Direct Code Research Articles

Strongly directional responses to tones and conspecific calls in the auditory nerve of the Tokay gecko, Gekko gecko.

The configuration of lizard ears, where sound can reach both surfaces of the eardrums, produces a strongly directional ear, but the subsequent processing of sound direction by the auditory pathway is unknown. We report here on directional responses from the first stage, the auditory nerve. We used laser vibrometry to measure eardrum responses in Tokay geckos and in the same animals recorded 117 auditory nerve single fiber responses to free-field sound from radially distributed speakers. Responses from all fibers showed strongly lateralized activity at all frequencies, with an ovoidal directivity that resembled the eardrum directivity. Geckos are vocal and showed pronounced nerve fiber directionality to components of the call. To estimate the accuracy with which a gecko could discriminate between sound sources, we computed the Fisher information (FI) for each neuron. FI was highest just contralateral to the midline, front and back. Thus, the auditory nerve could provide a population code for sound source direction, and geckos should have a high capacity to differentiate between midline sound sources. In brain, binaural comparisons, for example, by IE (ipsilateral excitatory, contralateral inhibitory) neurons, should sharpen the lateralized responses and extend the dynamic range of directionality.NEW & NOTEWORTHY In mammals, the two ears are unconnected pressure receivers, and sound direction is computed from binaural interactions in the brain, but in lizards, the eardrums interact acoustically, producing a strongly directional response. We show strongly lateralized responses from gecko auditory nerve fibers to directional sound stimulation and high Fisher information on either side of the midline. Thus, already the auditory nerve provides a population code for sound source direction in the gecko.

Some important results on 𝒯-Direct codes

[Formula: see text]-Direct codes are an extension to the class of linear codes having complementary duals (LCD codes). Defined over a finite field [Formula: see text], it is comprised of [Formula: see text] linear codes [Formula: see text], [Formula: see text] with [Formula: see text], where [Formula: see text] is the dual with respect to [Formula: see text]. A 2-Direct code [Formula: see text] with respect to [Formula: see text] is comprised of only LCD codes: [Formula: see text]. On the contrary, two LCD codes do not set up a [Formula: see text]-Direct code in general. This paper presents some important and generalized results on [Formula: see text]-Direct codes, in that it attempts to construct [Formula: see text]-Direct codes from LCD codes. The class of [Formula: see text]-cyclic maximum rank distance (MRD) codes as having complementary duals over [Formula: see text] are generalized. Dual bases such as self-dual basis and self-dual normal basis play a crucial role in constructions. Further, construction implausibility of [Formula: see text]-Direct codes from almost self-dual bases is also dealt. Results obtained are demonstrated through examples.

Parallel-sequential adder-subtractor with the highest digits forward on neurons

The article deals with the development of a parallel-sequential adder-subtractor that performs arithmetic operations of addition and subtraction of binary numbers in the format with a fixed comma with the highest digits forward. The result of performing arithmetic operations is the sum and difference of binary numbers in the direct code of eight digits. The sum and difference of numbers is calculated on neuropositive elements, the transfer to the highest digits when summing and the loan from the highest digits when subtracting is determined by the majority elements. The algorithm for adding numbers in direct codes allows you to get the result in direct code. The signed digits of numbers determine which operation should be performed on numbers using the sum modulo two operation. If the characters are the same, the result will be zero. Otherwise, the result will be one. After that, the addition or subtraction operation is selected. Summation is performed if the numbers have the same signs, the result is assigned the sign of the first number. Subtraction is performed if the numbers have different signs, the result is assigned the sign of a larger modulo number. The adder-subtracter senior digits forward on neurons contains: block input, block comparatii, the block parallel-serial addersubtracter, the unit registers a larger number, the unit of determining the transfer and loan, a unit registers a smaller number of unit registers a result, the control unit, majority, threshold and neural elements. The device can be used as an arithmetic co-processor in a computer system. It significantly speeds up calculations of both simple arithmetic operations and results of various mathematical functions.

On the Fidelity of NS-3 Simulations of Wireless Multipath TCP Connections.

