Unusual Interference Research Articles

Evidence for time-reversal symmetry-breaking kagome superconductivity.

Superconductivity and magnetism are often antagonistic in quantum matter, although their intertwining has long been considered in frustrated-lattice systems. Here we utilize scanning tunnelling microscopy and muon spin resonance to demonstrate time-reversal symmetry-breaking superconductivity in kagome metal Cs(V, Ta)3Sb5, where the Cooper pairing exhibits magnetism and is modulated by it. In the magnetic channel, we observe spontaneous internal magnetism in a fully gapped superconducting state. Under the perturbation of inverse magnetic fields, we detect a time-reversal asymmetrical interference of Bogoliubov quasi-particles at a circular vector. At this vector, the pairing gap spontaneously modulates, which is distinct from pair density waves occurring at a point vector and consistent with the theoretical proposal of an unusual interference effect under time-reversal symmetry breaking. The correlation between internal magnetism, Bogoliubov quasi-particles and pairing modulation provides a chain of experimental indications for time-reversal symmetry-breaking kagome superconductivity.

Shirking Self-Regulation? Parliamentary Standards in the UK

In 2021, the UK system for regulating the conduct of parliamentarians was briefly plunged into crisis. The government responded to a proposal to sanction one of its MPs—who had been found to have egregiously breached the Code of Conduct and accompanying rules—by threatening to change the whole system. This highly unusual interference by the executive branch, though withdrawn within 24 h, violated the axiom that the executive should not have a say in disciplining members of the legislature because this might compromise parliament’s ability to hold the government to account. Yet the ensuing debate has prompted calls to move the UK system yet further away from self-regulation and grant more powers of oversight to “external” roles and bodies. This article draws on interviews with MPs to analyze whether this longstanding trajectory of reform is in line with how these “rule makers” perceive the system’s flaws. It concludes that, over the years, MPs have to a large extent forfeited the right to regulate their own conduct by repeatedly shirking their responsibilities to regulate themselves effectively. Moreover, the constant focus on “fixing” the procedures for investigating and sanctioning misconduct has crowded out a more constructive discussion about how to promote ethical behavior.

On Dispersion and Multipath Effects in Harmonic Radar Imaging Applications

In harmonic radar applications, images produced using algorithms of conventional radar applications experience some defocusing effects of the electronic targets’ impulse responses. This is typically explained by the dispersive transfer functions of the targets. In addition, it was experimentally observed that objects with a linear transfer behavior do not contribute to the received signal of a harmonic radar measurement. However, some signal contributions based on a multipath propagation can overlay the desired signal, which leads to an undesired and unusual interference caused by the nonlinear character of the electronic targets. Here, motivated by the analysis of measured harmonic radar data, the effects of both phenomena are investigated by theoretical derivations and simulation studies. By analyzing measurement data, we show that the dispersion effects are caused by the target and not by the measurement system or the measurement geometry. To this end, a signal model is developed, with which it is possible to describe both effects, dispersion and multipath propagation. In addition, the discrepancy between classic radar imaging and harmonic radar is analyzed.

Matrix interference in LC-ESI-MS/MS analysis of metanephrines in protein precipitated plasma samples

Metanephrine and normetanephrine are measured in blood plasma to diagnose different diseases. Simpler sample preparation procedures are preferred but tend to yield less purified extracts. Therefore, thorough investigation of matrix effects is required. In this work, several sample preparation methods and chromatographic modes were compared for liquid chromatography tandem mass spectrometric (with electrospray ionization; LC-ESI-MS/MS) analysis of metanephrine and normetanephrine in blood plasma. Protein precipitation with methanol was found to be sufficient for sample preparation and pentafluorophenyl column provided adequate chromatographic separation. A new cheaper and less labor-intensive approach is proposed where necessary quantitation limits are achieved through a sample preparation containing only protein precipitation and dilution of the sample extract. Matrix effects for different sample preparation methods and the use of isotope-labeled internal standards were evaluated. Unusual interference to D3-labeled internal standard of normetanephrine was discovered - signal of interfering compound increased while the matrix effects were reduced by dilution, e.g. dilution eliminates matrix suppression on interfering compound. The results stress the need to monitor interfering compounds and evaluate matrix effects at every step of method development. Matrix effects and interferences can be different for analytes and their corresponding isotopically labeled internal standards. This means that the use of isotopically labeled internal standards cannot guarantee accuracy of obtained results. New method allows quantification of the low nanomolar concentrations of metanephrine and normetanephrine in plasma samples.

