used to analyze the electron transport through molecules are presented. Various effects that manifest in the electron transport through MMMs, as well as the basics of density-functional theory and its applications to electronic structure calculations in molecules are presented. Nanoelectronic applications of molecular junctions and similar systems are discussed as well. Molecular electronics is a diverse and rapidly growing field. Transport Properties of Molecular Junctions presents an up-to-date survey of the field suitable for researchers ...

Spatial inhomogeneous barrier heights at graphene/semiconductor Schottky junctions

Science.gov (United States)

Tomer, Dushyant

Graphene, a semimetal with linear energy dispersion, forms Schottky junction when interfaced with a semiconductor. This dissertation presents temperature dependent current-voltage and scanning tunneling microscopy/spectroscopy (STM/S) measurements performed on graphene Schottky junctions formed with both three and two dimensional semiconductors. To fabricate Schottky junctions, we transfer chemical vapor deposited monolayer graphene onto Si- and C-face SiC, Si, GaAs and MoS2 semiconducting substrates using polymer assisted chemical method. We observe three main type of intrinsic spatial inhomogeneities, graphene ripples, ridges and semiconductor steps in STM imaging that can exist at graphene/semiconductor junctions. Tunneling spectroscopy measurements reveal fluctuations in graphene Dirac point position, which is directly related to the Schottky barrier height. We find a direct correlation of Dirac point variation with the topographic undulations of graphene ripples at the graphene/SiC junction. However, no such correlation is established at graphene/Si and Graphene/GaAs junctions and Dirac point variations are attributed to surface states and trapped charges at the interface. In addition to graphene ripples and ridges, we also observe atomic scale moire patterns at graphene/MoS2 junction due to van der Waals interaction at the interface. Periodic topographic modulations due to moire pattern do not lead to local variation in graphene Dirac point, indicating that moire pattern does not contribute to fluctuations in electronic properties of the heterojunction. We perform temperature dependent current-voltage measurements to investigate the impact of topographic inhomogeneities on electrical properties of the Schottky junctions. We observe temperature dependence in junction parameters, such as Schottky barrier height and ideality factor, for all types of Schottky junctions in forward bias measurements. Standard thermionic emission theory which assumes a perfect

Spontaneous de novo vaginal adenosis resembling Bartholin’s ...

African Journals Online (AJOL)

Adebayo Alade Adewole

Spontaneous de novo vaginal adenosis resembling Bartholin's cyst: A case report ... 6 by 5 cm. The cervix, uterus, adnexa and Pouch of Douglas (POD) were normal. .... of vaginal cancer.2–4 Although, DES exposed daughters have an.

Systematic study of shallow junction formation on germanium substrates

DEFF Research Database (Denmark)

Hellings, Geert; Rosseel, Erik; Clarysse, Trudo

2011-01-01

Published results on Ge junctions are benchmarked systematically using RS–XJ plots. The electrical activation level required to meet the ITRS targets is calculated. Additionally, new results are presented on shallow furnace-annealed B junctions and shallow laser-annealed As junctions. Co-implanting...

MRI findings of uterine tumor resembling ovarian sex-cord tumor: A case report

Energy Technology Data Exchange (ETDEWEB)

Cho, Sung Hwan; Kim, Hee Jin; Han, Hyun Young; Hwang, In Taek; Kim, Ju Heon; Lee, Seung Yeon [Eulji University Hospital, Eulji University School of Medicine, Daejeon (Korea, Republic of)

2017-04-15

Uterine tumor resembling ovarian sex-cord tumor is a very rare uterine neoplasm that was first described by Clement and Scully in 1976. Since then, approximately 70 cases have been reported. However, these case reports have mainly described and discussed the pathologic and clinical features, and few radiologic findings have been presented. We experienced a case of a uterine tumor resembling ovarian sex-cord tumor, which was considered a uterine leiomyoma or leiomyosarcoma upon initial impression at preoperative evaluation including transvaginal ultrasonography and pelvic magnetic resonance imaging. Its diagnosis was pathologically confirmed after total abdominal hysterectomy.

Junction Potentials Bias Measurements of Ion Exchange Membrane Permselectivity.

Science.gov (United States)

Kingsbury, Ryan S; Flotron, Sophie; Zhu, Shan; Call, Douglas F; Coronell, Orlando

2018-04-17

Ion exchange membranes (IEMs) are versatile materials relevant to a variety of water and waste treatment, energy production, and industrial separation processes. The defining characteristic of IEMs is their ability to selectively allow positive or negative ions to permeate, which is referred to as permselectivity. Measured values of permselectivity that equal unity (corresponding to a perfectly selective membrane) or exceed unity (theoretically impossible) have been reported for cation exchange membranes (CEMs). Such nonphysical results call into question our ability to correctly measure this crucial membrane property. Because weighing errors, temperature, and measurement uncertainty have been shown to not explain these anomalous permselectivity results, we hypothesized that a possible explanation are junction potentials that occur at the tips of reference electrodes. In this work, we tested this hypothesis by comparing permselectivity values obtained from bare Ag/AgCl wire electrodes (which have no junction) to values obtained from single-junction reference electrodes containing two different electrolytes. We show that permselectivity values obtained using reference electrodes with junctions were greater than unity for CEMs. In contrast, electrodes without junctions always produced permselectivities lower than unity. Electrodes with junctions also resulted in artificially low permselectivity values for AEMs compared to electrodes without junctions. Thus, we conclude that junctions in reference electrodes introduce two biases into results in the IEM literature: (i) permselectivity values larger than unity for CEMs and (ii) lower permselectivity values for AEMs compared to those for CEMs. These biases can be avoided by using electrodes without a junction.

On simulation of local fluxes in molecular junctions

Science.gov (United States)

Cabra, Gabriel; Jensen, Anders; Galperin, Michael

2018-05-01

We present a pedagogical review of the current density simulation in molecular junction models indicating its advantages and deficiencies in analysis of local junction transport characteristics. In particular, we argue that current density is a universal tool which provides more information than traditionally simulated bond currents, especially when discussing inelastic processes. However, current density simulations are sensitive to the choice of basis and electronic structure method. We note that while discussing the local current conservation in junctions, one has to account for the source term caused by the open character of the system and intra-molecular interactions. Our considerations are illustrated with numerical simulations of a benzenedithiol molecular junction.

Shunted-Josephson-junction model. I. The autonomous case

DEFF Research Database (Denmark)

Belykh, V. N.; Pedersen, Niels Falsig; Sørensen, O. H.

1977-01-01

The shunted-Josephson-junction model: the parallel combination of a capacitance, a phase-dependent conductance, and an ideal junction element biased by a constant current, is discussed for arbitrary values of the junction parameters. The main objective is to provide a qualitative understanding...... current-voltage curves are presented. The case with a time-dependent monochromatic bias current is treated in a similar fashion in the companion paper....

Joint diseases: from connexins to gap junctions.

Science.gov (United States)

Donahue, Henry J; Qu, Roy W; Genetos, Damian C

2017-12-19

Connexons form the basis of hemichannels and gap junctions. They are composed of six tetraspan proteins called connexins. Connexons can function as individual hemichannels, releasing cytosolic factors (such as ATP) into the pericellular environment. Alternatively, two hemichannel connexons from neighbouring cells can come together to form gap junctions, membrane-spanning channels that facilitate cell-cell communication by enabling signalling molecules of approximately 1 kDa to pass from one cell to an adjacent cell. Connexins are expressed in joint tissues including bone, cartilage, skeletal muscle and the synovium. Indicative of their importance as gap junction components, connexins are also known as gap junction proteins, but individual connexin proteins are gaining recognition for their channel-independent roles, which include scaffolding and signalling functions. Considerable evidence indicates that connexons contribute to the function of bone and muscle, but less is known about the function of connexons in other joint tissues. However, the implication that connexins and gap junctional channels might be involved in joint disease, including age-related bone loss, osteoarthritis and rheumatoid arthritis, emphasizes the need for further research into these areas and highlights the therapeutic potential of connexins.

Electrochemically assisted mechanically controllable break junction studies on the stacking configurations of oligo(phenylene ethynylene)s molecular junctions

International Nuclear Information System (INIS)

Zheng, Jue-Ting; Yan, Run-Wen; Tian, Jing-Hua; Liu, Jun-Yang; Pei, Lin-Qi; Wu, De-Yin; Dai, Ke; Yang, Yang; Jin, Shan

2016-01-01

Highlights: • I-V characteristics of a series of oligo(phenylene ethynylene)s molecular junctions were measured. • Conductance values were found to be dependent on molecular length and substituent group. • The measured low conductance values were explained by theoretical calculations. • EC-MCBJ is feasible to fabricate and characterize molecular junctions. - Abstract: We demonstrate an electrochemically assisted mechanically controllable break junction (EC-MCBJ) approach for current-voltage characteristic (I-V curve) measurements of metal/molecule/metal junctions. A series of oligo(phenylene ethynylene)s compounds (OPEs), including those involving electron withdrawing substituent group and different backbone lengths, had been successfully designed, synthesized, and placed onto the fabricated nanogap to form molecular junctions. The observed evolution in the measured conductances of OPEs indicates that there is a dependence of conductance on molecular length and substituent group. Compared with those extracted from conductance histogram construction, the conductances of OPEs measured from I-V curves are considerably lower. Based on the transmission spectra of OPEs that calculated by density functional theory (DFT) combined with non-equilibrium Green’s function (NEGF) method, this difference was attributed to our distinct experimental operation, which may give rise to a stacking configuration of two OPE molecules.

ALTERNATIVE MATERIALS FOR RAMP-EDGE SNS JUNCTIONS

International Nuclear Information System (INIS)

Jia, Q.; Fan, Y.; Gim, Y.

1999-01-01

We report on the processing optimization and fabrication of ramp-edge high-temperature superconducting junctions by using alternative materials for both superconductor electrodes and normal-metal barrier. By using Ag-doped YBa 2 Cu 3 O 7-x (Ag:YBCO) as electrodes and a cation-modified compound of (Pr y Gd 0.6-y )Ca 0.4 Ba 1.6 La 0.4 Cu 3 O 7 (y = 0.4, 0.5, and 0.6) as a normal-metal barrier, high-temperature superconducting Josephson junctions have been fabricated in a ramp-edge superconductor/normal-metal/superconductor (SNS) configuration. By using Ag:YBCO as electrodes, we have found that the processing controllability /reproducibility and the stability of the SNS junctions are improved substantially. The junctions fabricated with these alternative materials show well-defined RSJ-like current vs voltage characteristics at liquid nitrogen temperature

Electron-beam damaged high-temperature superconductor Josephson junctions

International Nuclear Information System (INIS)

Pauza, A.J.; Booij, W.E.; Herrmann, K.; Moore, D.F.; Blamire, M.G.; Rudman, D.A.; Vale, L.R.

1997-01-01

Results are presented on the fabrication and characterization of high critical temperature Josephson junctions in thin films of YBa 2 Cu 3 O 7-δ produced by the process of focused electron-beam irradiation using 350 keV electrons. The junctions so produced have uniform spatial current densities, can be described in terms of the resistive shunted junction model, and their current densities can be tailored for a given operating temperature. The physical properties of the damaged barrier can be described as a superconducting material of either reduced or zero critical temperature (T c ), which has a length of ∼15nm. The T c reduction is caused primarily by oxygen Frenkel defects in the Cu - O planes. The large beam currents used in the fabrication of the junctions mean that the extent of the barrier is limited by the incident electron-beam diameter, rather than by scattering within the film. The properties of the barrier can be calculated using a superconductor/normal/superconductor (SNS) junction model with no boundary resistance. From the SNS model, we can predict the scaling of the critical current resistance (I c R n ) product and gain insight into the factors controlling the junction properties, T c , and reproducibility. From the measured I c R n scaling data, we can predict the I c R n product of a junction at a given operating temperature with a given current density. I c R n products of ∼2mV can be achieved at 4.2 K. The reproducibility of several junctions in a number of samples can be characterized by the ratio of the maximum-to-minimum critical currents on the same substrate of less than 1.4. Stability over several months has been demonstrated at room and refrigerator temperatures (297 and 281 K) for junctions that have been initially over damaged and then annealed at temperatures ∼380K. (Abstract Truncated)

Effect of facial self-resemblance on the startle response and subjective ratings of erotic stimuli in heterosexual men.

Science.gov (United States)

Lass-Hennemann, Johanna; Deuter, Christian E; Kuehl, Linn K; Schulz, Andre; Blumenthal, Terry D; Schachinger, Hartmut

2011-10-01

Cues of kinship are predicted to increase prosocial behavior due to the benefits of inclusive fitness, but to decrease approach motivation due to the potential costs of inbreeding. Previous studies have shown that facial resemblance, a putative cue of kinship, increases prosocial behavior. However, the effects of facial resemblance on mating preferences are equivocal, with some studies finding that facial resemblance decreases sexual attractiveness ratings, while other studies show that individuals choose mates partly on the basis of similarity. To further investigate this issue, a psychophysiological measure of affective processing, the startle response, was used in this study, assuming that differences in approach motivation to erotic pictures will modulate startle. Male volunteers (n = 30) viewed 30 pictures of erotic female nudes while startle eyeblink responses were elicited by acoustic noise probes. The female nude pictures were digitally altered so that the face either resembled the male participant or another participant, or were not altered. Non-nude neutral pictures were also included. Importantly, the digital alteration was undetected by the participants. Erotic pictures were rated as being pleasant and clearly reduced startle eyeblink magnitude as compared to neutral pictures. Participants showed greater startle inhibition to self-resembling than to other-resembling or non-manipulated female nude pictures, but subjective pleasure and arousal ratings did not differ among the three erotic picture categories. Our data suggest that visual facial resemblance of opposite-sex nudes increases approach motivation in men, and that this effect was not due to their conscious evaluation of the erotic stimuli.

Shot noise in YBCO bicrystal Josephson junctions

DEFF Research Database (Denmark)

Constantinian, K.Y.; Ovsyannikov, G.A.; Borisenko, I.V.

2003-01-01

We measured spectral noise density in YBCO symmetric bicrystal Josephson junctions on sapphire substrates at bias voltages up to 100 mV and T 4.2 K. Normal state resistance of the Josephson junctions, R-N = 20-90 Omega and ICRN up to 2.2 mV have been observed in the experimental samples. Noise...... may explain the experimentally measured linewidth broadening of Josephson oscillations at mm and submm wave frequencies in high-Tc superconducting junctions. Experimental results are discussed in terms of bound states existing at surfaces of d-wave superconducting electrodes....

Intraepithelial lymphocytes express junctional molecules in murine small intestine

International Nuclear Information System (INIS)

Inagaki-Ohara, Kyoko; Sawaguchi, Akira; Suganuma, Tatsuo; Matsuzaki, Goro; Nawa, Yukifumi

2005-01-01

Intestinal intraepithelial lymphocytes (IEL) that reside at basolateral site regulate the proliferation and differentiation of epithelial cells (EC) for providing a first line of host defense in intestine. However, it remains unknown how IEL interact and communicate with EC. Here, we show that IEL express junctional molecules like EC. We identified mRNA expression of the junctional molecules in IEL such as zonula occludens (ZO)-1, occludin and junctional adhesion molecule (JAM) (tight junction), β-catenin and E-cadherin (adherens junction), and connexin26 (gap junction). IEL constitutively expressed occludin and E-cadherin at protein level, while other T cells in the thymus, spleen, liver, mesenteric lymph node, and Peyer's patches did not. γδ IEL showed higher level of these expressions than αβ IEL. The expression of occludin was augmented by anti-CD3 Ab stimulation. These results suggest the possibility of a novel role of IEL concerning epithelial barrier and communication between IEL and EC

Affordance-based individuation of junctions in Open Street Map

Directory of Open Access Journals (Sweden)

Simon Scheider

2012-06-01

Full Text Available We propose an algorithm that can be used to identify automatically the subset of street segments of a road network map that corresponds to a junction. The main idea is to use turn-compliant locomotion affordances, i.e., restricted patterns of supported movement, in order to specify junctions independently of their data representation, and in order to motivate tractable individuation and classification strategies. We argue that common approaches based solely on geometry or topology of the street segment graph are useful but insufficient proxies. They miss certain turn restrictions essential to junctions. From a computational viewpoint, the main challenge of affordance-based individuation of junctions lies in its complex recursive definition. In this paper, we show how Open Street Map data can be interpreted into locomotion affordances, and how the recursive junction definition can be translated into a deterministic algorithm. We evaluate this algorithm by applying it to small map excerpts in order to delineate the contained junctions.

STIM proteins and the endoplasmic reticulum-plasma membrane junctions.

Science.gov (United States)

Carrasco, Silvia; Meyer, Tobias

2011-01-01

Eukaryotic organelles can interact with each other through stable junctions where the two membranes are kept in close apposition. The junction that connects the endoplasmic reticulum to the plasma membrane (ER-PM junction) is unique in providing a direct communication link between the ER and the PM. In a recently discovered signaling process, STIM (stromal-interacting molecule) proteins sense a drop in ER Ca(2+) levels and directly activate Orai PM Ca(2+) channels across the junction space. In an inverse process, a voltage-gated PM Ca(2+) channel can directly open ER ryanodine-receptor Ca(2+) channels in striated-muscle cells. Although ER-PM junctions were first described 50 years ago, their broad importance in Ca(2+) signaling, as well as in the regulation of cholesterol and phosphatidylinositol lipid transfer, has only recently been realized. Here, we discuss research from different fields to provide a broad perspective on the structures and unique roles of ER-PM junctions in controlling signaling and metabolic processes.

Morphological variation of the kidney secondary to junctional parenchyma on ultrasound

International Nuclear Information System (INIS)

Lee, Ji Yoon; Park, Byeong Ho; Nam, Kyeong Jin; Choi, Jong Cheol; Koo, Bong Sig; Kim, Jou Yeoun; Ahn, Seung Eon; Lee, Yung Il

1996-01-01

To evaluate the prevalance of morphological variation of the kidney secondary to junctional parenchyma, as well as to analyze the ultrasonographic features of junctional parenchyma. Two hundred and eighty two kidneys of 141 patient without clinical or radiologic evidence of renal disease were prospectively analysed using ultrasound. In all patients, ultrasonograms were obtained in sagittal, coronal and transaxial planes. The kidney was considered to have morphological variation if the ultrasonogram demonstrated junctional parenchymal defect of line ; those showing such variation were classified as one of three types : continuous, discontinuous, or junctional parenchymal line or defect without junctional parenchyma. The prevalance and ultrasonographic features of the kidneys were evaluated. Morphological variation was noted in 71 cases(25%). the continuous type accounted for 54% of these, the discontinuous type for 38%, and junctional parenchymal defect or line without junctional parenchyma for 8%. In all cases, junctional parenchyma was located approximately at the junction of the upper and middle third of the kidney, and had the same echogenecity as the renal cortex. An understanding of the morphological variation of the kidney resulting from junctional renal parenchyma would be helpful in differentiating pseudotumor from true renal neoplasm

Visualizing supercurrents in 0-{pi} ferromagnetic Josephson tunnel junctions

Energy Technology Data Exchange (ETDEWEB)

Goldobin, Edward; Guerlich, Christian; Gaber, Tobias; Koelle, Dieter; Kleiner, Reinhold [Physikalisches Institut and Center for Collective Quantum Phenomena, Universitaet Tuebingen (Germany); Weides, Martin; Kohlstedt, Hermann [Institute of Solid State Physics, Reserch Center Juelich (Germany)

2009-07-01

So-called 0 and {pi} Josephson junctions can be treated as having positive and negative critical currents. This implies that the same phase shift applied to a Josephson junction causes counterflow of supercurrents in 0 and in {pi} junctions connected in parallel provided they are short in comparison with Josephson penetration depth {lambda}{sub J}. We have fabricated several 0, {pi}, 0-{pi}, 0-{pi}-0 and 20 x (0-{pi}-) planar superconductor-insulator-ferromagnet-superconductor Josephson junctions and studied the spatial supercurrent density distribution j{sub s}(x,y) across the junction area using low temperature scanning electron microscopy. At zero magnetic field we clearly see counterflow of the supercurrents in 0 and {pi} regions. The picture also changes consistently in the applied magnetic field.

Fabrication of magnetic tunnel junctions with epitaxial and textured ferromagnetic layers

Science.gov (United States)

Chang, Y. Austin; Yang, Jianhua Joshua

2008-11-11

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

Spin, Vibrations and Radiation in Superconducting Junctions

NARCIS (Netherlands)

Padurariu, C.

2013-01-01

This thesis presents the theoretical study of superconducting transport in several devices based on superconducting junctions. The important feature of these devices is that the transport properties of the junction are modified by the interaction with another physical system integrated in the

Regulation of Tight Junctions in Upper Airway Epithelium

Directory of Open Access Journals (Sweden)

Takashi Kojima

2013-01-01

Full Text Available The mucosal barrier of the upper respiratory tract including the nasal cavity, which is the first site of exposure to inhaled antigens, plays an important role in host defense in terms of innate immunity and is regulated in large part by tight junctions of epithelial cells. Tight junction molecules are expressed in both M cells and dendritic cells as well as epithelial cells of upper airway. Various antigens are sampled, transported, and released to lymphocytes through the cells in nasal mucosa while they maintain the integrity of the barrier. Expression of tight junction molecules and the barrier function in normal human nasal epithelial cells (HNECs are affected by various stimuli including growth factor, TLR ligand, and cytokine. In addition, epithelial-derived thymic stromal lymphopoietin (TSLP, which is a master switch for allergic inflammatory diseases including allergic rhinitis, enhances the barrier function together with an increase of tight junction molecules in HNECs. Furthermore, respiratory syncytial virus infection in HNECs in vitro induces expression of tight junction molecules and the barrier function together with proinflammatory cytokine release. This paper summarizes the recent progress in our understanding of the regulation of tight junctions in the upper airway epithelium under normal, allergic, and RSV-infected conditions.

Spin-dependent quasiparticle tunneling in junction superconductor-isolator-ferromagnetic

International Nuclear Information System (INIS)

Shlapak, Yu.V.; Shaternik, V.E.; Rudenko, E.M.

2001-01-01

The influence of Andreev reflection of quasiparticles in transparent tunnel junctions of superconductor-isolator-ferromagnetic on electric-current transport is studied within the framework of the Blonder-Tinkham-Klapwijk (BTK) model. It's obtained that current and signal-to-noise ratio can be increased for the memory cell by using in it the double-barrier tunnel junction ferromagnetic-isolator-superconductor-isolator-ferromagnetic instead off the usual tunnel junction ferromagnetic-isolator-ferromagnetic. The evolution of non-linear (tunnel-type) current-voltage characteristics with increasing of the junction transparency is described. (orig.)

Ileocolic junction resection in dogs and cats: 18 cases.

Science.gov (United States)

Fernandez, Yordan; Seth, Mayank; Murgia, Daniela; Puig, Jordi

2017-12-01

There is limited veterinary literature about dogs or cats with ileocolic junction resection and its long-term follow-up. To evaluate the long-term outcome in a cohort of dogs and cats that underwent resection of the ileocolic junction without extensive (≥50%) small or large bowel resection. Medical records of dogs and cats that had the ileocolic junction resected were reviewed. Follow-up information was obtained either by telephone interview or e-mail correspondence with the referring veterinary surgeons. Nine dogs and nine cats were included. The most common cause of ileocolic junction resection was intussusception in dogs (5/9) and neoplasia in cats (6/9). Two dogs with ileocolic junction lymphoma died postoperatively. Only 2 of 15 animals, for which long-term follow-up information was available, had soft stools. However, three dogs with suspected chronic enteropathy required long-term treatment with hypoallergenic diets alone or in combination with medical treatment to avoid the development of diarrhoea. Four of 6 cats with ileocolic junction neoplasia were euthanised as a consequence of progressive disease. Dogs and cats undergoing ileocolic junction resection and surviving the perioperative period may have a good long-term outcome with mild or absent clinical signs but long-term medical management may be required.

Antireflection coating design for series interconnected multi-junction solar cells

International Nuclear Information System (INIS)

Aiken, Daniel J.

1999-01-01

AR coating design for multi-junction solar cells can be more challenging than in the single junction case. Reasons for this are discussed. Analytical expressions used to optimize AR coatings for single junction solar cells are extended for use in monolithic, series interconnected multi-junction solar cell AR coating design. The result is an analytical expression which relates the solar cell performance (through J(sub SC)) directly to the AR coating design through the device reflectance. It is also illustrated how AR coating design can be used to provide an additional degree of freedom for current matching multi-junction devices

Holographic s-wave and p-wave Josephson junction with backreaction

Energy Technology Data Exchange (ETDEWEB)

Wang, Yong-Qiang; Liu, Shuai [Institute of Theoretical Physics, Lanzhou University,Lanzhou 730000, People’s Republic of (China)

2016-11-22

In this paper, we study the holographic models of s-wave and p-wave Josephoson junction away from probe limit in (3+1)-dimensional spacetime, respectively. With the backreaction of the matter, we obtained the anisotropic black hole solution with the condensation of matter fields. We observe that the critical temperature of Josephoson junction decreases with increasing backreaction. In addition to this, the tunneling current and condenstion of Josephoson junction become smaller as backreaction grows larger, but the relationship between current and phase difference still holds for sine function. Moreover, condenstion of Josephoson junction deceases with increasing width of junction exponentially.

Functional anatomy of the human ureterovesical junction

NARCIS (Netherlands)

Roshani, H.; Dabhoiwala, N. F.; Verbeek, F. J.; Lamers, W. H.

1996-01-01

BACKGROUND: The valve function of the ureterovesical-junction (UVJ) is responsible for protection of the low pressure upper urinary tract from the refluxing of urine from the bladder. Controversy about the microanatomy of the human ureterovesical-junction persists. METHODS: Ten (3 male and 7 female)

Double-well potential in annular Josephson junction

International Nuclear Information System (INIS)

Shaju, P.D.; Kuriakose, V.C.

2004-01-01

A double-well potential suitable for quantum-coherent vortex tunnelling can be created in an annular Josephson junction by inserting a microshort in the junction and by applying an in-plane dc magnetic field. Analysis shows that the intensity of the magnetic field determines the depth of the potential well and the strength of the microshort controls the potential barrier height while a dc bias across the junction tilts the potential well. At milli-Kelvin temperatures, the system is expected to behave as a quantum two-level system and may be useful in designing vortex qubits

Parametric frequency conversion in long Josephson junctions

International Nuclear Information System (INIS)

Irie, F.; Ashihara, S.; Yoshida, K.

1976-01-01

Current steps at voltages corresponding to the parametric coupling between an applied r.f. field and junction resonant modes have been observed in long Josephson tunnel junctions in the flux-flow state. The observed periodic variations of the step height due to the applied magnetic field are explained quantitatively by a perturbational analysis using Josephson phase equations. The present study demonstrates that the moving vortex array can serve as a coherent pump wave for signal waves propagating in the barrier region, which indicates, as a result, the possibility of traveling-wave parametric devices with long Josephson tunnel junctions. (author)

Gravitation at the Josephson Junction

Directory of Open Access Journals (Sweden)

Victor Atanasov

2018-01-01

Full Text Available A geometric potential from the kinetic term of a constrained to a curved hyperplane of space-time quantum superconducting condensate is derived. An energy conservation relation involving the geometric field at every material point in the superconductor is demonstrated. At a Josephson junction the energy conservation relation implies the possibility of transforming electric energy into geometric field energy, that is, curvature of space-time. Experimental procedures to verify that the Josephson junction can act as a voltage-to-curvature converter are discussed.

The cranial-spinal junction in medulloblastoma: does it matter?

International Nuclear Information System (INIS)

Narayana, Ashwatha; Jeswani, Sam; Paulino, Arnold C.

1999-01-01

Purpose: Late effects of treatment in children and young adults with medulloblastoma can be influenced by the technique employed in radiating the craniospinal axis. The purpose of this study is to determine whether the placement of the cranial-spinal junction has an impact on dose to the cervical spinal cord and surrounding organs. Methods and Materials: Five patients underwent computed tomography (CT) simulation in the prone position for craniospinal irradiation. A dose of 36 Gy was prescribed to the entire neuraxis. The doses to the cervical spinal cord and surrounding organs were calculated using a cranial-spinal junction at the C1-C2 vertebral interspace (high junction) or at the lowest point in the neck, with exclusion of the shoulders in the lateral cranial fields (low junction).The volume of critical organs at risk, as well as dose to these structures using the cranial and spinal field(s) were outlined and calculated using the CMS FOCUS 3-dimensional treatment planning system. Results: The average dose to the cervical spinal cord was 11.9% higher than the prescribed dose with the low junction, and 6.7% higher with the high junction. However, doses to the thyroid gland, mandible, pharynx, and larynx were increased by an average of 29.6%, 75.8%, 70.6%, and 227.7%, respectively, by the use of the high junction compared to the low junction. Conclusion: A higher dose to the cervical spinal cord can be minimized by using a high junction. However, this would be at the cost of substantially increased doses to surrounding organs such as the thyroid gland, mandible, pharynx, and larynx. This can be critical in children and young adults, where hypothyroidism, mandibular hypoplasia, and development of second malignancies may be a late sequela of radiation therapy

Chirality effect in disordered graphene ribbon junctions

International Nuclear Information System (INIS)

Long Wen

2012-01-01

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. (paper)

Junction depth dependence of breakdown in silicon detector diodes

International Nuclear Information System (INIS)

Beck, G.A.; Carter, A.A.; Carter, J.R.; Greenwood, N.M.; Lucas, A.D.; Munday, D.J.; Pritchard, T.W.; Robinson, D.; Wilburn, C.D.; Wyllie, K.

1996-01-01

The high voltage capability of detector diodes fabricated in the planar process is limited by the high field generated at the edge of the junction.We have fabricated diodes with increased junction depth with respect to our standard process and find a significantly higher breakdown voltage,in reasonable agreement with previous studies of junction breakdown. (orig.)

Resemblances of Parents and Twins in Sport Participation and Heart Rate

NARCIS (Netherlands)

Boomsma, D.I.; van den Bree, M.B.; Orlebeke, J.F.; Molenaar, P.C.M.

1989-01-01

A model to analyze resemblances of twins and parents using LISREL is outlined and applied to sports participation and heart-rate data. Sports participation and heart rate were measured in 44 monozygotic and 46 dizygotic adolescent twin pairs and in their parents. Genetic factors influence variation

The fallopian tube-peritoneal junction: a potential site of carcinogenesis.

Science.gov (United States)

Seidman, Jeffrey D; Yemelyanova, Anna; Zaino, Richard J; Kurman, Robert J

2011-01-01

Junctions between different types of epithelia are hot spots for carcinogenesis, but the junction of the peritoneal mesothelium with the fallopian tubal epithelium, the tubal-peritoneal junction, has not been characterized earlier. A total of 613 junctional foci in 228 fallopian tube specimens from 182 patients who underwent surgery for a variety of indications, including 27 risk-reducing salpingo-oophorectomy specimens, were studied. Edema, congestion, and dilated lymphatic channels were commonly present. Transitional metaplasia was found at the junction in 20% of patients and mesothelial hyperplasia in 17%. Inflammation at the junction was seen predominantly in patients with salpingitis, torsion, or tubal pregnancy. Ovarian-type stroma was found at the junction in 5% of patients, and was found elsewhere in the tubal lamina propria in an additional 27% of patients. Findings in risk-reducing salpingo-oophorectomy specimens in women with BRCA mutations, a personal history of breast cancer, and/or a family history of breast/ovarian cancer were similar to those in controls. Transitional metaplasia specifically localizes to this junction, and is the probable source of Walthard cell nests. The recently highlighted significance of fimbrial tubal epithelium in the origin of serous ovarian carcinomas and a study suggesting that mucinous and Brenner tumors may arise from transitional-type epithelium in this location suggest that the tubal-peritoneal junction may play a role in the development of these tumors. This is the first comprehensive description of a hitherto unrecognized transitional zone in the adnexa.

Regulation of Endothelial Adherens Junctions by Tyrosine Phosphorylation

Science.gov (United States)

Adam, Alejandro Pablo

2015-01-01

Endothelial cells form a semipermeable, regulated barrier that limits the passage of fluid, small molecules, and leukocytes between the bloodstream and the surrounding tissues. The adherens junction, a major mechanism of intercellular adhesion, is comprised of transmembrane cadherins forming homotypic interactions between adjacent cells and associated cytoplasmic catenins linking the cadherins to the cytoskeleton. Inflammatory conditions promote the disassembly of the adherens junction and a loss of intercellular adhesion, creating openings or gaps in the endothelium through which small molecules diffuse and leukocytes transmigrate. Tyrosine kinase signaling has emerged as a central regulator of the inflammatory response, partly through direct phosphorylation and dephosphorylation of the adherens junction components. This review discusses the findings that support and those that argue against a direct effect of cadherin and catenin phosphorylation in the disassembly of the adherens junction. Recent findings indicate a complex interaction between kinases, phosphatases, and the adherens junction components that allow a fine regulation of the endothelial permeability to small molecules, leukocyte migration, and barrier resealing. PMID:26556953

Two-dimensional non-volatile programmable p-n junctions

Science.gov (United States)

Li, Dong; Chen, Mingyuan; Sun, Zhengzong; Yu, Peng; Liu, Zheng; Ajayan, Pulickel M.; Zhang, Zengxing

2017-09-01

Semiconductor p-n junctions are the elementary building blocks of most electronic and optoelectronic devices. The need for their miniaturization has fuelled the rapid growth of interest in two-dimensional (2D) materials. However, the performance of a p-n junction considerably degrades as its thickness approaches a few nanometres and traditional technologies, such as doping and implantation, become invalid at the nanoscale. Here we report stable non-volatile programmable p-n junctions fabricated from the vertically stacked all-2D semiconductor/insulator/metal layers (WSe2/hexagonal boron nitride/graphene) in a semifloating gate field-effect transistor configuration. The junction exhibits a good rectifying behaviour with a rectification ratio of 104 and photovoltaic properties with a power conversion efficiency up to 4.1% under a 6.8 nW light. Based on the non-volatile programmable properties controlled by gate voltages, the 2D p-n junctions have been exploited for various electronic and optoelectronic applications, such as memories, photovoltaics, logic rectifiers and logic optoelectronic circuits.

Thermionic refrigeration at CNT-CNT junctions

Science.gov (United States)

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).

Response of high Tc superconducting Josephson junction to nuclear radiation

International Nuclear Information System (INIS)

Ding Honglin; Zhang Wanchang; Zhang Xiufeng

1992-10-01

The development of nuclear radiation detectors and research on high T c superconducting nuclear radiation detectors are introduced. The emphases are the principle of using thin-film and thick-film Josephson junctions (bridge junction) based on high T c YBCO superconductors to detect nuclear radiation, the fabrication of thin film and thick-film Josephson junction, and response of junction to low energy gamma-rays of 59.5 keV emitted from 241 Am and beta-rays of 546 keV. The results show that a detector for measuring nuclear radiation spectrum made of high T c superconducting thin-film or thick-film, especially, thick-film Josephson junction, certainly can be developed

‘Gap Junctions and Cancer: Communicating for 50 Years’

Science.gov (United States)

Aasen, Trond; Mesnil, Marc; Naus, Christian C.; Lampe, Paul D.; Laird, Dale W.

2017-01-01

Fifty years ago, tumour cells were found to lack electrical coupling, leading to the hypothesis that loss of direct intercellular communication is commonly associated with cancer onset and progression. Subsequent studies linked this phenomenon to gap junctions composed of connexin proteins. While many studies support the notion that connexins are tumour suppressors, recent evidence suggests that, in some tumour types, they may facilitate specific stages of tumour progression through both junctional and non-junctional signalling pathways. This Timeline article highlights the milestones connecting gap junctions to cancer, and underscores important unanswered questions, controversies and therapeutic opportunities in the field. PMID:27782134

Dynamics of fractional vortices in long Josephson junctions

International Nuclear Information System (INIS)

Gaber, Tobias

2007-01-01

In this thesis static and dynamic properties of fractional vortices in long Josephson junctions are investigated. Fractional vortices are circulating supercurrents similar to the well-known Josephson fluxons. Yet, they show the distinguishing property of carrying only a fraction of the magnetic flux quantum. Fractional vortices are interesting non-linear objects. They spontaneously appear and are pinned at the phase discontinuity points of so called 0-κ junctions but can be bend or flipped by external forces like bias currents or magnetic fields. 0-κ junctions and fractional vortices are generalizations of the well-known 0-π junctions and semifluxons, where not only phase jumps of pi but arbitrary values denoted by kappa are considered. By using so-called artificial 0-κ junctions that are based on standard Nb-AlO x -Nb technology the classical dynamics of fractional vortices has been investigated experimentally for the very first time. Here, half-integer zero field steps could be observed. These voltage steps on the junction's current-voltage characteristics correspond to the periodic flipping/hopping of fractional vortices. In addition, the oscillatory eigenmodes of fractional vortices were investigated. In contrast to fluxons fractional vortices have an oscillatory eigenmode with a frequency within the plasma gap. Using resonance spectroscopy the dependence of the eigenmode frequency on the flux carried by the vortex and an applied bias current was determined. (orig.)

