Interference Happens Research Articles

Quantum Interference and Selectivity through Biological Ion Channels

The mechanism of selectivity in ion channels is still an open question in biology for more than half a century. Here, we suggest that quantum interference can be a solution to explain the selectivity mechanism in ion channels since interference happens between similar ions through the same size of ion channels. In this paper, we simulate two neighboring ion channels on a cell membrane with the famous double-slit experiment in physics to investigate whether there is any possibility of matter-wave interference of ions via movement through ion channels. Our obtained decoherence timescales indicate that the quantum states of ions can only survive for short times, i.e. ≈100 picoseconds in each channel and ≈17–53 picoseconds outside the channels, giving the result that the quantum interference of ions seems unlikely due to environmental decoherence. However, we discuss our results and raise few points, which increase the possibility of interference.

WLAN interference self‐optimization using som neural networks

SummaryIn order to suppress the interference in local area networks, this paper presents a Wireless Local Area Networks (WLAN) interference self‐optimization method based on a Self‐Organizing Feature Map (SOM) neural network model. This method trains the model by using original data sets as the initial vector set and using the whole Signal to Interference plus Noise Ratio (SINR) vector generated by the change of one Wireless Access Point (AP) channel as the basic feature. After the training, the SOM neural network can quickly locate the fault AP and optimize the network according to the changes of the network environment. Simulation results reveal that the proposed scheme can efficiently locate the AP where interference happens and optimize the interference with an improved user experience. Copyright © 2016 John Wiley & Sons, Ltd.

RGB visible light communication using mobile-phone camera and multi-input multi-output.

Red, green, blue (RGB) light-emitting-diodes (LEDs) are used to increase the visible light communication (VLC) transmission capacity via wavelength-division-multiplexing (WDM), and the color image sensor in mobile phone is used to separate different color signals via a color filter array. However, due to the wide optical bandwidths of the color filters, there is a high spectral overlap among different channels, and a high inter-channel interference (ICI) happens. Here, we propose and demonstrate an RGB VLC transmission using CMOS image sensor with multi-input multi-output (MIMO) technique to mitigate the ICI and retrieve the three independent color channels in the rolling shutter pattern. Data pattern extinction-ratio (ER) enhancement and thresholding are deployed.

Two Improved Normalized Subband Adaptive Filter Algorithms with Good Robustness Against Impulsive Interferences

To improve the robustness of subband adaptive filter (SAF) against impulsive interferences, we propose two modified SAF algorithms with an individual scale function for each subband, which are derived by maximizing correntropy-based cost function and minimizing logarithm-based cost function, respectively, called MCC-SAF and LC-SAF. Whenever the impulsive interference happens, the subband scale functions can sharply drop the step size, which eliminate the influence of outliers on the tap-weight vector update. Therefore, the proposed algorithms are robust against impulsive interferences, and exhibit the faster convergence rate and better tracking capability than the sign SAF (SSAF) algorithm. Besides, in impulse-free interference environments, the proposed algorithms achieve similar convergence performance as the normalized SAF (NSAF) algorithm. Simulation results have demonstrated the performance of our proposed algorithms.

Simultaneous evaluation of two branches of a multifunctional integrated optic chip with an ultra-simple dual-channel configuration

We propose an ultra-simple dual-channel configuration for simultaneously evaluating two branches of a multifunctional integrated optic chip (MFIOC). In the configuration, the MFIOC is employed as a beam splitter to construct the demodulation interferometer together with a 2×2 fiber coupler. Interference happens between polarization modes traveling through different channels of the MFIOC. The cross-couplings of each channel are respectively characterized by the interference peaks which distribute on opposite sides of the central interference peak. Temperature responses of the MFIOC are experimentally measured from −40°C to 80°C. Results show that the proposed configuration can achieve simultaneous dual-channel transient measurements with resolution of −90 dB and dynamic range of 90 dB. In addition, the two channels of the configuration have consistent measuring performance, and the two branches of the MFIOC have different responses to temperature variation.

