Anomalous Channels Research Articles

Robust Majorana bound states in magnetic topological insulator nanoribbons with fragile chiral edge channels

Magnetic topological insulators in the quantum anomalous Hall regime host ballistic chiral edge channels. When proximitized by an s-wave superconductor, these edge states offer the potential for realizing topological superconductivity and Majorana bound states without the detrimental effect of large externally applied magnetic fields on superconductivity. Realizing well-separated unpaired Majorana bound states requires magnetic topological insulator ribbons with a width of the order of the transverse extent of the edge state, however, which is expected to bring the required ribbon width down to around 100nm. In this regime, it is known to be extremely difficult to retain the ballistic nature of chiral edge channels and realize a quantized Hall conductance. In this paper, we study the impact of disorder in such magnetic topological insulator nanoribbons and compare the fragility of ballistic chiral edge channels with the stability of Majorana bound states when the ribbon is covered by a superconducting film. We find that the Majorana bound states exhibit greater robustness against disorder than the underlying chiral edge channels. Published by the American Physical Society 2024

Topological mechanics beyond wave dynamics

Topological phases of matter, originally derived from condensed matter physics, have been extensively exploited in photonics and phononics, and recently in mechanical metamaterial systems. Topological mechanics mainly aims at the anomalous edge channels of wave propagation in mechanical metamaterials that has potential applications like a one-way robust waveguide. However, most studies on topological mechanics focus on wave-based dynamics. Here, a novel class of static topology in one and two dimensions beyond wave dynamics is presented, via the static Rayleigh deformation mode in delicately designed two- and three-dimensional mechanical metamaterials. It is shown that the topological properties that are usually presented in dynamic systems, such as the topological invariants and bulk-edge correspondence, are also available in the static systems. It is demonstrated analytically and experimentally that for topologically protected zero modes, externally applied boundary loads can be fully blocked from penetrating the bulk, showing the effect of deformation shielding. Moreover, high-order topological corner states and valley Hall effects are also explored with the proposed prototypical mechanical metamaterials. This study generalizes the concepts of topological mechanics beyond frequency-based wave dynamics.

Reservoir characteristics and light hydrocarbon channeling revealed by production data: A case study of liquid rich Duvernay shale play with emphasis in Fox Creek area, Alberta Canada

This paper reports the findings on the major factors affecting the hydrocarbon productivity and ultimate resource recovery from the liquid-rich Duvernay Shale play in the Fox Creek area. Essential drilling and completion parameters, production rate, estimated ultimate reserves from monthly production time series and key geological variables were mapped and combined with statistical data analysis to reveal their spatial variation and statistical relationships among these parameters and variables. We found that fluid type of the hydrocarbons in shales is essential for hydrocarbon productivity and estimated ultimate recovery (EUR) in this area. Although production rate and EUR are proportional to measures of hydraulic treatment, not all the completion parameters are equally effective in enhancing productivity and recovery. Fracking water volume seems to boost productivity and recovery the most. Parameters from organic geochemistry and geology are essential for mapping the boundary of the resource play, and determining the hydrocarbon fluid types and their spatial variations. And high positive correlation of HCPV with monthly average production rate and EUR indicates the importance of those geological factors for the productivity and ultimate recovery of the study area. Gas-to-oil ratio (GOR) mapping from produced fluids in the first 12 months reveals high anomalous GOR channels or linear zones in low maturity areas that are inconsistent with thermal maturity trends spatially, indicating intra-formation migration of hydrocarbon fluids in the source rock along permeable networks. Major earthquake swarms induced by hydraulic fracturing appear to be associated with crossing formation faults, and are spatially coincident with reduced productivity and ultimate recovery in de-pressured reservoir spot. These findings provide insights to better understand the distribution of production sweet spots and for production optimization strategies to facilitate a low carbon energy transition.

Molecular Communication With Passive Receivers in Anomalous Diffusion Channels

We consider anomalous diffusion for molecular communication with a passive receiver. We first consider the probability density function of molecules’ location at a given time in a space of arbitrary dimension. The expected number of observed molecules inside a receptor space of the receiver at certain time is derived taking into account the life expectancy of the molecules. In addition, an implicit solution for the time that maximizes the expected number of observed molecules is obtained in terms of Fox’s <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$H$ </tex-math></inline-formula> -function. The closed-form expressions for the bit error rate of a single-bit interval transmission and a multi-bit interval transmission are derived. It is shown that lifetime limited molecules can reduce the inter-symbol interference while also enhancing the reliability of MC systems at a suitable observation time.