Functional Molecular Junctions Derived from Double Self-Assembled Monolayers.

Science.gov (United States)

Seo, Sohyeon; Hwang, Eunhee; Cho, Yunhee; Lee, Junghyun; Lee, Hyoyoung

2017-09-25

Information processing using molecular junctions is becoming more important as devices are miniaturized to the nanoscale. Herein, we report functional molecular junctions derived from double self-assembled monolayers (SAMs) intercalated between soft graphene electrodes. Newly assembled molecular junctions are fabricated by placing a molecular SAM/(top) electrode on another molecular SAM/(bottom) electrode by using a contact-assembly technique. Double SAMs can provide tunneling conjugation across the van der Waals gap between the terminals of each monolayer and exhibit new electrical functions. Robust contact-assembled molecular junctions can act as platforms for the development of equivalent contact molecular junctions between top and bottom electrodes, which can be applied independently to different kinds of molecules to enhance either the structural complexity or the assembly properties of molecules. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Gap junctions-guards of excitability

DEFF Research Database (Denmark)

Stroemlund, Line Waring; Jensen, Christa Funch; Qvortrup, Klaus

2015-01-01

Cardiomyocytes are connected by mechanical and electrical junctions located at the intercalated discs (IDs). Although these structures have long been known, it is becoming increasingly clear that their components interact. This review describes the involvement of the ID in electrical disturbances...... of the heart and focuses on the role of the gap junctional protein connexin 43 (Cx43). Current evidence shows that Cx43 plays a crucial role in organizing microtubules at the intercalated disc and thereby regulating the trafficking of the cardiac sodium channel NaV1.5 to the membrane....

Association of visceral adiposity with oesophageal and junctional adenocarcinomas.

LENUS (Irish Health Repository)

Beddy, P

2012-02-01

BACKGROUND: Obesity is associated with an increased incidence of oesophageal and oesophagogastric junction adenocarcinoma, in particular Siewert types I and II. This study compared abdominal fat composition in patients with oesophageal\\/junctional adenocarcinoma with that in patients with oesophageal squamous cell carcinoma and gastric adenocarcinoma, and in controls. METHOD: In total, 194 patients (110 with oesophageal\\/junctional adenocarcinoma, 38 with gastric adenocarcinoma and 46 with oesophageal squamous cell carcinoma) and 90 matched control subjects were recruited. The abdominal fat area was assessed using computed tomography (CT), and the total fat area (TFA), visceral fat area (VFA) and subcutaneous fat area (SFA) were calculated. RESULTS: Patients with oesophageal\\/junctional adenocarcinoma had significantly higher TFA and VFA values compared with controls (both P < 0.001), patients with gastric adenocarcinoma (P = 0.013 and P = 0.006 respectively) and patients with oesophageal squamous cell carcinoma (both P < 0.001). For junctional tumours, the highest TFA and VFA values were seen in patients with Siewert type I tumours (respectively P = 0.041 and P = 0.033 versus type III; P = 0.332 and P = 0.152 versus type II). CONCLUSION: Patients with oesophageal\\/junctional adenocarcinoma, in particular oesophageal and Siewert type I junctional tumours, have greater CT-defined visceral adiposity than patients with gastric adenocarcinoma or oesophageal squamous cell carcinoma, or controls.

Magnetic interaction between spatially extended superconducting tunnel junctions

DEFF Research Database (Denmark)

Grønbech-Jensen, Niels; Samuelsen, Mogens Rugholm

2002-01-01

A general description of magnetic interactions between superconducting tunnel junctions is given. The description covers a wide range of possible experimental systems, and we explicitly explore two experimentally relevant limits of coupled junctions. One is the limit of junctions with tunneling...... been considered through arrays of superconducting weak links based on semiconductor quantum wells with superconducting electrodes. We use the model to make direct interpretations of the published experiments and thereby propose that long-range magnetic interactions are responsible for the reported...

Cavity syncronisation of underdamped Josephson junction arrays

DEFF Research Database (Denmark)

Barbara, P.; Filatrella, G.; Lobb, C.

2003-01-01

the junctions in the array and an electromagnetic cavity. Here we show that a model of a one-dimensional array of Josephson junctions coupled to a resonator can produce many features of the coherent be havior above threshold, including coherent radiation of power and the shape of the array current...

impairs gap junction function causing congenital cataract

Indian Academy of Sciences (India)

Navya

2017-03-24

Mar 24, 2017 ... experiment showed a lower dye diffusion distance of Cx46 V44M cells, ... Studies of connexins show that channel gating and permeability .... have found that connexin assembled into gap junction plaques is not soluble in 1% ..... high glucose reduces gap junction activity in microvascular endothelial cells.

Micorrizas arbusculares del tipo 'Arum' y 'Paris' y endófitos radicales septados oscuros en Miconia ioneura y Tibouchina paratropica (Melastomataceae 'Arum' and 'Paris' arbuscular mycorrhizal types and dark septate root endophytes in Miconia ioneura and Tibouchina paratropica (Melastomataceae

Directory of Open Access Journals (Sweden)

Carlos Urcelay

2005-12-01

Full Text Available Se estudió la colonización de las raíces por simbiontes fúngicos en Miconia ioneura y Tibouchina paratropica (Melastomataceae. Se observaron y describen estructuras micorrícicas arbusculares pertenecientes a los tipos 'Paris' (hifas y rulos intracelulares y 'Arum' (hifas intercelulares y arbúsculos. Además se observaron endófitos septados oscuros (hifas y esclerocios. Se registra por primera vez la ocurrencia de ambos tipos micorrícicos arbusculares y de endófitos septados oscuros en raíces de especies pertenecientes a la familia Melastomataceae. Se discuten las implicancias ecológicas y evolutivas de la ocurrencia simultánea de los distintos tipos de colonización micorrícica en raíces de la misma especie.The roots of Miconia ioneura and Tibouchina paratropica (Melastomataceae were studied for fungal symbionts colonization. Typical structures of 'Paris' (intracellular hyphae and coils and 'Arum' (intercellular hyphae and arbuscules arbuscular mycorrhizal types were observed and are described here. Dark septate fungi (hyphae and sclerotia were also observed. The occurrence of both types of arbuscular mycorrhizal colonisation and dark septate fungi in the roots of species belonging to Melastomataceae is reported for the first time. The possible ecological and evolutionary implications of the co-occurrence of these mycorrhizal colonisation types in the same species are discussed.

Spatially resolved detection of mutually locked Josephson junctions in arrays

International Nuclear Information System (INIS)

Keck, M.; Doderer, T.; Huebener, R.P.; Traeuble, T.; Dolata, R.; Weimann, T.; Niemeyer, J.

1997-01-01

Mutual locking due to the internal coupling in two-dimensional arrays of Josephson junctions was investigated. The appearance of Shapiro steps in the current versus voltage curve of a coupled on-chip detector junction is used to indicate coherent oscillations in the array. A highly coherent state is observed for some range of the array bias current. By scanning the array with a low-power electron beam, mutually locked junctions remain locked while the unlocked junctions generate a beam-induced additional voltage drop at the array. This imaging technique allows the detection of the nonlocked or weakly locked Josephson junctions in a (partially) locked array state. copyright 1997 American Institute of Physics

Two coupled Josephson junctions: dc voltage controlled by biharmonic current

International Nuclear Information System (INIS)

Machura, L; Spiechowicz, J; Kostur, M; Łuczka, J

2012-01-01

We study transport properties of two Josephson junctions coupled by an external shunt resistance. One of the junctions (say, the first) is driven by an unbiased ac current consisting of two harmonics. The device can rectify the ac current yielding a dc voltage across the first junction. For some values of coupling strength, controlled by an external shunt resistance, a dc voltage across the second junction can be generated. By variation of system parameters such as the relative phase or frequency of two harmonics, one can conveniently manipulate both voltages with high efficiency, e.g. changing the dc voltages across the first and second junctions from positive to negative values and vice versa. (paper)

Probing electrical transport in individual carbon nanotubes and junctions

International Nuclear Information System (INIS)

Kim, Tae-Hwan; Wendelken, John F; Li Anping; Du Gaohui; Li Wenzhi

2008-01-01

The electrical transport properties of individual carbon nanotubes (CNTs) and multi-terminal junctions of CNTs are investigated with a quadraprobe scanning tunneling microscope. The CNTs used in this study are made of stacked herringbone-type conical graphite sheets with a cone angle of ∼20 deg. to the tube axis, and the CNT junctions have no catalytic particles in the junction areas. The CNTs have a significantly higher resistivity than conventional CNTs with concentric walls. The straight CNTs display linear current-voltage (I-V) characteristics, indicating diffusive transport rather than ballistic transport. The structural deformation in CNTs with bends substantially increases the resistivity in comparison with that for the straight segments on the same CNTs, and the I-V curve departs slightly from linearity in curved segments. The junction area of the CNT junctions behaves like an ohmic-type scattering center with linear I-V characteristics. In addition, a gating effect has not been observed, in contrast to the case for conventional multi-walled CNT junctions. These unusual transport properties can be attributed to the enhanced inter-layer interaction in the herringbone-type CNTs.

impairs gap junction function causing congenital cataract

Indian Academy of Sciences (India)

LIJUAN CHEN

2017-12-20

Dec 20, 2017 ... showed a lower dye diffusion distance of Cx46 V44M cells, which indicates that the gap junction intercellular ... permeability could be affected by alterations of charged residues of .... bled into gap junction plaques is not soluble in 1% Triton ..... regulation of connexin 43 expression by high glucose reduces.

Fast temporal fluctuations in single-molecule junctions.

Science.gov (United States)

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.

Axial p-n-junctions in nanowires.

Science.gov (United States)

Fernandes, C; Shik, A; Byrne, K; Lynall, D; Blumin, M; Saveliev, I; Ruda, H E

2015-02-27

The charge distribution and potential profile of p-n-junctions in thin semiconductor nanowires (NWs) were analyzed. The characteristics of screening in one-dimensional systems result in a specific profile with large electric field at the boundary between the n- and p- regions, and long tails with a logarithmic drop in the potential and charge density. As a result of these tails, the junction properties depend sensitively on the geometry of external contacts and its capacity has an anomalously large value and frequency dispersion. In the presence of an external voltage, electrons and holes in the NWs can not be described by constant quasi-Fermi levels, due to small values of the average electric field, mobility, and lifetime of carriers. Thus, instead of the classical Sah-Noice-Shockley theory, the junction current-voltage characteristic was described by an alternative theory suitable for fast generation-recombination and slow diffusion-drift processes. For the non-uniform electric field in the junction, this theory predicts the forward branch of the characteristic to have a non-ideality factor η several times larger than the values 1 < η < 2 from classical theory. Such values of η have been experimentally observed by a number of researchers, as well as in the present work.

Macroscopic Refrigeration Using Superconducting Tunnel Junctions

Science.gov (United States)

Lowell, Peter; O'Neil, Galen; Underwood, Jason; Zhang, Xiaohang; Ullom, Joel

2014-03-01

Sub-kelvin temperatures are often a prerequisite for modern scientific experiments, such as quantum information processing, astrophysical missions looking for dark energy signatures and tabletop time resolved x-ray spectroscopy. Existing methods of reaching these temperatures, such as dilution refrigerators, are bulky and costly. In order to increase the accessibility of sub-Kelvin temperatures, we have developed a new method of refrigeration using normal-metal/insulator/superconductor (NIS) tunnel junctions. NIS junctions cool the electrons in the normal metal since the hottest electrons selectively tunnel from the normal metal into the superconductor. By extending the normal metal onto a thermally isolated membrane, the cold electrons can cool the phonons through the electron-phonon coupling. When these junctions are combined with a pumped 3He system, they provide a potentially inexpensive method of reaching these temperatures. Using only three devices, each with a junction area of approximately 3,500 μm2, we have cooled a 2 cm3 Cu plate from 290 mK to 256 mK. We will present these experimental results along with recent modeling predictions that strongly suggest that further refinements will allow cooling from 300 mK to 120 mK. This work is supported by the NASA APRA program.

No junctional communication between epithelial cells in hydra

DEFF Research Database (Denmark)

de Laat, S W; Tertoolen, L G; Grimmelikhuijzen, C J

1980-01-01

junctions between epithelial cells of hydra. However, until now, there has been no report published on whether these junctions enable the epithelial cells to exchange molecules of small molecular weight, as has been described in other organisms. Therefore we decided to investigate the communicative...... properties of the junctional membranes by electrophysiological methods and by intracellular-dye iontophoresis. We report here that no electrotonic coupling is detectable between epithelial cells of Hydra attenuata in: (1) intact animals, (2) head-regenerating animals, (3) cell re-aggregates, and (4) hydra...

Spectrum of resonant plasma oscillations in long Josephson junctions

International Nuclear Information System (INIS)

Holst, T.

1996-01-01

An analysis is presented for the amplitude of the plasma oscillations in the zero-voltage state of a long and narrow Josephson tunnel junction. The calculation is valid for arbitrary normalized junction length and arbitrary bias current. The spectrum of the plasma resonance is found numerically as solutions to an analytical equation. The low-frequency part of the spectrum contains a single resonance, which is known to exist also in the limit of a short and narrow junction. Above a certain cutoff frequency, a series of high-frequency standing wave plasma resonances is excited, a special feature of long Josephson junctions. copyright 1996 The American Physical Society

Niobium nitride Josephson tunnel junctions with magnesium oxide barriers

International Nuclear Information System (INIS)

Shoji, A.; Aoyagi, M.; Kosaka, S.; Shinoki, F.; Hayakawa, H.

1985-01-01

Niobium nitride-niobium nitride Josephson tunnel junctions have been fabricated using amorphous magnesium oxide (a-MgO) films as barriers. These junctions have excellent tunneling characteristics. For example, a large gap voltage (V/sub g/ = 5.1 mV), a large product of the maximum critical current and the normal tunneling resistance (I/sub c/R/sub n/ = 3.25 mV), and a small subgap leakage current (V/sub m/ = 45 mV, measured at 3 mV) have been obtained for a NbN/a-MgO/NbN junction. The critical current of this junction remains finite up to 14.5 K

Squeezed States in Josephson Junctions.

Science.gov (United States)

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.

Molecular anatomy of interendothelial junctions in human blood-brain barrier microvessels.

Directory of Open Access Journals (Sweden)

Andrzej W Vorbrodt

2004-07-01

Full Text Available Immunogold cytochemical procedure was used to study the localization at the ultrastructural level of interendothelial junction-associated protein molecules in the human brain blood microvessels, representing the anatomic site of the blood-brain barrier (BBB. Ultrathin sections of Lowicryl K4M-embedded biopsy specimens of human cerebral cortex obtained during surgical procedures were exposed to specific antibodies, followed by colloidal gold-labeled secondary antibodies. All tight junction-specific integral membrane (transmembrane proteins--occludin, junctional adhesion molecule (JAM-1, and claudin-5--as well as peripheral zonula occludens protein (ZO-1 were highly expressed. Immunoreactivity of the adherens junction-specific transmembrane protein VE-cadherin was of almost similar intensity. Immunolabeling of the adherens junction-associated peripheral proteins--alpha-catenin, beta-catenin, and p120 catenin--although positive, was evidently less intense. The expression of gamma-catenin (plakoglobin was considered questionable because solitary immunosignals (gold particles appeared in only a few microvascular profiles. Double labeling of some sections made possible to observe strict colocalization of the junctional molecules, such as occludin and ZO-1 or JAM-1 and VE-cadherin, in the interendothelial junctions. We found that in human brain microvessels, the interendothelial junctional complexes contain molecular components specific for both tight and adherens junctions. It is assumed that the data obtained can help us find the immunodetectable junctional molecules that can serve as sensitive markers of normal or abnormal function of the BBB.

Phase-dependent noise in Josephson junctions

Science.gov (United States)

Sheldon, Forrest; Peotta, Sebastiano; Di Ventra, Massimiliano

2018-03-01

In addition to the usual superconducting current, Josephson junctions (JJs) support a phase-dependent conductance related to the retardation effect of tunneling quasi-particles. This introduces a dissipative current with a memory-resistive (memristive) character that should also affect the current noise. By means of the microscopic theory of tunnel junctions we compute the complete current autocorrelation function of a Josephson tunnel junction and show that this memristive component gives rise to both a previously noted phase-dependent thermal noise, and an undescribed non-stationary, phase-dependent dynamic noise. As experiments are approaching ranges in which these effects may be observed, we examine the form and magnitude of these processes. Their phase dependence can be realized experimentally as a hysteresis effect and may be used to probe defects present in JJ based qubits and in other superconducting electronics applications.

Several alternative approaches to the manufacturing of HTS Josephson junctions

OpenAIRE

Villegier , J.; Boucher , H.; Ghis , A.; Levis , M.; Méchin , Laurence; Moriceau , H.; Pourtier , F.; Vabre , M.; Nicoletti , S.; Correra , L.

1994-01-01

In this work we describe comparatively the fabrication and the characterization of various types of HTS Josephson junctions manufactured using different processes : grain boundary junctions have been studied both by the way of junctions on bicrystal substrates and of bi-epitaxial junctions. Ramp-edge types have been elaborated and characterized using mainly N-YBaCuO thin film as a barrier while the trilayer approach has been investigated through a-axis structures. YBaCuO or GdBaCuO supercondu...

The role of Rap1 in cell-cell junction formation

NARCIS (Netherlands)

Kooistra, M.R.H.

2008-01-01

Both epithelial and endothelial cells form cell-cell junctions at the cell-cell contacts to maintain tissue integrity. Proper regulation of cell-cell junctions is required for the organisation of the tissue and to prevent leakage of blood vessels. In endothelial cells, the cell-cell junctions are

What happens in Josephson junctions at high critical current densities

Science.gov (United States)

Massarotti, D.; Stornaiuolo, D.; Lucignano, P.; Caruso, R.; Galletti, L.; Montemurro, D.; Jouault, B.; Campagnano, G.; Arani, H. F.; Longobardi, L.; Parlato, L.; Pepe, G. P.; Rotoli, G.; Tagliacozzo, A.; Lombardi, F.; Tafuri, F.

2017-07-01

The impressive advances in material science and nanotechnology are more and more promoting the use of exotic barriers and/or superconductors, thus paving the way to new families of Josephson junctions. Semiconducting, ferromagnetic, topological insulator and graphene barriers are leading to unconventional and anomalous aspects of the Josephson coupling, which might be useful to respond to some issues on key problems of solid state physics. However, the complexity of the layout and of the competing physical processes occurring in the junctions is posing novel questions on the interpretation of their phenomenology. We classify some significant behaviors of hybrid and unconventional junctions in terms of their first imprinting, i.e., current-voltage curves, and propose a phenomenological approach to describe some features of junctions characterized by relatively high critical current densities Jc. Accurate arguments on the distribution of switching currents will provide quantitative criteria to understand physical processes occurring in high-Jc junctions. These notions are universal and apply to all kinds of junctions.

An ion-beam-assisted process for high-Tc Josephson junctions

International Nuclear Information System (INIS)

Huang, M.Q.; Chen, L.; Zhao, Z.X.; Yang, T.; Nie, J.C.; Wu, P.J.; Xiong, X.M.

1997-01-01

We have developed a non-ion-etching ion-beam-assisted-deposition (IBAD) process for fabricating high critical-temperature (T c ) grain boundary Josephson junctions through a photoresist liftoff mask. The YBa 2 Cu 3 O 7 (YBCO) junctions fabricated through this process exhibited the resistively-shunted-junction (RSJ)-like I - V characteristics. The well-defined Shapiro steps have been seen on the I - V curves under microwave radiation. The magnetic modulation of critical current of a 4 μm width YBCO junction tallied with the prior simulated Fraunhofer diffraction pattern of a Josephson junction with a spatially homogeneous critical current density. The maximum peak-to-peak modulation voltage across the dc superconducting quantum interference device (SQUID) fabricated by using these junctions reached up to 32 μV at 77 K. The magnetic modulation of the SQUID exhibited periodic behavior with the observed modulation period of 5.0x10 -4 G. copyright 1997 American Institute of Physics

Au nanowire junction breakup through surface atom diffusion

Science.gov (United States)

Vigonski, Simon; Jansson, Ville; Vlassov, Sergei; Polyakov, Boris; Baibuz, Ekaterina; Oras, Sven; Aabloo, Alvo; Djurabekova, Flyura; Zadin, Vahur

2018-01-01

Metallic nanowires are known to break into shorter fragments due to the Rayleigh instability mechanism. This process is strongly accelerated at elevated temperatures and can completely hinder the functioning of nanowire-based devices like e.g. transparent conductive and flexible coatings. At the same time, arranged gold nanodots have important applications in electrochemical sensors. In this paper we perform a series of annealing experiments of gold and silver nanowires and nanowire junctions at fixed temperatures 473, 673, 873 and 973 K (200 °C, 400 °C, 600 °C and 700 °C) during a time period of 10 min. We show that nanowires are especially prone to fragmentation around junctions and crossing points even at comparatively low temperatures. The fragmentation process is highly temperature dependent and the junction region breaks up at a lower temperature than a single nanowire. We develop a gold parametrization for kinetic Monte Carlo simulations and demonstrate the surface diffusion origin of the nanowire junction fragmentation. We show that nanowire fragmentation starts at the junctions with high reliability and propose that aligning nanowires in a regular grid could be used as a technique for fabricating arrays of nanodots.

Flicker (1/f) noise in tunnel junction DC SQUIDS

International Nuclear Information System (INIS)

Koch, R.H.; Clarke, J.; Goubau, W.M.; Martinis, J.M.; Pegrum, C.M.; Van Harlingen, D.J.

1983-01-01

We have measured the spectral density of the 1/f voltage noise in current-biased resistively shunted Josephson tunnel junctions and dc SQUIDs. A theory in which fluctuations in the temperature give rise to fluctuations in the critical current and hence in the voltage predicts the magnitude of the noise quite accurately for junctions with areas of about 2 x 10 4 μm 2 , but significantly overestimates the noise for junctions with areas of about 6 μm 2 . DC SQUIDs fabricated from these two types of junctions exhibit substantially more 1/f voltage noise than would be predicted from a model in which the noise arises from critical current fluctuations in the junctions. This result was confirmed by an experiment involving two different bias current and flux modulation schemes, which demonstrated that the predominant 1/f voltage noise arises not from critical current fluctuations, but from some unknown source that can be regarded as an apparent 1/f flux noise. Measurements on five different configurations of dc SQUIDs fabricated with thin-film tunnel junctions and with widely varying areas, inductances, and junction capacitances show that the spectral density of the 1/f equivalent flux noise is roughtly constant, within a factor of three of (10 -10 /f)phi 2 0 Hz -1 . It is emphasized that 1/f flux noise may not be the predominant source of 1/f noise in SQUIDS fabricated with other technologies

Many-junction photovoltaic device performance under non-uniform high-concentration illumination

Science.gov (United States)

Valdivia, Christopher E.; Wilkins, Matthew M.; Chahal, Sanmeet S.; Proulx, Francine; Provost, Philippe-Olivier; Masson, Denis P.; Fafard, Simon; Hinzer, Karin

2017-09-01

A parameterized 3D distributed circuit model was developed to calculate the performance of III-V solar cells and photonic power converters (PPC) with a variable number of epitaxial vertically-stacked pn junctions. PPC devices are designed with many pn junctions to realize higher voltages and to operate under non-uniform illumination profiles from a laser or LED. Performance impacts of non-uniform illumination were greatly reduced with increasing number of junctions, with simulations comparing PPC devices with 3 to 20 junctions. Experimental results using Azastra Opto's 12- and 20-junction PPC illuminated by an 845 nm diode laser show high performance even with a small gap between the PPC and optical fiber output, until the local tunnel junction limit is reached.

Josephson junctions array resonators

Energy Technology Data Exchange (ETDEWEB)

Gargiulo, Oscar; Muppalla, Phani; Mirzaei, Iman; Kirchmair, Gerhard [Institute for Quantum Optics and Quantum Information, Innsbruck (Austria)

2016-07-01

We present an experimental analysis of the self- and cross-Kerr effect of extended plasma resonances in Josephson junction chains. The chain consists of 1600 individual junctions and we can measure quality factors in excess of 10000. The Kerr effect manifests itself as a frequency shift that depends linearly on the number of photons in a resonant mode. By changing the input power we are able to measure this frequency shift on a single mode (self-kerr). By changing the input power on another mode while measuring the same one, we are able to evaluate the cross-kerr effect. We can measure the cross-Kerr effect by probing the resonance frequency of one mode while exciting another mode of the array with a microwave drive.

Doping enhanced barrier lowering in graphene-silicon junctions

Science.gov (United States)

Zhang, Xintong; Zhang, Lining; Chan, Mansun

2016-06-01

Rectifying properties of graphene-semiconductor junctions depend on the Schottky barrier height. We report an enhanced barrier lowering in graphene-Si junction and its essential doping dependence in this paper. The electric field due to ionized charge in n-type Si induces the same type doping in graphene and contributes another Schottky barrier lowering factor on top of the image-force-induced lowering (IFIL). We confirm this graphene-doping-induced lowering (GDIL) based on well reproductions of the measured reverse current of our fabricated graphene-Si junctions by the thermionic emission theory. Excellent matching between the theoretical predictions and the junction data of the doping-concentration dependent barrier lowering serves as another evidence of the GDIL. While both GDIL and IFIL are enhanced with the Si doping, GDIL exceeds IFIL with a threshold doping depending on the as-prepared graphene itself.

Magnetic properties of slablike Josephson-junction arrays

International Nuclear Information System (INIS)

Chen, D.; Sanchez, A.; Hernando, A.

1994-01-01

Magnetic properties of infinitely long and wide slablike Josephson-junction arrays (JJA's) consisting of 2N+1 rows of grains are calculated for the dc Josephson effect with gauge-invariant phase differences. When N is large, the intergranular magnetization curve, M J (H), of the JJA's in low fields approaches that of uniform Josephson junctions with lengths equal to the thicknesses of the JJA's, but in a larger field interval, its amplitude is dually modulated with periods determined by the junction and void areas. M J (H) curves for small N are more complicated. The concept of Josephson vortices and the application of the results to high-T c superconductors are discussed

Internal resonances in periodically modulated long Josephson junctions

DEFF Research Database (Denmark)

Larsen, Britt Hvolbæk; Mygind, Jesper; Ustinov, Alexey V.

1995-01-01

Current-voltage (I-V) characteristics of long Josephson junctions with a periodic lattice of localized inhomogeneities are studied. The interaction between the moving fluxons and the inhomogeneities causes resonant steps in the IV-curve. Some of these steps are due to a synchronization to resonant...... Fiske modes in the sub-junctions formed between the inhomogeneities. The voltage positions of the resonant steps oscillate as function of the applied magnetic field with a period corresponding to the inclusion of one magnetic flux quantum, Φ0=h/2e, per sub-junction. A qualitative explanation that takes...

Capacitance measurement of Josephson tunnel junctions with microwave-induced dc quasiparticle tunneling currents

International Nuclear Information System (INIS)

Hamasaki, K.; Yoshida, K.; Irie, F.; Enpuku, K.

1982-01-01

The microwave response of the dc quasiparticle tunneling current in Josephson tunnel junctions, where the Josephson current is suppressed by an external magnetic field, has been studied quantitatively in order to clarify its characteristics as a probe for the measurement of the junction capacitance. Extensive experiments for both small and long junctions are carried out for distinguishing between microwave behaviors of lumped and distributed constant junctions. It is shown that the observed voltage dependence of the dc quasiparticle tunneling current modified by an applied rf field is in good agreement with a theoretical result which takes into account the influence of the microwave circuit connected to the junction. The comparison between theory and experiment gives the magnitude of the internal rf field in the junction. Together with the applied rf field, this internal rf field leads to the junction rf impedance which is dominated by the junction capacitance in our experimental condition. In the case of lumped junctions, this experimental rf impedance is in reasonable agreement with the theoretical one with the junction capacitance estimated from the Fiske step of the distributed junction fabricated on the same substrate; the obtained ratio of the experimental impedance to the theoretical one is approximately 0.6--1.7. In the case of distributed junctions, however, experimental values of their characteristic impedances are approximately 0.2--0.3 of theoretical values calculated by assuming the one-dimensional junction model and taking account of the standing-wave effect in the junction

Manufacturing P-N junctions in germanium bodies

International Nuclear Information System (INIS)

Hall, R.N.

1980-01-01

A method of producing p-n junctions in Ge so as to facilitate their use as radiation detectors involves forming a body of high purity p-type germanium, diffusing lithium deep into the body, in the absence of electrolytic processes, to form a junction between n-type and p-type germanium greater than 1 mm depth. (UK)

Self-positioned thin Pb-alloy base electrode Josephson junction

International Nuclear Information System (INIS)

Kuroda, K.; Sato, K.

1986-01-01

A self-positioned thin (SPOT) Pb-alloy base electrode Josephson junction is developed. In this junction, a 50-nm thick Pb-alloy base electrode is restricted within the junction region on an Nb underlayer using a self-alignment technique. The grain size reduction and the base electrode area restriction greatly improve thermal cycling stability, where the thermal cycling tests of 4000 proposed junctions (5 x 5 μm 2 ) showed no failures after 4000 cycles. In addition, the elimination of insulator layer stress on the Pb-alloy base electrode rectifies the problem of size effect on current density. The Nb underlayers also serve to isolate the Pb-alloy base electrodes from the resistors

High-efficiency thermal switch based on topological Josephson junctions

Science.gov (United States)

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.

Family environment, not heredity, accounts for family resemblances in food preferences and attitudes: a twin study.

Science.gov (United States)

Rozin, P; Millman, L

1987-04-01

Monozygotic and same-sex dizygotic twin pairs reported on their food preferences, the variety of foods of the same general category (e.g. types of soup) in their diet, and their concern about contact of their food with disgusting or other unacceptable substances (contamination sensitivity). Although there was substantial resemblance between siblings for many of these items, there was no clear evidence for a heritable component on any item. The only case for which there was an interpretable and significantly greater resemblance among monozygotic than among dizygotic twins (out of 23 questions) was preferred degree of hotness resulting from chili pepper in foods. These results confirm the prediction that in omnivorous animals, such as humans, genetic predispositions will be minimal with respect to food. The modest sibling resemblances on a number of measures are primarily attributable to a shared environment.

Phonon spectroscopy with superconducting tunnel junctions

International Nuclear Information System (INIS)

Grimshaw, J.M.

1984-02-01

Superconducting tunnel junctions can be used as generators and detectors of monochromatic phonons of frequency larger than 80 GHz, as was first devised by Eisenmenger and Dayem (1967) and Kinder (1972a, 1973). In this report, we intend to give a general outline of this type of spectroscopy and to present the results obtained so far. The basic physics underlying phonon generation and detection are described in chapter I, a wider approach being given in the references therein. In chapter II, the different types of junctions are considered with respect to their use. Chapter III deals with the evaporation technique for the superconducting junctions. The last part of this report is devoted to the results that we have obtained on γ-irradiated LiF, pure Si and Phosphorous implanted Si. In these chapters, the limitations of the spectrometer are brought out and suggestions for further work are given [fr

Breaking into the epithelial apical-junctional complex--news from pathogen hackers.

Science.gov (United States)

Vogelmann, Roger; Amieva, Manuel R; Falkow, Stanley; Nelson, W James

2004-02-01

The epithelial apical-junctional complex is a key regulator of cellular functions. In addition, it is an important target for microbial pathogens that manipulate the cell to survive, proliferate and sometimes persist within a host. Out of a myriad of potential molecular targets, some bacterial and viral pathogens have selected a subset of protein targets at the apical-junctional complex of epithelial cells. Studying how microbes use these targets also teaches us about the inherent physiological properties of host molecules in the context of normal junctional structure and function. Thus, we have learned that three recently uncovered components of the apical-junctional complex of the Ig superfamily--junctional adhesion molecule, Nectin and the coxsackievirus and adenovirus receptor--are important regulators of junction structure and function and represent critical targets of microbial virulence gene products.

Unraveling the role of dark septate endophyte (DSE) colonizing maize (Zea mays) under cadmium stress: physiological, cytological and genic aspects.

Science.gov (United States)

Wang, Jun-ling; Li, Tao; Liu, Gao-yuan; Smith, Joshua M; Zhao, Zhi-wei

2016-02-25

A growing body of evidence suggests that plant root-associated fungi such as dark septate endophytes (DSE) can help plants overcome many biotic and abiotic stresses, of great interest is DSE-plant metal tolerance and alleviation capabilities on contaminated soils. However, the tolerance and alleviation mechanisms involved have not yet been elucidated. In the current study, the regulation and physiological response of Zea mays to its root-associated DSE, Exophiala pisciphila was analyzed under increased soil Cd stress (0, 10, 50, 100 mg kg(-1)). Under Cd stress, DSE inoculation significantly enhanced the activities of antioxidant enzymes and low-molecular weight antioxidants, while also inducing increased Cd accumulation in the cell wall and conversion of Cd into inactive forms by shoot and root specific regulation of genes related to metal uptake, translocation and chelation. Our results showed that DSE colonization resulted in a marked tolerance to Cd, with a significant decrease in cadmium phytotoxicity and a significant increase in maize growth by triggering antioxidant systems, altering metal chemical forms into inactive Cd, and repartitioning subcellular Cd into the cell wall. These results provide comprehensive evidence for the mechanisms by which DSE colonization bioaugments Cd tolerance in maize at physiological, cytological and molecular levels.

Unraveling the role of dark septate endophyte (DSE) colonizing maize (Zea mays) under cadmium stress: physiological, cytological and genic aspects

Science.gov (United States)

Wang, Jun-Ling; Li, Tao; Liu, Gao-Yuan; Smith, Joshua M.; Zhao, Zhi-Wei

2016-02-01

A growing body of evidence suggests that plant root-associated fungi such as dark septate endophytes (DSE) can help plants overcome many biotic and abiotic stresses, of great interest is DSE-plant metal tolerance and alleviation capabilities on contaminated soils. However, the tolerance and alleviation mechanisms involved have not yet been elucidated. In the current study, the regulation and physiological response of Zea mays to its root-associated DSE, Exophiala pisciphila was analyzed under increased soil Cd stress (0, 10, 50, 100 mg kg-1). Under Cd stress, DSE inoculation significantly enhanced the activities of antioxidant enzymes and low-molecular weight antioxidants, while also inducing increased Cd accumulation in the cell wall and conversion of Cd into inactive forms by shoot and root specific regulation of genes related to metal uptake, translocation and chelation. Our results showed that DSE colonization resulted in a marked tolerance to Cd, with a significant decrease in cadmium phytotoxicity and a significant increase in maize growth by triggering antioxidant systems, altering metal chemical forms into inactive Cd, and repartitioning subcellular Cd into the cell wall. These results provide comprehensive evidence for the mechanisms by which DSE colonization bioaugments Cd tolerance in maize at physiological, cytological and molecular levels.

Dilute Nitrides For 4-And 6- Junction Space Solar Cells

Science.gov (United States)

Essig, S.; Stammler, E.; Ronsch, S.; Oliva, E.; Schachtner, M.; Siefer, G.; Bett, A. W.; Dimroth, F.

2011-10-01

According to simulations the efficiency of conventional, lattice-matched GaInP/GaInAs/Ge triple-junction space solar cells can be strongly increased by the incorporation of additional junctions. In this way the existing excess current of the Germanium bottom cell can be reduced and the voltage of the stack can be increased. In particular, the use of 1.0 eV materials like GaInNAs opens the door for solar cells with significantly improved conversion efficiency. We have investigated the material properties of GaInNAs grown by metal organic vapour phase epitaxy (MOVPE) and its impact on the quantum efficiency of solar cells. Furthermore we have developed a GaInNAs subcell with a bandgap energy of 1.0 eV and integrated it into a GaInP/GaInAs/GaInNAs/Ge 4-junction and a AlGaInP/GaInP/AlGaInAs/GaInAs/GaInNAs/Ge 6- junction space solar cell. The material quality of the dilute nitride junction limits the current density of these devices to 9.3 mA/cm2 (AM0). This is not sufficient for a 4-junction cell but may lead to current matched 6- junction devices in the future.

Josephson junctions in high-T/sub c/ superconductors

Science.gov (United States)

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.

Modeling Bloch oscillations in ultra-small Josephson junctions

Science.gov (United States)

Vora, Heli; Kautz, Richard; Nam, Sae Woo; Aumentado, Jose

In a seminal paper, Likharev et al. developed a theory for ultra-small Josephson junctions with Josephson coupling energy (Ej) less than the charging energy (Ec) and showed that such junctions demonstrate Bloch oscillations which could be used to make a fundamental current standard that is a dual of the Josephson volt standard. Here, based on the model of Geigenmüller and Schön, we numerically calculate the current-voltage relationship of such an ultra-small junction which includes various error processes present in a nanoscale Josephson junction such as random quasiparticle tunneling events and Zener tunneling between bands. This model allows us to explore the parameter space to see the effect of each process on the width and height of the Bloch step and serves as a guide to determine whether it is possible to build a quantum current standard of a metrological precision using Bloch oscillations.

