Simple Morphology Research Articles

Morfološka i reproduktivna fenologija alohtone crvene alge Caulacanthus okamurae Yamada (Gigartinales, Caulacanthaceae) na području slovenske obale (Tršćanski zaljev, sjeverni Jadran)

This study reports the occurrence of the non-native red alga Caulacanthus okamurae, previously unknown on the Slovenian coast (Gulf of Trieste, northern Adriatic Sea). The distribution of the species, its abundance, morphological characteristics and reproductive phenology are described. The study is based on seasonal sampling conducted during one year, from winter to autumn 2021, on two different substrates (limestone and sandstone) of the midlittoral zone, and showed a moderate variation in the biomass of C. okamurae populations between the winter-spring and summer-autumn periods. The native algal assemblages of the two substrates impacted by C. okamurae were characterized by generally limited species diversity and consisted mainly of small-sized species with simple morphology. During the study, in addition to non-fertile thalli of C. okamurae, tetrasporophytic thalli with tetrasporocysts and female gametophytes with cystocarps were found.

Endoscopic observation of a rare duodenal tumor.

A 30-year-old young previously healthy man presented to our hospital with middle and upper abdominal discomfort. Abdominal computerized tomography (CT) showed no significant abnormalities. White light endoscopy showed the local mucosa in the descending part of the duodenum had granuloid uplift, some of which were fused into pieces with red color, and some other areas showed fading tone. Magnifying endoscopy with indigo-carmine staining and narrow-band imaging showed a finger-like, loose villous structure with irregular microvessels on the surface. Pathological examination of biopsy specimens showed that lymphocytes were diffused and dispersed in the mucosa with relatively simple morphology, no lymphoid follicles were observed, and local compression was obvious. Immunohistochemical staining revealed a lymphoid population highly positive for CD20 and CD10. These results were consistent with duodenal-type follicular lymphoma (D-FL).

Genome Editing of C. elegans.

Caenorhabditis elegans, a 1mm long free-living nematode, is a traditional model animal for genetic investigations of various biological processes. Characteristic features that make C. elegans a powerful model of choice for eukaryotic genetic studies include its rapid life cycle, well-annotated genome, simple morphology, and transparency. Recently, genome editing technologies have been increasingly used in C. elegans, thereby facilitating their genetic analyses. Here, I introduce a protocol frequently used in C. elegans genome editing.

All-inorganic lead-free halide perovskite Cs2TeBr6 enables real-time touchless human breath and finger related humidity monitoring

Halide perovskite (HP) materials have attracted much attention in recent years in the fields of smart home and medical detection due to their low fabrication cost, simple preparation process, controllable properties, and adjustable morphology. However, the inherent instability and toxicity of lead has been barriers limiting the practicality in electronical devices. Here, we demonstrate a high-performance impedimetric humidity sensor based on an all-inorganic lead-free HP Cs2TeBr6 for the first time. The Cs2TeBr6 sensor achieves ultra-high response value of 5 orders of magnitude (8.89 × 105) at 11–97 % relative humidity (RH), short response time (4 s), favorable repeatability, and good long-term stability. Moreover, high humidity sensing performance enables the Cs2TeBr6 sensor to enjoy great potentials in real-time touchless human breath and finger detections. In addition, the mechanism of moisture sensitivity is explained by complex impedance spectra at different humidity levels. This work contributes an attracting candidate material for humidity sensors, and furthermore provides new insights into next-generation sensory devices using lead-free HPs for human-related detections.

Parametric Modeling Method for 3D Symbols of Fold Structures

Most fabrication methods for three-dimensional (3D) geological symbols are limited to two types: directly increasing the dimensionality of a 2D geological symbol or performing appropriate modeling for an actual 3D geological situation. The former can express limited vertical information and only applies to the three-dimensional symbol-making of point mineral symbols, while the latter weakens the difference between 3D symbols and 3D geological models and has several disadvantages, such as high dependence on measured data, redundant 3D symbol information, and low efficiency when displayed in a 3D scene. Generating a 3D geological symbol is represented by the process of constructing a 3D geological model. This study proposes a parametric modeling method for 3D fold symbols according to the complexity and diversity of the fold structures. The method involves: (1) obtaining the location of each cross-section in the symbol model, based on the location parameters; (2) constructing the middle cross-section, based on morphological parameters and the Bezier curve; (3) performing affine transformation according to the morphology of the hinge zone and the middle section to generate the sections at both ends of the fold; (4) generating transition sections of the 3D symbol model, based on morphing interpolation; and (5) connecting the point sets of each transition section and stitching them to obtain a 3D fold-symbol model. Case studies for different typical fold structures show that this method can eliminate excessive dependence on geological survey data in the modeling process and realize efficient, intuitive, and abstract 3D symbol modeling of fold structures based on only a few parameters. This method also applies to the 3D geological symbol modeling of faults, joints, intrusions, and other geological structures and 3D geological modeling of typical geological structures with a relatively simple spatial morphology.