Manipulation of visible-light polarization with dendritic cell-cluster metasurfaces

Cross-polarization conversion plays an important role in visible light manipulation. Metasurface with asymmetric structure can be used to achieve polarization conversion of linearly polarized light. Based on this, we design a quasi-periodic dendritic metasurface model composed of asymmetric dendritic cells. The simulation indicates that the asymmetric dendritic structure can vertically rotate the polarization direction of the linear polarization wave in visible light. Silver dendritic cell-cluster metasurface samples were prepared by the bottom-up electrochemical deposition. It experimentally proved that they could realize the cross - polarization conversion in visible light. Cross-polarized propagating light is deflected into anomalous refraction channels. Dendritic cell-cluster metasurface with asymmetric quasi-periodic structure conveys significance in cross-polarization conversion research and features extensive practical application prospect and development potential.

PIEZO2 as the anomalous mechanotransducer channel in auditory hair cells.

Throughout postnatal maturation of the mouse inner ear, cochlear hair cells display at least two types of mechanically gated ion channel: normal mechanotransducer (MT) channels at the tips of the stereocilia, activated by tension in interciliary tip links, and anomalous mechanosensitive (MS) channels on the top surface of the cells. The anomalous MS channels are responsible for the reverse‐polarity current that appears in mutants in which normal transduction is lost. They are also seen in wild‐type hair cells around birth, appearing 2 days earlier than normal MT channels, and being down‐regulated with the emergence of the normal channels. We review the evidence that the normal and anomalous channels are distinct channel types, which includes differences in localization, susceptibility to pharmacological agents, single‐channel conductance and Ca2+ permeability. The dichotomy is reinforced by the observation that the anomalous current is absent in cochlear cells of Piezo2‐null mice, even though the normal MT current persists. The anomalous current is suppressed by high intracellular Ca2+, suggesting that influx of the divalent ion via more Ca2+‐permeable normal MT channels inhibits the anomalous channels, thus explaining the temporal relationship between the two. Piezo2‐null mice have largely normal hearing, exhibiting up to 20 dB elevation in threshold in the acoustic brainstem response, so raising questions about the significance of PIEZO2 in the cochlea. Since the anomalous current declines with postnatal age, PIEZO2 may contribute to hair cell development, but it does not underlie the normal MT current. Its role in the development of hearing is not understood.

Anomalous Features of Water Vapor Transport during Severe Summer and Early Fall Droughts in Southwest China

Water vapor transport (WVT) is an important element in drought development. In this study, we examined the geographical and vertical anomalies of WVT during severe summer and early fall drought processes and their occurrence, persistence and recovery phases in Southwest China (SWC) by using the method of standardized anomalies (SA) and composite analysis. The SA-based indices of WVT were built up to quantify composited anomalous WVT channels objectively. Essentially, we further explored the synchronous and lagged correlations between drought processes and these channels. Key points and limitations include: (1) Two drought-related WVT channels were geographically identified with composited SA below −0.2, based on the composite of severe drought processes. The Somali channel is characterized by zonally less-than-normal African-Asian continental WVT anomalies originating from Somalia, whereas the IndoChina-Peninsula channel represents meridionally less-than-normal WVT anomalies from the IndoChina-Peninsula; (2) Both geographical and vertical WVT anomalies were intensified and concentrated at the time of drought occurrence, and then weakened and became scattered at drought recovery; (3) Most drought-related WVT anomalies were distinguishable from those of wetter events; (4) The IndoChina-Peninsula channel performs better in correlations with these drought and wetter processes than the Somali channel. Therefore, dynamic and thermodynamic anomalies need to be investigated, which are important for exploring the drought mechanism.

“How to Pronounce Meme.” Three YouTube Channels

Internet anomalies produce data and images beyond any authorship or source. They seem to compute and display the depths and potentials of the net “as such.” Explanations and theories surround and attempt to account for anomalies, from ARGs to NSA recruiting tools. Examining three such anomalous YouTube channels, this essay does not propose a solution but rather maintains the anomalous as the constituent aesthetic and community of the net.