Majorana splitting from critical currents in Josephson junctions

Science.gov (United States)

Cayao, Jorge; San-Jose, Pablo; Black-Schaffer, Annica M.; Aguado, Ramón; Prada, Elsa

2017-11-01

A semiconducting nanowire with strong Rashba spin-orbit coupling and coupled to a superconductor can be tuned by an external Zeeman field into a topological phase with Majorana zero modes. Here we theoretically investigate how this exotic topological superconductor phase manifests in Josephson junctions based on such proximitized nanowires. In particular, we focus on critical currents in the short junction limit (LN≪ξ , where LN is the junction length and ξ is the superconducting coherence length) and show that they contain important information about nontrivial topology and Majoranas. This includes signatures of the gap inversion at the topological transition and a unique oscillatory pattern that originates from Majorana interference. Interestingly, this pattern can be modified by tuning the transmission across the junction, thus providing complementary evidence of Majoranas and their energy splittings beyond standard tunnel spectroscopy experiments, while offering further tunability by virtue of the Josephson effect.

AlGaAs/InGaAlP tunnel junctions for multijunction solar cells

Energy Technology Data Exchange (ETDEWEB)

SHARPS,P.R.; LI,N.Y.; HILLS,J.S.; HOU,H.; CHANG,PING-CHIH; BACA,ALBERT G.

2000-05-16

Optimization of GaInP{sub 2}/GaAs dual and GaInP{sub 2}/GaAs/Ge triple junction cells, and development of future generation monolithic multi-junction cells will involve the development of suitable high bandgap tunnel junctions. There are three criteria that a tunnel junction must meet. First, the resistance of the junction must be kept low enough so that the series resistance of the overall device is not increased. For AMO, 1 sun operation, the tunnel junction resistance should be below 5 x 10{sup {minus}2} {Omega}-cm. Secondly, the peak current density for the tunnel junction must also be larger than the J{sub sc} of the cell so that the tunnel junction I-V curve does not have a deleterious effect on the I-V curve of the multi-junction device. Finally, the tunnel junction must be optically transparent, i.e., there must be a minimum of optical absorption of photons that will be collected by the underlying subcells. The paper reports the investigation of four high bandgap tunnel junctions grown by metal-organic chemical vapor deposition.

Critical current fluctuation in a microwave-driven Josephson junction

International Nuclear Information System (INIS)

Dong Ning; Sun Guozhu; Wang Yiwen; Cao Junyu; Yu Yang; Chen Jian; Kang Lin; Xu Weiwei; Han Siyuan; Wu Peiheng

2007-01-01

Josephson junction devices are good candidates for quantum computation. A large energy splitting was observed in the spectroscopy of a superconducting Josephson junction. The presence of the critical current fluctuation near the energy splitting indicated coupling between the junction and a two-level system. Furthermore, we find that this fluctuation is microwave dependent. It only appears at certain microwave frequency. This relation suggested that the decoherence of qubits is influenced by the necessary computing operations

Junction Propagation in Organometal Halide Perovskite-Polymer Composite Thin Films.

Science.gov (United States)

Shan, Xin; Li, Junqiang; Chen, Mingming; Geske, Thomas; Bade, Sri Ganesh R; Yu, Zhibin

2017-06-01

With the emergence of organometal halide perovskite semiconductors, it has been discovered that a p-i-n junction can be formed in situ due to the migration of ionic species in the perovskite when a bias is applied. In this work, we investigated the junction formation dynamics in methylammonium lead tribromide (MAPbBr 3 )/polymer composite thin films. It was concluded that the p- and n- doped regions propagated into the intrinsic region with an increasing bias, leading to a reduced intrinsic perovskite layer thickness and the formation of an effective light-emitting junction regardless of perovskite layer thicknesses (300 nm to 30 μm). The junction propagation also played a major role in deteriorating the LED operation lifetime. Stable perovskite LEDs can be achieved by restricting the junction propagation after its formation.

Magnetic field behavior of current steps in long Josephson junctions

International Nuclear Information System (INIS)

Costabile, G.; Cucolo, A.M.; Pace, S.; Parmentier, R.D.; Savo, B.; Vaglio, R.

1980-01-01

The zero-field steps, or dc current singularities, in the current-voltage characteristics of long Josephson tunnel junctions, first reported by Chen et al., continue to attract research interest both because their study can provide fundamental information on the dynamics of fluxons in such junctions and because they are accompanied by the emission of microwave radiation from the junction, which may be exploitable in practical oscillator applications. The purpose of this paper is to report some experimental observations of the magnetic field behavior of the steps in junctions fabricated in our Laboratory and to offer a qualitative explanation for this behavior. Measurements have been made both for very long (L >> lambdasub(J)) and for slightly long (L approx. >= lambdasub(J)) junctions with a view toward comparing our results with those of other workers. (orig./WRI)

Environmental Audit of the Grand Junction Projects Office

Energy Technology Data Exchange (ETDEWEB)

1991-08-01

The Grand Junction Projects Office (GJPO) is located in Mesa County, Colorado, immediately south and west of the Grand Junction city limits. The US Atomic Energy Commission (AEC) established the Colorado Raw Materials Office at the present-day Grand Junction Projects Office in 1947, to aid in the development of a viable domestic uranium industry. Activities at the site included sampling uranium concentrate; pilot-plant milling research, including testing and processing of uranium ores; and operation of a uranium mill pilot plant from 1954 to 1958. The last shipment of uranium concentrate was sent from GJPO in January, 1975. Since that time the site has been utilized to support various DOE programs, such as the former National Uranium Resource Evaluation (NURE) Program, the Uranium Mill Tailings Remedial Action Project (UMTRAP), the Surplus Facilities Management Program (SFMP), and the Technical Measurements Center (TMC). All known contamination at GJPO is believed to be the result of the past uranium milling, analyses, and storage activities. Hazards associated with the wastes impounded at GJPO include surface and ground-water contamination and potential radon and gamma-radiation exposure. This report documents the results of the Baseline Environmental Audit conducted at Grand Junction Projects Office (GJPO) located in Grand Junction, Colorado. The Grand Junction Baseline Environmental Audit was conducted from May 28 to June 12, 1991, by the Office of Environmental Audit (EH-24). This Audit evaluated environmental programs and activities at GJPO, as well as GJPO activities at the State-Owned Temporary Repository. 4 figs., 12 tabs.

Environmental Audit of the Grand Junction Projects Office

International Nuclear Information System (INIS)

1991-08-01

The Grand Junction Projects Office (GJPO) is located in Mesa County, Colorado, immediately south and west of the Grand Junction city limits. The US Atomic Energy Commission (AEC) established the Colorado Raw Materials Office at the present-day Grand Junction Projects Office in 1947, to aid in the development of a viable domestic uranium industry. Activities at the site included sampling uranium concentrate; pilot-plant milling research, including testing and processing of uranium ores; and operation of a uranium mill pilot plant from 1954 to 1958. The last shipment of uranium concentrate was sent from GJPO in January, 1975. Since that time the site has been utilized to support various DOE programs, such as the former National Uranium Resource Evaluation (NURE) Program, the Uranium Mill Tailings Remedial Action Project (UMTRAP), the Surplus Facilities Management Program (SFMP), and the Technical Measurements Center (TMC). All known contamination at GJPO is believed to be the result of the past uranium milling, analyses, and storage activities. Hazards associated with the wastes impounded at GJPO include surface and ground-water contamination and potential radon and gamma-radiation exposure. This report documents the results of the Baseline Environmental Audit conducted at Grand Junction Projects Office (GJPO) located in Grand Junction, Colorado. The Grand Junction Baseline Environmental Audit was conducted from May 28 to June 12, 1991, by the Office of Environmental Audit (EH-24). This Audit evaluated environmental programs and activities at GJPO, as well as GJPO activities at the State-Owned Temporary Repository. 4 figs., 12 tabs

Absolute migration and the evolution of the Rodriguez triple junction ...

African Journals Online (AJOL)

The Rodriguez Triple Junction (RTJ) is a junction connecting three mid-ocean ridges in the Indian Ocean: the Southwest Indian Ridge (SWIR), the Central Indian Ridge (CIR) and the Southeast Indian Ridge (SEIR). The evolution of the RTJ has been studied extensively for the past 10 Ma and the triple junction is believed to ...

Supercurrent and multiple Andreev reflections in micrometer-long ballistic graphene Josephson junctions.

Science.gov (United States)

Zhu, Mengjian; Ben Shalom, Moshe; Mishchsenko, Artem; Fal'ko, Vladimir; Novoselov, Kostya; Geim, Andre

2018-02-08

Ballistic Josephson junctions are predicted to support a number of exotic physics processess, providing an ideal system to inject the supercurrent in the quantum Hall regime. Herein, we demonstrate electrical transport measurements on ballistic superconductor-graphene-superconductor junctions by contacting graphene to niobium with a junction length up to 1.5 μm. Hexagonal boron nitride encapsulation and one-dimensional edge contacts guarantee high-quality graphene Josephson junctions with a mean free path of several micrometers and record-low contact resistance. Transports in normal states including the observation of Fabry-Pérot oscillations and Sharvin resistance conclusively witness the ballistic propagation in the junctions. The critical current density J C is over one order of magnitude larger than that of the previously reported junctions. Away from the charge neutrality point, the I C R N product (I C is the critical current and R N the normal state resistance of junction) is nearly a constant, independent of carrier density n, which agrees well with the theory for ballistic Josephson junctions. Multiple Andreev reflections up to the third order are observed for the first time by measuring the differential resistance in the micrometer-long ballistic graphene Josephson junctions.

Shapiro and parametric resonances in coupled Josephson junctions

International Nuclear Information System (INIS)

Gaafar, Ma A; Shukrinov, Yu M; Foda, A

2012-01-01

The effect of microwave irradiation on the phase dynamics of intrinsic Josephson junctions in high temperature superconductors is investigated. We compare the current-voltage characteristics for a stack of coupled Josephson junctions under external irradiation calculated in the framework of CCJJ and CCJJ+DC models.

Towards molecular electronics with large-area molecular junctions

NARCIS (Netherlands)

Akkerman, HB; Blom, PWM; de Leeuw, DM; de Boer, B

2006-01-01

Electronic transport through single molecules has been studied extensively by academic(1-8) and industrial(9,10) research groups. Discrete tunnel junctions, or molecular diodes, have been reported using scanning probes(11,12), break junctions(13,14), metallic crossbars(6) and nanopores(8,15). For

Chlorpromazine reduces the intercellular communication via gap junctions in mammalian cells

International Nuclear Information System (INIS)

Orellana, Juan A.; Palacios-Prado, Nicolas; Saez, Juan C.

2006-01-01

In the work presented herein, we evaluated the effect of chlorpromazine (CPZ) on gap junctions expressed by two mammalian cell types; Gn-11 cells (cell line derived from mouse LHRH neurons) and rat cortical astrocytes maintained in culture. We also attempted to elucidate possible mechanisms of action of CPZ effects on gap junctions. CPZ, in concentrations comparable with doses used to treat human diseases, was found to reduce the intercellular communication via gap junctions as evaluated with measurements of dye coupling (Lucifer yellow). In both cell types, maximal inhibition of functional gap junctions was reached within about 1 h of treatment with CPZ, an recovery was almost complete at about 5 h after CPZ wash out. In both cell types, CPZ treatment increased the phosphorylation state of connexin43 (Cx43), a gap junction protein subunit. Moreover, CPZ reduced the reactivity of Cx43 (immunofluorescence) at cell interfaces and concomitantly increased its reactivity in intracellular vesicles, suggesting an increased retrieval from and/or reduced insertion into the plasma membrane. CPZ also caused cellular retraction reducing cell-cell contacts in a reversible manner. The reduction in contact area might destabilize existing gap junctions and abrogate formation of new ones. Moreover, the CPZ-induced reduction in gap junctional communication may depend on the connexins (Cxs) forming the junctions. If Cx43 were the only connexin expressed, MAPK-dependent phosphorylation of this connexin would induce closure of gap junction channels

Exotic hadron and string junction model

International Nuclear Information System (INIS)

Imachi, Masahiro

1978-01-01

Hadron structure is investigated adopting string junction model as a realization of confinement. Besides exotic hadrons (M 4 , B 5 etc.), unconventional hadrons appear. A mass formula for these hadrons is proposed. New selection rule is introduced which requires the covalence of constituent line at hadron vertex. New duality appears due to the freedom of junction, especially in anti BB→anti BB reaction. A possible assignment of exotic and unconventional hadrons to recently observed narrow meson states is presented. (auth.)

Plant growth promotion, metabolite production and metal tolerance of dark septate endophytes isolated from metal-polluted poplar phytomanagement sites.

Science.gov (United States)

Berthelot, Charlotte; Leyval, Corinne; Foulon, Julie; Chalot, Michel; Blaudez, Damien

2016-10-01

Numerous studies address the distribution and the diversity of dark septate endophytes (DSEs) in the literature, but little is known about their ecological role and their effect on host plants, especially in metal-polluted soils. Seven DSE strains belonging to Cadophora, Leptodontidium, Phialophora and Phialocephala were isolated from roots of poplar trees from metal-polluted sites. All strains developed on a wide range of carbohydrates, including cell-wall-related compounds. The strains evenly colonized birch, eucalyptus and ryegrass roots in re-synthesis experiments. Root and shoot growth promotion was observed and was both plant and strain dependent. Two Phialophora and Leptodontidium strains particularly improved plant growth. However, there was no correlation between the level of root colonization by DSEs and the intensity of growth promotion. All strains produced auxin and six also stimulated plant growth through the release of volatile organic compounds (VOCs). SPME-GC/MS analyses revealed four major VOCs emitted by Cadophora and Leptodontidium The strains exhibited growth at high concentrations of several metals. The ability of metal-resistant DSE strains to produce both soluble and volatile compounds for plant growth promotion indicates interesting microbial resources with high potential to support sustainable production of bioenergy crops within the context of the phytomanagement of metal-contaminated sites. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

ACCIDENT PREDICTION MODELS FOR UNSIGNALISED URBAN JUNCTIONS IN GHANA

OpenAIRE

Mohammed SALIFU, MSc., PhD, MIHT, MGhIE

2004-01-01

The main objective of this study was to provide an improved method for safety appraisal in Ghana through the development and application of suitable accident prediction models for unsignalised urban junctions. A case study was designed comprising 91 junctions selected from the two most cosmopolitan cities in Ghana. A wide range of traffic and road data together with the corresponding accident data for each junction for the three-year period 1996-1998 was utilized in the model development p...

Phase Sensitive Measurements of Ferromagnetic Josephson Junctions for Cryogenic Memory Applications

Science.gov (United States)

Niedzielski, Bethany Maria

A Josephson junction is made up of two superconducting layers separated by a barrier. The original Josephson junctions, studied in the early 1960's, contained an insulating barrier. Soon thereafter, junctions with normal-metal barriers were also studied. Ferromagnetic materials were not even theoretically considered as a barrier layer until around 1980, due to the competing order between ferromagnetic and superconducting systems. However, many exciting physical phenomena arise in hybrid superconductor/ferromagnetic devices, including devices where the ground state phase difference between the two superconductors is shifted by pi. Since their experimental debut in 2001, so-called pi junctions have been demonstrated by many groups, including my own, in systems with a single ferromagnetic layer. In this type of system, the phase of the junction can be set to either 0 or pi depending on the thickness of the ferromagnetic layer. Of interest, however, is the ability to control the phase of a single junction between the 0 and pi states. This was theoretically shown to be possible in a system containing two ferromagnetic layers (spin-valve junctions). If the materials and their thicknesses are properly chosen to manipulate the electron pair correlation function, then the phase state of a spin-valve Josephson junction should be capable of switching between the 0 and ? phase states when the magnetization directions of the two ferromagnetic layers are oriented in the antiparallel and parallel configurations, respectively. Such a phase-controllable junction would have immediate applications in cryogenic memory, which is a necessary component to an ultra-low power superconducting computer. A fully superconducting computer is estimated to be orders of magnitude more energy-efficient than current semiconductor-based supercomputers. The goal of this work was to experimentally verify this prediction for a phase-controllable ferromagnetic Josephson junction. To address this

Effects of ethanol and acetaldehyde on tight junction integrity: in vitro study in a three dimensional intestinal epithelial cell culture model.

Directory of Open Access Journals (Sweden)

Elhaseen Elamin

Full Text Available BACKGROUND: Intestinal barrier dysfunction and translocation of endotoxins are involved in the pathogenesis of alcoholic liver disease. Exposure to ethanol and its metabolite, acetaldehyde at relatively high concentrations have been shown to disrupt intestinal epithelial tight junctions in the conventional two dimensional cell culture models. The present study investigated quantitatively and qualitatively the effects of ethanol at concentrations detected in the blood after moderate ethanol consumption, of its metabolite acetaldehyde and of the combination of both compounds on intestinal barrier function in a three-dimensional cell culture model. METHODS AND FINDINGS: Caco-2 cells were grown in a basement membrane matrix (Matrigel™ to induce spheroid formation and were then exposed to the compounds at the basolateral side. Morphological differentiation of the spheroids was assessed by immunocytochemistry and transmission electron microscopy. The barrier function was assessed by the flux of FITC-labeled dextran from the basal side into the spheroids' luminal compartment using confocal microscopy. Caco-2 cells grown on Matrigel assembled into fully differentiated and polarized spheroids with a central lumen, closely resembling enterocytes in vivo and provide an excellent model to study epithelial barrier functionality. Exposure to ethanol (10-40 mM or acetaldehyde (25-200 µM for 3 h, dose-dependently and additively increased the paracellular permeability and induced redistribution of ZO-1 and occludin without affecting cell viability or tight junction-encoding gene expression. Furthermore, ethanol and acetaldehyde induced lysine residue and microtubules hyperacetylation. CONCLUSIONS: These results indicate that ethanol at concentrations found in the blood after moderate drinking and acetaldehyde, alone and in combination, can increase the intestinal epithelial permeability. The data also point to the involvement of protein hyperacetylation in

Droplet Traffic Control at a simple T junction

Science.gov (United States)

Panizza, Pascal; Engl, Wilfried; Colin, Annie; Ajdari, Armand

2006-03-01

A basic yet essential element of every traffic flow control is the effect of a junction where the flow is separated into several streams. How do pedestrians, vehicles or blood cells divide when they reach a junction? How does the outcome depend on their density? Similar fundamental questions hold for much simpler systems: in this paper, we have studied the behaviour of periodic trains of water droplets flowing in oil through a channel as they reach a simple, locally symmetric, T junction. Depending on their dilution, we observe that the droplets are either alternately partitioned between both outlets or sorted exclusively into the shortest one. We show that this surprising behaviour results from the hydrodynamic feed-back of drops in the two outlets on the selection process occurring at the junction. Our results offer a first guide for the design and modelling of droplet traffic in complex branched networks, a necessary step towards parallelized droplet-based ``lab-on-chip'' devices.

Polyploidization of glia in neural development links tissue growth to blood-brain barrier integrity.

Science.gov (United States)

Unhavaithaya, Yingdee; Orr-Weaver, Terry L

2012-01-01

Proper development requires coordination in growth of the cell types composing an organ. Many plant and animal cells are polyploid, but how these polyploid tissues contribute to organ growth is not well understood. We found the Drosophila melanogaster subperineurial glia (SPG) to be polyploid, and ploidy is coordinated with brain mass. Inhibition of SPG polyploidy caused rupture of the septate junctions necessary for the blood-brain barrier. Thus, the increased SPG cell size resulting from polyploidization is required to maintain the SPG envelope surrounding the growing brain. Polyploidization likely is a conserved strategy to coordinate tissue growth during organogenesis, with potential vertebrate examples.

The string-junction picture of multiquark states: an update

Energy Technology Data Exchange (ETDEWEB)

Rossi, G.C. [Dipartimento di Fisica, Università di Roma Tor Vergata, INFN, Sezione di Roma 2, Via della Ricerca Scientifica, 00133 Roma (Italy); Centro Fermi, Museo Storico della Fisica,Piazza del Viminale 1, 00184 Roma (Italy); Veneziano, G. [Collège de France,11 place M. Berthelot, 75005 Paris (France); Theory Division, CERN,CH-1211 Geneva 23 (Switzerland); Dipartimento di Fisica, Università di Roma La Sapienza,Piazzale A. Moro 5, 00185 Roma (Italy)

2016-06-07

We recall and update, both theoretically and phenomenologically, our (nearly) forty-years-old proposal of a string-junction as a necessary complement to the conventional classification of hadrons based just on their quark-antiquark constituents. In that proposal single (though in general metastable) hadronic states are associated with “irreducible' gauge-invariant operators consisting of Wilson lines (visualized as strings of color flux tubes) that may either end on a quark or an antiquark, or annihilate in triplets at a junction J or an anti-junction J̄. For the junction-free sector (ordinary q q̄ mesons and glueballs) the picture is supported by large-N (number of colors) considerations as well as by a lattice strong-coupling expansion. Both imply the famous OZI rule suppressing quark-antiquark annihilation diagrams. For hadrons with J and/or J̄ constituents the same expansions support our proposal, including its generalization of the OZI rule to the suppression of J−J̄ annihilation diagrams. Such a rule implies that hadrons with junctions are “mesophobic' and thus unusually narrow if they are below threshold for decaying into as many baryons as their total number of junctions (two for a tetraquark, three for a pentaquark). Experimental support for our claim, based on the observation that narrow multiquark states typically lie below (well above) the relevant baryonic (mesonic) thresholds, will be presented.

Mixing Hot and Cold Water Streams at a T-Junction

Science.gov (United States)

Sharp, David; Zhang, Mingqian; Xu, Zhenghe; Ryan, Jim; Wanke, Sieghard; Afacan, Artin

2008-01-01

A simple mixing of a hot- and cold-water stream at a T-junction was investigated. The main objective was to use mass and energy balance equations to predict mass low rates and the temperature of the mixed stream after the T-junction, and then compare these with the measured values. Furthermore, the thermocouple location after the T-junction and…

Vortex dynamics in Josephson ladders with II-junctions

DEFF Research Database (Denmark)

Kornev, Victor K.; Klenov, N. V.; Oboznov, V.A.

2004-01-01

Both experimental and numerical studies of a self-frustrated triangular array of pi-junctions are reported. The array of SFS Josephson junctions shows a transition to the pi-state and self-frustration with a decrease in temperature. This manifests itself in a half-period shift of the bias critica...

Arum-type of arbuscular mycorrhizae, dark septate endophytes and Olpidium spp. in fine roots of container-grown seedlings of Sorbus torminalis (Rosaceae

Directory of Open Access Journals (Sweden)

Roman M. Bzdyk

2016-06-01

Full Text Available The aim of this study was to determine the mycorrhizal status of nursery seedlings of the wild service tree (Sorbus torminalis, which belongs to the Rosaceae family. Its mycorrhizal associations are still fragmentarily known, and data from the few existing studies indicate that it forms ectomycorrhizal symbiosis (ECM. We analyzed the degree of mycorrhizal colonization of thirty 2-year-old container-grown S. torminalis nursery seedlings, which belonged to three single-tree progenies. The roots were dominated by arbuscular mycorrhizae (AM, with the morphology of the Arum-type containing arbuscules, vesicles and hyphae; however, no ECM structures were found. The degree of root colonization of the analyzed seedlings by AM fungi was 83.6% and did not differ significantly between the three single-tree progenies. In addition to AM, structures of dark septate endophytes (0.7% and sporangia of Olpidium spp. (1.1% were found in wild service tree roots. In agreement with previous studies, we confirmed arbuscular mycorrhizae for S. torminalis. Moreover, this is the first report that roots of this Sorbus species show the Arum-type morphology of AM and are associated with Olpidium species.

Optically induced bistable states in metal/tunnel-oxide/semiconductor /MTOS/ junctions

Science.gov (United States)

Lai, S. K.; Dressendorfer, P. V.; Ma, T. P.; Barker, R. C.

1981-01-01

A new switching phenomenon in metal-oxide semiconductor tunnel junction has been discovered. With a sufficiently large negative bias applied to the electrode, incident visible light of intensity greater than about 1 microW/sq cm causes the reverse-biased junction to switch from a low-current to a high-current state. It is believed that hot-electron-induced impact ionization provides the positive feedback necessary for switching, and causes the junction to remain in its high-current state after the optical excitation is removed. The junction may be switched back to the low-current state electrically. The basic junction characteristics have been measured, and a simple model for the switching phenomenon has been developed.

NbN-AlN-NbN Josephson junctions on different substrates

Energy Technology Data Exchange (ETDEWEB)

Merker, Michael; Bohn, Christian; Voellinger, Marvin; Ilin, Konstantin; Siegel, Michael [KIT, Karlsruhe (Germany)

2016-07-01

Josephson junction technology is important for the realization of high quality cryogenic devices such as SQUIDs, RSFQ or SIS-mixers. The material system based on NbN/AlN/NbN tri-layer has gained a lot of interest, because it offers higher gap voltages and critical current densities compared to the well-established Nb/Al-AlOx/Nb technology. However, the realization of high quality Josephson junctions is more challenging. We developed a technology of Josephson junctions on a variety of substrates such as Silicon, Sapphire and Magnesium oxide and compared the quality parameters of these junctions at 4.2 K. The gap voltages achieved a range from 4 mV (for the junctions on Si) to 5.8 mV (in case of MgO substrates) which is considerably higher than those obtained from Nb based Josephson junctions. Another key parameter is the ratio of the subgap resistance to the normal state resistance. This so-called subgap ratio corresponds to the losses in a Josephson junction which have to be minimized. So far, subgap ratios of 26 have been achieved. Further careful optimization of the deposition conditions is required to maximize this ratio, The details of the optimization of technology and of characterization of NbN/AlN/NbN junctions will be presented and discussed.

Superconducting tunnel-junction refrigerator

International Nuclear Information System (INIS)

Melton, R.G.; Paterson, J.L.; Kaplan, S.B.

1980-01-01

The dc current through an S 1 -S 2 tunnel junction, with Δ 2 greater than Δ 1 , when biased with eV 1 +Δ 2 , will lower the energy in S 1 . This energy reduction will be shared by the phonons and electrons. This device is shown to be analogous to a thermoelectric refrigerator with an effective Peltier coefficient π* approx. Δ 1 /e. Tunneling calculations yield the cooling power P/sub c/, the electrical power P/sub e/ supplied by the bias supply, and the cooling efficiency eta=P/sub c//P/sub e/. The maximum cooling power is obtained for eV= +- (Δ 2 -Δ 1 ) and t 1 =T 1 /T/sub c/1 approx. 0.9. Estimates are made of the temperature difference T 2 -T 1 achievable in Al-Pb and Sn-Pb junctions with an Al 2 O 3 tunneling barrier. The performance of this device is shown to yield a maximum cooling efficiency eta approx. = Δ 1 /(Δ 2 -Δ 1 ) which can be compared with that available in an ideal Carnot refrigerator of eta=T 1 /(T 2 -T 1 ). The development of a useful tunnel-junction refrigerator requires a tunneling barrier with an effective thermal conductance per unit area several orders of magnitude less than that provided by the A1 2 O 3 barrier in the Al-Pb and Sn-Pb systems

Marker of cemento-periodontal ligament junction associated with periodontal regeneration.

Science.gov (United States)

Hara, Ryohko; Wato, Masahiro; Tanaka, Akio

2005-06-01

The purpose of this study was to identify factors promoting formation of the cemento-periodontal ligament junction. Regeneration of the cemento-periodontal ligament junction is an important factor in recovery of the connective tissue attachment to the cementum and it is important to identify all specific substances that promote its formation. To clarify the substances involved in cemento-periodontal ligament junction formation, we produced a monoclonal antibody (mAb) to human cemento-periodontal ligament junction (designated as the anti-TAP mAb) and examined its immunostaining properties and reactive antigen. Hybridomas producing monoclonal antibody against human cemento-periodontal ligament junction antigens were established by fusing P3U1 mouse myeloma cells with spleen cells from BALB/c mice immunized with homogenized human cemento-periodontal ligament junction. The mAb, the anti-TAP mAb for cemento-periodontal ligament junction, was then isolated. The immunoglobulin class and light chain of the mAb were examined using an isotyping kit. Before immunostaining, antigen determination using an enzymatic method or heating was conducted. Human teeth, hard tissue-forming lesions, and animal tissues were immunostained by the anti-TAP mAb. The anti-TAP mAb was positive in human cemento-periodontal ligament junction and predentin but negative in all other human and animal tissues examined. In the cemento-osseous lesions, the anti-TAP mAb was positive in the peripheral area of the cementum and cementum-like hard tissues and not in the bone and bone-like tissues. The anti-TAP mAb showed IgM (kappa) and recognized phosphoprotein. The anti-TAP mAb is potentially useful for developing new agents promoting cementogenesis and periodontal regeneration.

A numerical model of p-n junctions bordering on surfaces

Energy Technology Data Exchange (ETDEWEB)

Altermatt, P.P.; Aberle, A.G.; Jianhua Zhao; Aihua Wang; Heiser, G. [University of New South Wales, Sydney (Australia). Centre for Photovolatic Engineering

2002-10-01

Many solar cell structures contain regions where the emitter p-n junction borders on the surface. If the surface is not well passivated, a large amount of recombination occurs in such regions. This type of recombination is influenced by the electrostatics of both the p-n junction and the surface, and hence it is different from the commonly described recombination phenomena occurring in the p-n junction within the bulk. We developed a two-dimensional model for the recombination mechanisms occurring in emitter p-n junctions bordering on surfaces. The model is validated by reproducing the experimental I-V curves of specially designed silicon solar cells. It is shown under which circumstances a poor surface passivation, near where the p-n junction borders on the surface, reduces the fill factor and the open-circuit voltage. The model can be applied to many other types of solar cells. (author)

Preparation of CN /Carbon Nanotube Intramolecular Junctions by ...

African Journals Online (AJOL)

NICO

intramolecular junctions composed of CNx with a bamboo-like structure and empty hollow carbon nanotubes were observed, ... and excellent thermal and mechanical properties.1,2 In recent .... tion of hexane, and the other segment with a curved compart- ... by an arrow lies at the interface of the junction between 'b' and.

Systematic optimization of quantum junction colloidal quantum dot solar cells

KAUST Repository

Liu, Huan

2012-01-01

The recently reported quantum junction architecture represents a promising approach to building a rectifying photovoltaic device that employs colloidal quantum dot layers on each side of the p-n junction. Here, we report an optimized quantum junction solar cell that leverages an improved aluminum zinc oxide electrode for a stable contact to the n-side of the quantum junction and silver doping of the p-layer that greatly enhances the photocurrent by expanding the depletion region in the n-side of the device. These improvements result in greater stability and a power conversion efficiency of 6.1 under AM1.5 simulated solar illumination. © 2012 American Institute of Physics.

Proliferation of sharp kinks on cosmic (super)string loops with junctions

International Nuclear Information System (INIS)

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

2010-01-01

Motivated by their effect on the gravitational wave signal emitted by cosmic strings, we study the dynamics of kinks on strings of different tensions meeting at junctions. The propagation of a kink through a Y junction leads to the formation of three 'daughter' kinks. Assuming a uniform distribution of the incoming wave vectors at the junction, we find there is a significant region of configuration space in which the sharpness of at least one of the daughter kinks is enhanced relative to the sharpness of the initial kink. For closed loops with junctions we show this leads to an exponential growth in time of very sharp kinks. Using numerical simulations of realistic, evolving cosmic string loops with junctions to calculate the distribution of kink amplitudes as a function of time, we show that loops of this kind typically develop several orders of magnitude of very sharp kinks before the two junctions collide. This collision, or other effects such as gravitational backreaction, may end the proliferation.

Field-In-Field Technique With Intrafractionally Modulated Junction Shifts for Craniospinal Irradiation

International Nuclear Information System (INIS)

Yom, Sue S.; Frija, Erik K. C.; Mahajan, Anita; Chang, Eric; Klein, Kelli C.; Shiu, Almon; Ohrt, Jared; Woo, Shiao

2007-01-01

Purpose: To plan craniospinal irradiation with 'field-in-field' (FIF) homogenization in combination with daily, intrafractional modulation of the field junctions, to minimize the possibility of spinal cord overdose. Methods and Materials: Lateral cranial fields and posterior spinal fields were planned using a forward-planned, step-and-shoot FIF technique. Field junctions were automatically modulated and custom-weighted for maximal homogeneity within each treatment fraction. Dose-volume histogram analyses and film dosimetry were used to assess results. Results: Plan inhomogeneity improved with FIF. Planning with daily modulated junction shifts provided consistent dose delivery during each fraction of treatment across the junctions. Modulation minimized the impact of a 5-mm setup error at the junction. Film dosimetry confirmed that no point in the junction exceeded the anticipated dose. Conclusions: Field-in-field planning and modulated junction shifts improve the homogeneity and consistency of daily dose delivery, simplify treatment, and reduce the impact of setup errors

Direct analysis of Holliday junction resolving enzyme in a DNA origami nanostructure.

Science.gov (United States)

Suzuki, Yuki; Endo, Masayuki; Cañas, Cristina; Ayora, Silvia; Alonso, Juan C; Sugiyama, Hiroshi; Takeyasu, Kunio

2014-06-01

Holliday junction (HJ) resolution is a fundamental step for completion of homologous recombination. HJ resolving enzymes (resolvases) distort the junction structure upon binding and prior cleavage, raising the possibility that the reactivity of the enzyme can be affected by a particular geometry and topology at the junction. Here, we employed a DNA origami nano-scaffold in which each arm of a HJ was tethered through the base-pair hybridization, allowing us to make the junction core either flexible or inflexible by adjusting the length of the DNA arms. Both flexible and inflexible junctions bound to Bacillus subtilis RecU HJ resolvase, while only the flexible junction was efficiently resolved into two duplexes by this enzyme. This result indicates the importance of the structural malleability of the junction core for the reaction to proceed. Moreover, cleavage preferences of RecU-mediated reaction were addressed by analyzing morphology of the reaction products. © The Author(s) 2014. Published by Oxford University Press on behalf of Nucleic Acids Research.

GaAs nanowire array solar cells with axial p-i-n junctions.

Science.gov (United States)

Yao, Maoqing; Huang, Ningfeng; Cong, Sen; Chi, Chun-Yung; Seyedi, M Ashkan; Lin, Yen-Ting; Cao, Yu; Povinelli, Michelle L; Dapkus, P Daniel; Zhou, Chongwu

2014-06-11

Because of unique structural, optical, and electrical properties, solar cells based on semiconductor nanowires are a rapidly evolving scientific enterprise. Various approaches employing III-V nanowires have emerged, among which GaAs, especially, is under intense research and development. Most reported GaAs nanowire solar cells form p-n junctions in the radial direction; however, nanowires using axial junction may enable the attainment of high open circuit voltage (Voc) and integration into multijunction solar cells. Here, we report GaAs nanowire solar cells with axial p-i-n junctions that achieve 7.58% efficiency. Simulations show that axial junctions are more tolerant to doping variation than radial junctions and lead to higher Voc under certain conditions. We further study the effect of wire diameter and junction depth using electrical characterization and cathodoluminescence. The results show that large diameter and shallow junctions are essential for a high extraction efficiency. Our approach opens up great opportunity for future low-cost, high-efficiency photovoltaics.

Contour junctions defined by dynamic image deformations enhance perceptual transparency.

Science.gov (United States)

Kawabe, Takahiro; Nishida, Shin'ya

2017-11-01

The majority of work on the perception of transparency has focused on static images with luminance-defined contour junctions, but recent work has shown that dynamic image sequences with dynamic image deformations also provide information about transparency. The present study demonstrates that when part of a static image is dynamically deformed, contour junctions at which deforming and nondeforming contours are connected facilitate the deformation-based perception of a transparent layer. We found that the impression of a transparent layer was stronger when a dynamically deforming area was adjacent to static nondeforming areas than when presented alone. When contour junctions were not formed at the dynamic-static boundaries, however, the impression of a transparent layer was not facilitated by the presence of static surrounding areas. The effect of the deformation-defined junctions was attenuated when the spatial pattern of luminance contrast at the junctions was inconsistent with the perceived transparency related to luminance contrast, while the effect did not change when the spatial luminance pattern was consistent with it. In addition, the results showed that contour completions across the junctions were required for the perception of a transparent layer. These results indicate that deformation-defined junctions that involve contour completion between deforming and nondeforming regions enhance the perception of a transparent layer, and that the deformation-based perceptual transparency can be promoted by the simultaneous presence of appropriately configured luminance and contrast-other features that can also by themselves produce the sensation of perceiving transparency.

Proposed differential-frequency-readout system by hysteretic Josephson junctions

International Nuclear Information System (INIS)

Wang, L.Z.; Duncan, R.V.