Super-Mitobarcoding in Plant Species Identification? It Can Work! The Case of Leafy Liverworts Belonging to the Genus Calypogeia

Molecular identification of species is especially important where traditional taxonomic methods fail. The genus Calypogeia belongs to one of the tricky taxons. The simple morphology of these species and a tendency towards environmental plasticity make them complicated in identification. The finding of the universal single-locus DNA barcode in plants seems to be 'the Holy Grail'; therefore, researchers are increasingly looking for multiloci DNA barcodes or super-barcoding. Since the mitochondrial genome has low sequence variation in plants, species delimitation is usually based on the chloroplast genome. Unexpectedly, our research shows that super-mitobarcoding can also work! However, our outcomes showed that a single method of molecular species delimitation should be avoided. Moreover, it is recommended to interpret the results of molecular species delimitation alongside other types of evidence, such as ecology, population genetics or comparative morphology. Here, we also presented genetic data supporting the view that C. suecica is not a homogeneous species.

On simulating shoreline evolution using a hybrid 2D/one-line model

Hybrid 2D/one-line shoreline models are becoming increasingly applied over the mesoscale (10 1 –10 2 years; 10 1 –10 2 km) to inform coastal management. These models typically apply the one-line theory to simulate changes in shoreline morphology based on littoral drift gradients calculated from a 2DH coupled wave, flow, and sediment transport model. However, the key boundary conditions needed to effectively apply hybrid 2D/one-line models and their applicability beyond simple planform morphologies are uncertain, which can potentially comprise coastal management decisions. To address these uncertainties, an extensive numerical modelling campaign is carried out to both assess the sensitivity and calibrate an advanced hybrid 2D/one-line model (MIKE21) against six variables in three different sandy coastal system morphologies: (a) a simple planform morphology with a gentle sloping profile, (b) a simple planform morphology with a steep sloping profile, and (c) a complex planform morphology. The six variables considered include nearshore discretisation, bathymetry, bed friction, sand grain diameter, sand porosity, sediment grading, and the weir coefficient of hard defence structures. Five key conclusions are derived from the sensitivity testing and calibration results. First , the optimal boundary conditions for modelling shoreline evolution vary according to coastal geomorphology and processes. Second , specifying boundary conditions within physically realistic ranges does not guarantee reliable shoreline evolution predictions. Third , nearshore discretisation should be treated as a typical calibration parameter as (a) the finest discretisation does not guarantee the most accurate predictions, and (b) defining a discretisation based on process length scales also does not guarantee reliable predictions. Fourth , hybrid 2D/one-line models are not valid for application in complex planform morphologies plausibly because of the one-line theory assumption of a spatially invariable closure depth. Fifth , hybrid 2D/one-line models have limited applicability in simple planform morphologies where the active beach profile is subject to direct human modification, plausibly due to the one-line theory assumption of a constant time-averaged coastal profile form. These findings provide key theoretical insights into the drivers of shoreline evolution in sandy coastal systems, which have practical implications for refining the continued application of shoreline evolution models. • The hybrid 2D/one-line shoreline modelling approach is tested in three coastal morphologies. • Optimal boundary conditions correspond to observed coastal morphology. • The nearshore discretisation in shoreline models should be treated as a calibration parameter. • The hybrid 2D/one-line shoreline modelling approach is limited to simple planform morphologies.

Efficient and Robust Method to Detect the Location of Macular Center Based on Optimal Temporal Determination.

