2,750 research outputs found

    Effect of a skin-deep surface zone on formation of two-dimensional electron gas at a semiconductor surface

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    Two dimensional electron gases (2DEGs) at surfaces and interfaces of semiconductors are described straightforwardly with a 1D self-consistent Poisson-Schr\"{o}dinger scheme. However, their band energies have not been modeled correctly in this way. Using angle-resolved photoelectron spectroscopy we study the band structures of 2DEGs formed at sulfur-passivated surfaces of InAs(001) as a model system. Electronic properties of these surfaces are tuned by changing the S coverage, while keeping a high-quality interface, free of defects and with a constant doping density. In contrast to earlier studies we show that the Poisson-Schr\"{o}dinger scheme predicts the 2DEG bands energies correctly but it is indispensable to take into account the existence of the physical surface. The surface substantially influences the band energies beyond simple electrostatics, by setting nontrivial boundary conditions for 2DEG wavefunctions.Comment: 9 pages, 7 figures, 2 table

    Analysis of instagram¬ģ posts referring to cleft lip

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    Background: Social media has become a source of medical information. Cleft lip and palate is a visible congenital anomaly. The aim of the study was to analyze Instagram¬ģ posts on the topic of cleft lip. Methods: Instagram¬ģ posts with ‚Äú#cleftlip‚ÄĚ from March 2014‚ÄďMarch 2017 were accessed. Separate lists of expressions (hashtags, meaningful words, words with emojis or emojis alone) were prepared for primary posts and for replies. Thirty expressions statistically most frequent in primary versus secondary posts and 30 in secondary versus primary posts were identified (Group 1) as well as 30 English words or hashtags (Group 2), non-English words or hashtags (Group 3) and emojis (Group 4). The frequencies of expressions were compared (Z-test for the difference of two population proportions). Results: There were 34,129 posts, (5427 primary posts and 28,702 replies), containing 62,163 expressions, (35,004 in primary posts). The occurrence of all expressions was 454,162, (225,418 in primary posts and 228,744 in replies). Posts with positive expressions such as ‚Äúbeautiful‚ÄĚ, ‚Äúlove‚ÄĚ, ‚Äúcute‚ÄĚ, ‚Äúgreat‚ÄĚ, ‚Äúawesome‚ÄĚ occurred more often than these with negative ones. In replies all emojis were positive. Conclusions: Numerous Instagram¬ģ posts referring to cleft lip are published and do provoke discussion. People express their solidarity and sympathize with persons affected by cleft

    Distributed low voltage power supply system for front end electronics of the TRT detector in ATLAS experiment

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    We present a low voltage power supply system which has to deliver to the front end electronics of the ATLAS TRT detector [1] ca. 23 kW of electrical power over the distance of 55 -106 m (which adds another 24 kW). The system has to operate in magnetic field and under radiation environment of the LHC experimental cavern. The system has ~ 3000 individual channels which are all monitored and controlled (voltage and current measurement). The hardware solutions are described as well as the system control software

    Knowledge of emergency management of avulsed teeth among Italian dentists-questionnaire study and next future perspectives

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    (1) Background: In Italy, about one fourth of all schoolchildren experience a trauma to the permanent dentition. Management of avulsion trauma is challenging and requires adherence to clinical protocols. The aim of this study was to investigate the management knowledge of avulsed teeth among Italian dentists and to promote the guidelines‚Äô dissemination through the use of new social media. (2) Methods: The survey was carried out during the COVID-19 lockdown in Italy (March‚ÄďMay 2020). The questionnaire was sent anonymously to a total of 600 dentists. The questionnaire consisted of two parts. Part A‚ÄĒdemographic and professional data and Part B‚ÄĒmanagement of traumatic avulsion. (3) Results: The response rate was 50.6% and the mean fraction of correct responses was 0.524. Issues related to the therapeutic management of avulsed teeth were shown to be not well understood by the respondents. Professionals with qualifications in dentistry and those who declared to know the guidelines responded better, while other demographic and professional factors were insignificant. (4) Conclusions: Italian dentists‚Äô knowledge of the management of avulsion trauma should be improved. Educational programs and campaigns must be undertaken to improve their awareness and adherence to the Italian and international guidelines

    Determination and haemolytic activity of saponins in hairy root culture of Platycodon grandiforum A.DC

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    S u m m a r y The sum of saponins in the hairy root lines (6, 17) of Platycodon grandiforum A.DC. was compared. Hairy root line 6 showed a higher total saponin content (6.92%) than the line 17 (6.01%). According to the Chinese Pharmacopoeia standards the content of saponins in Platycodi Radix should be not less than 2%. Our results seem to indicate that the hairy root culture of Platycodon grandiforum A.DC. is a good source of saponins. The Haemolytic 104 N. UrbaŇĄska, J. Nartowska, A. Skorupska, D. Ruszkowski, J. GiebuŇātowicz, O. Olszowska Index of the hairy root line 6 was 1600. Digitonin was used as a reference. Moreover, the haemolytic activity of TLC subfractions of saponins varied