1992-01-01

The Josephson relation V=nhν/2e has been verified experimentally to 3 parts in 10 19 [A. K. Jain, J. E. Lukens, and J.-S. Tsai, Phys. Rev. Lett. 58, 1165 (1987)]. Motivated by this result, we propose a differential-frequency-readout system by two sets of hysteretic Josephson junctions rf biased at millimeter wavelengths. Because of the Josephson relation, the proposed differential-frequency-readout system is not limited by photon fluctuation, which limits most photon-detection schemes. In the context of the Stewart-McCumber model [W. C. Stewart, Appl. Phys. Lett. 12, 277 (1968); D. E. McCumber, J. Appl. Phys. 39, 3113 (1968)] of Josephson junctions, we show theoretically that the differential frequency of the two milliwave biases can be read out by the proposed system to unprecedented accuracy. The stability of the readout scheme is also discussed. The measurement uncertainty of the readout system resulting from the intrinsic thermal noise in the hysteretic junctions is shown to be insignificant. The study of two single junctions can be extended to two sets of Josephson junctions connected in series (series array) in this measurement scheme provided that junctions are separated by at least 10 μm [D. W. Jillie, J. E. Lukens, and Y. H. Kao, Phys. Rev. Lett. 38, 915 (1977)]. The sensitivity for the differential frequency detection may be increased by biasing both series arrays to a higher constant-voltage step

Human zonulin, a potential modulator of intestinal tight junctions.

Science.gov (United States)

Wang, W; Uzzau, S; Goldblum, S E; Fasano, A

2000-12-01

Intercellular tight junctions are dynamic structures involved in vectorial transport of water and electrolytes across the intestinal epithelium. Zonula occludens toxin derived from Vibrio cholerae interacts with a specific intestinal epithelial surface receptor, with subsequent activation of a complex intracellular cascade of events that regulate tight junction permeability. We postulated that this toxin may mimic the effect of a functionally and immunologically related endogenous modulator of intestinal tight junctions. Affinity-purified anti-zonula occludens toxin antibodies and the Ussing chamber assay were used to screen for one or more mammalian zonula occludens toxin analogues in both fetal and adult human intestine. A novel protein, zonulin, was identified that induces tight junction disassembly in non-human primate intestinal epithelia mounted in Ussing chambers. Comparison of amino acids in the active zonula occludens toxin fragment and zonulin permitted the identification of the putative receptor binding domain within the N-terminal region of the two proteins. Zonulin likely plays a pivotal role in tight junction regulation during developmental, physiological, and pathological processes, including tissue morphogenesis, movement of fluid, macromolecules and leukocytes between the intestinal lumen and the interstitium, and inflammatory/autoimmune disorders.

Large eddy simulation of a wing-body junction flow

Science.gov (United States)

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)

Mechanical break junctions: enormous information in a nanoscale package.

Science.gov (United States)

Natelson, Douglas

2012-04-24

Mechanical break junctions, particularly those in which a metal tip is repeatedly moved in and out of contact with a metal film, have provided many insights into electronic conduction at the atomic and molecular scale, most often by averaging over many possible junction configurations. This averaging throws away a great deal of information, and Makk et al. in this issue of ACS Nano demonstrate that, with both simulated and real experimental data, more sophisticated two-dimensional analysis methods can reveal information otherwise obscured in simple histograms. As additional measured quantities come into play in break junction experiments, including thermopower, noise, and optical response, these more sophisticated analytic approaches are likely to become even more powerful. While break junctions are not directly practical for useful electronic devices, they are incredibly valuable tools for unraveling the electronic transport physics relevant for ultrascaled nanoelectronics.

BPS dynamics of the triple (p,q) string junction

International Nuclear Information System (INIS)

Rey, S.-J.; Yee, J.-T.

1998-01-01

We study the dynamics of the triple junction of (p,q) strings in type IIB string theory. We probe the tension and mass density of (p,q) strings by studying harmonic fluctuations of the triple junction. We show that they agree perfectly with the BPS formula provided a suitable geometric interpretation of the junction is given. We provide a precise statement of the BPS limit and force-balance property. At weak coupling and sufficiently dense limit, we argue that a (p,q) string embedded in the string network is a 'wiggly string', whose low-energy dynamics can be described via a renormalization group evolved, smooth effective non-relativistic string. We also suggest the possibility that, upon type IIB strings being promoted to the M-theory membrane, there can exist 'evanescent' bound-states at the triple junction in the continuum. (orig.)

Symmetry breaking in SNS junctions: edge transport and field asymmetries

Science.gov (United States)

Suominen, Henri; Nichele, Fabrizio; Kjaergaard, Morten; Rasmussen, Asbjorn; Danon, Jeroen; Flensberg, Karsten; Levitov, Leonid; Shabani, Javad; Palmstrom, Chris; Marcus, Charles

We study magnetic diffraction patterns in a tunable superconductor-semiconductor-superconductor junction. By utilizing epitaxial growth of aluminum on InAs/InGaAs we obtain transparent junctions which display a conventional Fraunhofer pattern of the critical current as a function of applied perpendicular magnetic field, B⊥. By studying the angular dependence of the critical current with applied magnetic fields in the plane of the junction we find a striking anisotropy. We attribute this effect to dephasing of Andreev states in the bulk of the junction, leading to SQUID like behavior when the magnetic field is applied parallel to current flow. Furthermore, in the presence of both in-plane and perpendicular fields, asymmetries in +/-B⊥ are observed. We suggest possible origins and discuss the role of spin-orbit and Zeeman physics together with a background disorder potential breaking spatial symmetries of the junction. Research supported by Microsoft Project Q, the Danish National Research Foundation and the NSF through the National Nanotechnology Infrastructure Network.

Charge splitters and charge transport junctions based on guanine quadruplexes

Science.gov (United States)

Sha, Ruojie; Xiang, Limin; Liu, Chaoren; Balaeff, Alexander; Zhang, Yuqi; Zhang, Peng; Li, Yueqi; Beratan, David N.; Tao, Nongjian; Seeman, Nadrian C.

2018-04-01

Self-assembling circuit elements, such as current splitters or combiners at the molecular scale, require the design of building blocks with three or more terminals. A promising material for such building blocks is DNA, wherein multiple strands can self-assemble into multi-ended junctions, and nucleobase stacks can transport charge over long distances. However, nucleobase stacking is often disrupted at junction points, hindering electric charge transport between the two terminals of the junction. Here, we show that a guanine-quadruplex (G4) motif can be used as a connector element for a multi-ended DNA junction. By attaching specific terminal groups to the motif, we demonstrate that charges can enter the structure from one terminal at one end of a three-way G4 motif, and can exit from one of two terminals at the other end with minimal carrier transport attenuation. Moreover, we study four-way G4 junction structures by performing theoretical calculations to assist in the design and optimization of these connectors.

E-cadherin junction formation involves an active kinetic nucleation process

Science.gov (United States)

Biswas, Kabir H.; Hartman, Kevin L.; Yu, Cheng-han; Harrison, Oliver J.; Song, Hang; Smith, Adam W.; Huang, William Y. C.; Lin, Wan-Chen; Guo, Zhenhuan; Padmanabhan, Anup; Troyanovsky, Sergey M.; Dustin, Michael L.; Shapiro, Lawrence; Honig, Barry; Zaidel-Bar, Ronen; Groves, Jay T.

2015-01-01

Epithelial (E)-cadherin-mediated cell−cell junctions play important roles in the development and maintenance of tissue structure in multicellular organisms. E-cadherin adhesion is thus a key element of the cellular microenvironment that provides both mechanical and biochemical signaling inputs. Here, we report in vitro reconstitution of junction-like structures between native E-cadherin in living cells and the extracellular domain of E-cadherin (E-cad-ECD) in a supported membrane. Junction formation in this hybrid live cell-supported membrane configuration requires both active processes within the living cell and a supported membrane with low E-cad-ECD mobility. The hybrid junctions recruit α-catenin and exhibit remodeled cortical actin. Observations suggest that the initial stages of junction formation in this hybrid system depend on the trans but not the cis interactions between E-cadherin molecules, and proceed via a nucleation process in which protrusion and retraction of filopodia play a key role. PMID:26290581

Tunnel magnetoresistance in double spin filter junctions

International Nuclear Information System (INIS)

Saffarzadeh, Alireza

2003-01-01

We consider a new type of magnetic tunnel junction, which consists of two ferromagnetic tunnel barriers acting as spin filters (SFs), separated by a nonmagnetic metal (NM) layer. Using the transfer matrix method and the free-electron approximation, the dependence of the tunnel magnetoresistance (TMR) on the thickness of the central NM layer, bias voltage and temperature in the double SF junction are studied theoretically. It is shown that the TMR and electron-spin polarization in this structure can reach very large values under suitable conditions. The highest value of the TMR can reach 99%. By an appropriate choice of the thickness of the central NM layer, the degree of spin polarization in this structure will be higher than that of the single SF junctions. These results may be useful in designing future spin-polarized tunnelling devices

Breaking gold nano-junctions simulation and analysis

DEFF Research Database (Denmark)

Lauritzen, Kasper Primdal

, to predict the structure of a gold junction just as it breaks. This method is based on artificial neural networks and can be used on experimental data, even when it is trained purely on simulated data. The method is extended to other types of experimental traces, where it is trained without the use......Simulating the movements of individual atoms allows us to look at and investigate the physical processes that happen in an experiment. In this thesis I use simulations to support and improve experimental studies of breaking gold nano-junctions. By using molecular dynamics to study gold nanowires, I...... can investigate their breaking forces under varying conditions, like stretching rate or temperature. This resolves a confusion in the literature, where the breaking forces of two different breaking structures happen to coincide. The correlations between the rupture and reformation of a gold junction...

Membrane junctions in Xenopus eggs: their distribution suggests a role in calcium regulation.

Science.gov (United States)

Gardiner, D M; Grey, R D

1983-04-01

We have observed the presence of membrane junctions formed between the plasma membrane and cortical endoplasmic reticulum of mature, unactivated eggs of xenopus laevis. The parallel, paired membranes of the junction are separated by a 10-mn gap within which electron-dense material is present. This material occurs in patches with an average center-to-center distance of approximately 30 nm. These junctions are rare in immature (but fully grown) oocytes (approximately 2 percent of the plasma membrane is associated with junctions) and increase dramatically during progesterone-induced maturation. Junctions in the mature, unactivated egg are two to three times more abundant in the animal hemisphere (25-30 percent of the plasma membrane associated with junction) as compared with the vegetal hemisphere (10-15 percent). Junction density decreases rapidly to values characteristic of immature oocytes in response to egg activation. The plasma membrane-ER junctions of xenopus eggs are strikingly similar in structure to membrane junctions in muscle cells thought to be essential in the triggering of intracellular calcium release from the sarcoplasmic reticulum. In addition, the junctions' distinctive, animal-vegetal polarity of distribution, their dramatic appearance during maturation, and their disapperance during activation are correlated with previously documented patterns of calcium-mediated events in anuran eggs. We discuss several lines of evidence supporting the hypothesis that these junctions in xenopus eggs are sites that transduce extracellular events into intracellular calcium release during fertilization and activation of development.

Stretching of BDT-gold molecular junctions: Thiol or thiolate termination?

KAUST Repository

Souza, Amaury De Melo; Rungger, Ivan; Pontes, Renato Borges; Rocha, Alexandre Reily; Da Silva, Antô nio José Roque; Schwingenschlö gl, Udo; Sanvito, S.

2014-01-01

It is often assumed that the hydrogen atoms in the thiol groups of a benzene-1,4-dithiol dissociate when Au-benzene-1,4-dithiol-Au junctions are formed. We demonstrate, by stability and transport property calculations, that this assumption cannot be made. We show that the dissociative adsorption of methanethiol and benzene-1,4-dithiol molecules on a flat Au(111) surface is energetically unfavorable and that the activation barrier for this reaction is as high as 1 eV. For the molecule in the junction, our results show, for all electrode geometries studied, that the thiol junctions are energetically more stable than their thiolate counterparts. Due to the fact that density functional theory (DFT) within the local density approximation (LDA) underestimates the energy difference between the lowest unoccupied molecular orbital and the highest occupied molecular orbital by several electron-volts, and that it does not capture the renormalization of the energy levels due to the image charge effect, the conductance of the Au-benzene-1,4-dithiol-Au junctions is overestimated. After taking into account corrections due to image charge effects by means of constrained-DFT calculations and electrostatic classical models, we apply a scissor operator to correct the DFT energy level positions, and calculate the transport properties of the thiol and thiolate molecular junctions as a function of the electrode separation. For the thiol junctions, we show that the conductance decreases as the electrode separation increases, whereas the opposite trend is found for the thiolate junctions. Both behaviors have been observed in experiments, therefore pointing to the possible coexistence of both thiol and thiolate junctions. Moreover, the corrected conductance values, for both thiol and thiolate, are up to two orders of magnitude smaller than those calculated with DFT-LDA. This brings the theoretical results in quantitatively good agreement with experimental data.

Steady-state properties of Josephson junctions with direct conductivity

International Nuclear Information System (INIS)

Zubkov, A.A.; Kupriyanov, M.Y.; Semenov, V.K.

1981-01-01

A new criterion for determining the kinetic inductance of Josephson junctions is introduced. The effects of temperature T, the critical temperatures of the superconducting electrodes T/sub c/1 and T/sub c/2, and the weak-link length on the kinetic inductance of ''dirty'' junctions with direct conductivity are analyzed within the framework of the Usadel equations. Numerical calculations show that both a large characteristic voltage and a nearly harmonic dependence of the current on the phase difference of the superconducting-electrode wave functions cannot be obtained by varying the junction parameters

Spin-transfer torque in spin filter tunnel junctions

KAUST Repository

Ortiz Pauyac, Christian

2014-12-08

Spin-transfer torque in a class of magnetic tunnel junctions with noncollinear magnetizations, referred to as spin filter tunnel junctions, is studied within the tight-binding model using the nonequilibrium Green\\'s function technique within Keldysh formalism. These junctions consist of one ferromagnet (FM) adjacent to a magnetic insulator (MI) or two FM separated by a MI. We find that the presence of the magnetic insulator dramatically enhances the magnitude of the spin-torque components compared to conventional magnetic tunnel junctions. The fieldlike torque is driven by the spin-dependent reflection at the MI/FM interface, which results in a small reduction of its amplitude when an insulating spacer (S) is inserted to decouple MI and FM layers. Meanwhile, the dampinglike torque is dominated by the tunneling electrons that experience the lowest barrier height. We propose a device of the form FM/(S)/MI/(S)/FM that takes advantage of these characteristics and allows for tuning the spin-torque magnitudes over a wide range just by rotation of the magnetization of the insulating layer.

Spin-transfer torque in spin filter tunnel junctions

KAUST Repository

Ortiz Pauyac, Christian; Kalitsov, Alan; Manchon, Aurelien; Chshiev, Mairbek

2014-01-01

Spin-transfer torque in a class of magnetic tunnel junctions with noncollinear magnetizations, referred to as spin filter tunnel junctions, is studied within the tight-binding model using the nonequilibrium Green's function technique within Keldysh formalism. These junctions consist of one ferromagnet (FM) adjacent to a magnetic insulator (MI) or two FM separated by a MI. We find that the presence of the magnetic insulator dramatically enhances the magnitude of the spin-torque components compared to conventional magnetic tunnel junctions. The fieldlike torque is driven by the spin-dependent reflection at the MI/FM interface, which results in a small reduction of its amplitude when an insulating spacer (S) is inserted to decouple MI and FM layers. Meanwhile, the dampinglike torque is dominated by the tunneling electrons that experience the lowest barrier height. We propose a device of the form FM/(S)/MI/(S)/FM that takes advantage of these characteristics and allows for tuning the spin-torque magnitudes over a wide range just by rotation of the magnetization of the insulating layer.

Neutron induced permanent damage in Josephson junctions

International Nuclear Information System (INIS)

Mueller, G.P.; Rosen, M.

1982-01-01

14 MeV neutron induced permanent changes in the critical current density of Josephson junctions due to displacement damage in the junction barrier are estimated using a worst case model and the binary collision simulation code MARLOWE. No likelihood of single event hard upsets is found in this model. It is estimated that a fluence of 10 18 -10 19 neutrons/cm 2 are required to change the critical current density by 5%

Spinal Gap Junction Channels in Neuropathic Pain

OpenAIRE

Jeon, Young Hoon; Youn, Dong Ho

2015-01-01

Damage to peripheral nerves or the spinal cord is often accompanied by neuropathic pain, which is a complex, chronic pain state. Increasing evidence indicates that alterations in the expression and activity of gap junction channels in the spinal cord are involved in the development of neuropathic pain. Thus, this review briefly summarizes evidence that regulation of the expression, coupling, and activity of spinal gap junction channels modulates pain signals in neuropathic pain states induced...

Junction temperature estimation for an advanced active power cycling test

DEFF Research Database (Denmark)

Choi, Uimin; Blaabjerg, Frede; Jørgensen, S.

2015-01-01

estimation method using on-state VCE for an advanced active power cycling test is proposed. The concept of the advanced power cycling test is explained first. Afterwards the junction temperature estimation method using on-state VCE and current is presented. Further, the method to improve the accuracy...... of the maximum junction temperature estimation is also proposed. Finally, the validity and effectiveness of the proposed method is confirmed by experimental results.......On-state collector-emitter voltage (VCE) is a good indicator to determine the wear-out condition of power device modules. Further, it is a one of the Temperature Sensitive Electrical Parameters (TSEPs) and thus can be used for junction temperature estimation. In this paper, the junction temperature...

Photovoltaic Cells Improvised With Used Bipolar Junction Transistors

International Nuclear Information System (INIS)

Akintayo, J. A

2002-01-01

The understanding of the underlying principle that the solar cell consists of a p-n junction is exploited to adapt the basic NPN or PNP Bipolar Junction Transistors (BJT) to serve as solar cells. In this mode the in improvised solar cell have employed just the emitter and the base sections with an intact emitter/base junction as the active PN area. The improvised devices tested screened and sorted are wired up in strings, blocks and modules. The photovoltaic modules realised tested as close replica of solar cells with output voltage following insolation level. Further work need be done on the modules to make them generate usable levels of output voltage and current

Tuning spin transport across two-dimensional organometallic junctions

Science.gov (United States)

Liu, Shuanglong; Wang, Yun-Peng; Li, Xiangguo; Fry, James N.; Cheng, Hai-Ping

2018-01-01

We study via first-principles modeling and simulation two-dimensional spintronic junctions made of metal-organic frameworks consisting of two Mn-phthalocyanine ferromagnetic metal leads and semiconducting Ni-phthalocyanine channels of various lengths. These systems exhibit a large tunneling magnetoresistance ratio; the transmission functions of such junctions can be tuned using gate voltage by three orders of magnitude. We find that the origin of this drastic change lies in the orbital alignment and hybridization between the leads and the center electronic states. With physical insight into the observed on-off phenomenon, we predict a gate-controlled spin current switch based on two-dimensional crystallines and offer general guidelines for designing spin junctions using 2D materials.

NbCN Josephson junctions with AlN barriers

International Nuclear Information System (INIS)

Thomasson, S.L.; Murduck, J.M.; Chan, H.

1991-01-01

This paper reports on niobium carbonitride (NbCN) Josephson circuits which operate over a wider temperature range than either niobium or niobium nitride circuits. Higher operating temperature places NbCN technology more comfortably within the range of closed cycle refrigerators, a key factor in aerospace applications. We have fabricated tunnel junctions from NbCN films with transition temperatures up to 18 Kelvin. High quality NbCN tunnel junction fabrication generally requires low stress films with roughness less than the barrier thickness (∼20 Angstrom). We have developed scanning tunneling microscopy as a tool for measuring and optimizing film smoothness. Junctions formed in situ with AIN tunneling barriers show reproducible I-V characteristics

Measurement of noise in YBCO bi-crystal junctions

International Nuclear Information System (INIS)

Kuznik, J.; Hao, L.; Macfarlane, J.C.; Pegrum, C.M.; Fischer, G.M.; Mygind, J.; Pedersen, N.F.; Beck, A.; Gross, R.

1993-01-01

This paper describes collaborative work between three institutions as part of an ESPRIT programme to fabricate and characterise grain-boundary junctions. Bi-crystal junctions were fabricated at Tuebingen on SrTiO 3 substrates with a 24 misorientation angle and a-b tilt. 200nm of c-axis YBCO was sputter-deposited using a hollow-cathode magnetron, and the films patterned with optical lithography and Ar ion beam etching (3). For test purposes junctions with a range of sizes were made, with widths between 4 and 20μm. These have been characterised for noise properties at 0.3 - 1kHz and 60kHz at Strathclyde, and at 70GHz at Lyngby. (orig.)

Resistance switch employing a simple metal nanogap junction

International Nuclear Information System (INIS)

Naitoh, Yasuhisa; Horikawa, Masayo; Abe, Hidekazu; Shimizu, Tetsuo

2006-01-01

In recent years, several researchers have reported the occurrence of reversible resistance switching effects in simple metal nanogap junctions. A large negative resistance is observed in the I-V characteristics of such a junction when high-bias voltages are applied. This phenomenon is characteristic behaviour on the nanometre scale; it only occurs for gap widths slightly under 13 nm. Furthermore, such a junction exhibits a non-volatile resistance hysteresis when the bias voltage is reduced very rapidly from a high level to around 0 V, and when the bias voltage is reduced slowly. This non-volatile resistance change occurs as a result of changes in the gap width between the metal electrodes, brought about by the applied bias voltage

Quantum Junction Solar Cells

KAUST Repository

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

2012-01-01

-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

Investigation on Single-Molecule Junctions Based on Current–Voltage Characteristics

Directory of Open Access Journals (Sweden)

Yuji Isshiki

2018-02-01

Full Text Available The relationship between the current through an electronic device and the voltage across its terminals is a current–voltage characteristic (I–V that determine basic device performance. Currently, I–V measurement on a single-molecule scale can be performed using break junction technique, where a single molecule junction can be prepared by trapping a single molecule into a nanogap between metal electrodes. The single-molecule I–Vs provide not only the device performance, but also reflect information on energy dispersion of the electronic state and the electron-molecular vibration coupling in the junction. This mini review focuses on recent representative studies on I–Vs of the single molecule junctions that cover investigation on the single-molecule diode property, the molecular vibration, and the electronic structure as a form of transmission probability, and electronic density of states, including the spin state of the single-molecule junctions. In addition, thermoelectronic measurements based on I–Vs and identification of the charged carriers (i.e., electrons or holes are presented. The analysis in the single-molecule I–Vs provides fundamental and essential information for a better understanding of the single-molecule science, and puts the single molecule junction to more practical use in molecular devices.

Simulations of signal amplification and oscillations using a SNS junction

International Nuclear Information System (INIS)

Luiz, A.M.; Soares, V.; Nicolsky, R.

1998-01-01

A superconducting - normal metal - superconducting junction (SNS junction) may exhibit a low voltage negative differential resistance (LVNDR) effect over part of its current voltage characteristic (CVC). As the LVNDR effect is stable against a bias voltage at this CVC range, it should be possible to combine a SNS junction with conventional electronic circuits to obtain electronic devices such as mixers, amplifiers and oscillators. Making use of this remarkable effect, we show that an amplifier may be feasible by assembling a simple voltage divider made up of a SNS junction in series with a resistor. The amplifier circuit includes an adjustable DC voltage supply (the bias voltage) and an AC signal source with a given voltage. The SNS junction is connected in series with a resistor R. Choosing values of the load resistance R approximately equal to the module of the negative differential resistance (dV/dI), at the bias voltage, we may obtain large gains in this amplifier device. In order to get an oscillator, the SNS junction should be connected to a RLC tank circuit with a bias voltage adjusted in the range of the LVNDR region of its CVC. A power output of the order of one microwatt may be easily obtained. (orig.)

Superconductor-Insulator transition in a single Josephson junction

International Nuclear Information System (INIS)

Sonin, E.B.; PenttilA, J.S.; Parts, O.; Hakonen, P.J.; Paalanen, M.A.

1999-01-01

For ultra small Josephson junctions, when quantum effects become important, dissipative phase transition (DPT) has been predicted. The physical origin of this transition is the suppression of macroscopic quantum tunneling of the phase by tile interaction with dissipative quantum-mechanical environment. Macroscopic quantum tunneling destroys superconductivity of a junction, whereas suppression of tunneling restores superconductivity. Hence, this transition is often called a superconductor-insulator transition (SIT). SIT was predicted for various systems, but its detection in a single Josephson junction is of principal importance since it is the simplest system where this transition is expected, without any risk of being masked by other physical processes, as is possible in more complicated systems like regular or' random Josephson junction arrays. In this Letter we present results of our measurements on R = dV/dI vs. I curves, for a variety of single small isolated Josephson junctions, shunted and un shunted, with different values of capacitance C and normal state tunneling resistance RT. We have detected a crossover. between two types of RI-curves with an essentially different behavior at small currents. On the basis of this crossover, we are able to map out the whole phase diagram for a Josephson junction. The position of the observed phase boundary did not agree with that expected from the original theory. However, the theory revised to take into account a finite accuracy of our voltage measurements (viz., the minimum voltage which we are able to detect), explains well the observed phase diagram. Our important conclusion is that the concept of dissipative phase transition (DPT) and superconductor-insulator transition (SIT) are not completely identical as assumed before. Both are accompanied by the sign change of the thermo resistance, which is traditionally considered as a signature of SIT. Thus any DPT is SIT, but not vice versa. We argue that the real signature

MoRe-based and NbN-based tunnel junctions and their characteristics

International Nuclear Information System (INIS)

Shaternik, V.E.; Noskov, V.L.; Chubatyy, V.V.; Larkin, S.Yu.; Sizontov, V.M.; Miroshnikov, A.M.; Karmazin, A.A.

2007-01-01

Full text: Perspective [1] Josephson Mo-Re alloy-oxide-Pb, Mo-Re alloy-normal metal-oxide-Pb and Mo-Re alloy-normal metal-oxide- normal metal-Mo-Re alloy junctions have been fabricated and investigated. Thin (∼50-100 nm) MoRe superconducting films are deposited on Al 2 O 3 substrates by using a dc magnetron sputtering of MoRe target. Normal metal (Sn, Al) thin films are deposited on the MoRe films surfaces by thermal evaporation of metals in vacuum and oxidized to fabricate junctions oxide barriers. Quasiparticle I-V curves of the fabricated junctions were measured in wide range of voltages. To investigate a transparency spread for the fabricated junctions barriers the computer simulation of the measured quasiparticle I-V curves have been done in framework of the model of multiple Andreev reflections in double-barrier junction interfaces. It's demonstrated the investigated junctions can be described as highly asymmetric double-barrier Josephson junctions with great difference between the two barrier transparencies [2,3]. The result of the comparison of experimental quasiparticle I-V curves and calculated ones is proposed and discussed. Results of computer simulation of quasiparticles I-V curves of NbN-based junctions are presented and discussed. Also I-V curves of the fabricated junctions have been measured under microwave irradiation with 60 GHz frequency , clear Shapiro steps in the measured I-V curves were observed and discussed. (authors)

Reliability of twin-dependent triple junction distributions measured from a section plane

International Nuclear Information System (INIS)

Hardy, Graden B.; Field, David P.

2016-01-01

Numerous studies indicate polycrystalline triple junctions are independent microstructural features with distinct properties from their constituent grain boundaries. Despite the influence of triple junctions on material properties, it is impractical to characterize triple junctions on a large scale using current three-dimensional methods. This work demonstrates the ability to characterize twin-dependent triple junction distributions from a section plane by adopting a grain boundary plane stereology. The technique is validated through simulated distributions and simulated electron back-scatter diffraction (EBSD) data. Measures of validation and convergence are adopted to demonstrate the quantitative reliability of the technique as well as the convergence behavior of twin-dependent triple junction distributions. This technique expands the characterization power of EBSD and prepares the way for characterizing general triple junction distributions from a section plane. - Graphical abstract: The distribution of planes forming a triple junction with a given twin boundary is shown partially in the stereographic projections below from a given projection. The plot on the left shows the ideal/measured distribution and the plot on the right shows the distribution obtained from the stereological method presented here.

Nonlinearity in superconductivity and Josephson junctions

International Nuclear Information System (INIS)

Lazarides, N.

1995-01-01

Within the framework of the Bardeen, Cooper and Schrieffers (BCS) theory, the influence of anisotropy on superconducting states are investigated. Crystal anisotropy exists in un-conventional low temperature superconductors as e.g. U 1-x Th x Be 13 and in high temperature superconductors. Starting from a phenomenological pairing interaction of the electrons or holes, the BCS approach is used to derive a set of coupled nonlinear algebraic equations for the momentum dependent gap parameter. The emphasis is put on bifurcation phenomena between s-, d-wave and mixed s- and d-wave symmetry and the influence on measurable quantities as the electron specific heat, spin susceptibility and Josephson tunnelling. Pitch-fork and perturbed pitch-fork bifurcations have been found separating s- and d-wave superconducting states from mixed s- and d-wave states. The additional superconducting states give rise to jumps in the electron specific heat below the transition temperature. These jumps are rounded in the case of perturbed pitch-fork bifurcations. An experiment to measure the sign of the interlayer interaction using dc SQUIDS is suggested. The Ambegaokar-Baratoff formalism has been used for calculating the quasiparticle current and the two phase coherent tunnelling currents in a Josephson junction made of anisotropic superconductors. It is shown that anisotropy can lead to a reduction in the product of the normal resistance and the critical current. For low voltages across the junction the usual resistively shunted Josephson model can be used. Finally, bunching in long circular Josephson junctions and suppression of chaos in point junctions have been investigated. (au) 113 refs

Breaking into the epithelial apical–junctional complex — news from pathogen hackers

Science.gov (United States)

Vogelmann, Roger; Amieva, Manuel R; Falkow, Stanley; Nelson, W James

2012-01-01

The epithelial apical–junctional complex is a key regulator of cellular functions. In addition, it is an important target for microbial pathogens that manipulate the cell to survive, proliferate and sometimes persist within a host. Out of a myriad of potential molecular targets, some bacterial and viral pathogens have selected a subset of protein targets at the apical–junctional complex of epithelial cells. Studying how microbes use these targets also teaches us about the inherent physiological properties of host molecules in the context of normal junctional structure and function. Thus, we have learned that three recently uncovered components of the apical–junctional complex of the Ig superfamily — junctional adhesion molecule, Nectin and the coxsackievirus and adenovirus receptor — are important regulators of junction structure and function and represent critical targets of microbial virulence gene products. PMID:15037310

Charge transport in junctions between d-wave superconductors

International Nuclear Information System (INIS)

Barash, Y.S.; Galaktionov, A.V.; Zaikin, A.D.

1995-01-01

We develop a microscopic analysis of superconducting and dissipative currents in junctions between superconductors with d-wave symmetry of the order parameter. We study the proximity effect in such superconductors and show that for certain crystal orientations the superconducting order parameter can be essentially suppressed in the vicinity of a nontransparent specularly reflecting boundary. This effect strongly influences the value and the angular dependence of the dc Josephson current j S . At T∼T c it leads to a crossover between j S ∝T c -T and j S ∝(T c -T) 2 respectively for homogeneous and nonhomogeneous distribution of the order parameter in the vicinity of a tunnel junction. We show that at low temperatures the current-phase relation j S (cphi) for superconductor--normal-metal--superconductor junctions and short weak links between d-wave superconductors is essentially nonharmonic and contains a discontinuity at cphi=0. This leads to further interesting features of such systems which can be used for pairing symmetry tests in high-temperature superconductors (HTSC). We also investigated the low-temperature I-V curves of normal-metal--superconductor and superconductor-superconductor tunnel junctions and demonstrated that depending on the junction type and crystal orientation these curves show zero-bias anomalies I∝V 2 , I∝V 2 ln(1/V), and I∝V 3 caused by the gapless behavior of the order parameter in d-wave superconductors. Many of our results agree well with recent experimental findings for HTSC compounds

Towards quantum signatures in a swept-bias Josephson junction

Energy Technology Data Exchange (ETDEWEB)

Losert, Harald; Vogel, Karl; Schleich, Wolfgang P. [Institut fuer Quantenphysik and Center for Integrated Quantum Science and Technology (IQST), Universitaet Ulm, D-89069 Ulm (Germany)

2016-07-01

Josephson junctions are one of the best examples for the observation of macroscopic quantum tunneling. The phase difference in a current-biased Josephson junction behaves like the position of a particle in a tilted washboard potential. The escape of this phase-particle corresponds to the voltage switching of the associated junction. Quantum mechanically, the escape from the washboard potential can be explained as tunneling from the ground state, or an excited state. However, it has been shown, that in the case of periodic driving the experimental data for quantum mechanical key features, e.g. Rabi oscillations or energy level quantization, can be reproduced by a completely classical description. Motivated by this discussion, we investigate a swept-bias Josephson junction in the case of a large critical current. In particular, we contrast the switching current distributions resulting from a quantum mechanical and classical description of the time evolution.

Hyperglycaemia and diabetes impair gap junctional communication among astrocytes.

Science.gov (United States)

Gandhi, Gautam K; Ball, Kelly K; Cruz, Nancy F; Dienel, Gerald A

2010-03-15

Sensory and cognitive impairments have been documented in diabetic humans and animals, but the pathophysiology of diabetes in the central nervous system is poorly understood. Because a high glucose level disrupts gap junctional communication in various cell types and astrocytes are extensively coupled by gap junctions to form large syncytia, the influence of experimental diabetes on gap junction channel-mediated dye transfer was assessed in astrocytes in tissue culture and in brain slices from diabetic rats. Astrocytes grown in 15-25 mmol/l glucose had a slow-onset, poorly reversible decrement in gap junctional communication compared with those grown in 5.5 mmol/l glucose. Astrocytes in brain slices from adult STZ (streptozotocin)-treated rats at 20-24 weeks after the onset of diabetes also exhibited reduced dye transfer. In cultured astrocytes grown in high glucose, increased oxidative stress preceded the decrement in dye transfer by several days, and gap junctional impairment was prevented, but not rescued, after its manifestation by compounds that can block or reduce oxidative stress. In sharp contrast with these findings, chaperone molecules known to facilitate protein folding could prevent and rescue gap junctional impairment, even in the presence of elevated glucose level and oxidative stress. Immunostaining of Cx (connexin) 43 and 30, but not Cx26, was altered by growth in high glucose. Disruption of astrocytic trafficking of metabolites and signalling molecules may alter interactions among astrocytes, neurons and endothelial cells and contribute to changes in brain function in diabetes. Involvement of the microvasculature may contribute to diabetic complications in the brain, the cardiovascular system and other organs.

Construction of tunable peptide nucleic acid junctions.

Science.gov (United States)

Duan, Tanghui; He, Liu; Tokura, Yu; Liu, Xin; Wu, Yuzhou; Shi, Zhengshuang

2018-03-15

We report here the construction of 3-way and 4-way peptide nucleic acid (PNA) junctions as basic structural units for PNA nanostructuring. The incorporation of amino acid residues into PNA chains makes PNA nanostructures with more structural complexity and architectural flexibility possible, as exemplified by building 3-way PNA junctions with tunable nanopores. Given that PNA nanostructures have good thermal and enzymatic stabilities, they are expected to have broad potential applications in biosensing, drug delivery and bioengineering.

Craniovertebral junction stenosis in Lenz-Majewski syndrome

Energy Technology Data Exchange (ETDEWEB)

Mizuguchi, Koichi; Ishigro, Akira [National Center for Child Health and Development, Department of General Pediatrics and Interdisciplinary Medicine, Setagaya-ku, Tokyo (Japan); Miyazaki, Osamu [National Center for Child Health and Development, Department of Radiology, Tokyo (Japan); Nishimura, Gen [Tokyo Metropolitan Children' s Medical Center, Department of Pediatric Imaging, Tokyo (Japan)

2015-09-15

We report a girl with Lenz-Majewski syndrome associated with craniovertebral junction stenosis that led to communicating hydrocephalus and cervical myelopathy. The life-threatening complication was related to progressive craniovertebral hyperostosis that rapidly exacerbated during early childhood. Despite initial success of surgical intervention at 2 years of age, she developed apneic spells and died suddenly at age 5 years. Close monitoring for craniovertebral junction stenosis is essential to reduce morbidity and mortality in children with Lenz-Majewski syndrome. (orig.)

Controlling formation of single-molecule junctions by electrochemical reduction of diazonium terminal groups.

Science.gov (United States)

Hines, Thomas; Díez-Pérez, Ismael; Nakamura, Hisao; Shimazaki, Tomomi; Asai, Yoshihiro; Tao, Nongjian

2013-03-06

We report controlling the formation of single-molecule junctions by means of electrochemically reducing two axialdiazonium terminal groups on a molecule, thereby producing direct Au-C covalent bonds in situ between the molecule and gold electrodes. We report a yield enhancement in molecular junction formation as the electrochemical potential of both junction electrodes approach the reduction potential of the diazonium terminal groups. Step length analysis shows that the molecular junction is significantly more stable, and can be pulled over a longer distance than a comparable junction created with amine anchoring bonds. The stability of the junction is explained by the calculated lower binding energy associated with the direct Au-C bond compared with the Au-N bond.