A self-assembled, silicone acrylate coating formulation and detection of the optically non-uniform structure with reflectance spectroscopy

A newly synthesized, single-step silicone acrylate formulation cured by conventional radiation produced a reflection spectrum that showed an unusual interference pattern for a single-step coating. The acrylate was prepared by transesterification of silicate oligomer with ω-functionalized acrylic alcohol. The reflectance spectrum was analyzed by means of the Fourier transformation, followed by a separation of variables and constrained conditions. The separation of variables was based on the refractive index as a function of the layer depth, which revealed the coating was non-uniform in refractive index. An interface within the coating was independently observed by microscopy, showing that the coating separated into two layers, supporting the numerical analysis. Although the coating was manufactured by a single-step coating process, the two-layer structure that was formed is normally constructed with multiple coating processes, such as applications of a primer and a top coat. Experiments varying the formulation components show that the new silicone acrylate and an aliphatic di-functional acrylic ester were essential components for the formation of the two-layer structure. Outdoor weathering results are presented after 1 year of testing in Florida and Arizona, which showed better performance than conventional coating systems.

Interferometric imaging of nonlocal electromechanical power transduction in ferroelectric domains

The electrical generation and detection of elastic waves are the foundation for acoustoelectronic and acoustooptic systems. For surface acoustic wave devices, microelectromechanical/nanoelectromechanical systems, and phononic crystals, tailoring the spatial variation of material properties such as piezoelectric and elastic tensors may bring significant improvements to the system performance. Due to the much slower speed of sound than speed of light in solids, it is desirable to study various electroacoustic behaviors at the mesoscopic length scale. In this work, we demonstrate the interferometric imaging of electromechanical power transduction in ferroelectric lithium niobate domain structures by microwave impedance microscopy. In sharp contrast to the traditional standing-wave patterns caused by the superposition of counterpropagating waves, the constructive and destructive fringes in microwave dissipation images exhibit an intriguing one-wavelength periodicity. We show that such unusual interference patterns, which are fundamentally different from the acoustic displacement fields, stem from the nonlocal interaction between electric fields and elastic waves. The results are corroborated by numerical simulations taking into account the sign reversal of piezoelectric tensor in oppositely polarized domains. Our work paves ways to probe nanoscale electroacoustic phenomena in complex structures by near-field electromagnetic imaging.

Negative Full Counting Statistics Arise from Interference Effects.

The Keldysh-ordered full counting statistics is a quasiprobability distribution describing the fluctuations of a time-integrated quantum observable. While it is well known that this distribution can fail to be positive, the interpretation and origin of this negativity has been somewhat unclear. Here, we show how the full counting statistics can be tied to trajectories through Hilbert space, and how this directly connects negative quasiprobabilities to an unusual interference effect. Our findings are illustrated with the example of energy fluctuations in a driven bosonic resonator; we discuss how negative quasiprobability here could be detected experimentally using superconducting microwave circuits.