지면 반사효과를 이용한 비행 궤적 추정에 대한 실험적 연구와 스펙트로그램 및 캡스트로그램 방법 비교

A methodology is proposed to estimate a trajectory of a flying target and its velocity using the time and frequency analysis of the acoustic signal. The measurement of sound emitted from a flying acoustic source with a microphone above a ground shall receive both direct and ground-reflected sound waves. For certain frequency contents, the destructive interference happens in received signal waveform reflected path lengths are in multiple integers of direct path length. This phenomenon is referred to as the acoustical mirror effect and it can be observed in a spectrogram plot. The spectrogram of acoustic measurement for a flying vehicle measurement shows several orders of destructive interference curves. The first or second order of curve is used to find the best approximate path by using nonlinear least-square method. Simulated acoustic signal is generated for the condition of known geometric of a sensor and a source in flight. The estimation based on cepstrogram analysis provides more accurate estimate than spectrogram.

Intrinsic Fabry-Pérot Interferometer Based on Concave Well on Fiber End

miniature fiber-optic Fabry-Perot cavity interferometerA miniature fiber-optic Fabry-Perot cavity interferometer is presented. The interferometer is fabricated at the fiber tip by wet chemical etching using hydrofluoric acid. A concave well is created on the fiber end face. Interference happens between the reflections from the fiber core and the end of the cladding. We demonstrate applications of the interferometric sensor for temperature and gas refractive index sensing.

Effect of Covalent Fluorescence Labeling of Plasmid DNA on Its Intracellular Processing and Transfection with Lipid-Based Carriers

The development of biotechnological pharmaceutics, like macro- and nanocarriers, can benefit greatly from studying their characteristics in situ using advanced fluorescence microscopy methods. While choosing the optimal labeling method for visualizing the carrier or its cargo is crucial, it seldom receives attention. The possibility that high labeling densities alter the intracellular processing of the molecule is considered, but how and at which point this interference happens is not yet studied. The aim of this study was to elucidate the effect of labeling density on the cellular trafficking of labeled pDNA. Due to the drastic effect on expression levels for higher labeling densities, we tried to determine at which steps in the intracellular processing labeled pDNA behaves different than its nonlabeled counterpart. Therefore, different labeling densities, up to the manufacturer's recommended density, were tested. It was found that the cellular uptake remains unaffected, while the affinity for lipids is increased, which affects dissociation from the lipid-based complex and may affect endosomal escape. Also, nuclear injections clearly demonstrated that transcription is affected. The information and methodology, included in this work, could be helpful in determining if the labeling method and density used yields biological relevant results for the intended research question.

MODELLING OF ACOUSTIC EMISSION SOURCE AND WAVE RESPONSE IN LAYERED MATERIALS

Abstract This study proposes a model of wave propagation in layered media for the use in acoustic emission (AE) studies. This model aims to find an AE response at a free surface to the propagating waves originating at a dislocation source either in one layer medium or a layer-to-layer interface. Each of the layered media is assumed to be homogenous, linear elastic and isotropic. An integral transformation method has been applied to determine the wave response in frequency-wave number domain, which is then converted to time-space domain. In the numerical examples, we first select truncated values with the finite integral transformation, so that no wave interference happens in the responses from wave reflection at truncated boundaries. Next, we simulate wave propagation in an elastic half space, and compare results obtained with that from other kind bottom boundary. Next, we introduce a dis- location source in interface and compare a simulated AE wave response obtained with that computed in the layered medium to demonstrate the performance of the model. In each simulation, the results show good agreement with the reference solutions.

Fano Resonance of the Symmetry‐Reduced Metal Bar Grating Structure

We demonstrate that Fano resonance and even multipole Fano resonance can be obtained in a symmetry‐reduced structure composed of gold bars with different bar sizes or bar shapes on a layer of dielectric. There is a transparency window opened within the frequency region of the absorptive dipole resonance by metallic bars, as long as the narrow grating waveguide mode induced by reducing symmetry is coincided in spectrum with the dipole resonance such that a destructive interference happens between these two resonant modes. Line shape of the transmission spectra of the nanostructure can be modulated effectively by changing the size or shape of the series of metal bars. The results found can be useful in the design of novel optical device.