The location of the macular central is very important for the examination of macular edema when using an automated screening system. The erratic character of the macular light intensity and the absence of a clear border make this anatomical structure difficult to detect. This paper presents a new method for detecting the macular center based on its geometrical location in the temporal direction of the optic disc. Also, a new method of determining the temporal direction using the vascular features visible on the optic disc is proposed. After detecting the optic disc, the temporal direction is determined by considering blood vessel positions. The macular center is detected using thresholding and simple morphology operations with optimum macular region of interest (ROI) direction. The results show that the proposed method has a low computation time of 0.34 s/image with 100% accuracy for the DRIVE dataset, while that of DiaretDB1 was 0.57 s/image with 98.87% accuracy.

Filtering artifactual signal increases support for Xenacoelomorpha and Ambulacraria sister relationship in the animal tree of life

Conflicting studies place a group of bilaterian invertebrates containing xenoturbellids and acoelomorphs, the Xenacoelomorpha, as either the primary emerging bilaterian phylum1,2,3,4,5,6 or within Deuterostomia, sister to Ambulacraria.7,8,9,10,11 Although their placement as sister to the rest of Bilateria supports relatively simple morphology in the ancestral bilaterian, their alternative placement within Deuterostomia suggests a morphologically complex ancestral bilaterian along with extensive loss of major phenotypic traits in the Xenacoelomorpha. Recent studies have questioned whether Deuterostomia should be considered monophyletic at all.10,12,13 Hidden paralogy and poor phylogenetic signal present a major challenge for reconstructing species phylogenies.14,15,16,17,18 Here, we assess whether these issues have contributed to the conflict over the placement of Xenacoelomorpha. We reanalyzed published datasets, enriching for orthogroups whose gene trees support well-resolved clans elsewhere in the animal tree.16 We find that most genes in previously published datasets violate incontestable clans, suggesting that hidden paralogy and low phylogenetic signal affect the ability to reconstruct branching patterns at deep nodes in the animal tree. We demonstrate that removing orthogroups that cannot recapitulate incontestable relationships alters the final topology that is inferred, while simultaneously improving the fit of the model to the data. We discover increased, but ultimately not conclusive, support for the existence of Xenambulacraria in our set of filtered orthogroups. At a time when we are progressing toward sequencing all life on the planet, we argue that long-standing contentious issues in the tree of life will be resolved using smaller amounts of better quality data that can be modeled adequately.19.

Oxygen vacancies enriched multi-channel-like metal-doped Co3O4 nanosheets by Lewis acid etching for detection of small biological molecules in apple juice and wine

Excessive small biological molecules such as Cd(II), Pb(II) and glucose in food pose a non-negligible threat to its inherent quality and human health, which makes it imperative to develop the highly sensitive sensor for Cd(II), Pb(II) and glucose detection. Metal cation-doped Co3O4 modified electrode materials have attracted vital interest in the electrochemical detection of Cd(II), Pb(II) and glucose because of their synergetic effect on Cu/Co and oxygen vacancies. Herein, a simple morphology and defect modulation strategy is proposed to synthesize multi-channel-like M-doped Co3O4 nanosheets (M = Cu, Mn, Fe, Ni, and Zn) via the Lewis acid etching process. The Cu/Co interaction and oxygen vacancies of Cu-Co3O4 multichannel nanosheets play an important role in the simultaneous detection of small biological molecules. The Cu-Co3O4 multichannel nanosheets exhibit the sensitivity of 20.59 µA µM−1 for Pb(II), 8.73 µA µM−1 for Cd(II) as well as 1613.86 µA mM−1 cm−2 for glucose, which is successfully applied in food applications such as apple juice and wine and maintain excellent stability and anti-interference. This design not only successfully constructs oxygen vacancies enriched M-Co3O4 multichannel nanosheets, but also demonstrates the application potential of electrochemical sensors in food safety.

Hidden diversity in Selenastraceae (Sphaeropleales, Chlorophyceae): Molecular phylogeny revealed a nannoplanktonic species, with the description of Viridiparva madeirensis gen. et sp. nov.