Effectiveness and Desirability of Private Higher Education in Nigeria

The influx of the establishment of private higher educational institutions in Nigeria since the inception of the present democratic dispensation in 1999 is unprecedented. Their effectiveness compared to public institutions is the focus of this paper. Content analysis method was used in this study and the focus was on private universities. Most of these private institutions were established purely for business motives as costs are beyond many Nigerians. The shortcomings in respect of dearth of qualified personnel and infrastructural facilities are more pronounced in these institutions. The unusual interferences of proprietors were common in academic affairs and academic freedom is nonexistent. The fear of the public in respect of acceptability and performance of the outputs to the challenges of graduate unemployment is being allayed by the outstanding performances of some of these graduates in open competitive labour markets. The regulatory and supervisory organs for universities should properly monitor these institutions in order not to turn them to either glorified secondary schools or intellectual prison yards. These private institutions should concentrate on courses that can address the challenges of the time as the liberalisation of higher education will go a long way to ameliorate the social welfare of the citizens like what is being witnessed in the telecommunication industry. DOI: 10.5901/jesr.2015.v5n1p151

An unusual interference in CK MB assay caused by a macro enzyme creatine phosphokinase (CK) type 2 in HIV-infected patients

Article An unusual interference in CK MB assay caused by a macro enzyme creatine phosphokinase (CK) type 2 in HIV-infected patients was published on February 1, 2013 in the journal Clinical Chemistry and Laboratory Medicine (CCLM) (volume 51, issue 2).

Determination of manganese and zinc in coastal waters by anodic stripping voltammetry with a vibrating gold microwire electrode

Environmental contextMetals in the marine environment play a role in biological processes but can also be toxic. An electrochemical method with a simple microwire electrode is presented that facilitates detection of zinc and manganese in coastal waters. The method is very sensitive and will likely lead to the development of an in-situ monitoring apparatus. AbstractA vibrating, gold, microwire electrode (VGME) is used here to detect low nanomolar levels of dissolved Mn by anodic stripping chronopotentiometry (ASC) and sub-nanomolar levels of dissolved Zn by anodic stripping voltammetry (ASV) in seawater. Mn is detected using a deposition potential (Edep) of –1.35 V, and Zn using Edep = –0.9 V, at pH 8. The method is an example of under-potential deposition (UPD), with positive shifts of the metal oxidation potentials of 0.4–0.6 V compared to the mercury electrode. The limits of detection for Mn (1.4 nM) and for Zn (0.3 nM) in seawater with a 300-s plating time, are better than achieved using other non-mercury based electrodes and nearly as good as a mercury film electrode for Zn. The detection of sub-nanomolar Mn is subject to an unusual interference by arsenate, which lowers the sensitivity when the deposition time is extended beyond 300 s. The VGME has advantages related to robustness, stability and ease of use (no polishing, simple regeneration) facilitating on-site and in-situ use. Zn and Mn are readily measured in seawater of natural pH without the need for reagents, facilitating use of this method in a system for in-situ monitoring. The methods are applied here to coastal seawater (Liverpool Bay, Irish Sea) and can be used for freshwaters such as river water.

An unusual interference in parathormone assay caused by anti-goat IgG: a case report

We report the case of a 29-year-old woman, working as a nurse, who underwent a blood analysis to monitor hypothyroidism. In addition to the ‘‘classical’’ parameters, her physician ordered a parathormone (PTH) determination. The result of the PTH test was found to be )2000 pg/mL (normal range: 12–54 pg/mL) with the Liaison analyser (Diasorin, Stillwater, MN, USA). As recently published (1), we considered this result as ‘‘spurious’’ and we treated the sample with HBR 1 (Scantibodies, Santee, CA, USA) and RF-Absorbent (IBL, Hamburg, Germany) to remove a possible interference due to human anti-animal antibodies (HAAA) and rheumatoid factor (RF), respectively. We also determined PTH with another method (Roche Elecsys, Mannheim, Germany). We observed that the result remained unchanged after HBR treatment, whereas PTH dramatically fell to 40 pg/mL after anti-RF treatment. With the Elecsys analyser, the PTH was also normal (24 pg/mL). We thus suspected an interference due to RF, but the patient neither suffered from rheumatoid arthritis (and other autoimmune diseases), nor was positive when we tested for RF (BN2, Siemens, Marburg, Germany). To explore the cause of this interference with the Liaison analyser, we then performed a chromatographic separation with a Superdex 200 HR 10/30 column (Amersham Biosciences, Piscataway, NJ, USA) and we concluded that there was PTH reactivity in the fraction that corresponded to the molecular weight of the IgGs. This confirmed the results of the RF-Absorbent treatment, which, indeed, is a treatment of the sample with antiIgG antibody. As the antibodies used for the PTH Liaison analyser are polyclonal goat antibodies (whereas Roche Elecsys use monoclonal mouse antibodies), we suspected that there was anti-goat IgG present in the serum of the patient that could interfere with the assay. To confirm this hypothesis, we incubated 400 mL of the patient’s serum with 40 mL of goat serum. In this condition, we observed that PTH dropped from )2000 to 41 pg/mL. Human anti-animal antibodies are a known cause of interferences in immunoassays (2). This patient had no obvious reason to present anti-goat antibodies (any animal contact, professional exposition, coeliac disease, drug, vaccination or blood transfusion). She did not eat goat’s cheese or drink milk. A possible cause could be a pregnancy 3 years prior, even if she was primiparous (3). Even if the manufacturers include in the inserts of the kits that this type of interference remains possible, one should be careful when interpreting the results of any immunoassay. We must keep in mind the tragic outcomes that can be observed with these interferences (4). Indeed, these antibodies can give spurious results, leading to unnecessary cost-effective and stressful extra investigations. Conflict of interest: None.