Negative tunnel magnetoresistance and spin transport in ferromagnetic graphene junctions

International Nuclear Information System (INIS)

Zou Jianfei; Jin Guojun; Ma Yuqiang

2009-01-01

We study the tunnel magnetoresistance (TMR) and spin transport in ferromagnetic graphene junctions composed of ferromagnetic graphene (FG) and normal graphene (NG) layers. It is found that the TMR in the FG/NG/FG junction oscillates from positive to negative values with respect to the chemical potential adjusted by the gate voltage in the barrier region when the Fermi level is low enough. Particularly, the conventionally defined TMR in the FG/FG/FG junction oscillates periodically from a positive to negative value with increasing the barrier height at any Fermi level. The spin polarization of the current through the FG/FG/FG junction also has an oscillating behavior with increasing barrier height, whose oscillating amplitude can be modulated by the exchange splitting in the ferromagnetic graphene.

Negative tunnel magnetoresistance and spin transport in ferromagnetic graphene junctions.

Science.gov (United States)

Zou, Jianfei; Jin, Guojun; Ma, Yu-Qiang

2009-03-25

We study the tunnel magnetoresistance (TMR) and spin transport in ferromagnetic graphene junctions composed of ferromagnetic graphene (FG) and normal graphene (NG) layers. It is found that the TMR in the FG/NG/FG junction oscillates from positive to negative values with respect to the chemical potential adjusted by the gate voltage in the barrier region when the Fermi level is low enough. Particularly, the conventionally defined TMR in the FG/FG/FG junction oscillates periodically from a positive to negative value with increasing the barrier height at any Fermi level. The spin polarization of the current through the FG/FG/FG junction also has an oscillating behavior with increasing barrier height, whose oscillating amplitude can be modulated by the exchange splitting in the ferromagnetic graphene.

A shift from arbuscular mycorrhizal to dark septate endophytic colonization in Deschampsia flexuosa roots occurs along primary successional gradient.

Science.gov (United States)

Huusko, K; Ruotsalainen, A L; Markkola, A M

2017-02-01

Soil fungal community and dominant mycorrhizal types are known to shift along with plant community changes during primary succession. However, it is not well understood how and why root fungal symbionts and colonization types vary within the plant host when the host species is able to thrive both at young and at old successional stages with different light and nutrient resource availability. We asked (i) how root fungal colonization of Deschampsia flexuosa (Poaceae) by arbuscular mycorrhizal (AM) fungi and dark septate endophytes (DSE) changes along a postglacial primary successional land uplift gradient. As neighboring vegetation may play a role in root fungal colonization, we also asked (ii) whether removal of the dominant neighbor, Empetrum nigrum ssp. hermaphroditum (Ericaceae), affects root fungal colonization of Deschampsia. We also studied whether (iii) foliar carbon (C) and nitrogen (N) concentration of Deschampsia is related to successional changes along a land uplift gradient. AM colonization decreased (-50 %), DSE colonization increased (+200 %), and foliar C declined in Deschampsia along with increasing successional age, whereas foliar N was not affected. Empetrum removal did not affect AM colonization but increased DSE sclerotial colonization especially at older successional stages. The observed decrease in foliar C coincides with an increase in canopy closure along with increasing successional age. We suggest that the shift from an AM-dominated to a DSE-dominated root fungal community in Deschampsia along a land uplift successional gradient may be related to different nutritional benefits gained through these root fungal groups.

Gap junction protein connexin-43 interacts directly with microtubules

NARCIS (Netherlands)

Giepmans, B N; Verlaan, I; Hengeveld, T; Janssen, H; Calafat, J; Falk, M M; Moolenaar, W H

2001-01-01

Gap junctions are specialized cell-cell junctions that mediate intercellular communication. They are composed of connexin proteins, which form transmembrane channels for small molecules [1, 2]. The C-terminal tail of connexin-43 (Cx43), the most widely expressed connexin member, has been implicated

Voltage-dependent conductance states of a single-molecule junction

DEFF Research Database (Denmark)

Wang, Y F; Néel, N; Kröger, J

2012-01-01

Ag–Sn-phthalocyanine–Ag junctions are shown to exhibit three conductance states. While the junctions are conductive at low bias, their impedance drastically increases above a critical bias. Two-level fluctuations occur at intermediate bias. These characteristics may be used to protect a nanoscale...

Superconducting proximity effect in mesoscopic superconductor/normal-metal junctions

CERN Document Server

Takayanagi, H; Toyoda, E

1999-01-01

The superconducting proximity effect is discussed in mesoscopic superconductor/normal-metal junctions. The newly-developed theory shows long-range phase-coherent effect which explaines early experimental results of giant magnetoresistance oscillations in an Andreev interferometer. The theory also shows that the proximity correction to the conductance (PCC) has a reentrant behavior as a function of energy. The reentrant behavior is systematically studied in a gated superconductor-semiconductor junction. A negative PCC is observed in the case of a weak coupling between the normal metal and the external reservoir. Phase coherent ac effect is also observed when rf is irradiated to the junction.

Building memristive and radiation hardness TiO{sub 2}-based junctions

Energy Technology Data Exchange (ETDEWEB)

Ghenzi, N., E-mail: n.ghenzi@gmail.com [Gerencia de Investigación y Aplicaciones, Comisión Nacional de Energía Atómica (Argentina); Rubi, D. [Gerencia de Investigación y Aplicaciones, Comisión Nacional de Energía Atómica (Argentina); ECyT, UNSAM, Martín de Irigoyen 3100, 1650 San Martín, Bs As (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) (Argentina); Mangano, E.; Gimenez, G. [Instituto Nacional de Tecnología Industrial (INTI) (Argentina); Lell, J. [Gerencia de Investigación y Aplicaciones, Comisión Nacional de Energía Atómica (Argentina); Zelcer, A. [Gerencia Química, Comisión Nacional de Energía Atómica (Argentina); ECyT, UNSAM, Martín de Irigoyen 3100, 1650 San Martín, Bs As (Argentina); Stoliar, P. [ECyT, UNSAM, Martín de Irigoyen 3100, 1650 San Martín, Bs As (Argentina); IMN, Université de Nantes, CNRS, 2 rue de la Houssinière, BP 32229, 44322 Nantes (France); and others

2014-01-01

We study micro-scale TiO{sub 2} junctions that are suitable to be used as resistive random-access memory nonvolatile devices with radiation hardness memristive properties. The fabrication and structural and electrical characterization of the junctions are presented. We obtained a retentivity of 10{sup 5} s, an endurance of 10{sup 4} cycles and reliable switching with short electrical pulses (time-width below 10 ns). Additionally, the devices were exposed to 25 MeV oxygen ions. Then, we performed electrical measurements comparing pristine and irradiated devices in order to check the feasibility of using these junctions as memory elements with memristive and radiation hardness properties. - Highlights: • We fabricated radiation hardness memristive metal insulator metal junctions. • We characterized the structural properties of the devices. • We showed the feasibility of the junctions as a non-volatile memory.

Microwave oscillator using arrays of long Josephson junctions

International Nuclear Information System (INIS)

Pagano, S.; Monaco, R.; Costabile, G.

1989-01-01

The authors report on measurements performed on integrated superconducting devices based on arrays of long Josephson tunnel junctions operating in the resonant fluxon oscillation regime (i.e. biased on the Zero Field Steps). The electromagnetic coupling among the junction causes a mutual phase-locking of the fluxon oscillations with a corresponding increase of the emitted power and a decrease of the signal linewidth. This phase-locked state can be controlled by means of an external dc bias current and magnetic field. The effect of the generated microwave signal has been observed on a small Josephson tunnel junction coupled to the array via a microstrip transmission line. The feasibility of the reported devices as local oscillators in an integrated microwave Josephson receiver is discussed

Filtering microfluidic bubble trains at a symmetric junction.

Science.gov (United States)

Parthiban, Pravien; Khan, Saif A

2012-02-07

We report how a nominally symmetric microfluidic junction can be used to sort all bubbles of an incoming train exclusively into one of its arms. The existence of this "filter" regime is unexpected, given that the junction is symmetric. We analyze this behavior by quantifying how bubbles modulate the hydrodynamic resistance in microchannels and show how speeding up a bubble train whilst preserving its spatial periodicity can lead to filtering at a nominally symmetric junction. We further show how such an asymmetric traffic of bubble trains can be triggered in symmetric geometries by identifying conditions wherein the resistance to flow decreases with an increase in the number of bubbles in the microchannel and derive an exact criterion to predict the same.

Creation of stable molecular junctions with a custom-designed scanning tunneling microscope.

Science.gov (United States)

Lee, Woochul; Reddy, Pramod

2011-12-02

The scanning tunneling microscope break junction (STMBJ) technique is a powerful approach for creating single-molecule junctions and studying electrical transport in them. However, junctions created using the STMBJ technique are usually mechanically stable for relatively short times (scanning tunneling microscope that enables the creation of metal-single molecule-metal junctions that are mechanically stable for more than 1 minute at room temperature. This stability is achieved by a design that minimizes thermal drift as well as the effect of environmental perturbations. The utility of this instrument is demonstrated by performing transition voltage spectroscopy-at the single-molecule level-on Au-hexanedithiol-Au, Au-octanedithiol-Au and Au-decanedithiol-Au junctions.

75 FR 76294 - Radio Broadcasting Services: Pacific Junction, IA

Science.gov (United States)

2010-12-08

... FEDERAL COMMUNICATIONS COMMISSION 47 CFR Part 73 [DA 10-2236; MB Docket No. 10-108] Radio Broadcasting Services: Pacific Junction, IA AGENCY: Federal Communications Commission. ACTION: Final rule. SUMMARY: The staff deletes FM Channel 299C2 at Pacific Junction, Iowa, because the record in this...

P-N semiconductor junctions used as X-ray detectors

International Nuclear Information System (INIS)

Pela, C.A.; Bruco, J.L.; Navas, E.A.; Paula, E. de; Guilardi Neto, T.

1987-01-01

The current response of some comercial P-N semiconductor junctions in function of X-ray incidency, in 40 to 140 KVp band used in diagnosis was characterized. Some junctions were also exposed to radiation of 80 to 250 KVp used in therapy. (C.G.C.) [pt

Effect of quasi-particle injection on retrapping current of Josephson junction

OpenAIRE

Utsunomiya, K.; Yagi, Ryuta

2006-01-01

We report that the energy dissipation of Josephson junction can be controlled by quasi-particle injection. We fabricated two Josephson junctions on the narrow aluminum wire and controlled the energy dissipation of one junction by quasi-particle injection from the other. We observed the retrapping current increased as the quasi-particles were injected. We also studied the heating effect of our measurement.

Autosomal dominant syndrome resembling Coffin-Siris syndrome.

Science.gov (United States)

Flynn, Maureen A; Milunsky, Jeff M

2006-06-15

Coffin-Siris syndrome is a multiple congenital anomaly/mental retardation syndrome with phenotypic variability [OMIM 135900]. The diagnosis is based solely on clinical findings, as there is currently no molecular, biochemical, or cytogenetic analysis available to confirm a diagnosis. Although typically described as an autosomal recessive disorder, autosomal dominant inheritance has also been infrequently reported. We describe a mother and her two daughters who all have features that resemble Coffin-Siris syndrome. However, this is not a completely convincing diagnosis given that hypertelorism is not a feature of Coffin-Siris syndrome and the family is relatively mildly affected. Yet, this family provides further evidence of an autosomal dominant mode of inheritance for a likely variant of Coffin-Siris syndrome (at least in some families). In addition, Sibling 1 had premature thelarche. She is the second reported individual within the spectrum of Coffin-Siris syndrome to have premature thelarche, indicating that it may be a rare clinical feature. Copyright 2006 Wiley-Liss, Inc.

Multicentre dosimetric comparison of photon-junctioning techniques in head and neck radiotherapy

International Nuclear Information System (INIS)

Kron, T.

2003-01-01

Because many head and neck radiotherapy treatment techniques rely on a junction between X-ray fields, it was the aim of the present study to investigate the use of different junctioning techniques and the affect on the dose across the junction. Techniques in use at nine radiotherapy centres in Australia were investigated using thermoluminescence dosimetry (TLD). The techniques could broadly be divided into two groups: (i) use of the light field to match the fields after moving the patient; and (ii) use of asymmetric collimation to create a single isocentre located in the junction. The mean dose at the junction and its reproducibility was studied in five consecutive treatments in each centre using 25 TLD chips placed throughout the junction in an anthropomorphic phantom. There was a tendency for the mono-isocentric technique to deliver a lower, more accurate mean dose at the junction (Group I: 1.22 Gy (n = 8) vs Group II: 0.96 Gy (n = 5) for 1 Gy planned, some centres contributed to both technique) with greater reproducibility (Group I: 9.6%, Group II: 5.1 % of the mean dose). We conclude that a mono-isocentric treatment technique has the potential to deliver a more accurate and reproducible dose distribution at the field junction of photon beams in head and neck treatment. Copyright (2003) Blackwell Science Pty Ltd

The string-junction picture of multiquark states: an update

CERN Document Server

Rossi, Giancarlo

2016-06-07

We recall and update, both theoretically and phenomenologically, our (nearly) forty-years-old proposal of a string-junction as a necessary complement to the conventional classification of hadrons based just on their quark-antiquark constituents. In that proposal single (though in general metastable) hadronic states are associated with "irreducible" gauge-invariant operators consisting of Wilson lines (visualized as strings of color flux tubes) that may either end on a quark or an antiquark, or annihilate in triplets at a junction $J$ or an anti-junction $\\bar{J}$. For the junction-free sector (ordinary $q\\, \\bar{q}$ mesons and glueballs) the picture is supported by large-$N$ (number of colors) considerations as well as by a lattice strong-coupling expansion. Both imply the famous OZI rule suppressing quark-antiquark annihilation diagrams. For hadrons with $J$ and/or $\\bar{J}$ constituents the same expansions support our proposal, including its generalization of the OZI rule to the suppression of $J-\\bar{J}$ a...

The physical analysis on electrical junction of junctionless FET

Directory of Open Access Journals (Sweden)

Lun-Chun Chen

2017-02-01

Full Text Available We propose the concept of the electrical junction in a junctionless (JL field-effect-transistor (FET to illustrate the transfer characteristics of the JL FET. In this work, nanowire (NW junctionless poly-Si thin-film transistors are used to demonstrate this conception of the electrical junction. Though the dopant and the dosage of the source, of the drain, and of the channel are exactly the same in the JL FET, the transfer characteristics of the JL FET is similar to these of the conventional inversion-mode FET rather than these of a resistor, which is because of the electrical junction at the boundary of the gate and the drain in the JL FET. The electrical junction helps us to understand the JL FET, and also to explain the superior transfer characteristic of the JL FET with the gated raised S/D (Gout structure which reveals low drain-induced-barrier-lowering (DIBL and low breakdown voltage of ion impact ionization.

Molecular electronics: some views on transport junctions and beyond.

Science.gov (United States)

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.

Microscopic tunneling theory of long Josephson junctions

DEFF Research Database (Denmark)

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

1992-01-01

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

Mechanically controllable break junctions for molecular electronics.

Science.gov (United States)

Xiang, Dong; Jeong, Hyunhak; Lee, Takhee; Mayer, Dirk

2013-09-20

A mechanically controllable break junction (MCBJ) represents a fundamental technique for the investigation of molecular electronic junctions, especially for the study of the electronic properties of single molecules. With unique advantages, the MCBJ technique has provided substantial insight into charge transport processes in molecules. In this review, the techniques for sample fabrication, operation and the various applications of MCBJs are introduced and the history, challenges and future of MCBJs are discussed. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Bar dynamics and channel junctions in scale-experiments of estuaries

Science.gov (United States)

Leuven, J.; Braat, L.; van Dijk, W. M.; Haas, T. D.; Kleinhans, M. G.

2017-12-01

The evolution of channels and bars in estuaries has high socio-economic relevance, with strong implications for navigation, dredging and ecology. However, the spatial and temporal evolution of channels and bars in estuaries is poorly understood. Here, we study feedbacks of bar morphodynamics on widening and narrowing of estuaries. Therefore, we conducted an experiment in a 20 m long and 3 m wide tilting flume (the 'Metronome'), in which we monitored the evolution of a self-formed estuary that developed from an intial straight channel into an irregular planform with multiple channels, braided bars and a meandering ebb channel. At locations where the estuary width is confined, major channel junctions occur, while the zones between the junctions are characterised by high braiding indices, periodically migrating channels and a relatively large estuary width. The junction locations were forced by the in- and outflow locations on the sides of the ebb-tidal delta and at the location where the channel pattern transitions from multiple channels into a single channel. In the middle of the estuary, self-confinement occurred by sedimentation on the sides of the estuary, which caused another major junction. The channel orientation at the junctions steers the morphodynamics of channels and bars immediately landward and seaward, because the orientation of inflow from the ebb-tidal delta and landward river perpetually varies. In natural systems major junction locations are mostly forced by inherited geology or human engineering. However, this study concludes that even without external forcing, the estuary planform will not converge to an ideal shape but will self-confine at major junctions and widens in the adjacent zones, resulting in an irregular planform shape.

T-junction cross-flow mixing with thermally driven density stratification

Energy Technology Data Exchange (ETDEWEB)

Kickhofel, John, E-mail: jkickhofel@gmail.com [Laboratory of Nuclear Energy Systems, ETH Zurich, Sonneggstrasse 3, 8057 Zurich (Switzerland); Prasser, Horst-Michael, E-mail: prasser@lke.mavt.ethz.ch [Laboratory of Nuclear Energy Systems, ETH Zurich, Sonneggstrasse 3, 8057 Zurich (Switzerland); Selvam, P. Karthick, E-mail: karthick.selvam@ike.uni-stuttgart.de [Institute of Nuclear Technology and Energy Systems (IKE), University of Stuttgart, Pfaffenwaldring 31, 70569 Stuttgart (Germany); Laurien, Eckart, E-mail: eckart.laurien@ike.uni-stuttgart.de [Institute of Nuclear Technology and Energy Systems (IKE), University of Stuttgart, Pfaffenwaldring 31, 70569 Stuttgart (Germany); Kulenovic, Rudi, E-mail: rudi.kulenovic@ike.uni-stuttgart.de [Institute of Nuclear Technology and Energy Systems (IKE), University of Stuttgart, Pfaffenwaldring 31, 70569 Stuttgart (Germany)

2016-12-01

Highlights: • Mesh sensor for realistic nuclear thermal hydraulic scenarios is demonstrated. • Flow temperature behavior across a wide range of Richardson numbers measured. • Upstream stratified flow in the T-junction results in a thermal shock scenario. • Large, stable near-wall thermal gradients exist in spite of turbulent flows. - Abstract: As a means of further elucidating turbulence- and stratification-driven thermal fatigue in the vicinity of T-junctions in nuclear power plants, a series of experiments have been conducted at the high temperature high pressure fluid–structure interaction T-junction facility of the University of Stuttgart with novel fluid measurement instrumentation. T-junction mixing with large fluid temperature gradients results in complex flow behavior, the result of density driven effects. Deionized water mixing at temperature differences of up to 232 K at 7 MPa pressure have been investigated in a T-junction with main pipe diameter 71.8 mm and branch line diameter 38.9 mm. The experiments have been performed with fixed flow rates of 0.4 kg/s in the main pipe and 0.1 kg/s in the branch line. A novel electrode-mesh sensor compatible with the DN80 PN100 pipeline upstream and downstream of the T-junction has been utilized as a temperature sensor providing a high density information in the pipe cross-section in both space and time. Additionally, in-flow and in-wall thermocouples quantify the damping of thermal fluctuations by the wall material. The results indicate that large inflow temperature differences lead to strong turbulence damping, and ultimately stable stratification extending both downstream and upstream of the T-junction resulting in large local thermal gradients.

Realization of φ Josephson junctions with a ferromagnetic interlayer

International Nuclear Information System (INIS)

Sickinger, Hanna Sabine

2014-01-01

In this thesis, φ Josephson junctions based on 0-π junctions with a ferromagnetic interlayer are studied. Josephson junctions (JJs) with a ferromagnetic interlayer can have a phase drop of 0 or π in the ground state, depending on the thickness of the ferromagnet (0 JJs or π JJs). Also, 0-π JJs can be realized, where one segment of the junction (if taken separately) is in the 0 state, while the other segment is in the π state. One can use these π Josephson junctions as a device in superconducting circuits, where it provides a constant phase shift, i.e., it acts as a π phase battery. A generalization of a π JJ is a φ JJ, which has the phase ±φ in the ground state. The value of φ can be chosen by design and tuned in the interval 0<φ<π. The φ JJs used in this experiment were fabricated as 0-π JJs with asymmetric current densities in the 0 and π facets. This system can be described by an effective current-phase relation which is tunable by an externally applied magnetic field. The first experimental evidence of such a φ JJ is presented in this thesis. In particular it is demonstrated that (a) a φ JJ has two ground states +φ and -φ, (b) the unknown state can be detected (read out) by measuring the critical current I c (I c+ or I c- ), and (c) a particular state can be prepared by applying a magnetic field or a special bias sweep sequence. These properties of a φ JJ can be utilized, for example, as a memory cell (classical bit). Furthermore, a φ Josephson junction can be used as a deterministic ratchet. This is due to the tunable asymmetry of the potential that can be changed by the external magnetic field. Rectification curves are observed for the overdamped and the underdamped case. Moreover, experimental data of the retrapping process of the phase of a φ Josephson junction depending on the temperature is presented.

Andreev reflexion studies on planar hybrid SNS-junctions based on 122-thin films

Energy Technology Data Exchange (ETDEWEB)

Doering, Sebastian; Schmidt, Stefan; Schmidl, Frank; Tympel, Volker; Seidel, Paul [Friedrich-Schiller-Universitaet Jena, Institut fuer Festkoerperphysik, Helmholtzweg 5, Jena (Germany); Haindl, Silvia; Kurth, Fritz; Iida, Kazumasa; Holzapfel, Bernhard [IFW Dresden, Institut fuer Metallische Werkstoffe, 01069 Dresden (Germany)

2012-07-01

To investigate the properties of iron-based superconductors, we prepared hybrid junctions in thin film technique. Therefore two geometries were prepared, a planar SNS-junction and an edge junction. The base electrode was made of Ba(Fe{sub 0.9}Co{sub 0.1}){sub 2}As{sub 2} thin films, a sputtered gold layer acts as normal barrier for the planar junction and for the counter electrode we used the conventional superconductor lead. We measured the electrical properties of each electrode, as well as the junctions itself. To obtain information about the order parameter symmetry, we show the differential conductance and compare with different variations of an extended BTK-model. We show differences and commonalities between the results of both junction geometries.

The Control of Junction Flows

National Research Council Canada - National Science Library

Smith, Charles

1997-01-01

An experimental study of the effects of spatially-limited (i.e. localized) surface suction on unsteady laminar and turbulent junction flows was performed using hydrogen bubble flow visualization and Particle Image Velocimetry (PIV...

Spin-flip effects on the supercurrent through mesoscopic superconducting junctions

International Nuclear Information System (INIS)

Pan Hui; Lin Tsunghan

2005-01-01

We investigate the spin-flip effects on the Andreev bound states and the supercurrent in a superconductor/quantum-dot/superconductor system, theoretically. The spin-flip scattering in the quantum dot can reverse the supercurrent flowing through the system, which results in a π-junction transition. By controlling the energy level of the quantum dot, the π-junction transition can be caused to occur again. The two mechanisms of the π-junction transitions are interpreted within the picture of Andreev bound states

Electron Transport through Porphyrin Molecular Junctions

Science.gov (United States)

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

Gap junctions and epileptic seizures--two sides of the same coin?

Directory of Open Access Journals (Sweden)

Vladislav Volman

Full Text Available Electrical synapses (gap junctions play a pivotal role in the synchronization of neuronal ensembles which also makes them likely agonists of pathological brain activity. Although large body of experimental data and theoretical considerations indicate that coupling neurons by electrical synapses promotes synchronous activity (and thus is potentially epileptogenic, some recent evidence questions the hypothesis of gap junctions being among purely epileptogenic factors. In particular, an expression of inter-neuronal gap junctions is often found to be higher after the experimentally induced seizures than before. Here we used a computational modeling approach to address the role of neuronal gap junctions in shaping the stability of a network to perturbations that are often associated with the onset of epileptic seizures. We show that under some circumstances, the addition of gap junctions can increase the dynamical stability of a network and thus suppress the collective electrical activity associated with seizures. This implies that the experimentally observed post-seizure additions of gap junctions could serve to prevent further escalations, suggesting furthermore that they are a consequence of an adaptive response of the neuronal network to the pathological activity. However, if the seizures are strong and persistent, our model predicts the existence of a critical tipping point after which additional gap junctions no longer suppress but strongly facilitate the escalation of epileptic seizures. Our results thus reveal a complex role of electrical coupling in relation to epileptiform events. Which dynamic scenario (seizure suppression or seizure escalation is ultimately adopted by the network depends critically on the strength and duration of seizures, in turn emphasizing the importance of temporal and causal aspects when linking gap junctions with epilepsy.

Ligament augmentation for prevention of proximal junctional kyphosis and proximal junctional failure in adult spinal deformity.

Science.gov (United States)

Safaee, Michael M; Deviren, Vedat; Dalle Ore, Cecilia; Scheer, Justin K; Lau, Darryl; Osorio, Joseph A; Nicholls, Fred; Ames, Christopher P

2018-05-01

OBJECTIVE Proximal junctional kyphosis (PJK) is a well-recognized, yet incompletely defined, complication of adult spinal deformity surgery. There is no standardized definition for PJK, but most studies describe PJK as an increase in the proximal junctional angle (PJA) of greater than 10°-20°. Ligament augmentation is a novel strategy for PJK reduction that provides strength to the upper instrumented vertebra (UIV) and adjacent segments while also reducing junctional stress at those levels. METHODS In this study, ligament augmentation was used in a consecutive series of adult spinal deformity patients at a single institution. Patient demographics, including age; sex; indication for surgery; revision surgery; surgical approach; and use of 3-column osteotomies, vertebroplasty, or hook fixation at the UIV, were collected. The PJA was measured preoperatively and at last follow-up using 36-inch radiographs. Data on change in PJA and need for revision surgery were collected. Univariate and multivariate analyses were performed to identify factors associated with change in PJA and proximal junctional failure (PJF), defined as PJK requiring surgical correction. RESULTS A total of 200 consecutive patients were included: 100 patients before implementation of ligament augmentation and 100 patients after implementation of this technique. The mean age of the ligament augmentation cohort was 66 years, and 67% of patients were women. Over half of these cases (51%) were revision surgeries, with 38% involving a combined anterior or lateral and posterior approach. The mean change in PJA was 6° in the ligament augmentation group compared with 14° in the control group (p historical cohort, ligament augmentation is associated with a significant decrease in PJK and PJF. These data support the implementation of ligament augmentation in surgery for adult spinal deformity, particularly in patients with a high risk of developing PJK and PJF.

Nonlocal Cooper pair splitting in a pSn-junction

NARCIS (Netherlands)

Veldhorst, M.; Brinkman, Alexander

2010-01-01

Perfect Cooper pair splitting is proposed, based on crossed Andreev reflection (CAR) in a p-type semiconductor-superconductor-n-type semiconductor (pSn) junction. The ideal splitting is caused by the energy filtering that is enforced by the band structure of the electrodes. The pSn junction is

Gas-liquid flow splitting in T-junction with inclined lateral arm

Science.gov (United States)

Yang, Le-le; Liu, Shuo; Li, Hua; Zhang, Jian; Wu, Ying-xiang; Xu, Jing-yu

2018-02-01

This paper studies the gas-liquid flow splitting in T-junction with inclined lateral arm. The separation mechanism of the T-junction is related to the pressure distribution in the T-junction. It is shown that the separation efficiency strongly depends on the inclination angle, when the angle ranges from 0° to 30°, while not so strongly for angles in the range from 30° to 90° Increasing the number of connecting tubes is helpful for the gas-liquid separation, and under the present test conditions, with four connecting tubes, a good separation performance can be achieved. Accordingly, a multi-tube Y-junction separator with four connecting tubes is designed for the experimental investigation. A good agreement between the simulated and measured data shows that there is an optimal split ratio to achieve the best performance for the multi-tube Y-junction separator.

Thermopower in double planar tunnel junctions with ferromagnetic barriers and nonmagnetic electrodes

Energy Technology Data Exchange (ETDEWEB)

Wilczyński, M., E-mail: wilczyns@if.pw.edu.pl

2017-01-01

The Seebeck effect is investigated in double planar tunnel junctions consisting of nonmagnetic electrodes and the central layer separated by ferromagnetic barriers. Calculations are performed in the linear response theory using the free-electron model. The thermopower is analyzed as a function of the thickness of the central layer, temperature of the junctions and the relative orientation of magnetic moments of the barriers. It has been found that the thermopower can be significantly enhanced in the junction with special central layer thickness due to electron tunneling by resonant states. The thickness of the central layer for which the thermopower is enhanced depends not only on the temperature of the junction but also on the orientation of magnetic moments in the barriers. - Highlights: • Thermopower in the double planar junctions with magnetic barriers is analyzed. • Thermopower can be enhanced due to the resonant tunneling. • Thermopower depends on the magnetic configuration of the junction.

Single-molecule detection of dihydroazulene photo-thermal reaction using break junction technique

Science.gov (United States)

Huang, Cancan; Jevric, Martyn; Borges, Anders; Olsen, Stine T.; Hamill, Joseph M.; Zheng, Jue-Ting; Yang, Yang; Rudnev, Alexander; Baghernejad, Masoud; Broekmann, Peter; Petersen, Anne Ugleholdt; Wandlowski, Thomas; Mikkelsen, Kurt V.; Solomon, Gemma C.; Brøndsted Nielsen, Mogens; Hong, Wenjing

2017-05-01

Charge transport by tunnelling is one of the most ubiquitous elementary processes in nature. Small structural changes in a molecular junction can lead to significant difference in the single-molecule electronic properties, offering a tremendous opportunity to examine a reaction on the single-molecule scale by monitoring the conductance changes. Here, we explore the potential of the single-molecule break junction technique in the detection of photo-thermal reaction processes of a photochromic dihydroazulene/vinylheptafulvene system. Statistical analysis of the break junction experiments provides a quantitative approach for probing the reaction kinetics and reversibility, including the occurrence of isomerization during the reaction. The product ratios observed when switching the system in the junction does not follow those observed in solution studies (both experiment and theory), suggesting that the junction environment was perturbing the process significantly. This study opens the possibility of using nano-structured environments like molecular junctions to tailor product ratios in chemical reactions.

A semiconductor nanowire Josephson junction microwave laser

Science.gov (United States)

Cassidy, Maja; Uilhoorn, Willemijn; Kroll, James; de Jong, Damaz; van Woerkom, David; Nygard, Jesper; Krogstrup, Peter; Kouwenhoven, Leo

We present measurements of microwave lasing from a single Al/InAs/Al nanowire Josephson junction strongly coupled to a high quality factor superconducting cavity. Application of a DC bias voltage to the Josephson junction results in photon emission into the cavity when the bias voltage is equal to a multiple of the cavity frequency. At large voltage biases, the strong non-linearity of the circuit allows for efficient down conversion of high frequency microwave photons down to multiple photons at the fundamental frequency of the cavity. In this regime, the emission linewidth narrows significantly below the bare cavity linewidth to 50%. The junction-cavity coupling and laser emission can be tuned rapidly via an external gate, making it suitable to be integrated into a scalable qubit architecture as a versatile source of coherent microwave radiation. This work has been supported by the Netherlands Organisation for Scientific Research (NWO/OCW), Foundation for Fundamental Research on Matter (FOM), European Research Council (ERC), and Microsoft Corporation Station Q.

Magnetometry with Low-Resistance Proximity Josephson Junction

Science.gov (United States)

Jabdaraghi, R. N.; Peltonen, J. T.; Golubev, D. S.; Pekola, J. P.

2018-06-01

We characterize a niobium-based superconducting quantum interference proximity transistor (Nb-SQUIPT) and its key constituent formed by a Nb-Cu-Nb SNS weak link. The Nb-SQUIPT and SNS devices are fabricated simultaneously in two separate lithography and deposition steps, relying on Ar ion cleaning of the Nb contact surfaces. The quality of the Nb-Cu interface is characterized by measuring the temperature-dependent equilibrium critical supercurrent of the SNS junction. In the Nb-SQUIPT device, we observe a maximum flux-to-current transfer function value of about 55 nA/Φ_0 in the sub-gap regime of bias voltages. This results in suppression of power dissipation down to a few fW. Low-bias operation of the device with a relatively low probe junction resistance decreases the dissipation by up to two orders of magnitude compared to a conventional device based on an Al-Cu-Al SNS junction and an Al tunnel probe (Al-SQUIPT).

A case report of craniovertebral junction intradural extramedullary neurenteric cyst

Directory of Open Access Journals (Sweden)

Rajeshwari S Vhora

2014-01-01

Full Text Available A neurenteric cyst of the craniocervical (CV junction, as a cause of bulbomedullary compression, is very rare. An abnormal communication between the endoderm and neuroectoderm during the third week of embryogenesis may be responsible for its formation. It is a rare spinal condition. The most frequent location is at the lower cervical and higher thoracic spine. Neurenteric cysts of the craniocervical junction are even rarer. We report the case of a CV junction intradural neurenteric cyst. Magnetic Resonance Imaging (MRI of our patient demonstrated an intradural extramedullary process of the craniocervical junction. A surgical posterior approach allowed gross total resection of the lesion. The histopathology of the surgical specimen showed that the cyst wall was made up of fibrocollagen walls lined with a partially ciliated columnar epithelium.

Instabilities in thin tunnel junctions

International Nuclear Information System (INIS)

Konkin, M.K.; Adler, J.G.

1978-01-01

Tunnel junctions prepared for inelastic electron tunneling spectroscopy are often plagued by instabilities in the 0-500-meV range. This paper relates the bias at which the instability occurs to the barrier thickness

Single-electron tunnel junction array

International Nuclear Information System (INIS)

Likharev, K.K.; Bakhvalov, N.S.; Kazacha, G.S.; Serdyukova, S.I.

1989-01-01

The authors have carried out an analysis of statics and dynamics of uniform one-dimensional arrays of ultrasmall tunnel junctions. The correlated single-electron tunneling in the junctions of the array results in its behavior qualitatively similar to that of the Josephson transmission line. In particular, external electric fields applied to the array edges can inject single-electron-charged solitons into the array interior. Shape of such soliton and character of its interactions with other solitons and the array edges are very similar to those of the Josephson vortices (sine-Gordon solitons) in the Josephson transmission line. Under certain conditions, a coherent motion of the soliton train along the array is possible, resulting in generation of narrowband SET oscillations with frequency f/sub s/ = /e where is the dc current flowing along the array

Three-dimensional models of conventional and vertical junction laser-photovoltaic energy converters

Science.gov (United States)

Heinbockel, John H.; Walker, Gilbert H.

1988-01-01

Three-dimensional models of both conventional planar junction and vertical junction photovoltaic energy converters have been constructed. The models are a set of linear partial differential equations and take into account many photoconverter design parameters. The model is applied to Si photoconverters; however, the model may be used with other semiconductors. When used with a Nd laser, the conversion efficiency of the Si vertical junction photoconverter is 47 percent, whereas the efficiency for the conventional planar Si photoconverter is only 17 percent. A parametric study of the Si vertical junction photoconverter is then done in order to describe the optimum converter for use with the 1.06-micron Nd laser. The efficiency of this optimized vertical junction converter is 44 percent at 1 kW/sq cm.

Creation of stable molecular junctions with a custom-designed scanning tunneling microscope

International Nuclear Information System (INIS)

Lee, Woochul; Reddy, Pramod

2011-01-01

The scanning tunneling microscope break junction (STMBJ) technique is a powerful approach for creating single-molecule junctions and studying electrical transport in them. However, junctions created using the STMBJ technique are usually mechanically stable for relatively short times (<1 s), impeding detailed studies of their charge transport characteristics. Here, we report a custom-designed scanning tunneling microscope that enables the creation of metal–single molecule–metal junctions that are mechanically stable for more than 1 minute at room temperature. This stability is achieved by a design that minimizes thermal drift as well as the effect of environmental perturbations. The utility of this instrument is demonstrated by performing transition voltage spectroscopy—at the single-molecule level—on Au–hexanedithiol–Au, Au–octanedithiol–Au and Au–decanedithiol–Au junctions.

Superconductive junctions for x-ray spectroscopy

International Nuclear Information System (INIS)

Grand, J.B. le; Bruijn, M.P.; Frericks, M.; Korte, P.A.J. de; Houwman, E.P.; Flokstra, J.