The simple morphology of the members of the family Selenastraceae, common in freshwater phytoplankton, has led to misidentifications. But the use of molecular tools is untangling their phylogeny and unveiling new genera and species hidden under the same morphotype or overlooked by microscopic analysis. Here we propose a description of Viridiparva madeirensis gen. et sp. nov., a small Selenastraceae member, based on the study of three strains by light, scanning and transmission microscopy and 18S rDNA and rbcL phylogenies. The phylogenetic analyses by 18S rDNA and rbcL show, respectively, that the closest relatives to Viridiparva madeirensis are Monoraphidium dybowskii and Raphidocelis microscopica, but with no or low statistical support. V. madeirensis is smaller than M. dybowski and has no cell wall incrustations typical for Raphidocelis. Thus, phylogeny and morphological analyses indicate a novel lineage within Selenastraceae. Furthermore, also reinforce the necessary revision of the genera within Selenastraceae, as Monoraphidium and Raphidocelis. Therefore study contributes to clarify the phylogeny and taxonomy of the family and add genetic sequences of neglected nanophytoplankton to GenBank, including one strain with known potential for biodiesel production.

Acoustic metamaterials with controllable bandgap gates based on magnetorheological elastomers

Acoustic metamaterials allow for creating selective pass- and stop-bands on the frequency spectrum. We demonstrate the possibility of designing acoustic metamaterials as core-shell 2D-phononic media with an extremely simple morphology, the frequency spectrum of which contains many real-time tunable bandgaps. The connected shells of such metamaterials form a grid with square cells filled with nuclei partitionable into two subsystems. Both subsystems are characterized by their frequency spectra, and it is the coupling between them that generates the bandgaps. If the structural elements of the metamaterial are built based on magnetoelastomers, then bandgaps can be easily controlled by an external magnetic field that changes the elastic moduli of shells/cores. We have shown the possibility of manipulating single bandgaps in different parts of the spectrum, and simultaneous control of all bandgaps up to their complete disappearance. This manipulation can be carried out, specifically, with no change in the maximum achievable frequency in the metamaterial. The results obtained can be used for selective filtering of damaging wave components, active control of seismic or blast waves, sonar systems, ultrasound imaging, impact-resistant structures, and noise cancelation protocols. The physical concepts developed are extendable to 3D-structures in a similar fashion so can benefit a wider community.

Genomic Adaptations to an Endoparasitic Lifestyle in the Morphologically Atypical Crustacean Sacculina carcini (Cirripedia: Rhizocephala).

The endoparasitic crustacean Sacculina carcini (Cirripedia: Rhizocephala) has a much simpler morphology than conventional filter-feeding barnacles, reflecting its parasitic lifestyle. To investigate the molecular basis of its refined developmental program, we produced a draft genome sequence for comparison with the genomes of nonparasitic barnacles and characterized the transcriptomes of internal and external tissues. The comparison of clusters of orthologous genes revealed the depletion of multiple gene families but also several unanticipated expansions compared to non-parasitic crustaceans. Transcriptomic analyses comparing interna and externa tissues revealed an unexpected variation of gene expression between rootlets sampled around host midgut and thoracic ganglia. Genes associated with lipid uptake were strongly expressed by the internal tissues. We identified candidate genes probably involved in host manipulation (suppression of ecdysis and gonad development) including those encoding crustacean neurohormones and the juvenile hormone binding protein. The evolution of Rhizocephala therefore appears to have involved a rapid turnover of genes (losses and expansions) as well as the fine tuning of gene expression.

Simulation Study of Electric Double-Layer Capacitance of Ordered Carbon Electrodes.

Supercapacitors are electrochemical energy storage devices having high capacitance, high power density, long cycle life, low cost, easy maintenance, and negligible environmental pollution. The formation of an electric double layer at the electrode-electrolyte interface is mostly responsible for supercapacitors' energy storage. The simulation study of equilibrium electric double-layer capacitance (EDLC) in 3D arranged mesoporous carbon electrodes with a simple cubic morphology and interdigitated electrodes has been done. Continuum theory has been utilized to study the underlying processes involved in EDLC. Interfacial polarization and ion crowding depend on the electrode's critical thickness. Porosity increases the capacitance due to the increase in the electrode surface area. The diffuse-layer specific capacitance of ordered mesoporous carbon electrodes in a (C2H5)4NBF4/propylene carbonate organic electrolyte is in the range of 3.2-13.3 μF cm-2, varying according to the electrode thickness. The Stern-layer specific capacitance is 167.6 μF cm-2, and total equilibrium EDLC is in the range of 3.1-12.3 μF cm-2. The effect of the electric field at the electrode-electrolyte interface on reducing electrolyte permittivity has also been discussed. The EDLC of carbonized interdigitated electrodes is analyzed in a 6 M KOH electrolyte. The diffuse-layer specific capacitance ranges from 118.7 to 352.0 μF cm-2 depending on the width of the interdigitated electrodes. The Stern-layer specific capacitance is 91.2 μF cm-2, and the total EDLC value is 51.6-72.4 μF cm-2. The modeling and simulation approach can be applied to different mesoporous electrodes by varying the supercapacitor component's parameters and geometry.