The multipath transmission control protocol (MPTCP) is considered a promising wireless multihoming solution, and the 3rd generation partnership project (3GPP) includes it as a standard feature in the fifth-generation (5G) networks. Currently, ns-3 (Network Simulator-3) is widely used to evaluate the performance of wireless networks and protocols, including the emerging MPTCP protocol. This paper investigates the fidelity of the Linux kernel implementation of MPTCP in the ns-3 direct code execution module. The fidelity of MPTCP simulation is tested by comparing its performance with a real Linux stack implementation of MPTCP using a hardware testbed for two different setups. One setup emulates the existence of a bottleneck link between the sending and receiving networks, whereas the other setup does not have such a bottleneck. The fidelity of ns-3’s simulation is tested for four congestion control algorithms, namely Cubic, linked-increases algorithm (LIA), opportunistic LIA (OLIA) and wVegas for relatively short and long data flows. It is found that the uplink MPTCP throughput performance exhibited by the ns-3 simulator matches the hardware testbed results only if the flows are long-lived and share no common bottleneck link. Likewise, the MPTCP throughput achieved during a downlink scenario using the ns-3 simulator and the hardware testbed are close to each other across all algorithms except wVegas regardless of the flow size if there is no bottleneck link. Moreover, it is observed that the impact of LTE handover on MPTCP throughput is less significant in the simulator than the real hardware testbed, and it is setup-dependent.

Novel Descriptors for Effective Recognition of Face and Facial Expressions

In this paper, we present a face recognition approach based on extended Histogram Oriented Gradient (HOG) descriptors to extract the facial expressions features allowing classifying the faces and facial expressions. The approach is based on determining the different directional codes on the face image based on edge response values to define the feature vector from the face image. Its size is reduced to improve the performance of the SVM (Support Vector Machine) classifier. Experiments are conducted using two public datasets: JAFFE for facial expression recognition and YALE for face recognition. Experimental results show that the proposed descriptor achieves recognition rate of 92.12% and execution time ranging from 0.4s to 0.7s in all evaluated databases compared with existing works. Experiments demonstrate and confirm both the effectiveness and the efficiency of the proposed descriptor.

New Constructions of Codebooks Nearly Meeting the Welch Bound

Optimal codebooks meeting the Welch bound with equality are desirable in many areas, such as direct spread code division multiple access communications, compressed sensing and so on. However, it is difficult to construct such optimal codebooks. There have been a number of attempts to construct codebooks nearly meeting the Welch bound. In this paper, we introduce a generic construction of codebooks using generalized bent functions from [Formula: see text] to [Formula: see text], where [Formula: see text] is a prime and [Formula: see text] is a positive integer with [Formula: see text]. With this construction, we obtain two new families of codebooks nearly meeting the Welch bound. These codebooks have new parameters and could have a small alphabet size. In particular, a class of regular generalized bent functions from [Formula: see text] to [Formula: see text] is presented.

Matched-filter coding of sky polarization results in an internal sun compass in the brain of the desert locust

Many animals use celestial cues for spatial orientation. These include the sun and, in insects, the polarization pattern of the sky, which depends on the position of the sun. The central complex in the insect brain plays a key role in spatial orientation. In desert locusts, the angle of polarized light in the zenith above the animal and the direction of a simulated sun are represented in a compass-like fashion in the central complex, but how both compasses fit together for a unified representation of external space remained unclear. To address this question, we analyzed the sensitivity of intracellularly recorded central-complex neurons to the angle of polarized light presented from up to 33 positions in the animal's dorsal visual field and injected Neurobiotin tracer for cell identification. Neurons were polarization sensitive in large parts of the virtual sky that in some cells extended to the horizon in all directions. Neurons, moreover, were tuned to spatial patterns of polarization angles that matched the sky polarization pattern of particular sun positions. The horizontal components of these calculated solar positions were topographically encoded in the protocerebral bridge of the central complex covering 360° of space. This whole-sky polarization compass does not support the earlier reported polarization compass based on stimulation from a small spot above the animal but coincides well with the previously demonstrated direct sun compass based on unpolarized light stimulation. Therefore, direct sunlight and whole-sky polarization complement each other for robust head direction coding in the locust central complex.

Grid cells are modulated by local head direction

Grid and head direction codes represent cognitive spaces for navigation and memory. Pure grid cells generate grid codes that have been assumed to be independent of head direction, whereas conjunctive cells generate grid representations that are tuned to a single head direction. Here, we demonstrate that pure grid cells also encode head direction, but through distinct mechanisms. We show that individual firing fields of pure grid cells are tuned to multiple head directions, with the preferred sets of directions differing between fields. This local directional modulation is not predicted by previous continuous attractor or oscillatory interference models of grid firing but is accounted for by models in which pure grid cells integrate inputs from co-aligned conjunctive cells with firing rates that differ between their fields. We suggest that local directional signals from grid cells may contribute to downstream computations by decorrelating different points of view from the same location.