Study of Isobaric Interference in Quantification of Citrulline by Parallel Fragmentation Monitoring.

Parallel Fragmentation Monitoring (PFM), which is an analogue of selected reaction monitoring (SRM), is a recently developed method for quantification of small molecules by MALDI-TOF/TOF mass spectrometry (MS). It is well known that isobaric interference substances can be occasionally present in complex biological samples, and affect the accuracy of measurement by SRM. Unfortunately, by design it is not possible to assess whether isobaric interference happens in a SRM analysis. In contrast, the unique design of PFM should allow quick inspection for isobaric interference and subsequent correction. In this study, using arginine as an example, interference effect of isobaric structural analogs on the quantification of citrulline by PFM was evaluated. Our results showed that the presence of arginine affected the measured concentrations of citrulline standard solutions in a concentration dependent manner. Such interference could be observed readily in the MS/MS spectra, and contributed by [arginine+H-NH3](+) fragment ion. Because of having highly similar mass, (13)C-isotope of [arginine+H-NH3](+) fragment ion overlapped with monoisotope of [citrulline+H-NH3](+) fragment ion, which was used as the report ion for quantification. However, such interference could be mathematically eliminated or minimized through estimation of the signal intensity of the (13)C-isotopic peak of [arginine+H-NH3](+) from the intensity of the corresponding monoisotopic peak according to isotope distribution of elements. Furthermore, the presence of interfering fragment ions could be avoided by optimizing MALDI ionization condition. In conclusion, isobaric interference can happen in PFM, but can be easily identified in the mass spectra and eliminated (minimized) with simple methods.

Diffraction radiation of a sub-wavelength hole array with dielectric medium loading

In this paper we show that under the excitation of a line current of electron beam, a dielectric medium loading in the lower half-space of a sub-wavelength hole array brings essential changes to the diffraction radiation. In the lower half-space, the surface wave becomes a radiation wave. The fundamental space harmonic is transformed into Cherenkov radiation with unique characteristics and the first negative space harmonic is converted into a radiation wave with the angle of Smith–Purcell radiation. Consequently, in the lower half-space interference happens due to these two kinds of diffraction radiation. The results of numerical calculations based on analytical theory agree well with that obtained by computer simulations. The mechanism may have good potential applications in modern physics.

Effectiveness of RTS/CTS handshake in IEEE 802.11 based ad hoc networks

IEEE 802.11 MAC mainly relies on two techniques to combat interference: physical carrier sensing and RTS/CTS handshake (also known as “virtual carrier sensing”). Ideally, the RTS/CTS handshake can eliminate most interference. However, the effectiveness of RTS/CTS handshake is based on the assumption that hidden nodes are within transmission range of receivers. In this paper, we prove using analytic models that in ad hoc networks, such an assumption cannot hold due to the fact that power needed for interrupting a packet reception is much lower than that of delivering a packet successfully. Thus, the “virtual carrier sensing” implemented by RTS/CTS handshake cannot prevent all interference as we expect in theory. Physical carrier sensing can complement this in some degree. However, since interference happens at receivers, while physical carrier sensing is detecting transmitters (the same problem causing the hidden terminal situation), physical carrier sensing cannot help much, unless a very large carrier sensing range is adopted, which is limited by the antenna sensitivity. In this paper, we investigate how effective is the RTS/CTS handshake in terms of reducing interference. We show that in some situations, the interference range is much larger than transmission range, where RTS/CTS cannot function well. Two independent solutions are proposed in this paper. One is a simple enhancement to the IEEE 802.11 MAC protocol. The other is to utilize directional antennas. Simulation results verify that the proposed schemes indeed can help IEEE 802.11 resolve most interference caused by large interference range.