    Conductance spectra of (Nb, Pb, In)/NbP -- superconductor/Weyl semimetal junctions

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    The possibility of inducing superconductivity in type-I Weyl semimetal through coupling its surface to a superconductor was investigated. A single crystal of NbP, grown by chemical vapor transport method, was carefully characterized by XRD, EDX, SEM, ARPES techniques and by electron transport measurements. The mobility spectrum of the carriers was determined. For the studies of interface transmission, the (001) surface of the crystal was covered by several hundred nm thick metallic layers of either Pb, or Nb, or In. DC current-voltage characteristics and AC differential conductance through the interfaces as a function of the DC bias were investigated. When the metals become superconducting, all three types of junctions show conductance increase, pointing out the Andreev reflection as a prevalent contribution to the subgap conductance. In the case of Pb-NbP and Nb-NbP junctions, the effect is satisfactorily described by modified Blonder-Tinkham-Klapwijk model. The absolute value of the conductance is much smaller than that for the bulk crystal, indicating that the transmission occurs through only a small part of the contact area. An opposite situation occurs in In-NbP junction, where the conductance at the peak reaches the bulk value indicating that almost whole contact area is transmitting and, additionally, a superconducting proximity phase is formed in the material. We interpret this as a result of indium diffusion into NbP, where the metal atoms penetrate the surface barrier and form very transparent superconductor-Weyl semimetal contact inside. However, further diffusion occurring already at room temperature leads to degradation of the effect, so it is observed only in the pristine structures. Despite of this, our observation directly demonstrates possibility of inducing superconductivity in a type-I Weyl semimetal.Comment: Accepted for Phys. Rev. B. 13 pages, 12 figures. Second version with major revisions. The title was changed. One author R. Jakiela added. New inset to Fig. 8(A). New fits in Fig. 8 (B) and Fig. 10 (B). Added figures 12 (C)-(E). Added Fig. 12 (F) with SIMS data. Rewritten chapters III-C-2 and III-C-3. Reference no. 38 removed, 11 new references: 9, 21, 22, 40-44, 46-49 were adde

    Identification and quantitative determination of pinoresinol in Taxus √ómedia Rehder needles, cell suspension and shoot cultures

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    The aim of our study was to investigate the presence and quantitative contents of lignans in the tissues of Taxus √ómedia. The presence of the lignans: pinoresinol, matairesinol and secoisolariciresinol was assessed in needles, shoots cultures and suspension culture. Pinoresinol was the only lignan found in the tissue of T. √ómedia. The total pinoresinol content in the needles and in the shoots was 1.24 mg/g dry weight (dw) and 0.69 mg/g dw, respectively. Most of the pinoresinol identified was appeared glycosidically bound. In needles, the amount of glycosidically bound pinoresinol (0.81 mg/g dw) was about twice as high as that of free pinoresinol (0.43 mg/g dw). The content of free and glycosidically bound pinoresinol showed the level of 0.18 mg/g dw and 0.51 mg/g dw, respectively in the in vitro shoot cultures. In the cell culture, no pinoresinol was found

    Fluorocarbon evaporative cooling developments for the ATLAS pixel and semiconductor tracking detectors

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    Heat transfer coefficients 2-5.103 Wm-2K-1 have been measured in a 3.6 mm I.D. heated tube dissipating 100 Watts - close to the full equivalent power (~110 W) of a barrel SCT detector "stave" - over a range of power dissipations and mass flows in the above fluids. Aspects of full-scale evaporative cooling circulator design for the ATLAS experiment are discussed, together with plans for future development

    Single hadron response measurement and calorimeter jet energy scale uncertainty with the ATLAS detector at the LHC

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    The uncertainty on the calorimeter energy response to jets of particles is derived for the ATLAS experiment at the Large Hadron Collider (LHC). First, the calorimeter response to single isolated charged hadrons is measured and compared to the Monte Carlo simulation using proton-proton collisions at centre-of-mass energies of sqrt(s) = 900 GeV and 7 TeV collected during 2009 and 2010. Then, using the decay of K_s and Lambda particles, the calorimeter response to specific types of particles (positively and negatively charged pions, protons, and anti-protons) is measured and compared to the Monte Carlo predictions. Finally, the jet energy scale uncertainty is determined by propagating the response uncertainty for single charged and neutral particles to jets. The response uncertainty is 2-5% for central isolated hadrons and 1-3% for the final calorimeter jet energy scale.Comment: 24 pages plus author list (36 pages total), 23 figures, 1 table, submitted to European Physical Journal

    Measurement of the cross-section and charge asymmetry of WW bosons produced in proton-proton collisions at s=8\sqrt{s}=8 TeV with the ATLAS detector