Phase-sensitive transport at a normal metal–superconductor interface close to a Josephson junction

Phase- and voltage bias-sensitive quasiparticle transport at a double $NI{S}_{1}I{S}_{2}$ interface is considered. The barriers $I$ range from tunnel to transparent, and the intermediate region ${S}_{1}$ has a width comparable to the superconducting coherence length. A phase difference $\ensuremath{\varphi}$ is applied to the Josephson junction ${S}_{1}I{S}_{2}$. The normal and Andreev reflections at the $NI{S}_{1}$ interface become $\ensuremath{\varphi}$ sensitive, and transport is governed by interferences within the narrow ${S}_{1}$ region in both the normal and the anomalous channels. The subgap conductance is separately (energy $E$) and (phase $\ensuremath{\varphi}$) symmetric. Above the superconducting gap, the conductance is, in general, not symmetric even if $(E,\ensuremath{\varphi})$ is changed in $(\ensuremath{-}E,\ensuremath{-}\ensuremath{\varphi})$, but the symmetry is restored by averaging Fermi oscillations. The Tomasch oscillations are amplified by the phase difference. The subgap conductance exhibits a resonant structure at the energy of the Andreev bound states (ABSs) of the ${S}_{1}I{S}_{2}$ junction, providing a side spectroscopy of such states. Depending on the relative transparencies of the junctions, the resonance can increase or reduce the conductance, and it can even vanish for $\ensuremath{\varphi}=\ensuremath{\pi}$, featuring total reflection of quasiparticles at $N{S}_{1}$ by the ABS at ${S}_{1}{S}_{2}$.

Effective interactions and fluctuation effects in spin-singlet superfluids

We derive and evaluate one-loop functional flow equations for the effective interactions, self-energy, and gap function in spin-singlet superfluids. The flow is generated by a fermionic frequency cutoff, which is supplemented by an external pairing field to treat divergencies associated with the Goldstone boson. To parametrize the singular momentum and frequency dependencies of the effective interactions, the Nambu interaction vertex is decomposed in charge, magnetic, and normal and anomalous pairing channels. The one-loop flow solves reduced (mean-field) models for superfluidity exactly, and captures also important fluctuation effects. The Ward identity from charge conservation is generally violated, but can be enforced by projecting the flow. Applying the general formalism to the two-dimensional attractive Hubbard model, we obtain detailed results on the momentum and frequency dependencies of the effective interactions for weak and moderate bare interactions. The gap is reduced by fluctuations, with a stronger reduction at weaker interactions, as expected.

Bilateral Mediastinal Lymphangiohemangiomas Containing Anomalous Venous Components - A case report -

Lymphangiohemangiomas of the mediastinum are exceedingly rare and few cases have been published in the English literature. This report may be the only reported case in which lymphangiohemangiomas were found bilaterally. We report a case of a 7-year-old boy with an incidental finding of an abnormal mediastinal shadow on a chest X-ray. The chest CT showed a large mass in the left superior mediastinum and another in the right posterior mediastinum. The left mass had anomalous venous channels connected to the left innominate vein, and the right mass to the left atrium. We performed an excision of the mass in the left side first and then the right side one month later. Anomalous venous channels were dissected carefully and ligated. There were no complications and no signs of recurrence 30 months after the operation.

Renal lymphangiomatosis, interrupted IVC with persistent primitive hepatic venous plexus and multiple anomalous venous channels: parts of an overlap syndrome?

A 5-year-old girl with cutis marmorata telangiectasia congenita (CMTC) and congenital glaucoma, who had previously presented with seizures, transient hemiplegia, upper gastrointestinal bleeding and hemihypertrophy, developed a large pleural effusion. Subsequent imaging revealed renal lymphangiomatosis, multiple anomalous intra-abdominal venous channels, an interrupted inferior vena cava with a persistent primitive hepatic venous plexus (PPHVP) and meningeal angiomas. To the best of our knowledge, the CT findings of PPHVP and the combination of the demonstrated abnormalities have not been previously reported. They may represent an overlap syndrome of CMTC, Sturge-Weber syndrome and Klippel-Trenaunay syndrome. The complexity and degree of overlap highlights the importance of an accurate clinical and anatomical description and good communication among clinicians.