Interference Impact Analysis of Multibody Systems

A new computer aided analysis method for frictionless impact problems due to interference between two bodies in a constrained multibody system is presented in this paper. A virtual contact joint concept is used to detect interference between two bodies and calculate the jump in the body momenta, velocity discontinuities and rebounds. The interference surfaces can be described by the joint coordinates of the virtual contact joint, which are very useful for determining the impact time, the types and positions of two impact surfaces and impact initial conditions when an interference happens between two bodies.

An Experimental Model: Bacterial Specialists and Generalists Competing in Chemostats

An experimental model was used to test the ecological axiom that a generalist is less efficient than a specialist. The generalist in this model were strains of Escherichia coli which can use both maltose and lactose. The specialists were strains of E. coli which can use only maltose because of a deletion of the lactose genes. These generalists and specialists competing for maltose in energy—limited chemostats containing both sugars achieved coexistence under certain conditions. The equilibrium frequency depended upon the pair of strains used and the percentage of the sugar which is lactose. A genetic change was important in the outcome of these experiments: a lac constitutive mutation replaced the lac/ of the generalist. (Cells with a lactose constitutive mutation produce lactose enzyme whether or not lactose is present.) This allowed the generalist to coexist on lower amounts of lactose that it would have been able to otherwise. We propose that the lactose consititutive is selected for over the wild—type in a lactose—limited chemostat because the concentration of lactose required for growth, if the operon is constitutively depressed, is less than that required for continued depression of the lactose operon. The equilibrium frequency predicted by chemostate competition theory gave a much higher frequency of the generalist than seen in the experiments. When only the generalist was added to a chemostat containing both maltose and lactose, an equilibrium of both lac/ and lac constitutive cells was established. This implies that there exists "resource interference." Resource interference happens when an organism is not as efficient at using a resource when it is using other resources as when it was using that resource alone. When a constant for resource interference was incorporated into the equations, the theoretical predictions agreed with the experimental results. We hypothesize that this resource interferences is due to competition for permease sites.

On Geology and Swelling Earth Pressure of the Mineoka Tunnel, Kamogawa, Chiba Prefecture, Japan

The Mineoka highway tunnel constructed during 1970-1973, is situated in the southeastern area of Boso Peninsula, Japan.The tunnel is 725m in length and about 80 m in maximum depth under the ground surface.The route of tunnel intersects the so-called Mineoka Up-lift which is lithologically composed of serpentinite, basalt, sandstone and mudstone. The geological age of these rocks has been regarded as Tertiary.All rocks encountered in this tunnel are so much sheared, crushed, foliated and intermingled with each other that in cases they can only be recognized by the different assemblages of such minerals as serpentine, chlorite, montmorillonite, talc, etc.As a matter of fact, it was realized before the construction of the tunnel that the rocks along the tunnel route are of quite low from 1, 300-2, 600m/sec. in velocity of seismic refrection. Therefore, it was also assumed that large swelling earth pressure of rocks might be produced by the excavation of the tunnel.Accordingly the side drift method was employed for the construction work of the Mineoka tunnel.Actual costruction work turned up to be very difficult owing to very strong expansibility of rocks in the tunnel. As a result of this enormous earth pressure, many steel supports were bent, buckled and failed.It is obvious that the swelling is due to less strength in mechanical property of the rocks, and is also supported from measured value of uniaxial compressive strength, which is about 2 ton/m2 in average.Expansion of the tunnel surface increased remarkably for about ten days after excavation, but it became rather constant afterwards. When the face of a pilot tunnel approached 5 to 10m to the proceeding one, the same kind of rock expansion as above mentioned took place. In this case, the swelling pressure nearly doubled what it was for a single tunnel. Such a phenomenon may be interpreted as a result of mutual interference between plastic domains of both tunnels. Also such a interference happens between up and down tunnels, and left and right, and it has a close relationship to distance between neighbouring tunnels and the rock property.