The Hippocampus Maps Concept Space, Not Feature Space.

The hippocampal formation encodes maps of space and a key question in neuroscience is whether its spatial coding principles also provide a universal metric for the organization of nonspatial, conceptual information. Previous work demonstrated directional coding during navigation through a continuous stimulus feature space as well as mapping of distances in a feature space that was relevant for concept learning. Here we provide the first unambiguous evidence for a hippocampal representation of the actual concept space, by showing that the hippocampal distance signal selectively reflects the mapping of specifically conceptually relevant rather than of all feature dimensions. During fMRI scanning of 32 human participants (21 females), we presented everyday objects, which had beforehand been associated with specific values on three continuous feature dimensions. Crucially, only two dimensions were relevant to prior concept learning. We find that hippocampal responses to the objects reflect their relative distances in a space defined along conceptually relevant dimensions compared with distances in a space defined along all feature dimensions. These findings suggest that the hippocampus supports knowledge acquisition by dynamically encoding information in a space spanned along dimensions that are relevant in relation to define concepts.SIGNIFICANCE STATEMENT How are neural representations of conceptual knowledge organized, such that humans are able to infer never experienced relations or categorize new exemplars? Map-like representations as supported by the hippocampal formation to encode physical space during navigation have been suggested as a suitable format. Here we provide the first evidence for a hippocampal representation of a conceptual space compared with a general feature-based space.

Children\u2019s Password-Related Books: Efficacious, Vexatious and Incongruous

Software is developed specifically for children and this often requires them to authenticate themselves, usually by entering a password. Password hygiene is important for children, because the principles they learn in early life will often endure across their life span. Children learn from their parents, siblings, teachers, and peers. They also learn from educational resources, such as children’s books. We carried out a content analysis of a range of children’s books that aims to educate children about passwords. We used directional coding, as informed by a systematic literature review of methods, such as those used in other content analysis-based studies of children’s books. We examined the principles the books taught, and whether these were correct. We also analysed how the books portrayed the genders of characters, in various roles. We found that principle coverage was variable, with books sometimes teaching outdated principles. Genders were evenly represented in the books. Finally, our analysis revealed conflation of the terms “safety” and “security” in the cyber domain. We conclude the paper by justifying the adjectives we use in the title.

Behavior-dependent directional tuning in the human visual-navigation network

The brain derives cognitive maps from sensory experience that guide memory formation and behavior. Despite extensive efforts, it still remains unclear how the underlying population activity unfolds during spatial navigation and how it relates to memory performance. To examine these processes, we combined 7T-fMRI with a kernel-based encoding model of virtual navigation to map world-centered directional tuning across the human cortex. First, we present an in-depth analysis of directional tuning in visual, retrosplenial, parahippocampal and medial temporal cortices. Second, we show that tuning strength, width and topology of this directional code during memory-guided navigation depend on successful encoding of the environment. Finally, we show that participants’ locomotory state influences this tuning in sensory and mnemonic regions such as the hippocampus. We demonstrate a direct link between neural population tuning and human cognition, where high-level memory processing interacts with network-wide visuospatial coding in the service of behavior.

Linking Sustainable Development Assessment in Ireland and the European Union with Economic Theory

Economists offer what is arguably the most internally consistent framework for sustainable development assessment, the so-called “capital approach”. To operationalise the capital approach, measures of the changes in comprehensive national wealth (Genuine Savings) are required. In this paper, we present estimates of Ireland’s Genuine Savings using the updated public spending code for direction and compare our results with existing estimates in the literature. For practical sustainability assessment, no single indicator is capable of providing an all-encompassing answer, but as we demonstrate, the current monitoring of sustainable development in Ireland and across the EU lacks coherence. We suggest potential paths forward for sustainability policy and assessment that preserve the link with economic theory. We show that regardless of the viewpoint taken on sustainability, the capital approach can provide guidance for a coherent assessment framework.

Leaving No Large Vessel Occlusion Stroke Behind: Reorganizing Stroke Systems of Care to Improve Timely Access to Endovascular Therapy.