Intravitreal ranibizumab, photodynamic therapy, and vitreous surgery for the treatment of juxtapapillary retinal capillary hemangioma

Dear Editor, Retinal capillary hemangiomas (RCH) are capillary angiomatous hamartomas of the retina and optic nerve head. The median age of diagnosing the disease is 31 years old [1]. Although most RCH is isolated, 10–30% in the 31–40 age group are associated with Von Hippel Lindau disease (VHL). Up to 15% of RCHs are juxtapapillary, where most are located temporally [2]. They are often associated with epiretinal membrane (ERM) formation and serous and tractional retinal detachment of the macula, which leads to a poor prognosis [1]. We report a typical case of isolated juxtapapillary RCH that underwent successful combined therapy with intravitreal ranibizumab injection and photodynamic therapy (PDT) 1 week before PPV and ERM peeling surgery. A 32-year-old woman presented with reduced right eye vision and metamorphopsia for 3 months. At presentation, her best-corrected visual acuity was 20/50 and 20/25 for the right and left eyes, respectively. Right eye fundus examination revealed a reddish mass measuring 2.0 × 1.5 mm in the inferotemporal juxtapapillary region associated with macular subretinal fluid and ERM (Fig. 1a). Fig. 1 Imaging results (color fundus photography, FFA and OCT) of the patient at initial presentation. a Fundus photograph of the right eye showing juxtapapillary retinal capillary hemangioma, measured 2.0 × 1.5 mm, located inferotemporal ... Fundus fluorescein angiogram (FFA) showed early filling of the lesion with late leakage into the subretinal space. Anomalous vascular channels were seen sprouting from the lesion (Fig. 1b). Optical coherence tomography (OCT) confirmed serous detachment of the macula with vitreomacular traction (Fig. 1c). Central foveal thickness was increased to 570 µm (normal values = < 315 µm) [3]. A diagnosis of juxtapapillary retinal capillary hemangioma was made. Systemic workup for Von Hippel Lindau (VHL) disease did not reveal any other tumors. Her visual acuity continued to deteriorate to 20/100 in the subsequent 2 months. She was treated once with PDT using standard fluence at that time, with reduced diameter laser spot centering on the lesion avoiding the optic disc. There was no clinical response and her vision continued to deteriorate to 20/200 3 months after the initial PDT. Combined therapy, using standard fluence PDT and intravitreal injection of ranibizumab were performed 2 months later (7 months since presentation). Reduction of lesion size (1.5 × 1.5 mm) and vascularity was noted 1 day after the combined therapy (Fig. 2a). One week later, PPV and ERM peel were carried out and intravitreal triamcinolone injection (2 mg in 0.05 ml) was given at the conclusion of surgery. Fig. 2 Imaging results (color fundus photography and FFA) of the patient after combined treatment with injection of ranibizumab, PDT, and intravitreal surgery. a Day 1 after combined intravitreal ranibizumab injection and PDT, showing regression of the tumor ... The patient's visual acuity improved to 20/25 after successful surgery and the lesion remained stable for 12 months, up to the latest follow-up (Fig. 2b). The central foveal thickness remained reduced within normal limits at 324 μm. FFA showed hyperfluorescence in the late phase (Fig. 2c). A small superotemporal branch retinal vein occlusion developed secondary to an iatrogenic break resolved spontaneously.

Frequency and phenotypes of cutaneous vascular malformations in a consecutive series of 417 patients with familial cerebral cavernous malformations