High-Resolution Mode-Spacing Measurement of the Blue-Violet Diode Laser Using Interference of Felds Created with Time Delays Greater than the Coherence Time

It is observed that the multi-mode cw blue-violet diode laser exhibits revival of interference when the interferometric path length difference is much greater than the coherence time of the laser and that the recurring interference peaks are separated by the same distance. We report that this unusual interference phenomenon can be used for high-resolution mode spacing measurement of the multi-mode cw blue-violet diode laser without using a high-resolution spectrometer.

Correlation between superconducting critical temperature and normal-state resistivity parameters from the codopedErBa2Cu3−x−yZnxFeyO7−δsystem

The Zn and Fe codoped ${\mathrm{ErBa}}_{2}{\mathrm{Cu}}_{3\ensuremath{-}x\ensuremath{-}y}{\mathrm{Zn}}_{x}{\mathrm{Fe}}_{y}{\mathrm{O}}_{7\ensuremath{-}\ensuremath{\delta}}$ system for $0<~x<~0.45,$ $0<~y<~0.18,$ and $0.02<~\ensuremath{\delta}<~0.21$ has been investigated. Superconducting critical temperature ${T}_{c},$ residual resistivity ${\ensuremath{\rho}}_{0},$ resistivity slope corresponding to the linear \ensuremath{\rho}-T region $(d\ensuremath{\rho}{/dT)}_{\mathrm{cc}},$ and a characteristic temperature where \ensuremath{\rho}-T goes through a minima ${T}_{\mathrm{min}}$ are extracted from resistivity measurements. Interestingly, Zn and Fe in general are found to interfere with each other in determining the values of ${T}_{c},$ ${\ensuremath{\rho}}_{0},$ $(d\ensuremath{\rho}{/dT)}_{\mathrm{cc}},$ and ${T}_{\mathrm{min}}.$ In one particular case of cosubstitution, ${T}_{c}$ is found to enhance. ${T}_{c}$ correlates with ${T}_{\mathrm{min}},$ ${\ensuremath{\rho}}_{0},$ and $(d\ensuremath{\rho}{/dT)}_{\mathrm{cc}}$ such that an increase in the former two parameters tends to degrade ${T}_{c},$ while an increase in the latter tends to enhance it. These observations suggest that pinning of the dynamically fluctuating striped phase due to Zn and Fe is a reasonable source of ${T}_{c}$ suppression in the present system. We further discuss the reasons and possible consequences of the unusual interference effects of Zn and Fe.