1992-01-01

Biasing of SIS-junctions for the purpose of high energy resolution x-ray detection is complicated by the presence of a DC Josephson current and AC Josephson current resonances, so that a large magnetic field is normally used for the suppression of these Josephson features. A transimpedance amplifier is proposed for biasing and signal amplification at low magnetic field. X-ray spectroscopy detectors for astronomy require a high detection efficiency in the 0.5-10 keV energy band and a reasonable (∼1 cm 2 ) detector area. Calculations on absorber-junctions combinations which might meet these requirements are presented. (author) 9 refs.; 10 figs

Systematic optimization of quantum junction colloidal quantum dot solar cells

KAUST Repository

Liu, Huan; Zhitomirsky, David; Hoogland, Sjoerd; Tang, Jiang; Kramer, Illan J.; Ning, Zhijun; Sargent, Edward H.

2012-01-01

The recently reported quantum junction architecture represents a promising approach to building a rectifying photovoltaic device that employs colloidal quantum dot layers on each side of the p-n junction. Here, we report an optimized quantum

Optical photon detection in Al superconducting tunnel junctions

International Nuclear Information System (INIS)

Brammertz, G.; Peacock, A.; Verhoeve, P.; Martin, D.; Venn, R.

2004-01-01

We report on the successful fabrication of low leakage aluminium superconducting tunnel junctions with very homogeneous and transparent insulating barriers. The junctions were tested in an adiabatic demagnetisation refrigerator with a base temperature of 35 mK. The normal resistance of the junctions is equal to ∼7 μΩ cm 2 with leakage currents in the bias voltage domain as low as 100 fA/μm 2 . Optical single photon counting experiments show a very high responsivity with charge amplification factors in excess of 100. The total resolving power λ/Δλ (including electronic noise) for 500 nm photons is equal to 13 compared to a theoretical tunnel limited value of 34. The current devices are found to be limited spectroscopically by spatial inhomogeneities in the detectors response

Temporal correlations and structural memory effects in break junction measurements

DEFF Research Database (Denmark)

Magyarkuti, A.; Lauritzen, Kasper Primdal; Balogh, Zoltan Imre

2017-01-01

that correlations between the opening and subsequent closing traces may indicate structural memory effects in atomic-sized metallic and molecular junctions. Applying these methods on measured and simulated gold metallic contacts as a test system, we show that the surface diffusion induced flattening of the broken......-molecule junctions, we demonstrate pronounced contact memory effects and recovery of the molecule for junctions breaking before atomic chains are formed. However, if chains are pulled the random relaxation of the chain and molecule after rupture prevents opening-closing correlations....

Intercellular coupling mediated by potassium accumulation in peg-and-socket junctions

DEFF Research Database (Denmark)

Vigmond, Edward J.; Bardakjian, Berj L.; Thuneberg, Lars

2000-01-01

Physiology, peg-and-socket junctions, smooth muscle, boundary element method, coupling, morphology......Physiology, peg-and-socket junctions, smooth muscle, boundary element method, coupling, morphology...

Josephson junction analog and quasiparticle-pair current

DEFF Research Database (Denmark)

Bak, Christen Kjeldahl; Pedersen, Niels Falsig

1973-01-01

A close analogy exists between a Josephson junction and a phase-locked loop. A new type of electrical analog based on this principle is presented. It is shown that the inclusion in this analog of a low-pass filter gives rise to a current of the same form as the Josephson quasiparticle-pair current....... A simple picture of the quasiparticle-pair current, which gives the right dependences, is obtained by assuming a junction cutoff frequency to be at the energy gap. ©1973 American Institute of Physics...

Fabrication and characterization of graphene/molecule/graphene vertical junctions with aryl alkane monolayers

Science.gov (United States)

Jeong, Inho; Song, Hyunwook

2017-11-01

In this study, we fabricated and characterized graphene/molecule/graphene (GMG) vertical junctions with aryl alkane monolayers. The constituent molecules were chemically self-assembled via electrophilic diazonium reactions into a monolayer on the graphene bottom electrode, while the other end physically contacted the graphene top electrode. A full understanding of the transport properties of molecular junctions is a key step in the realization of molecular-scale electronic devices and requires detailed microscopic characterization of the junction's active region. Using a multiprobe approach combining a variety of transport techniques, we elucidated the transport mechanisms and electronic structure of the GMG junctions, including temperature- and length-variable transport measurements, and transition voltage spectroscopy. These results provide criteria to establish a valid molecular junction and to determine the most probable transport characteristics of the GMG junctions.

High-speed carrier-depletion silicon Mach-Zehnder optical modulators with lateral PN junctions

Directory of Open Access Journals (Sweden)

Graham Trevor Reed

2014-12-01

Full Text Available This paper presents new experimental data from a lateral PN junction silicon Mach-Zehnder optical modulator. Efficiencies in the 1.4V.cm to 1.9V.cm range are demonstrated for drive voltages between 0V and 6V. High speed operation up to 52Gbit/s is also presented. The performance of the device which has its PN junction positioned in the centre of the waveguide is then compared to previously reported data from a lateral PN junction device with the junction self-aligned to the edge of the waveguide rib. An improvement in modulation efficiency is demonstrated when the junction is positioned in the centre of the waveguide. Finally we propose schemes for achieving high modulation efficiency whilst retaining self-aligned formation of the PN junction.

Dielectric effect on electric fields in the vicinity of the metal–vacuum–dielectric junction

International Nuclear Information System (INIS)

Chung, M.S.; Mayer, A.; Miskovsky, N.M.; Weiss, B.L.; Cutler, P.H.

2013-01-01

The dielectric effect was theoretically investigated in order to describe the electric field in the vicinity of a junction of a metal, dielectric, and vacuum. The assumption of two-dimensional symmetry of the junction leads to a simple analytic form and to a systematic numerical calculation for the field. The electric field obtained for the triple junction was found to be enhanced or reduced according to a certain criterion determined by the contact angles and dielectric constant. Further numerical calculations of the dielectric effect show that an electric field can experience a larger enhancement or reduction for a quadruple junction than that achieved for the triple junction. It was also found that even though it changes slowly in comparison with the shape effect, the dielectric effect was noticeably large over the entire range of the shape change. - Highlights: ► This work explains how a very strong electric field can be produced due to the dielectric in the vicinity of metal–dielectric contact. ► This work deals with configurations which enhance electric fields using the dielectric effect. The configuration is a type of junction at which metal, vacuum and dielectric meet. ► This work suggests the criterion to determine whether field enhancement occurs or not in the triple junction of metal, vacuum and dielectric. ► This work suggests that a quadruple junction is more effective in enhancing the electric field than a triple junction. The quadruple junction is formed by an additional vacuum portion to the triple junction. ► This work suggests that a triple junction can be a breakthrough candidate for a cold electron source

Children and Adolescents' Understandings of Family Resemblance: A Study of Naive Inheritance Concepts

Science.gov (United States)

Williams, Joanne M.

2012-01-01

This paper aims to provide developmental data on two connected naive inheritance concepts and to explore the coherence of children's naive biology knowledge. Two tasks examined children and adolescents' (4, 7, 10, and 14 years) conceptions of phenotypic resemblance across kin (in physical characteristics, disabilities, and personality traits). The…

Single-Molecule Photocurrent at a Metal-Molecule-Semiconductor Junction.

Science.gov (United States)

Vezzoli, Andrea; Brooke, Richard J; Higgins, Simon J; Schwarzacher, Walther; Nichols, Richard J

2017-11-08

We demonstrate here a new concept for a metal-molecule-semiconductor nanodevice employing Au and GaAs contacts that acts as a photodiode. Current-voltage traces for such junctions are recorded using a STM, and the "blinking" or "I(t)" method is used to record electrical behavior at the single-molecule level in the dark and under illumination, with both low and highly doped GaAs samples and with two different types of molecular bridge: nonconjugated pentanedithiol and the more conjugated 1,4-phenylene(dimethanethiol). Junctions with highly doped GaAs show poor rectification in the dark and a low photocurrent, while junctions with low doped GaAs show particularly high rectification ratios in the dark (>10 3 for a 1.5 V bias potential) and a high photocurrent in reverse bias. In low doped GaAs, the greater thickness of the depletion layer not only reduces the reverse bias leakage current, but also increases the volume that contributes to the photocurrent, an effect amplified by the point contact geometry of the junction. Furthermore, since photogenerated holes tunnel to the metal electrode assisted by the HOMO of the molecular bridge, the choice of the latter has a strong influence on both the steady state and transient metal-molecule-semiconductor photodiode response. The control of junction current via photogenerated charge carriers adds new functionality to single-molecule nanodevices.

Q factor and resonance amplitude of Josephson tunnel junctions

International Nuclear Information System (INIS)

Broom, R.F.; Wolf, P.

1977-01-01

The surface impedance of the superconducting films comprising the electrodes of Josephson tunnel junctions has been derived from the BCS theory in the extreme London limit. Expressions have been obtained for (i) the dependence of the penetration depth lambda on frequency and temperature, and (ii) the quality factor Q of the junction cavity, attributable to surface absorption in the electrodes. The effect of thin electrodes (t 9 or approx. = lambda) is also included in the calculations. Comparison of the calculated frequency dependence of lambda with resonance measurements on Pb-alloy and all-Nb tunnel junctions yields quite good agreement, indicating that the assumptions made in the theory are reasonable. Measurements of the (current) amplitude of the resonance peaks of the junctions have been compared with the values obtained from inclusion of the calculated Q in the theory by Kulik. In common with observations on microwave cavities by other workers, we find that a small residual conductivity must be added to the real part of the BCS value. With its inclusion, good agreement is found between calculation and experiment, within the range determined by the simplifying assumptions of Kulik's theory. From the results, we believe the calculation of Q to be reasonably accurate for the materials investigated. It is shown that the resonance amplitude of Josephson junctions can be calculated directly from the material constants and a knowledge of the residual conductivity

Spatially inhomogeneous barrier height in graphene/MoS2 Schottky junctions

Science.gov (United States)

Tomer, Dushyant; Rajput, Shivani; Li, Lian

Graphene interfaced with a semiconductor forms a Schottky junction with rectifying properties. In this study, graphene Schottky junctions are fabricated by transferring CVD monolayer graphene on mechanically exfoliated MoS2 multilayers. The forward bias current-voltage characteristics are measured in the temperature range of 210-300 K. An increase in the zero bias barrier height and decrease in the ideality factor are observed with increasing temperature. Such behavior is attributed to Schottky barrier inhomogeneities possibly due to graphene ripples and ridges at the junction interface as suggested by atomic force microscopy. Assuming a Gaussian distribution of the barrier height, mean barrier of 0.97+/-0.10 eV is found for the graphene MoS2 junction. Our findings provide significant insight on the barrier height inhomogeneities in graphene/two dimensional semiconductor Schottky junctions. U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering Award No. DEFG02-07ER46228.

Inhomogeneity in barrier height at graphene/Si (GaAs) Schottky junctions.

Science.gov (United States)

Tomer, D; Rajput, S; Hudy, L J; Li, C H; Li, L

2015-05-29

Graphene (Gr) interfaced with a semiconductor forms a Schottky junction with rectifying properties, however, fluctuations in the Schottky barrier height are often observed. In this work, Schottky junctions are fabricated by transferring chemical vapor deposited monolayer Gr onto n-type Si and GaAs substrates. Temperature dependence of the barrier height and ideality factor are obtained by current-voltage measurements between 215 and 350 K. An increase in the zero bias barrier height and decrease in the ideality factor are observed with increasing temperature for both junctions. Such behavior is attributed to barrier inhomogeneities that arise from interfacial disorders as revealed by scanning tunneling microscopy/spectroscopy. Assuming a Gaussian distribution of the barrier heights, mean values of 1.14 ± 0.14 eV and 0.76 ± 0.10 eV are found for Gr/Si and Gr/GaAs junctions, respectively. These findings resolve the origin of barrier height inhomogeneities in these Schottky junctions.

Inhomogeneity in barrier height at graphene/Si (GaAs) Schottky junctions

International Nuclear Information System (INIS)

Tomer, D; Rajput, S; Hudy, L J; Li, L; Li, C H

2015-01-01

Graphene (Gr) interfaced with a semiconductor forms a Schottky junction with rectifying properties, however, fluctuations in the Schottky barrier height are often observed. In this work, Schottky junctions are fabricated by transferring chemical vapor deposited monolayer Gr onto n-type Si and GaAs substrates. Temperature dependence of the barrier height and ideality factor are obtained by current–voltage measurements between 215 and 350 K. An increase in the zero bias barrier height and decrease in the ideality factor are observed with increasing temperature for both junctions. Such behavior is attributed to barrier inhomogeneities that arise from interfacial disorders as revealed by scanning tunneling microscopy/spectroscopy. Assuming a Gaussian distribution of the barrier heights, mean values of 1.14 ± 0.14 eV and 0.76 ± 0.10 eV are found for Gr/Si and Gr/GaAs junctions, respectively. These findings resolve the origin of barrier height inhomogeneities in these Schottky junctions. (paper)

Changes of junctions of endothelial cells in coronary sclerosis: A review

Directory of Open Access Journals (Sweden)

Li-Zi Zhang

2016-03-01

Full Text Available Atherosclerosis, the major cause of cardiovascular diseases, has been a leading contributor to morbidity and mortality in the United States and it has been on the rise globally. Endothelial cell–cell junctions are critical for vascular integrity and maintenance of vascular function. Endothelial cell junctions dysfunction is the onset step of future coronary events and coronary artery disease. Keywords: Coronary atherosclerosis, Junctions, Endothelial cells

Structure modeling and mutational analysis of gap junction beta 2 ...

African Journals Online (AJOL)

Yomi

2012-04-03

Apr 3, 2012 ... Three dimensional (3 D) structure is very useful for understanding biological functions. Gap junction beta 2 (GJB2), human gene encoding for gap junction beta 2 protein is involved in ... Research in deafness became real.

Triple junction polymer solar cells for photoelectrochemical water splitting

NARCIS (Netherlands)

Esiner, S.; Eersel, van H.; Wienk, M.M.; Janssen, R.A.J.

2013-01-01

A triple junction polymer solar cell in a novel 1 + 2 type configuration provides photoelectrochemical water splitting in its maximum power point at V ˜ 1.70 V with an estimated solar to hydrogen energy conversion efficiency of 3.1%. The triple junction cell consists of a wide bandgap front cell and

AcvR1-mediated BMP signaling in second heart field is required for arterial pole development: implications for myocardial differentiation and regional identity.

Science.gov (United States)

Thomas, Penny S; Rajderkar, Sudha; Lane, Jamie; Mishina, Yuji; Kaartinen, Vesa

2014-06-15

BMP signaling plays an essential role in second heart field-derived heart and arterial trunk development, including myocardial differentiation, right ventricular growth, and interventricular, outflow tract and aortico-pulmonary septation. It is mediated by a number of different BMP ligands, and receptors, many of which are present simultaneously. The mechanisms by which they regulate morphogenetic events and degree of redundancy amongst them have still to be elucidated. We therefore assessed the role of BMP Type I receptor AcvR1 in anterior second heart field-derived cell development, and compared it with that of BmpR1a. By removing Acvr1 using the driver Mef2c[AHF]-Cre, we show that AcvR1 plays an essential role in arterial pole morphogenesis, identifying defects in outflow tract wall and cushion morphology that preceded a spectrum of septation defects from double outlet right ventricle to common arterial trunk in mutants. Its absence caused dysregulation in gene expression important for myocardial differentiation (Isl1, Fgf8) and regional identity (Tbx2, Tbx3, Tbx20, Tgfb2). Although these defects resemble to some degree those in the equivalent Bmpr1a mutant, a novel gene knock-in model in which Bmpr1a was expressed in the Acvr1 locus only partially restored septation in Acvr1 mutants. These data show that both BmpR1a and AcvR1 are needed for normal heart development, in which they play some non-redundant roles, and refine our understanding of the genetic and morphogenetic processes underlying Bmp-mediated heart development important in human congenital heart disease. Copyright © 2014 Elsevier Inc. All rights reserved.

Variability study of Si nanowire FETs with different junction gradients

Directory of Open Access Journals (Sweden)

Jun-Sik Yoon

2016-01-01

Full Text Available Random dopant fluctuation effects of gate-all-around Si nanowire field-effect transistors (FETs are investigated in terms of different diameters and junction gradients. The nanowire FETs with smaller diameters or shorter junction gradients increase relative variations of the drain currents and the mismatch of the drain currents between source-drain and drain-source bias change in the saturation regime. Smaller diameters decreased current drivability critically compared to standard deviations of the drain currents, thus inducing greater relative variations of the drain currents. Shorter junction gradients form high potential barriers in the source-side lightly-doped extension regions at on-state, which determines the magnitude of the drain currents and fluctuates the drain currents greatly under thermionic-emission mechanism. On the other hand, longer junction gradients affect lateral field to fluctuate the drain currents greatly. These physical phenomena coincide with correlations of the variations between drain currents and electrical parameters such as threshold voltages and parasitic resistances. The nanowire FETs with relatively-larger diameters and longer junction gradients without degrading short channel characteristics are suggested to minimize the relative variations and the mismatch of the drain currents.

Photodetectors based on junctions of two-dimensional transition metal dichalcogenides

International Nuclear Information System (INIS)

Wei Xia; Yan Fa-Guang; Shen Chao; Lv Quan-Shan; Wang Kai-You

2017-01-01

Transition metal dichalcogenides (TMDCs) have gained considerable attention because of their novel properties and great potential applications. The flakes of TMDCs not only have great light absorption from visible to near infrared, but also can be stacked together regardless of lattice mismatch like other two-dimensional (2D) materials. Along with the studies on intrinsic properties of TMDCs, the junctions based on TMDCs become more and more important in applications of photodetection. The junctions have shown many exciting possibilities to fully combine the advantages of TMDCs, other 2D materials, conventional and organic semiconductors together. Early studies have greatly enriched the application of TMDCs in photodetection. In this review, we investigate the efforts in photodetectors based on the junctions of TMDCs and analyze the properties of those photodetectors. Homojunctions based on TMDCs can be made by surface chemical doping, elemental doping and electrostatic gating. Heterojunction formed between TMDCs/2D materials, TMDCs/conventional semiconductors and TMDCs/organic semiconductor also deserve more attentions. We also compare the advantages and disadvantages of different junctions, and then give the prospects for the development of junctions based on TMDCs. (topical reviews)

The Wiedemann—Franz law in a normal metal—superconductor junction

International Nuclear Information System (INIS)

Ghanbari R; Rashedi G

2011-01-01

In this paper the influence of superconducting correlations on the thermal and charge conductances in a normal metal—superconductor (NS) junction in the clean limit is studied theoretically. First we solve the quasiclassical Eilenberger equations, and using the obtained density of states we can acquire the thermal and electrical conductances for the NS junction. Then we compare the conductance in a normal region of an NS junction with that in a single layer of normal metal (N). Moreover, we study the Wiedemann—Franz (WF) law for these two cases (N and NS). From our calculations we conclude that the behaviour of the NS junction does not conform to the WF law for all temperatures. The effect of the thickness of normal metal on the thermal conductivity is also theoretically investigated in the paper. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

On the stability of large-area Al-p-Si junction

International Nuclear Information System (INIS)

Tsyganov, Yu.S.

2006-01-01

Design of silicon radiation detector made of 12 kΩ · cm p-silicon with both amine- and amine-free hardeners epoxy resin junction edge passivation is presented. Before producing large-area detectors for measurements of efficiency of evaporation residues collection at the focal plane of the Dubna Gas-Filled Recoil Separator (DGFRS), a set of small-area test detectors was produced. Stability of the Al-(p)Si junction has been studied for a long time. Estimate of a realistic lifetime for the mentioned type of Al-Si rectifying junction is done

Effects of parenting quality on adolescents' personality resemblance to their parents. The TRAILS study

NARCIS (Netherlands)

Langenhof, M Rohaa; Komdeur, Jan; Oldehinkel, Albertine J.

This study considers the development of resemblance between 741 adolescents and their biological parents, across six NEO-PI-R personality traits known to be important in psychological problems: anger-hostility, impulsiveness, vulnerability, assertiveness, excitement-seeking, and self-discipline. We

Dielectric properties of biological tissues in which cells are connected by communicating junctions

International Nuclear Information System (INIS)

Asami, Koji

2007-01-01

The frequency dependence of the complex permittivity of biological tissues has been simulated using a simple model that is a cubic array of spherical cells in a parallel plate capacitor. The cells are connected by two types of communicating junctions: one is a membrane-lined channel for plasmodesmata in plant tissues, and the other is a conducting patch of adjoining plasma membranes for gap junctions in animal tissues. Both junctions provided similar effects on the dielectric properties of the tissue model. The model without junction showed a dielectric relaxation (called β-dispersion) that was expected from an interfacial polarization theory for a concentrated suspension of spherical cells. The dielectric relaxation was the same as that of the model in which neighbouring cells were connected by junctions perpendicular to the applied electric field. When neighbouring cells were connected by junctions parallel to the applied electric field or in all directions, a dielectric relaxation appeared at a lower frequency side in addition to the β-dispersion, corresponding to the so called α-dispersion. When junctions were randomly introduced at varied probabilities P j , the low-frequency (LF) relaxation curve became broader, especially at P j of 0.2-0.5, and its intensity was proportional to P j up to 0.7. The intensity and the characteristic frequency of the LF relaxation both decreased with decreasing junction conductance. The simulations indicate that communicating junctions are important for understanding the LF dielectric relaxation in tissues

Dielectric properties of biological tissues in which cells are connected by communicating junctions

Science.gov (United States)

Asami, Koji

2007-06-01

The frequency dependence of the complex permittivity of biological tissues has been simulated using a simple model that is a cubic array of spherical cells in a parallel plate capacitor. The cells are connected by two types of communicating junctions: one is a membrane-lined channel for plasmodesmata in plant tissues, and the other is a conducting patch of adjoining plasma membranes for gap junctions in animal tissues. Both junctions provided similar effects on the dielectric properties of the tissue model. The model without junction showed a dielectric relaxation (called β-dispersion) that was expected from an interfacial polarization theory for a concentrated suspension of spherical cells. The dielectric relaxation was the same as that of the model in which neighbouring cells were connected by junctions perpendicular to the applied electric field. When neighbouring cells were connected by junctions parallel to the applied electric field or in all directions, a dielectric relaxation appeared at a lower frequency side in addition to the β-dispersion, corresponding to the so called α-dispersion. When junctions were randomly introduced at varied probabilities Pj, the low-frequency (LF) relaxation curve became broader, especially at Pj of 0.2-0.5, and its intensity was proportional to Pj up to 0.7. The intensity and the characteristic frequency of the LF relaxation both decreased with decreasing junction conductance. The simulations indicate that communicating junctions are important for understanding the LF dielectric relaxation in tissues.

Effect of single Abrikosov vortices on the properties of Josephson tunnel junctions

International Nuclear Information System (INIS)

Golubov, A.A.; Kupriyanov, M.Yu.

1987-01-01

The effect of single Abrikosov vortices, trapped in the electrodes of a Josephson tunnel junction perpendicularly to the junction surface, on the tunnel current through the junction is studied within the framework of the microscopic theory. The current-voltage characteristic and the critical junction current I c are calculated for temperatures 0 c . It is shown that if the vortices at the junction are misaligned, singularities on the current-voltage characteristic appear at eV Δ (T), and in some cases the magnitude of suppression of I c may be of the order of magnitude of I c itself. The temperature dependence of the critical current is calculated for the case of one of the electrodes being a two-dimensional superconducting film in which the creation of opposite sign vortex pairs is significant

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

International Nuclear Information System (INIS)

Lewandowski, S.J.

1991-01-01

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-T 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-T c materials are pointed out as a potential source of additional noise

Innovative architecture design for high performance organic and hybrid multi-junction solar cells

Science.gov (United States)

Li, Ning; Spyropoulos, George D.; Brabec, Christoph J.

2017-08-01

The multi-junction concept is especially attractive for the photovoltaic (PV) research community owing to its potential to overcome the Schockley-Queisser limit of single-junction solar cells. Tremendous research interests are now focused on the development of high-performance absorbers and novel device architectures for emerging PV technologies, such as organic and perovskite PVs. It has been predicted that the multi-junction concept is able to boost the organic and perovskite PV technologies approaching the 20% and 30% benchmarks, respectively, showing a bright future of commercialization of the emerging PV technologies. In this contribution, we will demonstrate innovative architecture design for solution-processed, highly functional organic and hybrid multi-junction solar cells. A simple but elegant approach to fabricating organic and hybrid multi-junction solar cells will be introduced. By laminating single organic/hybrid solar cells together through an intermediate layer, the manufacturing cost and complexity of large-scale multi-junction solar cells can be significantly reduced. This smart approach to balancing the photocurrents as well as open circuit voltages in multi-junction solar cells will be demonstrated and discussed in detail.

Fluctuation of heat current in Josephson junctions

Directory of Open Access Journals (Sweden)

P. Virtanen

2015-02-01

Full Text Available 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.

Spin-filtering junctions with double ferroelectric barriers

International Nuclear Information System (INIS)

Yan, Ju; Ding-Yu, Xing

2009-01-01

An FS/FE/NS/FE/FS double tunnel junction is suggested to have the ability to inject, modulate and detect the spin-polarized current electrically in a single device, where FS is the ferromagnetic semiconductor electrode, NS is the nonmagnetic semiconductor, and FE the ferroelectric barrier. The spin polarization of the current injected into the NS region can be switched between a highly spin-polarized state and a spin unpolarized state. The high spin polarization may be detected by measuring the tunneling magnetoresistance ratio of the double tunnel junction

Roles of gap junctions, connexins and pannexins in epilepsy

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Shanthini eMylvaganam

2014-05-01

Full Text Available Enhanced gap junctional communication (GJC between neurons is considered a major factor underlying the neuronal synchrony driving seizure activity. In addition, the hippocampal sharp wave ripple complexes, associated with learning and seizures, are diminished by GJC blocking agents. Although gap junctional blocking drugs inhibit experimental seizures, they all have other nonspecific actions. Besides interneuronal GJC between dendrites, inter-axonal and inter-glial GJC is also considered important for seizure generation. Interestingly, in most studies of cerebral tissue from animal seizure models and from human patients with epilepsy, there is up-regulation of glial, but not neuronal gap junctional mRNA and protein. Significant changes in the expression and post-translational modification of the astrocytic connexin Cx43, and Panx1 were observed in an in vitro Co++ seizure model, further supporting a role for glia in seizure-genesis, although the reasons for this remain unclear. Further suggesting an involvement of astrocytic GJC in epilepsy, is the fact that the expression of astrocytic Cx mRNAs (Cxs 30 and 43 is several fold higher than that of neuronal Cx mRNAs (Cxs 36 and 45, and the number of glial cells outnumber neuronal cells in mammalian hippocampal and cortical tissue. Pannexin expression is also increased in both animal and human epileptic tissues. Specific Cx43 mimetic peptides, Gap 27 and SLS, inhibit the docking of astrocytic connexin Cx43 proteins from forming intercellular gap junctions, diminishing spontaneous seizures. Besides GJs, Cx membrane hemichannels in glia and Panx membrane channels in neurons and glia are also inhibited by gap junctional pharmacological blockers. Although there is no doubt that connexin-based gap junctions and hemichannels, and pannexin-based membrane channels are related to epilepsy, the specific details of how they are involved and how we can modulate their function for therapeutic purposes remain to

p - n junction diodes fabricated from isolated electrospun fibers of (P(NDI2ODT2)) and an inorganic p-doped semiconductor

Science.gov (United States)

Rosado, Alexander; Pinto, Nicholas

2013-03-01

A simple method to fabricate, under ambient conditions and within seconds, p - n diodes using an individual electrospun poly{[N, N'-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5'-(2,2'-bithiophene)}-(P(NDI2ODT2)) fiber and a commercially available p-doped Si/SiO2 substrate is presented. Band bending at the fiber/Si+ interface leads to asymmetric I-V characteristic curves resembling that of a diode. The diode turn-on voltage was in the range 1V and was unaffected via UV light irradiation. The rectification ratio however could be tuned reversibly thereby making this device multifunctional. In addition to being a rectifier, the advantage of our design is the complete exposure of the rectifying junction to the surrounding environment. This has the advantage of making them attractive candidates in the potential fabrication of low power, sensitive and rapid response photo-sensors. NSF

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

International Nuclear Information System (INIS)

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

2011-01-01

Using magnetron sputtering, we have prepared Co-Fe-B/tunnel barrier/Co-Fe-B magnetic tunnel junctions with tunnel barriers consisting of alumina, magnesia, and magnesia-alumina bilayer systems. The highest tunnel magnetoresistance ratios we found were 73% for alumina and 323% for magnesia-based tunnel junctions. Additionally, tunnel junctions with a unified layer stack were prepared for the three different barriers. In these systems, the tunnel magnetoresistance ratios at optimum annealing temperatures were found to be 65% for alumina, 173% for magnesia, and 78% for the composite tunnel barriers. The similar tunnel magnetoresistance ratios of the tunnel junctions containing alumina provide evidence that coherent tunneling is suppressed by the alumina layer in the composite tunnel barrier. - Research highlights: → Transport properties of Co-Fe-B/tunnel barrier/Co-Fe-B magnetic tunnel junctions. → Tunnel barrier consists of MgO, Al-Ox, or MgO/Al-Ox bilayer systems. → Limitation of TMR-ratio in composite barrier tunnel junctions to Al-Ox values. → Limitation indicates that Al-Ox layer is causing incoherent tunneling.

Electrical resistivity of monolayers and bilayers of alkanethiols in tunnel junction with gate electrode

International Nuclear Information System (INIS)

York, Roger L.; Nacionales, David; Slowinski, Krzysztof

2005-01-01

The tunneling resistances of monolayers and bilayers of n-alkanethiols in macroscopic Hg-Hg junctions with an electrochemical gate are reported. The resistances near zero bias calculated per 1 hydrocarbon chain vary from (5 ± 4) x 10 12 Ω for n-nonanethiol to (4 ± 2) x 10 16 Ω for n-octadecanethiol. These values indicate that monolayers of hydrocarbons in Hg-Hg junctions are substantially more resistive as compared to measurements employing microscopic tunnel junctions. The tunneling resistances of monolayer junctions are approximately 1 order of magnitude larger than those of bilayer junctions containing the same number of atoms indicating inefficient electronic coupling across the non-bonded -CH 3 |Hg interface. The symmetric current-voltage curves observed for the asymmetric junctions of Hg-S-(CH 2 ) n -CH 3 |Hg type suggest that these junctions do not behave as molecular diodes. Additional experimental evidence for the nature of the -CH 3 |Hg interface in the Hg-S-(CH 2 ) n -CH 3 |Hg junction is also presented

Performance comparison between p–i–n and p–n junction tunneling field-effect transistors

Science.gov (United States)

Yoon, Young Jun; Seo, Jae Hwa; Kang, In Man

2018-06-01

In this study, we investigated the direct-current (DC) and radio-frequency (RF) performances of p–i–n and p–n junction tunneling field-effect transistors (TFETs). Compared to the p–i–n junction TFET, the p–n junction TFET exhibited higher on-state current (I on) because the channel formation mechanism of the p–n junction TFET resulted in a narrower tunneling barrier and an expanded tunneling area. Further, the reduction of I on of the p–n junction TFET by the interface trap was smaller. Moreover, the p–n junction TFET exhibited lower gate-to-drain capacitance (C gd) because a depletion capacitance (C gd,dep) was formed by the depletion region under gate dielectric. Consequently, the p–n junction TFET achieved an improvement of cut-off frequency (f T) and intrinsic delay time (τ), which are related to the current performance and total gate capacitance (C gg). We confirmed the enhancement of device performances in terms of I on, f T, and τ by the conduction mechanism of the p–n junction TFET.

Age and Gender Differences in Facial Attractiveness, but Not Emotion Resemblance, Contribute to Age and Gender Stereotypes

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Rocco Palumbo

2017-09-01

Full Text Available Considerable research has shown effects of facial appearance on trait impressions and group stereotypes. We extended those findings in two studies that investigated the contribution of resemblance to emotion expressions and attractiveness to younger adults (YA and older adults (OA age and gender stereotypes on the dimensions of warmth and competence. Using connectionist modeling of facial metrics of 240 neutral younger and older faces, Study 1 found that, neutral expression older faces or female faces showed greater structural resemblance to happy expressions and less resemblance to angry expressions than did younger or male faces, respectively. In addition, neutral female faces showed greater resemblance to surprise expressions. In Study 2, YA and OA rated the faces of Study 1 for attractiveness and for 4 traits that we aggregated on the dimensions of competence (competent, healthy and warmth (trustworthy, not shrewd. We found that YA, but not OA, age stereotypes replicated previous research showing higher perceived warmth and lower perceived competence in older adults. In addition, previously documented gender stereotypes were moderated by face age for both YA and OA. The greater attractiveness of younger than older faces and female than male faces influenced age and gender stereotypes, including these deviations from prior research findings using category labels rather than faces. On the other hand, face age and face sex differences in emotion resemblance did not influence age or gender stereotypes, contrary to prediction. Our results provide a caveat to conclusions about age and gender stereotypes derived from responses to category labels, and they reveal the importance of assessing stereotypes with a methodology that is sensitive to influences of group differences in appearance that can exacerbate or mitigate stereotypes in more ecologically valid contexts. Although the gender differences in attractiveness in the present study may not have

Age and Gender Differences in Facial Attractiveness, but Not Emotion Resemblance, Contribute to Age and Gender Stereotypes.

Science.gov (United States)

Palumbo, Rocco; Adams, Reginald B; Hess, Ursula; Kleck, Robert E; Zebrowitz, Leslie

2017-01-01

Considerable research has shown effects of facial appearance on trait impressions and group stereotypes. We extended those findings in two studies that investigated the contribution of resemblance to emotion expressions and attractiveness to younger adults (YA) and older adults (OA) age and gender stereotypes on the dimensions of warmth and competence. Using connectionist modeling of facial metrics of 240 neutral younger and older faces, Study 1 found that, neutral expression older faces or female faces showed greater structural resemblance to happy expressions and less resemblance to angry expressions than did younger or male faces, respectively. In addition, neutral female faces showed greater resemblance to surprise expressions. In Study 2, YA and OA rated the faces of Study 1 for attractiveness and for 4 traits that we aggregated on the dimensions of competence (competent, healthy) and warmth (trustworthy, not shrewd). We found that YA, but not OA, age stereotypes replicated previous research showing higher perceived warmth and lower perceived competence in older adults. In addition, previously documented gender stereotypes were moderated by face age for both YA and OA. The greater attractiveness of younger than older faces and female than male faces influenced age and gender stereotypes, including these deviations from prior research findings using category labels rather than faces. On the other hand, face age and face sex differences in emotion resemblance did not influence age or gender stereotypes, contrary to prediction. Our results provide a caveat to conclusions about age and gender stereotypes derived from responses to category labels, and they reveal the importance of assessing stereotypes with a methodology that is sensitive to influences of group differences in appearance that can exacerbate or mitigate stereotypes in more ecologically valid contexts. Although the gender differences in attractiveness in the present study may not have generalizability

Traumatic Tear of the Latissimus Dorsi Myotendinous Junction

Science.gov (United States)

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

LTS junction technology for RSFQ and qubit circuit applications

International Nuclear Information System (INIS)

Buchholz, F.-Im.; Balashov, D.V.; Dolata, R.; Hagedorn, D.; Khabipov, M.I.; Kohlmann, J.; Zorin, A.B.; Niemeyer, J.

2006-01-01

The potentials of LTS junction technology and electronics offer innovative solutions for the processing of quantum information in RSFQ and qubit circuits. We discuss forthcoming approaches based on standard SIS technology and addressed to the development of new superconducting device concepts. The challenging problem of reducing back action noise of the RSFQ circuits deteriorating coherent properties of the qubit is currently solved by implementing Josephson junctions with non-linear shunts based on LTS SIS-SIN technology. Upgraded NbAlO x trilayer technology enables the fabrication of high-quality mesoscopic Josephson junction transistors down to the nanometer range suitable for a qubit-operation regime. As applications, circuit concepts are presented which combine superconducting devices of different nature

Coherence in a transmon qubit with epitaxial tunnel junctions

Energy Technology Data Exchange (ETDEWEB)

Weides, Martin [National Institute of Standards and Technology, Boulder, Colorado 80305 (United States); Karlsruhe Institute of Technology (Germany); Kline, Jeffrey; Vissers, Michael; Sandberg, Martin; Pappas, David [National Institute of Standards and Technology, Boulder, Colorado 80305 (United States); Wisbey, David [National Institute of Standards and Technology, Boulder, Colorado 80305 (United States); Saint Louis University, St. Louis, Missouri 63103 (United States); Johnson, Blake; Ohki, Thomas [Raytheon BBN Technologies, Cambridge, Massachusetts 02138 (United States)

2012-07-01

Transmon qubits based on epitaxial tunnel junctions and interdigitated capacitors were developed. This multileveled qubit, patterned by use of all-optical lithography, is a step towards scalable qubits with a high integration density. The relaxation time T{sub 1} is.72-.86 {mu} sec and the ensemble dephasing time T{sub 2}{sup *} is slightly larger than T{sub 1}. The dephasing time T{sub 2} (1.36 {mu} sec) is nearly energy-relaxation-limited. Qubit spectroscopy yields weaker level splitting than observed in qubits with amorphous barriers in equivalent-size junctions. The qubit's inferred microwave loss closely matches the weighted losses of the individual elements (junction, wiring dielectric, and interdigitated capacitor), determined by independent resonator measurements.