Familial cerebral cavernous malformations (FCCM) are vascular malformations inherited as an autosomal-dominant condition. Three genes (KRIT1/CCM1, MGC4607/CCM2, PDCD10/CCM3) have been identified so far. Extra-neurological manifestations include retinal and cutaneous vascular malformations. The cutaneous vascular malformation, which had been more specifically associated with FCCM, is hyperkeratotic cutaneous capillary venous malformation (HCCVM). To define the frequency of cutaneous vascular malformations in patients with FCCM, to precise their different phenotypes, and to study the association of each cutaneous vascular malformation subtype with the different three mutated CCM genes. Dermatological inquiry was systematically performed in a large series of consecutive FCCM patients. Cutaneous biopsies were reviewed when available. Cutaneous vascular malformations classification was based on predominant anomalous channels, using the current International Society for the Study of Vascular Anomalies classification. Molecular screening of CCM genes was performed. Results Four hundred seventeen consecutive FCCM patients from 182 unrelated families were included. 38 patients (9%) from 25 different families had cutaneous vascular malformations. In these 38 patients, cutaneous vascular malformations were classified as follows: 13 capillary malformations (CM), 15 HCCVM, 8 venous malformations (VM) and 2 unclassified lesions. All patients (92%), but one with CM had a KRIT1/CCM1 mutation. The last patient had no detectable mutation. All of the 15 patients with HCCVM had a KRIT1/CCM1 mutation; 86.7% of cutaneous vascular malformation patients (33 of 38) had a KRIT1/CCM1 mutation. Cutaneous vascular malformations are seen in 9% of FCCM patients. Three distinct major cutaneous vascular malformations phenotypes were identified: HCCVM (39%), CM (34%) and VM (21%). CCM1 is the most frequently mutated gene in cutaneous vascular malformations-FCCM patients.

Expediting the Identification of Impaired Channels in Cochlear Implants Via Analysis of Speech-Based Confusion Matrices

There is significant variability in the benefit provided by cochlear implants to severely deafened individuals. The reasons why some subjects exhibit low speech recognition scores are unknown; however, underlying physiological or psychophysical factors may be involved. Certain phenomena, such as indiscriminable electrodes and nonmonotonic pitch rankings, might hint at limitations in the ability of individual channels in the cochlear implant and/or sensorineural pathway to convey speech information. In this paper, four approaches for analyzing the results of a simple listening test using speech stimuli are investigated for the purpose of targeting channels of concern in order for follow-on psychophysical experiments to correctly identify channels performing in an "impaired" or anomalous manner. Listening tests were first conducted with normal-hearing subjects and acoustic models simulating channel-specific anomalies. Results indicate that these proposed analyses perform significantly better than chance in providing information about the location of anomalous channels. Vowel and consonant confusion matrices from six cochlear implant subjects were also analyzed to test the robustness of the proposed analyses to variability intrinsic to cochlear implant data. The current study suggests that confusion matrix analyses have the potential to expedite the identification of impaired channels by providing preliminary information prior to exhaustive psychophysical testing.

Tunneling through the Quantum Dot Coupled to Incoherent Superconductor

There have been done numerous theoretical and experimental studies of the quantum dot (QD) at an interface with the superconducting leads [1–6]. Such issue is of a fundamental as well as practical importance and covers a rich area of the physical aspects. It resembles, in principle, the case of a quantum impurity (here understood as some finite system of a discrete energy spectrum) interacting with a sea of the conduction band electrons. Impurities are usually known to have a detrimental effect on the superconducting state (except nonmagnetic impurities weakly interacting with s-wave superconductors). In a configuration of the single electron transistor, where QD serves as a charge and energy transmitter between the external electrodes, this issue becomes even more challenging. If one or both electrodes are superconducting then one needs to establish rather the opposite relation, i.e. of superconductor on the impurity itself. This effect is crucial for the transport properties because the charge and energy currents are very sensitive to energy spectrum of the QD. According to a general description of the tunneling [7] it has been found that besides the ordinary single electron current there can arise additional contributions from the anomalous channels. They are activated whenever junctions involve the superconducting lead(s) where the particle and hole excitations are mixed with

Three-dimensional finite-element model of the ion Bernstein wave antenna and excitation of coaxial electrostatic edge modes in the tokamak fusion test reactor

Externally launched ion Bernstein wave (IBW) experiments have demonstrated localized electron heating, sheared flows and transport barriers in several tokamaks. Experiments in the tokamak fusion test reactor (TFTR) showed that IBW waves launched from low-field side IBW antennas could drive a velocity shear layer in the central plasma, but the power coupled to the IBW was not sufficient to achieve a transport barrier. This experiment raised important questions concerning where the radio-frequency (rf) power went and whether the anomalous loss channels are more important in larger machines. Recently, it was proposed that the power loss was due to a coaxial electron plasma wave (EPW) mode excited in the low density plasma halo near the vessel wall (Myra et al 2000 Phys. Plasmas 7 283). This mode could dissipate a significant power fraction by sheath and collisional mechanisms, fits more easily in larger machines like TFTR and has the phasing dependence observed in the experiments. Here we extend that work by demonstrating the existence and phasing dependence of the coaxial mode (CM) in a realistic rf coupling calculation. A three-dimensional finite-element electromagnetic code couples a detailed model of the antenna geometry with a plasma dielectric model that retains CM physics. Quantitative results show the dependence of the CM rf fields and power dissipation on the phasing of the multiple-strap array. Unlike conventional rf coupling codes, this paper enables the antenna limiters to be immersed in tenuous plasma, an important feature for correctly modelling parasitic coupling to the CM.