Development of a Novel Diagnostic Tool for Cercospora Species Based on BOX-PCR System.

The genus Cercospora contains many devastating plant pathogens linked to leaf spot diseases afflicting various plants. Identification of Cercospora species based on morphology or host plant association has proven unreliable due to simple morphology and wide host range in many cases; hence, multi-gene DNA sequence data are essential for accurate species identification. Considering the complexity and cost involved in application of multi-locus DNA phylogenetic approaches for species delineation in Cercospora; rapid and cost-effective methods are urgently needed for species recognition. In this study, we applied rep-PCR (repetitive-sequence based polymerase chain reaction) fingerprinting methods referred to as BOX-PCR to differentiate species of Cercospora. Cluster analysis of the banding patterns of 52 Cercospora strains indicated the ability of BOX-PCR technique using BOXA1R primer to generate species-specific DNA fingerprints from all the tested strains. Since this technique was able to discriminate between all the 20 examined Cercospora species during this study, which corresponded well to the species identified based on multi-gene DNA sequence data, our findings revealed the efficiency of BOX-PCR system as a suitable complementary method for molecular identification of the genus Cercospora at species level.

In-depth understanding of the relationship between dislocation substructure and tensile properties in a low-carbon microalloyed steel

At present, the microstructure-tensile property relationship of low carbon microalloyed steel has been widely investigated, mainly with the effects of microstructure type and its simple morphology including size and shape etc. The correlation between dislocation substructure and tensile properties, however, seems more essential and needs in-depth analysis. In this study, four typical Mn containing (from 1.08 to 1.77 wt%) low-carbon microalloyed steels were prepared by Thermo Mechanical Control Process, and the correlations among Mn content, dislocation substructure and tensile properties were investigated. A mixed microstructure consisting of polygonal ferrite, degenerated pearlite, granular bainitic ferrite and martensite/austenite (M/A) constituents formed in each steel, with highly complex dislocation configuration and distribution. For the 1.08% Mn steel, the dislocation substructures appeared mainly in dislocation wall distributing in the ferrite matrix of degenerated pearlite, and dislocation tangle in the granular bainitic ferrite around the M/A constituents and the bainitic ferrite lath boundary. As the Mn content increased from 1.45% to 1.77%, the dislocation cells appeared and increased. Simultaneously with the rising of Mn content, the mean equivalent diameter (MED) of all the ferrite matrix decreased. The ferrite grains whose MED was defined by the misorientation tolerance angles (MTAs) from 2 to 8°, featured a variety of dislocation substructures including dislocation cell boundaries, dislocation walls, bainitic ferrite lath boundaries, and dislocation tangles. They effectively governed the yield strength due to their determined close Hall–Petch relationship. Moreover, the significant increase in the amount of M/A constituents enhanced the strain hardening capacity, leading to an elevated tensile strength. Dislocation tangles exhibiting around the M/A caused a microstrain concentration, promoted additional microvoids and deteriorated the elongation.