46 CFR 111.81-1 - Outlet boxes and junction boxes; general.

Science.gov (United States)

2010-10-01

... fixture, wiring device, or similar item, including each separately installed connection and junction box... used. (d) As appropriate, each outlet-box or junction-box installation must meet the following...

Triptycene: A Nucleic Acid Three-Way Junction Binder Scaffold

Science.gov (United States)

Yoon, Ina

Nucleic acids play a critical role in many biological processes such as gene regulation and replication. The development of small molecules that modulate nucleic acids with sequence or structure specificity would provide new strategies for regulating disease states at the nucleic acid level. However, this remains challenging mainly because of the nonspecific interactions between nucleic acids and small molecules. Three-way junctions are critical structural elements of nucleic acids. They are present in many important targets such as trinucleotide repeat junctions related to Huntington's disease, a temperature sensor sigma32 in E. coli, Dengue virus, and HIV. Triptycene-derived small molecules have been shown to bind to nucleic acid three-way junctions, resulting from their shape complementary. To develop a better understanding of designing molecules for targeting different junctions, a rapid screening of triptycene-based small molecules is needed. We envisioned that the installation of a linker at C9 position of the bicyclic core would allow for a rapid solid phase diversification. To achieve this aim, we synthesized 9-substituted triptycene scaffolds by using two different synthetic routes. The first synthetic route installed the linker from the amidation reaction between carboxylic acid at C9 position of the triptycene and an amine linker, beta-alanine ethyl ester. This new 9-substituted triptycene scaffold was then attached to a 2-chlorotrityl chloride resin for solid-phase diversification. This enabled a rapid diversification and an easy purification of mono-, di-, and tri-peptide triptycene derivatives. The binding affinities of these compounds were investigated towards a (CAG)˙(CTG) trinucleotide repeat junction. In the modified second synthetic route, we utilized a combined Heck coupling/benzyne Diels-Alder strategy. This improved synthetic strategy reduced the number of steps and total reaction times, increased the overall yield, improved solubilities of

Familial resemblance of borderline personality disorder features: genetic or cultural transmission?

Directory of Open Access Journals (Sweden)

Marijn A Distel

Full Text Available Borderline personality disorder is a severe personality disorder for which genetic research has been limited to family studies and classical twin studies. These studies indicate that genetic effects explain 35 to 45% of the variance in borderline personality disorder and borderline personality features. However, effects of non-additive (dominance genetic factors, non-random mating and cultural transmission have generally not been explored. In the present study an extended twin-family design was applied to self-report data of twins (N = 5,017 and their siblings (N = 1,266, parents (N = 3,064 and spouses (N = 939 from 4,015 families, to estimate the effects of additive and non-additive genetic and environmental factors, cultural transmission and non-random mating on individual differences in borderline personality features. Results showed that resemblance among biological relatives could completely be attributed to genetic effects. Variation in borderline personality features was explained by additive genetic (21%; 95% CI 17-26% and dominant genetic (24%; 95% CI 17-31% factors. Environmental influences (55%; 95% CI 51-60% explained the remaining variance. Significant resemblance between spouses was observed, which was best explained by phenotypic assortative mating, but it had only a small effect on the genetic variance (1% of the total variance. There was no effect of cultural transmission from parents to offspring.

Improved tolerance of maize (Zea mays L.) to heavy metals by colonization of a dark septate endophyte (DSE) Exophiala pisciphila

International Nuclear Information System (INIS)

Li, T.; Liu, M.J.; Zhang, X.T.; Zhang, H.B.; Sha, T.; Zhao, Z.W.

2011-01-01

Dark septate endophytes (DSE) are ubiquitous and abundant in stressful environments including heavy metal (HM) stress. However, our knowledge about the roles of DSE in improving HM tolerance of their host plants is poor. In this study, maize (Zea mays L.) was inoculated with a HM tolerant DSE strain Exophiala pisciphila H93 in lead (Pb), zinc (Zn), and cadmium (Cd) contaminated soils. E. pisciphila H93 successfully colonized and formed typical DSE structures in the inoculated maize roots. Colonization of E. pisciphila H93 alleviated the deleterious effects of excessive HM supplements and promoted the growth of maize (roots and shoots) under HM stress conditions, though it significantly decreased the biomass of inoculated maize under no HM stress. Further analysis showed that the colonization of E. pisciphila H93 improved the tolerance of maize to HM by restricting the translocation of HM ions from roots to shoots. This study demonstrated that under higher HM stress, such a mutual symbiosis between E. pisciphila and its host (maize) may be an efficient strategy to survive in the stressful environments. - Research Highlights: →Effect of DSE (E. pisciphila) on heavy metal tolerance of maize host was studied. →DSE alleviated the deleterious effect of excessive heavy metals on maize. →DSE restricted the transfer of heavy metals from the roots to shoots in maize. →DSE colonization improved the tolerance of their host plants to heavy metals.

Improved tolerance of maize (Zea mays L.) to heavy metals by colonization of a dark septate endophyte (DSE) Exophiala pisciphila

Energy Technology Data Exchange (ETDEWEB)

Li, T.; Liu, M.J.; Zhang, X.T. [Key Laboratory of Conservation and Utilization for Bioresources, Yunnan University, Kunming, 650091 Yunnan (China); Zhang, H.B. [Key Laboratory of Conservation and Utilization for Bioresources, Yunnan University, Kunming, 650091 Yunnan (China); Department of Biology, Yunnan University, Kunming, 650091 Yunnan (China); Sha, T. [Key Laboratory of Conservation and Utilization for Bioresources, Yunnan University, Kunming, 650091 Yunnan (China); Zhao, Z.W., E-mail: zhaozhw@ynu.edu.cn [Key Laboratory of Conservation and Utilization for Bioresources, Yunnan University, Kunming, 650091 Yunnan (China)

2011-02-15

Dark septate endophytes (DSE) are ubiquitous and abundant in stressful environments including heavy metal (HM) stress. However, our knowledge about the roles of DSE in improving HM tolerance of their host plants is poor. In this study, maize (Zea mays L.) was inoculated with a HM tolerant DSE strain Exophiala pisciphila H93 in lead (Pb), zinc (Zn), and cadmium (Cd) contaminated soils. E. pisciphila H93 successfully colonized and formed typical DSE structures in the inoculated maize roots. Colonization of E. pisciphila H93 alleviated the deleterious effects of excessive HM supplements and promoted the growth of maize (roots and shoots) under HM stress conditions, though it significantly decreased the biomass of inoculated maize under no HM stress. Further analysis showed that the colonization of E. pisciphila H93 improved the tolerance of maize to HM by restricting the translocation of HM ions from roots to shoots. This study demonstrated that under higher HM stress, such a mutual symbiosis between E. pisciphila and its host (maize) may be an efficient strategy to survive in the stressful environments. - Research Highlights: {yields}Effect of DSE (E. pisciphila) on heavy metal tolerance of maize host was studied. {yields}DSE alleviated the deleterious effect of excessive heavy metals on maize. {yields}DSE restricted the transfer of heavy metals from the roots to shoots in maize. {yields}DSE colonization improved the tolerance of their host plants to heavy metals.

Surgical excision of Essure® devices with ESHRE Class IIb uterine malformation: sequential hysteroscopic-laparoscopic approach to the septate uterus.

Science.gov (United States)

Sills, E S; Palermo, G D

2016-03-28

While contraindications to Essure® placement have been provided by the manufacturer, there is no consensus on how best to remove these contraceptive devices. Here, we describe a non-hysterectomy removal of Essure® for a patient with a septate uterus (ESHRE Class IIb uterine malformation). A 35yr old G4 P2 presented for removal of Essure® implants after three years of gradually increasing pelvic pain, weight gain, headache, dizziness, lower extremity paresthesia, and fatigue which followed hysteroscopic sterilization (HS). Prior to HS, the patient was in good general health. She did not smoke and had never had a miscarriage. HS was performed under general anesthesia in October 2012. HSG obtained three months later, confirmed bilateral tubal occlusion but revealed an abnormal uterine cavity. A repeat HSG in 2015 showed minimal device migration, no contrast dye spill and a deeply bifid uterine cavity. At our center laparoscopic cornual dissection and bilateral partial tubal resection achieved removal of both devices intact and the patient was discharged three hours after surgery. Her postoperative recovery was uneventful. The presence of a Müllerian anomaly is a relative contraindication to the Essure® procedure. This is the first reported description of successful removal of Essure® coils in the setting of an ESHRE Class IIb uterine anomaly, and underscores the importance of careful patient selection, accurate pre-operative imaging and a conservative technique which renders hysterectomy unnecessary.

Vibrationally coupled electron transport through single-molecule junctions

Energy Technology Data Exchange (ETDEWEB)

Haertle, Rainer

2012-04-26

Single-molecule junctions are among the smallest electric circuits. They consist of a molecule that is bound to a left and a right electrode. With such a molecular nanocontact, the flow of electrical currents through a single molecule can be studied and controlled. Experiments on single-molecule junctions show that a single molecule carries electrical currents that can even be in the microampere regime. Thereby, a number of transport phenomena have been observed, such as, for example, diode- or transistor-like behavior, negative differential resistance and conductance switching. An objective of this field, which is commonly referred to as molecular electronics, is to relate these transport phenomena to the properties of the molecule in the contact. To this end, theoretical model calculations are employed, which facilitate an understanding of the underlying transport processes and mechanisms. Thereby, one has to take into account that molecules are flexible structures, which respond to a change of their charge state by a profound reorganization of their geometrical structure or may even dissociate. It is thus important to understand the interrelation between the vibrational degrees of freedom of a singlemolecule junction and the electrical current flowing through the contact. In this thesis, we investigate vibrational effects in electron transport through singlemolecule junctions. For these studies, we calculate and analyze transport characteristics of both generic and first-principles based model systems of a molecular contact. To this end, we employ a master equation and a nonequilibrium Green's function approach. Both methods are suitable to describe this nonequilibrium transport problem and treat the interactions of the tunneling electrons on the molecular bridge non-perturbatively. This is particularly important with respect to the vibrational degrees of freedom, which may strongly interact with the tunneling electrons. We show in detail that the resulting

Changes in cholinergic parameters associated with failure of conotruncal septation in embryonic chick hearts after neural crest ablation

International Nuclear Information System (INIS)

Kirby, M.L.; Aronstam, R.S.; Buccafusco, J.J.

1985-01-01

Cells from the neural crest over occipital somites migrate to the heart, where they give rise to parasympathetic postganglionic neurons as well as ectomesenchymal elements which contribute to conotruncal septation. With a microcautery needle, the neural crest over occipital somites was ablated bilaterally in chicken embryos at an early stage of development. Histological examination on incubation day 15 revealed conotruncal malformations, involving malformation or absence of the conotruncal septum in all embryos. Two peaks of embryo mortality were observed. One peak (incubation days 6-8) occurred at the same time as conotruncal septal closure; the second peak (incubation days 11-13) was concurrent with the onset of functional parasympathetic innervation. A disruption of parasympathetic innervation was indicated by: (1) a decrease in acetylcholinesterase staining, (2) a decrease (27%) in the number of ganglion cells in the conotruncus, (3) decreases in the acetylcholine content of atrium (31%) and ventricle (39%), and (4) a decrease (21%) in muscarinic acetylcholine receptor density on incubation day 15. Radiolabeled ligand-binding studies revealed no change in the affinity of cardiac muscarinic receptors for [ 3 H]methylscopolamine (K/sub D/ . 0.17-0.21 nM). Agonist-binding affinity and sensitivity to guanine nucleotides were similarly unaffected. The reasons for the limited extent of the parasympathetic lesion are unclear, but may involve recruitment of precursor cells from other regions of the neural crest, partial regeneration of the neural crest following surgical removal, or an alteration in the contribution of incoming sympathetic or preganglionic parasympathetic elements. No such plasticity was associated with neural crest contributions to the structural development of the conotruncus. Malformations were observed in all lesioned embryos

Testicular cell junction: a novel target for male contraception.

Science.gov (United States)

Lee, Nikki P Y; Wong, Elissa W P; Mruk, Dolores D; Cheng, C Yan

2009-01-01

Even though various contraceptive methods are widely available, the number of unwanted pregnancies is still on the rise in developing countries, pressurizing the already resource limited nations. One of the major underlying reasons is the lack of effective, low cost, and safe contraceptives for couples. During the past decade, some studies were performed using animal models to decipher if the Sertoli-germ cell junction in the testis is a target for male fertility regulation. Some of these study models were based on the use of hormones and/or chemicals to disrupt the hypothalamic-pituitary-testicular axis (e.g., androgen-based implants or pills) and others utilized a panel of chemical entities or synthetic peptides to perturb spermatogenesis either reversibly or non-reversibly. Among them, adjudin, a potential male contraceptive, is one of the compounds exerting its action on the unique adherens junctions, known as ectoplasmic specializations, in the testis. Since the testis is equipped with inter-connected cell junctions, an initial targeting of one junction type may affect the others and these accumulative effects could lead to spermatogenic arrest. This review attempts to cover an innovative theme on how male infertility can be achieved by inducing junction instability and defects in the testis, opening a new window of research for male contraceptive development. While it will still take much time and effort of intensive investigation before a product can reach the consumable market, these findings have provided hope for better family planning involving men.

Large resistance change on magnetic tunnel junction based molecular spintronics devices

Science.gov (United States)

Tyagi, Pawan; Friebe, Edward

2018-05-01

Molecular bridges covalently bonded to two ferromagnetic electrodes can transform ferromagnetic materials and produce intriguing spin transport characteristics. This paper discusses the impact of molecule induced strong coupling on the spin transport. To study molecular coupling effect the octametallic molecular cluster (OMC) was bridged between two ferromagnetic electrodes of a magnetic tunnel junction (Ta/Co/NiFe/AlOx/NiFe/Ta) along the exposed side edges. OMCs induced strong inter-ferromagnetic electrode coupling to yield drastic changes in transport properties of the magnetic tunnel junction testbed at the room temperature. These OMCs also transformed the magnetic properties of magnetic tunnel junctions. SQUID and ferromagnetic resonance studies provided insightful data to explain transport studies on the magnetic tunnel junction based molecular spintronics devices.

Droplet formation in Hele-Shaw T-junction.

Science.gov (United States)

Ricouvier, Joshua; Yazhgur, Pavel; Leshansky, Alexander; Tabeling, Patrick; Microflusa Team

The development of digital microfluidics has attracted considerable interest towards generation of highly monodisperse microdroplets. T-junction has become an essential element of most of microfluidic chips. Despite its importance, theoretical analysis of droplet formation at T-junction is still incomplete due to complexity of physics involved. We focused on droplet generation at the Hele-Shaw T-junction. The effect of various experimental parameters, such as channel geometry, flow rates, surface tension and fluid viscosities, was thoroughly investigated. Our results show that the experimental system exhibits three distinct regimes (squeezing, dripping and jetting regimes) and point out the effect of confinement on the transitions. We demonstrate that the size of the ''plug'' droplet depends not only on the flow rate ratio (as described in the literature), but also on the capillary number and the channel cross-section aspect ratio. Quasi-2D flow equations allow us to perform numerical simulations and to compare them with experimental results. The Microflusa project receives funding from the European Union's Horizon 2020 research and innovation programme under Grant Agreement No. 664823.

Humidity dependence of molecular tunnel junctions with an AlOx/COOH- interface

Science.gov (United States)

Zhang, Xiaohang; McGill, Stephen; Xiong, Peng

2006-03-01

We have studied the electron transport in planar tunneling junctions with aluminum oxide and an organic self-assembled monolayer (SAM) as the tunnel barrier. The structure of the junctions is Al/AlOx/SAM/(Au, Pb) with a junction area of ˜ 0.4mm^2. The organic molecules investigated include mercaptohexadecanoic acid (MHA), hexadecanoic acid (HDA), and octadecyltrichlorosilane (OTS); all of which form ordered SAMs on top of aluminum oxide. The use of a superconducting electrode (Al) enables us to determine unambiguously that these are high-quality tunnel junctions. For junctions incorporating MHA, the transport behavior is found to be strongly humidity dependent. The resistance of these junctions drops more than 50% when placed in dry nitrogen and recovers when returned into the ambient. The same drop also occurs when the sample is placed into a vacuum, and backfilling the vacuum with either dry N2 or O2 has negligible effect on the resistance. For comparison, junctions with HDA show the same humidity dependence, while OTS samples do not. Since both MHA and HDA have carboxylic groups and OTS does not, the results suggest that water molecules at the AlOx/COOH- interface play the central role in the observed behavior. Inelastic tunneling spectroscopy (IETS) has also been performed to understand the role of water. This work was supported by a FSU Research Foundation PEG grant.

Magnetoresistance in Co/AlO sub x /Co tunnel junction arrays

CERN Document Server

Urech, M; Haviland, D B

2002-01-01

Lateral arrays of Co/AlO sub x /Co junctions with dimensions down to 60 nm and inter-junction separations approx 60-100 nm have been fabricated and analyzed for possible coherent tunneling effects. Extra attention is paid to avoid uncertainties due to inconsistencies in switching and/or resistance of successive barriers. We observe approx 10% magnetoresistance enhancement at moderate bias in double junctions that cannot be accounted for by a simple model of two resistsors in series.

Water and suspended sediment division at a stratified tidal junction

NARCIS (Netherlands)

Buschman, F.A.; Vegt, M. van der; Hoitink, A.J.F.; Hoekstra, P.

2013-01-01

Tidal junctions play a crucial role in the transport of water, salt, and sediment through a delta distributary network. Water, salt and sediment are exchanged at tidal junctions, thereby influencing the transports in the connecting branches and the overall dynamics of the system. This paper

Routing trains through railway junctions: A new set-packing approach

DEFF Research Database (Denmark)

Lusby, Richard Martin; Larsen, Jesper; Ryan, David

2011-01-01

The problem of routing trains through railway junctions is an integral part of railway operations. Large junctions are highly interconnected networks of track where multiple railway lines merge, intersect, and split. The number of possible routings makes this a very complicated problem. We show h...

Amorphous molecular junctions produced by ion irradiation on carbon nanotubes

International Nuclear Information System (INIS)

Wang Zhenxia; Yu Liping; Zhang Wei; Ding Yinfeng; Li Yulan; Han Jiaguang; Zhu Zhiyuan; Xu Hongjie; He Guowei; Chen Yi; Hu Gang

2004-01-01

Experiments and molecular dynamics have demonstrated that electron irradiation could create molecular junctions between crossed single-wall carbon nanotubes. Recently molecular dynamics computation predicted that ion irradiation could also join single-walled carbon nanotubes. Employing carbon ion irradiation on multi-walled carbon nanotubes, we find that these nanotubes evolve into amorphous carbon nanowires, more importantly, during the process of which various molecular junctions of amorphous nanowires are formed by welding from crossed carbon nanotubes. It demonstrates that ion-beam irradiation could be an effective way not only for the welding of nanotubes but also for the formation of nanowire junctions

Ischemic preconditioning protects against gap junctional uncoupling in cardiac myofibroblasts.

Science.gov (United States)

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.

An EMMPRIN–γ-catenin–Nm23 complex drives ATP production and actomyosin contractility at endothelial junctions

Science.gov (United States)

Moreno, Vanessa; Gonzalo, Pilar; Gómez-Escudero, Jesús; Pollán, Ángela; Acín-Pérez, Rebeca; Breckenridge, Mark; Yáñez-Mó, María; Barreiro, Olga; Orsenigo, Fabrizio; Kadomatsu, Kenji; Chen, Christopher S.; Enríquez, José A.; Dejana, Elisabetta; Sánchez-Madrid, Francisco; Arroyo, Alicia G.

2014-01-01

ABSTRACT Cell–cell adhesions are important sites through which cells experience and resist forces. In endothelial cells, these forces regulate junction dynamics and determine endothelial barrier strength. We identify the Ig superfamily member EMMPRIN (also known as basigin) as a coordinator of forces at endothelial junctions. EMMPRIN localization at junctions correlates with endothelial junction strength in different mouse vascular beds. Accordingly, EMMPRIN-deficient mice show altered junctions and increased junction permeability. Lack of EMMPRIN alters the localization and function of VE-cadherin (also known as cadherin-5) by decreasing both actomyosin contractility and tugging forces at endothelial cell junctions. EMMPRIN ensures proper actomyosin-driven maturation of competent endothelial junctions by forming a molecular complex with γ-catenin (also known as junction plakoglobin) and Nm23 (also known as NME1), a nucleoside diphosphate kinase, thereby locally providing ATP to fuel the actomyosin machinery. These results provide a novel mechanism for the regulation of actomyosin contractility at endothelial junctions and might have broader implications in biological contexts such as angiogenesis, collective migration and tissue morphogenesis by coupling compartmentalized energy production to junction assembly. PMID:24994937

An EMMPRIN-γ-catenin-Nm23 complex drives ATP production and actomyosin contractility at endothelial junctions.

Science.gov (United States)

Moreno, Vanessa; Gonzalo, Pilar; Gómez-Escudero, Jesús; Pollán, Ángela; Acín-Pérez, Rebeca; Breckenridge, Mark; Yáñez-Mó, María; Barreiro, Olga; Orsenigo, Fabrizio; Kadomatsu, Kenji; Chen, Christopher S; Enríquez, José A; Dejana, Elisabetta; Sánchez-Madrid, Francisco; Arroyo, Alicia G

2014-09-01

Cell-cell adhesions are important sites through which cells experience and resist forces. In endothelial cells, these forces regulate junction dynamics and determine endothelial barrier strength. We identify the Ig superfamily member EMMPRIN (also known as basigin) as a coordinator of forces at endothelial junctions. EMMPRIN localization at junctions correlates with endothelial junction strength in different mouse vascular beds. Accordingly, EMMPRIN-deficient mice show altered junctions and increased junction permeability. Lack of EMMPRIN alters the localization and function of VE-cadherin (also known as cadherin-5) by decreasing both actomyosin contractility and tugging forces at endothelial cell junctions. EMMPRIN ensures proper actomyosin-driven maturation of competent endothelial junctions by forming a molecular complex with γ-catenin (also known as junction plakoglobin) and Nm23 (also known as NME1), a nucleoside diphosphate kinase, thereby locally providing ATP to fuel the actomyosin machinery. These results provide a novel mechanism for the regulation of actomyosin contractility at endothelial junctions and might have broader implications in biological contexts such as angiogenesis, collective migration and tissue morphogenesis by coupling compartmentalized energy production to junction assembly. © 2014. Published by The Company of Biologists Ltd.

Result of surgical therapy in esophagogastric junction adenocarcinoma

International Nuclear Information System (INIS)

Shirinzadeh, A.; Fakhrjoo, E.

2007-01-01

To assess the outcome of surgical therapy and choice of surgical strategy for patients with adenocarcinoma of the gastroesophageal junction. Between February 1989 and January 2005 during 16 years, 335 patients (65 female, 270 male, mean age 56 years) with esophagogastric junction adenocarcinoma underwent surgical operation. The choice of surgical approach was based on the anatomical location of the tumor mass. Outcome of surgery, histopathologic characteristics, demographic data and long term survival rates were compared among three types of tumor defined as follows. Type I: Adenocarcinoma of the distal esophagus which infiltrates the esophagogastric junction from above. Type II: True carcinoma of the cardia arising immediately at the esophagogastric junction. Type III: Subcardial gastric carcinoma that infiltrates the esophagogastric junction and distal esophagus from below. Of the 335 patients undergoing resection, 110 (33%) had type I, 96 (28%) had type II, and 129 (39%) had type III. The preponderance of the male sex and the prevalence of metaplasia in distal esophagus decreased from type I to type III tumors (P<0.01). The prevalence of undifferentiated tumors increased from type I to type III tumors (P<0.01). Esophagectomy with resection of the proximal stomach for type I and extended total gastrectomy with transhiatal resection of the distal esophagus for type II and III were the primary procedures. The mean number of removed lymph node was higher in type III and II compared to type I tumors. The overall postoperative 30-day mortality was 8.4%. The death rate in transthoracic esophagectomy was higher than with extended total gastrectomy. The classification of adenocarcinoma of the esophagogastric junction into type I, II and III tumors helps in the selection of surgical approach. Type I tumors are approached as distal esophageal cancer. Type III tumors are a special form of gastric cancer and treated as a gastric cancer. The relation of type II tumors to

Fabrication of Schottky Junction Between Au and SrTiO3

Science.gov (United States)

Inoue, Akira; Izumisawa, Kei; Uwe, Hiromoto

2001-05-01

A Schottky junction with a high rectification ratio between Au and La-doped SrTiO3 has been fabricated using a simple surface treatment. Highly La-doped (5%) SrTiO3 single crystals are annealed in O2 atmosphere at about 1000°C for 1 h and etched in HNO3 for more than five min. The HNO3 etching is performed in a globe box containing N2 to prevent pollution from the air. After the treatment, Au is deposited on the SrTiO3 surface in a vacuum (˜ 10-7 Torr) with an e-gun evaporator. The current voltage characteristics of the junction have shown excellent rectification properties, although junctions using neither annealed nor etched SrTiO3 exhibit high leak current in reverse voltage. The rectification ratio of the junction at 1 V is more than six orders of magnitude and there is no hysteresis in the current voltage spectra. The logarithm of the current is linear with the forward bias voltage. The ideal factor of the junction is estimated to be about 1.68. These results suggest that, if prevented from being pollution by the air, a good Schottky junction can be obtained by easy processes such as annealing in oxygen atmosphere and surface etching with acid.

Mutual Phase Locking of Fluxons in Stacked Long Josephson Junctions: Simulations and Experiment

DEFF Research Database (Denmark)

Carapella, Giovanni; Costabile, Giovanni; Filatrella, Giovanni

1997-01-01

We report on the experimental observation of reciprocal phase-locking in stacked $Nb-AlO_x-Nb$ Josephson junctions having overlap geometry. When the junctions are independently biased in zero external magnetic field, they each exhibit several Zero Field Steps. Biasing both the junctions on the Ze...

Robust spin transfer torque in antiferromagnetic tunnel junctions

KAUST Repository

Saidaoui, Hamed Ben Mohamed

2017-04-18

We theoretically study the current-induced spin torque in antiferromagnetic tunnel junctions, composed of two semi-infinite antiferromagnetic layers separated by a tunnel barrier, in both clean and disordered regimes. We find that the torque enabling electrical manipulation of the Néel antiferromagnetic order parameter is out of plane, ∼n×p, while the torque competing with the antiferromagnetic exchange is in plane, ∼n×(p×n). Here, p and n are the Néel order parameter direction of the reference and free layers, respectively. Their bias dependence shows behavior similar to that in ferromagnetic tunnel junctions, the in-plane torque being mostly linear in bias, while the out-of-plane torque is quadratic. Most importantly, we find that the spin transfer torque in antiferromagnetic tunnel junctions is much more robust against disorder than that in antiferromagnetic metallic spin valves due to the tunneling nature of spin transport.

Household and familial resemblance in risk factors for type 2 diabetes and related cardiometabolic diseases in rural Uganda

DEFF Research Database (Denmark)

Nielsen, Jannie; Bahendeka, Silver K.; Whyte, Susan R.

2017-01-01

prevention and screening, we investigated the resemblance of T2D risk factors at household level and by type of familial dyadic relationship in a rural Ugandan community. Methods: This cross-sectional household-based study included 437 individuals ≥13 years of age from 90 rural households in south......-western Uganda. Resemblance in glycosylated haemoglobin (HbA1c), anthropometry, blood pressure, fitness status and sitting time were analysed using a general mixed model with random effects (by household or dyad) to calculate household intraclass correlation coefficients (ICCs) and dyadic regression coefficients...... (ICC=0.24), HbA1c (ICC=0.18) and systolic blood pressure (ICC=0.11). Regarding dyadic resemblance, the highest standardised regression coefficient was seen in fitness status for spouses (0.54, 95% CI 0.32 to 0.76), parent–offspring (0.41, 95% CI 0.28 0.54) and siblings (0.41, 95% CI 0.25 to 0...

Dynamic Control of Tunneling Conductance in Ferroelectric Tunnel Junctions

International Nuclear Information System (INIS)

Zou Ya-Yi; Zhou Yan; Chew Khian-Hooi

2013-01-01

We investigate the dynamic characteristics of electric polarization P(t) in a ferroelectric junction under ac applied voltage and stress, and calculate the frequency response and the cut-off frequency f 0 , which provides a reference for the upper limit of the working frequency. Our study might be significant for sensor and memory applications of nanodevices based on ferroelectric junctions

Temperature behavior of SNS-like Nb/Al-AlO x/Nb Josephson junctions

International Nuclear Information System (INIS)

Lacquaniti, V.; Andreone, D.; Maggi, S.; Rocci, R.; Sosso, A.; Steni, R.

2006-01-01

Overdamped Nb/Al-AlO x /Nb Josephson junctions are an intermediate state between the SIS and SNS Josephson junctions. Stable and reproducible non-hysteretic current-voltage characteristics have been obtained with a proper choice of the fabrication parameters, featuring critical current densities J c up to 25 kA/cm 2 and characteristic voltages up to 450 μV. While these values make the junctions interesting for RSFQ electronic circuits, their response to an RF signal at 70 GHz has demonstrated their suitability for both programmable and ac voltage standard. In these work we analyse the temperature behavior of these junctions up to T/T c = 1, T c being the niobium critical temperature, which gives relevant information on the junction structure and, especially, on the oxide insulator/metallic film barrier, which is the key for the reproducible transition from an hysteretic to a non-hysteretic behavior. The results are also compared with other data of hysteretic and overdamped junctions

Gap Junctions Contribute to Ictal/Interictal Genesis in Human Hypothalamic Hamartomas

Directory of Open Access Journals (Sweden)

Jie Wu

2016-06-01

Full Text Available Human hypothalamic hamartoma (HH is a rare subcortical lesion associated with treatment-resistant epilepsy. Cellular mechanisms responsible for epileptogenesis are unknown. We hypothesized that neuronal gap junctions contribute to epileptogenesis through synchronous activity within the neuron networks in HH tissue. We studied surgically resected HH tissue with Western-blot analysis, immunohistochemistry, electron microscopy, biocytin microinjection of recorded HH neurons, and microelectrode patch clamp recordings with and without pharmacological blockade of gap junctions. Normal human hypothalamus tissue was used as a control. Western blots showed increased expression of both connexin-36 (Cx36 and connexin-43 (Cx43 in HH tissue compared with normal human mammillary body tissue. Immunohistochemistry demonstrated that Cx36 and Cx43 are expressed in HH tissue, but Cx36 was mainly expressed within neuron clusters while Cx43 was mainly expressed outside of neuron clusters. Gap-junction profiles were observed between small HH neurons with electron microscopy. Biocytin injection into single recorded small HH neurons showed labeling of adjacent neurons, which was not observed in the presence of a neuronal gap-junction blocker, mefloquine. Microelectrode field recordings from freshly resected HH slices demonstrated spontaneous ictal/interictal-like discharges in most slices. Bath-application of gap-junction blockers significantly reduced ictal/interictal-like discharges in a concentration-dependent manner, while not affecting the action-potential firing of small gamma-aminobutyric acid (GABA neurons observed with whole-cell patch-clamp recordings from the same patient's HH tissue. These results suggest that neuronal gap junctions between small GABAergic HH neurons participate in the genesis of epileptic-like discharges. Blockade of gap junctions may be a new therapeutic strategy for controlling seizure activity in HH patients.

Degradation rate of acetylcholine receptors inserted into denervated vertebrate neuromuscular junctions

International Nuclear Information System (INIS)

Shyng, S.L.; Salpeter, M.M.

1989-01-01

Many studies exist on the effect of denervation on the degradation of acetylcholine receptors (AChRs) at the vertebrate neuromuscular junction (nmj). These studies have described the behavior of either the total population of junctional receptors at different times after denervation, or of the receptors present at the time of denervation. No experimental studies yet exist on the degradation rate of the receptors newly inserted into denervated junctions. In the previous studies, the original receptors of mouse sternomastoid muscles were found to retain the slow degradation (t 1/2) of approximately 8-10 d of innervated junctional receptors for up to 10 d after denervation before accelerating to a t 1/2 of approximately 3 d. The total junctional receptors, on the other hand, showed a progressive increase in degradation rate from a t 1/2 of 8-10 d to a t 1/2 of 1 d. To reconcile these earlier observations, the present study examines the degradation of new receptors inserted into the nmj after denervation. To avoid possible contamination of the data with postdenervation extrajunctional receptors, we used transmission electron microscope autoradiography to study only receptors located at the postjunctional fold of the nmj. We established that the new receptors inserted into denervated junctions have a t 1/2 of approximately 1 d, considerably faster than that of the original receptors and equivalent to that of postdenervation extrajunctional receptors. Both original and new receptors are interspersed at the top of the junctional folds. Thus, until all the original receptors are degraded, the postjunctional membrane contains two populations of AChRs that maintain a total steady-state site density but degrade at different rates

Effect of surface losses on soliton propagation in Josephson junctions

DEFF Research Database (Denmark)

Davidson, A.; Pedersen, Niels Falsig; Pagano, S.

1986-01-01

We have explored numerically the effects on soliton propagation of a third order damping term in the modified sine-Gordon equation. In Josephson tunnel junctions such a term corresponds physically to quasiparticle losses within the metal electrodes of the junction. We find that this loss term pla...

Water and suspended sediment division at a stratified tidal junction

NARCIS (Netherlands)

Buschman, F.A.; Vegt, van der M.; Hoitink, A.J.F.; Hoekstra, P.

2013-01-01

[1] Tidal junctions play a crucial role in the transport of water, salt, and sediment through a delta distributary network. Water, salt and sediment are exchanged at tidal junctions, thereby influencing the transports in the connecting branches and the overall dynamics of the system. This paper

Electroplated Ni on the PN Junction Semiconductor

Energy Technology Data Exchange (ETDEWEB)

Kim, Jin Joo; Uhm, Young Rang; Son, Kwang Jae; Kim, Jong Bum; Choi, Sang Moo; Park, Jong Han; Hong, Jintae [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2015-05-15

Nickel (Ni) electroplating was implemented by using a metal Ni powder in order to establish a Ni-63 plating condition on the PN junction semiconductor needed for production of betavoltaic battery. PN junction semiconductors with a Ni seed layer of 500 and 1000 A were coated with Ni at current density from 10 to 50 mA cm{sup 2}. The surface roughness and average grain size of Ni deposits were investigated by XRD and SEM techniques. The roughness of Ni deposit was increased as the current density was increased, and decreased as the thickness of Ni seed layer was increased.

Fluoride barriers in Nb/Pb Josephson junctions

Science.gov (United States)

Asano, H.; Tanabe, K.; Michikami, O.; Igarashi, M.; Beasley, M. R.

1985-03-01

Josephson tunnel junctions are fabricated using a new class of artificial barriers, metal fluorides (Al fluoride and Zr fluoride). These fluoride barriers are deposited on the surface of a Nb base electrode, which are previously cleaned using a CF4 cleaning process, and covered by a Pb counterelectrode. The junctions with both Al fluoride and Zr fluoride barriers exhibit good tunneling characteristics and have low specific capacitance. In the case of Zr fluoride, it is observed that reasonable resistances are obtained even at thickness greater than 100 A. This phenomenon might be explained by tunneling via localized states in Zr fluoride.

Electroplated Ni on the PN Junction Semiconductor

International Nuclear Information System (INIS)

Kim, Jin Joo; Uhm, Young Rang; Son, Kwang Jae; Kim, Jong Bum; Choi, Sang Moo; Park, Jong Han; Hong, Jintae

2015-01-01

Nickel (Ni) electroplating was implemented by using a metal Ni powder in order to establish a Ni-63 plating condition on the PN junction semiconductor needed for production of betavoltaic battery. PN junction semiconductors with a Ni seed layer of 500 and 1000 A were coated with Ni at current density from 10 to 50 mA cm 2 . The surface roughness and average grain size of Ni deposits were investigated by XRD and SEM techniques. The roughness of Ni deposit was increased as the current density was increased, and decreased as the thickness of Ni seed layer was increased

A graphene/single GaAs nanowire Schottky junction photovoltaic device.