Anomalous L-type calcium channels of rat spinal motoneurons.

Single channel patch-clamp recordings show that embryonic rat spinal motoneurons express anomalous L-type calcium channels, which reopen upon repolarization to resting potentials, displaying both short and long reopenings. The probability of reopening increases with increasing voltage of the preceding depolarization without any apparent correlation with inactivation during the depolarization. The probability of long with respect to short reopenings increases with increasing length of the depolarization, with little change in the total number of reopenings and in their delay. With less negative repolarization voltages, the delay increases, while the mean duration of both short and long reopenings decreases, remaining longer than that of the openings during the preceding depolarization. Open times decrease with increasing voltage in the range -60 to +40 mV. Closed times tend to increase at V > 20 mV. The open probability is low at all voltages and has an anomalous bell-shaped voltage dependence. We provide evidence that short and long reopenings of anomalous L-type channels correspond to two gating modes, whose relative probability depends on voltage. Positive voltages favor both the transition from a short-opening to a long-opening mode and the occupancy of a closed state outside the activation pathway within each mode from which the channel reopens upon repolarization. The voltage dependence of the probability of reopenings reflects the voltage dependence of the occupancy of these closed states, while the relative probability of long with respect to short reopenings reflects the voltage dependence of the equilibrium between modes. The anomalous gating persists after patch excision, and therefore our data rule out voltage-dependent block by diffusible ions as the basis for the anomalous gating and imply that a diffusible cytosolic factor is not necessary for voltage-dependent potentiation of anomalous L-type channels.

Brachiocephalic Vein Dilatation

In infancy, total anomalous pulmonary venous return above the diaphragm and congenital cerebral arteriovenous malformations are difficult to diagnose. To assist in diagnosing these lesions, the brachiocephalic vein (BCV) and transverse arch diameters were obtained and compared, to provide a BCV index, the ratio of the BCV diameter to the transverse arch diameter. Fifty-six infants were studied. Six infants had arteriovenous malformations (mean age, 46 ± 76 days; mean weight, 3.8 ± 1.2 kg). Eight infants had total anomalous pulmonary venous return draining above the diaphragm (mean age, 22 ± 30 days; mean weight, 3.2 ± 0.5 kg). A healthy control group (those without heart disease) consisted of 42 infants (mean age, 23 ± 47 days, mean weight 3.0 ± 1.4kg). There were no significant differences in the age, gender, and weight of these patients versus the controls. An absolute BCV diameter of 0.52 cm and a brachiocephalic vein (BCV/transverse arch) index greater than 1.06 should alert the sonographer to the presence of an arteriovenous malformation or total anomalous pulmonary venous return above the diaphragm. This finding will then permit a greater focus on identifying the course of the anomalous venous channels.

Breakdown of the quantum Hall effect in InAs/AlSb quantum wells due to counterflowing edge channels.

We investigated magnetotransport in the two-dimensional electron gas (2DEG) present in InAs/AlSb quantum wells. The filling factor Ng underneath a gate electrode was reduced relative to the bulk filling factor Nb. For Ng<Nb the resistance at the minima of the Shubnikov–de Haas oscillations failed to vanish, and the corresponding plateaus in the Hall resistance deviated from their expected quantized values Rxy=h/(e2Ng). The results are explained by the presence of anomalous edge channels at the 2DEG boundaries, which flow in opposite direction compared to the regular ones. They result from the band bending due to the combination of Fermi level pinning at the exposed InAs surface and the electrostatic potential generated by the gate electrode. This picture is supported by a comparison between the measured resistances and the resistances calculated with an edge channel model.