DESCRIBING DIFFICULT SHELL-HASH ASSEMBLAGES FROM THE LOWER CAMBRIAN SOLTANIEH FORMATION, ALBORZ MOUNTAINS, NORTHERN IRAN

ABSTRACTThe fossil record spanning the latest Ediacaran and earliest Cambrian is characterized by the proliferation of small, mineralized organisms that comprise the well-known and abundant deposits of small shelly fauna. Many of these fossils are tubular or conical forms with simple morphologies, and thus present difficulties in both taxonomic and phylogenetic interpretation. This study investigates a community of poorly preserved shelly tubicolous organisms in two fossiliferous slabs from the Soltanieh Formation, northern Iran. Analysis of the taphonomy of this fossil assemblage using thin-section petrography, scanning electron microscopy, and energy dispersive X-ray spectroscopy, suggests a two-part preservational pathway involving phosphatic replacement of the shell wall and separate, diagenetically later infillings of void space with either phosphatic or calcium carbonate cements. In parallel with the taphonomic study and given the difficulty in assigning the observed fossils taxonomically, morphometrics of the shelly organisms were also explored. Biometric measurements were collected from high-resolution photomosaic images of the slab-surface fossils, as well as from a three-dimensional volume of the interior of one of the slabs generated via X-ray tomographic microscopy. Statistical analysis of these measurements revealed a separation of the fossils into two morphologically distinct groups of conical and tubular forms, which we characterize respectively as ‘conomorphs' and ‘tubomorphs'. Based on previous studies of fossils from the Soltanieh Fm., we can offer tentative generic-level assignment to Anabarites and Cambrotubulus to at least some of the fossils present, though these are dependent on views in thin section rather than morphometric distinction. Cumulatively, we provide a conservative, taxonomy-free approach for detailing the morphology and preservation of poorly preserved fossils from the Ediacaran–Cambrian transition.

Green Crop Yam-Derived Carbons: Off-Plane Active Sites for Oxygen Electroreduction Identified by First-Principles.

Plant-derived nonprecious metal catalysts are considered one of the promising candidates of platinum for oxygen reduction reaction (ORR). In this work, the typical microscopic morphology of fresh green crop yam is first detected by cryoscanning electronic microscopy. Using the green and widely sourced yam with spherical starch in nature as a precursor, well-defined spherical carbons are prepared via hypersaline-assisted hydrothermal carbonization and NH3activation, featuring a high heteroatom doping level and a hierarchical porous structure. Experimental results and density functional theory (DFT) calculations reveal that diverse off-plane Fe-Nx-Cy ensembles on the spherical carbons trigger the high performance that exceeds state-of-art Pt/C and most reported carbon catalysts toward ORR in a KOH solution. The increased charge density and the bond length of Fe coordinated in the sites should be responsible for the significantly improved property. The easily editing of off-plane active sites from the simple carbon morphology may shed light on optimizing nonprecious carbons as next-generation catalysts for ORR.

Beydere 3: a new early Miocene small mammal assemblage from the western Anatolia, Turkey

ABSTRACT The new micromammal site of Beydere 3 represents a typical Anatolian MN3 fauna in the high diversification and abundance of Eumyarion. Notably, two Eumyarion species are new; combined, they make up almost half of the assemblage. While Eumyarion beyderensis sp. nov. shows simple morphology in upper molars, Eumyarion aegeaniensis sp. nov. shows a more complex lophs pattern. In addition, Beydere 3 yielded nine species of rodents and an ochotonid: the hamsters Cricetodon kasapligili, Mirrabella crenulata, Megacricetodon hellenicus, Democricetodon doukasi, Vallaris zappai and Eumyarion sp., the dormice Glirulus ekremi and Glis sp., the beaver Steneofiber eseri, the squirrel Palaeosciurus fissurae and Ochotonidae indet. The fauna is significant in that it represents the first common occurrence of Megacricetodon in Anatolia. Eumyarion and Megacricetodon are both dominant groups which may indicate a signal of environmental change, but still closer to wet conditions. This, in combination with the new species of Eumyarion, suggests that Beydere 3 represents a time slice which was previously not recorded in Anatolia. Radiometric dating of ashes overlying the section indicates that the age of the locality is older than 18.21 (± 0.19) Ma.

A varying-radius cable equation for the modelling of impulse propagation in excitable fibres.

In this study, we present a varying-radius cable equation for nerve fibres taking into account the varying diameter along the neuronal segments. Finite element neuronal models utilising the classical (fixed-radius) and varying-radius cable formulations were compared using simple and realistic morphologies under intra- and extracellular electrical stimulation protocols. We found that the use of the classical cable equation to model intracellular neural electrical stimulation exhibited an error of 17% in a passive resistive cable model with abrupt change in radius from 1 to 2 μm, when compared to the known analytical solution and varying-radius cable formulation. This error was observed to increase substantially using more realistic neuron morphologies and branching structures. In the case of extracellular stimulation however, the difference between the classical and varying-radius formulations was less pronounced, but we expect this difference will increase under more complex stimulation paradigms such as high-frequency stimulation. We conclude that for computational neuroscience applications, it is essential to use the varying-radius cable equation for accurate prediction of neuronal responses under electrical stimulation.