Science.gov (United States)

Luo, Yanbin; Yan, Xin; Zhang, Jinnan; Li, Bang; Wu, Yao; Lu, Qichao; Jin, Chenxiaoshuai; Zhang, Xia; Ren, Xiaomin

2018-05-04

A graphene/nanowire Schottky junction is a promising structure for low-cost high-performance optoelectronic devices. Here we demonstrate a graphene/single GaAs nanowire Schottky junction photovoltaic device. The Schottky junction is fabricated by covering a single layer graphene onto an n-doped GaAs nanowire. Under 532 nm laser excitation, the device exhibits a high responsivity of 231 mA W-1 and a short response/recover time of 85/118 μs at zero bias. Under AM 1.5 G solar illumination, the device has an open-circuit voltage of 75.0 mV and a short-circuit current density of 425 mA cm-2, yielding a remarkable conversion efficiency of 8.8%. The excellent photovoltaic performance of the device is attributed to the strong built-in electric field in the Schottky junction as well as the transparent property of graphene. The device is promising for self-powered high-speed photodetectors and low-cost high-efficiency solar cells.

Gas selectivity of SILAR grown CdS nano-bulk junction

Science.gov (United States)

Jayakrishnan, R.; Nair, Varun G.; Anand, Akhil M.; Venugopal, Meera

2018-03-01

Nano-particles of cadmium sulphide were deposited on cleaned copper substrate by an automated sequential ionic layer adsorption reaction (SILAR) system. The grown nano-bulk junction exhibits Schottky diode behavior. The response of the nano-bulk junction was investigated under oxygen and hydrogen atmospheric conditions. The gas response ratio was found to be 198% for Oxygen and 34% for Hydrogen at room temperature. An increase in the operating temperature of the nano-bulk junction resulted in a decrease in their gas response ratio. A logarithmic dependence on the oxygen partial pressure to the junction response was observed, indicating a Temkin isothermal behavior. Work function measurements using a Kelvin probe demonstrate that the exposure to an oxygen atmosphere fails to effectively separate the charges due to the built-in electric field at the interface. Based on the benefits like simple structure, ease of fabrication and response ratio the studied device is a promising candidate for gas detection applications.

Tuning the thermal conductance of molecular junctions with interference effects

Science.gov (United States)

Klöckner, J. C.; Cuevas, J. C.; Pauly, F.

2017-12-01

We present an ab initio study of the role of interference effects in the thermal conductance of single-molecule junctions. To be precise, using a first-principles transport method based on density functional theory, we analyze the coherent phonon transport in single-molecule junctions made of several benzene and oligo(phenylene ethynylene) derivatives. We show that the thermal conductance of these junctions can be tuned via the inclusion of substituents, which induces destructive interference effects and results in a decrease of the thermal conductance with respect to the unmodified molecules. In particular, we demonstrate that these interference effects manifest as antiresonances in the phonon transmission, whose energy positions can be tuned by varying the mass of the substituents. Our work provides clear strategies for the heat management in molecular junctions and, more generally, in nanostructured metal-organic hybrid systems, which are important to determine how these systems can function as efficient energy-conversion devices such as thermoelectric generators and refrigerators.

Experiments on the interaction between long Josephson junctions and a coplanar strip resonator

DEFF Research Database (Denmark)

Davidson, A.; Pedersen, Niels Falsig

1992-01-01

Experiments are reported on a new geometry designed to couple long Josephson junction fluxon oscillators to a resonant cavity. The junctions were made with a niobium-aluminum oxide-niobium trilayer process with a critical-current density of around 1000 A/cm2. Various numbers of such junctions wer...

Junction structures based on the high-Tc superconductor YBa2Cu3O7-δ

International Nuclear Information System (INIS)

Gijs, M.A.M.

1993-01-01

An overview is given of the investigations of the Josephson effect in junction structures based on the high-T c superconductor YBa 2 Cu 3 O 7-δ , which were carried out at the Philips Research Laboratories in Eindhoven in the 1988-1990 period. The reported results are presented in their international scientific context, without attempting a complete review of the subject. However, the various junction types studied give a good idea of the scientific pursuits of high-T c junction researchers in this period. The following junctions are considered: in the category of 'weak link'-type junctions we have investigated YBa 2 Cu 3 O 7-δ -Ag-Nb point contact junctions, YBa 2 Cu 3 O 7-δ Dayem bridges and YBa 2 Cu 3 O 7-δ -Ag(-Al)-Pb proximity junctions. In these structures we combine a high-T c with a low-T c superconductor. We also fabricated planar 'all high-T c ' YBa 2 Cu 3 O 7-δ -Ag-YBa 2 Cu 3 O 7-δ junctions using a submicron structuring process. Next we have made tunnel junctions to study density of states effects of the high-T c superconductor : YBa 2 Cu 3 O 7-δ -Pb junctions using the degraded YBa 2 Cu 3 O 7-δ -Pb interface as a tunnel barrier, and YBa 2 Cu 3 O 7-δ -Ag-Al/Al 2 O 3 /Pb tunnel junctions based on the superconducting proximity effect. Our junction structures are electrically characterized and mostly studied in microwave and magnetic fields. Results are compared with current theoretical models. (orig.)

Nanometer-scale patterning of high-Tc superconductors for Josephson junction-based digital circuits

International Nuclear Information System (INIS)

Wendt, J.R.; Plut, T.A.; Corless, R.F.; Martens, J.S.; Berkowitz, S.; Char, K.; Johansson, M.; Hou, S.Y.; Phillips, J.M.

1994-01-01

A straightforward method for nanometer-scale patterning of high-T c superconductor thin films is discussed. The technique combines direct-write electron beam lithography with well-controlled aqueous etches and is applied to the fabrication of Josephson junction nanobridges in high-quality, epitaxial thin-film YBa 2 Cu 3 O 7 . We present the results of our studies of the dimensions, yield, uniformity, and mechanism of the junctions along with the performance of a representative digital circuit based on these junctions. Direct current junction parameter statistics measured at 77 K show critical currents of 27.5 μA±13% for a sample set of 220 junctions. The Josephson behavior of the nanobridge is believed to arise from the aggregation of oxygen vacancies in the nanometer-scale bridge

R.f.-induced steps in mutually coupled, two-dimensional distributed Josephson tunnel junctions

International Nuclear Information System (INIS)

Klein, U.; Dammschneider, P.

1991-01-01

This paper reports on the amplitudes of the current steps in the I-V characteristics of mutually coupled two-dimensional distributed Josephson tunnel junctions driven by microwaves. For this purpose we use a numerical computation algorithm based on a planar resonator model for the individual Josephson tunnel junctions to calculate the d.c. current density distribution. In addition to the fundamental microwave frequency, harmonic contents of the tunneling current are also considered. The lateral dimensions of the individual junctions are small compared to the microwave wavelength and the Josephson penetration depth, giving an almost constant current density distribution. Therefore, the coupled junctions can give much greater step amplitudes than a single junction with an equal tunneling area, because of their nonuniform current density distribution

Extended Majorana zero modes in a topological superconducting-normal T-junction

Science.gov (United States)

Spånslätt, Christian; Ardonne, Eddy

2017-03-01

We investigate the sub gap properties of a three terminal Josephson T-junction composed of topologically superconducting wires connected by a normal metal region. This system naturally hosts zero energy Andreev bound states which are of self-conjugate Majorana nature and we show that they are, in contrast to ordinary Majorana zero modes, spatially extended in the normal metal region. If the T-junction respects time-reversal symmetry, we show that a zero mode is distributed only in two out of three arms in the junction and tuning the superconducting phases allows for transfer of the mode between the junction arms. We further provide tunneling conductance calculations showing that these features can be detected in experiments. Our findings suggest an experimental platform for studying the nature of spatially extended Majorana zero modes.

Transport Properties of ZnSe- ITO Hetero Junction

Science.gov (United States)

Ichibakase, Tsuyoshi

In this report, ITO(Indium Tin Oxide) was used on the glass substrates as the transparent electrode, and ZnSe layer was prepared by the vacuum deposition on this ITO. Then, the electrical characteristics of this sample were investigated by mans of the electric current transport analysis. The sample that ZnSe was prepared as 3.4 μm in case of ITO-ZnSe sample, has high density level at the junction surface. The ITO-ZnSe junction has two type of diffusion current. However, the ITO-ZnSe sample that ZnSe layer was prepared as 0.1 μm can be assumed as the ohmic contact, and ITO-ZnSe(0.1μm) -CdTe sample shows the avalanche breakdown, and it is considered that the avalanche breakdown occurs in CdTe layer. It is difficult to occur the avalanche breakdown, if ZnSe-CdTe junction has high-density level and CdTe layer has high-density defect. Hence, the ZnSe-CdTe sample that CdTe layer was prepared on ITO-ZnSe(0.1μm) substrate has not high-density level at the junction surface, and the CdTe layer with little lattice imperfection can be prepared. It found that ITO-ZnSe(0.1μm) substrate is available for the II-VI compounds semiconductor device through above analysis result.

Conductance spectra of asymmetric ferromagnet/ferromagnet/ferromagnet junctions

Energy Technology Data Exchange (ETDEWEB)

Pasanai, K., E-mail: krisakronmsu@gmail.com

2017-01-15

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. - Highlights: • The conductance spectra of a FM/FM/FM junction were calculated. • The conductance spectra were suppressed by the exchange energy. • The exchange energy and the potential strength play similar roles in the junctions.

Conductance spectra of asymmetric ferromagnet/ferromagnet/ferromagnet junctions

International Nuclear Information System (INIS)

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. - Highlights: • The conductance spectra of a FM/FM/FM junction were calculated. • The conductance spectra were suppressed by the exchange energy. • The exchange energy and the potential strength play similar roles in the junctions.

The postoperative complication for adenocarcinoma of esophagogastric junction

Directory of Open Access Journals (Sweden)

Hui Zhang

2015-01-01

Full Text Available Objective: The purpose of this study was to evaluate the postoperative complications for patients with adenocarcinoma of esophagogastric junction. Methods: Two hundred and eighty subjects with adenocarcinoma of esophagogastric junction who received operation were retrospectively analyzed from June 2006 to December 2010 in the Department of Oncology of First Affiliated Hospital of Bengbu Medical College, Bengbu, China. The postoperative complication such as ventricular premature beat, atrial fibrillation, supraventricular tachycardia, heart failure, pulmonary infection, pulmonary atelectasis, respiratory failure, bronchospasm, anastomotic leakage, gastroplegia, pleural infection, and cerebral accident were reviewed and recorded by to doctors. Moreover, the correlation between clinical characteristics and postoperative complication was analyzed by statistical methods. Results: A total of 70 complications were found for the included 280 cases of adenocarcinoma of esophagogastric junction with general incidence of 25%. For the relationship between clinical characteristics and postoperative complication analysis, no significant association of gender, age, operation time, operative approach, tumor differentiation, and clinical states was found with the postoperative complications (P > 0.05; but the complication rate in patients with basic disease of heart and lung was significant than the patients without this kind of disease (P < 0.05. Conclusion: The positive operative complications for patients with adenocarcinoma of esophagogastric junction were relative high. Moreover, basic heart and lung diseases can increase the risk of developing positive operative complications.

From FRA to RFN, or How the Family Resemblance Approach Can Be Transformed for Science Curriculum Analysis on Nature of Science

Science.gov (United States)

Kaya, Ebru; Erduran, Sibel

2016-01-01

The inclusion of Nature of Science (NOS) in the science curriculum has been advocated around the world for several decades. One way of defining NOS is related to the family resemblance approach (FRA). The family resemblance idea was originally described by Wittgenstein. Subsequently, philosophers and educators have applied Wittgenstein's idea to…

Versatile multi-layer Josephson junction process for vortex molecules

Energy Technology Data Exchange (ETDEWEB)

Meckbach, Johannes Maximilian; Buehler, Simon; Merker, Michael; Il' in, Konstantin; Siegel, Michael [Institut fuer Mikro- und Nanoelektronische Systeme, KIT (Germany); Buckenmaier, Kai; Gaber, Tobias; Kienzle, Uta; Neumaier, Benjamin; Goldobin, Edward; Kleiner, Reinhold; Koelle, Dieter [Physikalisches Institut - Experimentalphysik II, Universitaet Tuebingen (Germany)

2012-07-01

In long Josephson junctions magnetic flux may penetrate the barrier resulting in a so-called Josephson-Vortex carrying one flux quantum Φ{sub 0}. In recent years a new type of Josephson-Vortex became available, which carries any arbitrary fraction Φ = -Φ{sub 0}κ/2π of magnetic flux. These fractional vortices (p-vortices) spontaneously appear at discontinuities of the Josephson phase along the junction, which in turn are created using a pair of current injectors. We present a new Nb/Al-AlO{sub x}/Nb process for the fabrication of Josephson junctions of very high quality. Placing two injector pairs along the strongly underdamped long junctions allows the investigation of fractional vortex molecules. The topological charge of each vortex and their interaction can be altered even during experiment by changing the individual injector currents. Vortex molecule states have been measured using asymmetric DC-SQUIDs coupled to the vortices by overlying pick-up loops. To uphold the p-vortices we use persistent currents, which can be altered using heat switches. Fractional vortex molecules are promising candidates for a new type of qubits.

Manipulating Josephson junctions in thin-films by nearby vortices

International Nuclear Information System (INIS)

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

2014-01-01

Highlights: • Vortex located in a bank of a planar Josephson junction changes its character. • Vortex located at some discreet positions in thin strip bank suppresses to zero the zero-field current. • The number of these positions is equal to the number of vortices trapped. • Critical current-field patterns are strongly affected by the vortex position. - Abstract: 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 ∼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

Non-Lagrangian theories from brane junctions

Energy Technology Data Exchange (ETDEWEB)

Bao, Ling [Chalmers Univ. of Technology, Goeteborg (Sweden); Mitev, Vladimir [Humboldt Univ., Berlin (Germany). Inst. fuer Mathematik und Inst. fuer Physik; Pomoni, Elli [Deutsches Elektronen-Synchrotron DESY, Hamburg (Germany). Theory Group; Taki, Masato [RIKEN Nishina Center, Saitama (Japan). Mathematical Physics Lab.; Yagi, Futoshi [International School of Advanced Studies (SISSA), Trieste (Italy); INFN, Trieste (Italy); Korea Institute for Advanced Study (KIAS), Seoul (Korea, Republic of)

2013-10-15

In this article we use 5-brane junctions to study the 5D T{sub N} SCFTs corresponding to the 5D N=1 uplift of the 4D N=2 strongly coupled gauge theories, which are obtained by compactifying N M5 branes on a sphere with three full punctures. Even though these theories have no Lagrangian description, by using the 5-brane junctions proposed by Benini, Benvenuti and Tachikawa, we are able to derive their Seiberg-Witten curves and Nekrasov partition functions. We cross-check our results with the 5D superconformal index proposed by Kim, Kim and Lee. Through the AGTW correspondence, we discuss the relations between 5D superconformal indices and n-point functions of the q-deformed W{sub N} Toda theories.

Non-Lagrangian theories from brane junctions

International Nuclear Information System (INIS)

Bao, Ling; Mitev, Vladimir

2013-10-01

In this article we use 5-brane junctions to study the 5D T N SCFTs corresponding to the 5D N=1 uplift of the 4D N=2 strongly coupled gauge theories, which are obtained by compactifying N M5 branes on a sphere with three full punctures. Even though these theories have no Lagrangian description, by using the 5-brane junctions proposed by Benini, Benvenuti and Tachikawa, we are able to derive their Seiberg-Witten curves and Nekrasov partition functions. We cross-check our results with the 5D superconformal index proposed by Kim, Kim and Lee. Through the AGTW correspondence, we discuss the relations between 5D superconformal indices and n-point functions of the q-deformed W N Toda theories.

Fabrication of TiN/AlN/TiN tunnel junctions

Energy Technology Data Exchange (ETDEWEB)

Nakayama, Takeru; Naruse, Masato; Myoren, Hiroaki; Taino, Tohru, E-mail: taino@mail.saitama-u.ac.jp

2016-11-15

Highlights: • We have fabricated TiN/AlN/TiN tunnel junctions with an epitaxial layer. • TiN and AlN films were deposited by dc and rf magnetron sputtering at ambient substrate temperatures. • The junctions have a V{sub g} = 1.1 mV, J{sub c} = 0.24 A/cm{sup 2}, R{sub sg}/R{sub n} of 7.2, and low subgap leakage current of 180 nA. - Abstract: We have fabricated TiN/AlN/TiN tunnel junctions with an epitaxial layer. The critical temperature of TiN can be changed in the range from 0.5 to 5.0 K. Therefore, it is easy to set 5.0 K as the target critical temperature. When a Superconducting Tunnel Junction (STJ) is operated as a photon detector, it is necessary to cool it to within 0.1 K of the critical temperature in consideration of the noise of the thermally stimulated currents. Because 0.3 K was desirable, as for the manufacture of general purpose photon detectors, the critical temperature 5.0 K. TiN and AlN films were deposited by dc and rf magnetron sputtering in a load-lock sputtering system at ambient substrate temperatures. The junctions have a gap voltage of V{sub g} = 1.1 mV, and critical current density of J{sub c} = 0.24 A/cm{sup 2}, and R{sub sg}/R{sub n} of 7.2, and low subgap leakage current (I{sub sub}@ 500 µV = 180 nA). We report our experiment system, the manufacture method and the junction properties in this paper.

Junction leakage measurements with micro four-point probes

DEFF Research Database (Denmark)

Lin, Rong; Petersen, Dirch Hjorth; Wang, Fei

2012-01-01

We present a new, preparation-free method for measuring the leakage current density on ultra-shallow junctions. The junction leakage is found by making a series of four-point sheet resistance measurements on blanket wafers with variable electrode spacings. The leakage current density is calculated...... using a fit of the measured four-point resistances to an analytical two-sheet model. The validity of the approximation involved in the two-sheet model is verified by a comparison to finite element model calculations....

Intracellular trafficking pathways of Cx43 gap junction channels.

Science.gov (United States)

Epifantseva, Irina; Shaw, Robin M

2018-01-01

Gap Junction (GJ) channels, including the most common Connexin 43 (Cx43), have fundamental roles in excitable tissues by facilitating rapid transmission of action potentials between adjacent cells. For instance, synchronization during each heartbeat is regulated by these ion channels at the cardiomyocyte cell-cell border. Cx43 protein has a short half-life, and rapid synthesis and timely delivery of those proteins to particular subdomains are crucial for the cellular organization of gap junctions and maintenance of intracellular coupling. Impairment in gap junction trafficking contributes to dangerous complications in diseased hearts such as the arrhythmias of sudden cardiac death. Of recent interest are the protein-protein interactions with the Cx43 carboxy-terminus. These interactions have significant impact on the full length Cx43 lifecycle and also contribute to trafficking of Cx43 as well as possibly other functions. We are learning that many of the known non-canonical roles of Cx43 can be attributed to the recently identified six endogenous Cx43 truncated isoforms which are produced by internal translation. In general, alternative translation is a new leading edge for proteome expansion and therapeutic drug development. This review highlights recent mechanisms identified in the trafficking of gap junction channels, involvement of other proteins contributing to the delivery of channels to the cell-cell border, and understanding of possible roles of the newly discovered alternatively translated isoforms in Cx43 biology. This article is part of a Special Issue entitled: Gap Junction Proteins edited by Jean Claude Herve. Copyright © 2017 Elsevier B.V. All rights reserved.

Stability of fluxon motion in long Josephson junctions at high bias

DEFF Research Database (Denmark)

Pagano, S.; Sørensen, Mads Peter; Christiansen, Peter Leth

1988-01-01

In long Josephson junctions the motion of fluxons is revealed by the existence of current steps, zero-field steps, in the current-voltage characteristics. In this paper we investigate the stability of the fluxon motion when high values of the current bias are involved. The investigation is carried...... dissipations and of the junction length on the switching-current value is investigated. A simple boundary model is able to describe, for junctions of overlap geometry, the qualitative dependence of the switching current on the system parameters....

Evaluation of the Electronic Structure of Single-Molecule Junctions Based on Current-Voltage and Thermopower Measurements: Application to C60 Single-Molecule Junction.

Science.gov (United States)

Komoto, Yuki; Isshiki, Yuji; Fujii, Shintaro; Nishino, Tomoaki; Kiguchi, Manabu

2017-02-16

The electronic structure of molecular junctions has a significant impact on their transport properties. Despite the decisive role of the electronic structure, a complete characterization of the electronic structure remains a challenge. This is because there is no straightforward way of measuring electron spectroscopy for an individual molecule trapped in a nanoscale gap between two metal electrodes. Herein, a comprehensive approach to obtain a detailed description of the electronic structure in single-molecule junctions based on the analysis of current-voltage (I-V) and thermoelectric characteristics is described. It is shown that the electronic structure of the prototypical C 60 single-molecule junction can be resolved by analyzing complementary results of the I-V and thermoelectric measurement. This combined approach confirmed that the C 60 single-molecule junction was highly conductive with molecular electronic conductances of 0.033 and 0.003 G 0 and a molecular Seebeck coefficient of -12 μV K -1 . In addition, we revealed that charge transport was mediated by a LUMO whose energy level was located 0.5≈0.6 eV above the Fermi level of the Au electrode. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Conduction gap in graphene strain junctions: direction dependence

International Nuclear Information System (INIS)

Nguyen, M Chung; Nguyen, V Hung; Dollfus, P; Nguyen, Huy-Viet

2014-01-01

It has been shown in a recent study (Nguyen et al 2014 Nanotechnology 25 165201) that unstrained/strained graphene junctions are promising candidates to improve the performance of graphene transistors which is usually hindered by the gapless nature of graphene. Although the energy bandgap of strained graphene still remains zero, the shift of Dirac points in the k-space due to strain-induced deformation of graphene lattice can lead to the appearance of a finite conduction gap of several hundred meV in strained junctions with a strain of only a few per cent. However, since it depends essentially on the magnitude of the Dirac point shift, this conduction gap strongly depends on the direction of applied strain and the transport direction. In this work, a systematic study of conduction-gap properties with respect to these quantities is presented and the results are carefully analyzed. Our study provides useful information for further investigations to exploit graphene-strained junctions in electronic applications and strain sensors. (paper)

Metal-semiconductor Schottky barrier junctions and their applications

CERN Document Server

1984-01-01

The present-day semiconductor technology would be inconceivable without extensive use of Schottky barrier junctions. In spite of an excellent book by Professor E.H. Rhoderick (1978) dealing with the basic principles of metal­ semiconductor contacts and a few recent review articles, the need for a monograph on "Metal-Semiconductor Schottky Barrier Junctions and Their Applications" has long been felt by students, researchers, and technologists. It was in this context that the idea of publishing such a monograph by Mr. Ellis H. Rosenberg, Senior Editor, Plenum Publishing Corporation, was considered very timely. Due to the numerous and varied applications of Schottky barrier junctions, the task of bringing it out, however, looked difficult in the beginning. After discussions at various levels, it was deemed appropriate to include only those typical applications which were extremely rich in R&D and still posed many challenges so that it could be brought out in the stipulated time frame. Keeping in view the la...

Expression pattern of adhesion molecules in junctional epithelium differs from that in other gingival epithelia.

Science.gov (United States)

Hatakeyama, S; Yaegashi, T; Oikawa, Y; Fujiwara, H; Mikami, T; Takeda, Y; Satoh, M

2006-08-01

The gingival epithelium is the physiologically important interface between the bacterially colonized gingival sulcus and periodontal soft and mineralized connective tissues, requiring protection from exposure to bacteria and their products. However, of the three epithelia comprising the gingival epithelium, the junctional epithelium has much wider intercellular spaces than the sulcular epithelium and oral gingival epithelium. Hence, the aim of the present study was to characterize the cell adhesion structure in the junctional epithelium compared with the other two epithelia. Gingival epithelia excised at therapeutic flap surgery from patients with periodontitis were examined for expression of adhesion molecules by immunofluorescence. In the oral gingival epithelium and sulcular epithelium, but not in the junctional epithelium, desmoglein 1 and 2 in cell-cell contact sites were more abundant in the upper than the suprabasal layers. E-cadherin, the main transmembranous molecule of adherens junctions, was present in spinous layers of the oral gingival epithelium and sulcular epithelium, but was scarce in the junctional epithelium. In contrast, desmoglein 3 and P-cadherin were present in all layers of the junctional epithelium as well as the oral gingival epithelium and sulcular epithelium. Connexin 43 was clearly localized to spinous layers of the oral gingival epithelium, sulcular epithelium and parts of the junctional epithelium. Claudin-1 and occludin were expressed in the cell membranes of a few superficial layers of the oral gingival epithelium. These findings indicated that the junctional epithelium contains only a few desmosomes, composed of only desmoglein 3; adherens junctions are probably absent because of defective E-cadherin. Thus, the anchoring junctions connecting junctional epithelium cells are lax, causing widened intercellular spaces. In contrast, the oral gingival epithelium, which has a few tight junctions, functions as a barrier.

Macroscopic Quantum Tunneling in Superconducting Junctions of β-Ag2Se Topological Insulator Nanowire.

Science.gov (United States)

Kim, Jihwan; Kim, Bum-Kyu; Kim, Hong-Seok; Hwang, Ahreum; Kim, Bongsoo; Doh, Yong-Joo

2017-11-08

We report on the fabrication and electrical transport properties of superconducting junctions made of β-Ag 2 Se topological insulator (TI) nanowires in contact with Al superconducting electrodes. The temperature dependence of the critical current indicates that the superconducting junction belongs to a short and diffusive junction regime. As a characteristic feature of the narrow junction, the critical current decreases monotonously with increasing magnetic field. The stochastic distribution of the switching current exhibits the macroscopic quantum tunneling behavior, which is robust up to T = 0.8 K. Our observations indicate that the TI nanowire-based Josephson junctions can be a promising building block for the development of nanohybrid superconducting quantum bits.

Gap junctional coupling in the vertebrate retina: variations on one theme?

Science.gov (United States)

Völgyi, Béla; Kovács-Oller, Tamás; Atlasz, Tamás; Wilhelm, Márta; Gábriel, Róbert

2013-05-01

Gap junctions connect cells in the bodies of all multicellular organisms, forming either homologous or heterologous (i.e. established between identical or different cell types, respectively) cell-to-cell contacts by utilizing identical (homotypic) or different (heterotypic) connexin protein subunits. Gap junctions in the nervous system serve electrical signaling between neurons, thus they are also called electrical synapses. Such electrical synapses are particularly abundant in the vertebrate retina where they are specialized to form links between neurons as well as glial cells. In this article, we summarize recent findings on retinal cell-to-cell coupling in different vertebrates and identify general features in the light of the evergrowing body of data. In particular, we describe and discuss tracer coupling patterns, connexin proteins, junctional conductances and modulatory processes. This multispecies comparison serves to point out that most features are remarkably conserved across the vertebrate classes, including (i) the cell types connected via electrical synapses; (ii) the connexin makeup and the conductance of each cell-to-cell contact; (iii) the probable function of each gap junction in retinal circuitry; (iv) the fact that gap junctions underlie both electrical and/or tracer coupling between glial cells. These pan-vertebrate features thus demonstrate that retinal gap junctions have changed little during the over 500 million years of vertebrate evolution. Therefore, the fundamental architecture of electrically coupled retinal circuits seems as old as the retina itself, indicating that gap junctions deeply incorporated in retinal wiring from the very beginning of the eye formation of vertebrates. In addition to hard wiring provided by fast synaptic transmitter-releasing neurons and soft wiring contributed by peptidergic, aminergic and purinergic systems, electrical coupling may serve as the 'skeleton' of lateral processing, enabling important functions such

SOAPsplice: genome-wide ab initio detection of splice junctions from RNA-Seq data

Directory of Open Access Journals (Sweden)

Songbo eHuang

2011-07-01

Full Text Available RNA-Seq, a method using next generation sequencing technologies to sequence the transcriptome, facilitates genome-wide analysis of splice junction sites. In this paper, we introduce SOAPsplice, a robust tool to detect splice junctions using RNA-Seq data without using any information of known splice junctions. SOAPsplice uses a novel two-step approach consisting of first identifying as many reasonable splice junction candidates as possible, and then, filtering the false positives with two effective filtering strategies. In both simulated and real datasets, SOAPsplice is able to detect many reliable splice junctions with low false positive rate. The improvement gained by SOAPsplice, when compared to other existing tools, becomes more obvious when the depth of sequencing is low. SOAPsplice is freely available at http://soap.genomics.org.cn/soapsplice.html.

Giant electroresistance of super-tetragonal BiFeO3-based ferroelectric tunnel junctions.

Science.gov (United States)

Yamada, Hiroyuki; Garcia, Vincent; Fusil, Stéphane; Boyn, Sören; Marinova, Maya; Gloter, Alexandre; Xavier, Stéphane; Grollier, Julie; Jacquet, Eric; Carrétéro, Cécile; Deranlot, Cyrile; Bibes, Manuel; Barthélémy, Agnès

2013-06-25

Ferroelectric tunnel junctions enable a nondestructive readout of the ferroelectric state via a change of resistance induced by switching the ferroelectric polarization. We fabricated submicrometer solid-state ferroelectric tunnel junctions based on a recently discovered polymorph of BiFeO3 with giant axial ratio ("T-phase"). Applying voltage pulses to the junctions leads to the highest resistance changes (OFF/ON ratio >10,000) ever reported with ferroelectric tunnel junctions. Along with the good retention properties, this giant effect reinforces the interest in nonvolatile memories based on ferroelectric tunnel junctions. We also show that the changes in resistance scale with the nucleation and growth of ferroelectric domains in the ultrathin BiFeO3 (imaged by piezoresponse force microscopy), thereby suggesting potential as multilevel memory cells and memristors.

Comparison of band-to-band tunneling models in Si and Si—Ge junctions

International Nuclear Information System (INIS)

Jiao Yipeng; Wang Taihuan; Wei Kangliang; Du Gang; Liu Xiaoyan

2013-01-01

We compared several different band-to-band tunneling (BTBT) models with both Sentaurus and the two-dimensional full-band Monte Carlo simulator in Si homo-junctions and Si—Ge hetero-junctions. It was shown that in Si homo-junctions, different models could achieve similar results. However, in the Si—Ge hetero-junctions, there were significant differences among these models at high reverse biases (over 2 V). Compared to the nonlocal model, the local models in Sentaurus underrated the BTBT rate distinctly, and the Monte Carlo method was shown to give a better approximation. Additionally, it was found that in the Si region near the interface of the Si—Ge hetero-junctions, the direct tunneling rates increased largely due to the interaction of the band structures of Si and Ge. (semiconductor physics)

Fabrication of sub-micron whole waffer SIS tunnel junctions for millimeter wave mixers

International Nuclear Information System (INIS)

Huq, S.E.; Blamire, M.G.; Evetts, J.E.; Hasko, D.G.; Ahmed, H.

1991-01-01

As a part of a programme for the development of a space-qualified sub-mm-wave mixer operating in the region of one terahertz we have been developing the processes required for the fabrication of submicron whole wafer tunnel junctions. Using the self-aligned whole-wafer process (SAWW) with electron beam lithography we have been able to reliably fabricate high quality (V m > 20 mV) submicron tunnel junctions from whole wafer Nb/AlO x /Nb structures. In particular we show that the junction quality is independent of size down to 0.3 μm 2 junction area. The problems of film stress, anodization, registration for electron beam lithography and lift-off, which limit the yield of good quality sub-micron scale junctions are addressed in this paper

HMP-1/α-catenin promotes junctional mechanical integrity during morphogenesis.

Directory of Open Access Journals (Sweden)

Thanh Thi Kim Vuong-Brender

Full Text Available Adherens junctions (AJs are key structures regulating tissue integrity and maintaining adhesion between cells. During morphogenesis, junctional proteins cooperate closely with the actomyosin network to drive cell movement and shape changes. How the junctions integrate the mechanical forces in space and in time during an in vivo morphogenetic event is still largely unknown, due to a lack of quantitative data. To address this issue, we inserted a functional Fluorescence Resonance Energy Transfer (FRET-based force biosensor within HMP-1/α-catenin of Caenorhabditis elegans. We find that the tension exerted on HMP-1 has a cell-specific distribution, is actomyosin-dependent, but is regulated differently from the tension on the actin cortex during embryonic elongation. By using time-lapse analysis of mutants and tissue-specific rescue experiments, we confirm the role of VAB-9/Claudin as an actin bundle anchor. Nevertheless, the tension exerted on HMP-1 did not increase in the absence of VAB-9/Claudin, suggesting that HMP-1 activity is not upregulated to compensate for loss of VAB-9. Our data indicate that HMP-1 does not modulate HMR-1/E-cadherin turnover, is required to recruit junctional actin but not stress fiber-like actin bundles. Altogether, our data suggest that HMP-1/α-catenin acts to promote the mechanical integrity of adherens junctions.

Origin of the transition voltage in gold–vacuum–gold atomic junctions

International Nuclear Information System (INIS)

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

2013-01-01

The origin and the distance dependence of the transition voltage of gold–vacuum–gold junctions are investigated by employing first-principles quantum transport simulations. Our calculations show that atomic protrusions always exist on the electrode surface of gold–vacuum–gold junctions fabricated using the mechanically controllable break junction (MCBJ) method. The transition voltage of these gold–vacuum–gold junctions with atomically sharp electrodes is determined by the local density of states (LDOS) of the apex gold atom on the electrode surface rather than by the vacuum barrier shape. More specifically, the absolute value of the transition voltage roughly equals the rising edge of the LDOS peak contributed by the 6p atomic orbitals of the gold atoms protruding from the electrode surface, whose local Fermi level is shifted downwards when a bias voltage is applied. Since the LDOS of the apex gold atom depends strongly on the exact shape of the electrode, the transition voltage is sensitive to the variation of the atomic configuration of the junction. For asymmetric junctions, the transition voltage may also change significantly depending on the bias polarity. Considering that the occurrence of the transition voltage requires the electrode distance to be larger than a critical value, the interaction between the two electrodes is actually rather weak. Consequently, the LDOS of the apex gold atom is mainly determined by its local atomic configuration and the transition voltage only depends weakly on the electrode distance as observed in the MCBJ experiments. (paper)

[Inhibition of gap junctional intercellular communication protects astrocytes from hypoxia/reoxygenation injury].

Science.gov (United States)

Tong, Xu-Hui; Gu, Yu-Chen; Jiao, Hao; Yu, Li; Dong, Shu-Ying

2015-01-01

To investigate the effects of inhibiting gap junctional intercellular communication on hypoxia/reoxygenation injury in astrocytes. Primary cultured cerebral cortical astrocytes of neonate rats were divided into normal control group, hypoxia reoxygenation injury group and 18-α-glycyrrhetinic acid and oleamide (gap junctional intercellular channel inhibitors) group. The gap junction intercellular communication was determined by Parachute assay. The viability of astrocyes was detected by MTT assay. The apoptosis of astrocytes were detected with annexin V/PI and Hoechst 33258 staining. Compared with the normal control group, the gap junctional function of astrocytes was increased significantly in ischemia/reperfusion group (Pastrocytes decreased significantly (Pastrocytes in18-α-glycyrrhetinic acid and oleamide group decreased significantly (Pastrocytes increased significantly (Pastrocytes.

Scale resolved simulations of the OECD/NEA–Vattenfall T-junction benchmark

Energy Technology Data Exchange (ETDEWEB)

Höhne, Thomas, E-mail: t.hoehne@hzdr.de

2014-04-01

Mixing of fluids in T-junction geometries is of significant interest for nuclear safety research. The most prominent example is the thermal striping phenomena in piping T-junctions, where hot and cold streams join and turbulently mix, however not completely or not immediately at the T-junction. This result in significant temperature fluctuations near the piping wall, either at the side of the secondary pipe branch or at the opposite side of the main branch pipe. The wall temperature fluctuation can cause cyclical thermal stresses and subsequently fatigue cracking of the wall. Thermal mixing in a T-junction has been studied for validation of CFD-calculations. A T-junction thermal mixing test was carried out at the Älvkarleby Laboratory of Vattenfall Research and Development (VRD) in Sweden. Data from this test have been reserved specifically for a OECD CFD benchmark exercise. The computational results show that RANS fail to predict a realistic mixing between the fluids. The results were significantly better with scale-resolving methods such as LES, showing fairly good predictions of the velocity field and mean temperatures. The calculation predicts also similar fluctuations and frequencies observed in the model test.

ATP- and gap junction-dependent intercellular calcium signaling in osteoblastic cells

DEFF Research Database (Denmark)

Jorgensen, N R; Geist, S T; Civitelli, R

1997-01-01

mechanically induced calcium waves in two rat osteosarcoma cell lines that differ in the gap junction proteins they express, in their ability to pass microinjected dye from cell to cell, and in their expression of P2Y2 (P2U) purinergic receptors. ROS 17/2.8 cells, which express the gap junction protein......Many cells coordinate their activities by transmitting rises in intracellular calcium from cell to cell. In nonexcitable cells, there are currently two models for intercellular calcium wave propagation, both of which involve release of inositol trisphosphate (IP3)- sensitive intracellular calcium...... stores. In one model, IP3 traverses gap junctions and initiates the release of intracellular calcium stores in neighboring cells. Alternatively, calcium waves may be mediated not by gap junctional communication, but rather by autocrine activity of secreted ATP on P2 purinergic receptors. We studied...

Assessing Urinary Tract Junction Obstruction Defects by Methylene Blue Dye Injection.

Science.gov (United States)

Yun, Kangsun