Liquid helium, vortices, helices and laser light scattering

Initial consideration of quantized vortices led to a detailed study of light scattering in liquid helium with very high resolution classical instruments and observation of novel spectra. The need for yet higher resolution led in turn to study of time-domain spectroscopy. Precise control of optical wave front and coherence is required in these techniques, and this initiated the discovery of optical vortices with multistart helical cophasal surfaces as demonstrated by unusual interference fringes. Finally the application of such laser scattering techniques has revealed the presence of descending ring vortices in thunderstorm microbursts and has been used to study the powerful wake vortices generated by aircraft.

Retrofit of 22 pipeline pumping stations with 3000-hp motors and variable-frequency drives

Learning experiences encountered on a large variable-frequency induction motor drive installation are reported. The drives were widely dispersed at multiple locations and generally fed from very weak power systems. This paper discusses several different and unusual interferences and power quality issues encountered with different electrical utilities and makes suggestions with respect to specifications, logistics, installation and field measurements for the benefit of future projects.

Unusual interference from primary collection tube in a high‐performance liquid chromatography assay of amiodarone

Unusual interference from primary collection tube in a high‐performance liquid chromatography assay of amiodarone

Unusual interference from primary collection tube in a high-performance liquid chromatography assay of amiodarone

We describe an unusual interference in our routine high-performance liquid chromatography (HPLC) assay of amiodarone and its active metabolite, desethylamiodarone, used to quantify the parent drug and the active metabolite in serum from the primary sample collection tube. The interfering peak had a retention time very similar to that of the authentic desethylamiodarone. Substitution of Corvac tubes with Vacutainer tubes for the collection and transportation of serum samples eliminated the source of interference. We routinely suggest the use of Vacutainer collection tubes for obtaining blood samples of cardiac patients undergoing amiodarone therapy.

Artifact Induced by Roller Pump Tubing on EEG Tracings of Neonatal ECMO Patients

A type of electrical artifact seen on EEG records of neonatal patients supported with Extracorporeal Membrane Oxygenation (ECMO) is described. An analysis of this unusual interference related to roller-pump-driven perfusion systems leads to the suggestion that the piezoelectric properties of polyvinyl chloride (PVC) tubing in conjunction with roller action is the source of this artifact. The phenomenon has previously been documented, but not fully explained. The investigators offer practical solutions for eliminating the effects of this electrical noise in the clinical setting.

Gibbon ape leukemia virus and the amphotropic murine leukemia virus 4070A exhibit an unusual interference pattern on E36 Chinese hamster cells

The gibbon ape leukemia virus (GaLV), the amphotropic mouse leukemia virus (A-MLV) 4070A, and the xenotropic mouse leukemia virus (X-MLV) exhibit wide but not identical species host ranges. However, most Chinese hamster cells resist infection by all three viruses. We have now determined that the Chinese hamster cell line E36 differs from other Chinese hamster cell lines in that it is susceptible to infection by wild-type GaLV, A-MLV, and X-MLV. Surprisingly, analysis of the interference pattern of GaLV and A-MLV in E36 cells indicated that GaLV and A-MLV interfere in a nonreciprocal fashion. E36 cells productively infected with GaLV were resistant to superinfection by both GaLV and amphotropically packaged recombinant retroviral vectors. In contrast, E36 cells infected with A-MLV were resistant to superinfection with an amphotropic vector but could still be infected by a GaLV vector. These results imply the existence of a receptor on E36 cells that interacts with both GaLV and A-MLV.

Resonant tunneling through low dimensional quantum structures

Tunneling mechanism in zero- and one-dimensional quantum structures is studied. Several new results, peculiar to low dimensions, are predicted. We find that subband mixing and multichannel tunneling induce the appearance of new tunneling channels with unusual interference patterns, and allow for longer lifetime of the resonances at higher energies in various channels. It is shown that in low dimensions, there exists a critical size of the structure below which the resonance nature of the tunneling process is diminished. In zero and one dimensions, there exists a critical magnitude of the confinement potential, below which there are no resonances in the transmission function for any size of the well. Negative differential resistance and other phenomena related to the resonance characters of the tunneling will not appear in this case. We also develop a generalized transfer matrix method that takes into account subband mixing; this formalism can be used to describe any transport problem in low dimensions.