Leaving No Large Vessel Occlusion Stroke Behind: Reorganizing Stroke Systems of Care to Improve Timely Access to Endovascular Therapy.

Об одном алгоритмическом решении задачи восстановления остатка числа в системе остаточных классов

При выполнении операций расширения диапазона представления чисел, деления, определения переполнения, масштабирования, контроля ошибок вычислений возникает задача восстановления остатка числа по данному модулю на основании остатков этого числа по остальным модулям системы. Табличное выполнение операции восстановления остатка числа реализуется с помощью базового алгоритма. Метод решения основан на определении остатка по данному модулю на основании полученных остатков по остальным модулям системы. Такое определение выполняется последовательным вычитанием констант из полученных остатков и суммированием этих констант к результататам, которые формируются по данному модулю. При этом константы на каждой итерации выбираются в зависимости от значения остатка в анализируемом разряде. При несомненном достоинстве метода сохраняются требования к быстродействию выполнения операции восстановления остатка числа. Целью исследования является аналитическое рассмотрение подхода к ускоренной реализации базовой операции восстановления остатка числа по данному модулю на основании остатков этого числа по остальным модулям системы. Одна из реализаций алгоритма состоит в одновременном его выполнении по базовому варианту для искомого числа и числа, обратного искомому. При этом искомый остаток определяется по значению остатка того из чисел, для которого первым получается результат поиска. Приведены варианты реализации алгоритма с переходами от представления числа в прямом коде к представлению этого числа в обратном коде и от представления числа в обратном коде к его представлению в прямом коде. Рассмотренный алгоритм реализации в системе остаточних классов базовой немодульной операции восстановления значения остатка числа по данному модулю на основании значений остатков этого числа по остальным модулям системы обеспечивает получение искомого результата. На основе предложенных подходов достигается ускоренная реализация базовой операции восстановления остатка числа по данному модулю. Представляется целесообразным применить предложенные подходы в качестве перспективных направлений исследований этой операции в системе остаточных классов.

Effect of Stimulus-Dependent Spike Timing on Population Coding of Sound Location in the Owl's Auditory Midbrain.

In the auditory system, the spectrotemporal structure of acoustic signals determines the temporal pattern of spikes. Here, we investigated this effect in neurons of the barn owl’s auditory midbrain (Tyto furcata) that are selective for auditory space and whether it can influence the coding of sound direction. We found that in the nucleus where neurons first become selective to combinations of sound localization cues, reproducibility of spike trains across repeated trials of identical sounds, a metric of across-trial temporal fidelity of spiking patterns evoked by a stimulus, was maximal at the sound direction that elicited the highest firing rate. We then tested the hypothesis that this stimulus-dependent patterning resulted in rate co-modulation of cells with similar frequency and spatial selectivity, driving stimulus-dependent synchrony of population responses. Tetrodes were used to simultaneously record multiple nearby units in the optic tectum (OT), where auditory space is topographically represented. While spiking of neurons in OT showed lower reproducibility across trials compared with upstream nuclei, spike-time synchrony between nearby OT neurons was highest for sounds at their preferred direction. A model of the midbrain circuit explained the relationship between stimulus-dependent reproducibility and synchrony, and demonstrated that this effect can improve the decoding of sound location from the OT output. Thus, stimulus-dependent spiking patterns in the auditory midbrain can have an effect on spatial coding. This study reports a functional connection between spike patterning elicited by spectrotemporal features of a sound and the coding of its location.

Numerical benchmark study for flow in highly heterogeneous aquifers

This article presents numerical investigations on accuracy and convergence properties of several numerical approaches for simulating steady state flows in heterogeneous aquifers. Finite difference, finite element, discontinuous Galerkin, spectral, and random walk methods are tested on two-dimensional benchmark flow problems. Realizations of log-normal hydraulic conductivity fields are generated by Kraichnan algorithms in closed form as finite sums of random periodic modes, which allow direct code verification by comparisons with manufactured reference solutions. The quality of the methods is assessed for increasing number of random modes and for increasing variance of the log-hydraulic conductivity fields with Gaussian and exponential correlation. Experimental orders of convergence are calculated from successive refinements of the grid. The numerical methods are further validated by comparisons between statistical inferences obtained from Monte Carlo ensembles of numerical solutions and theoretical first-order perturbation results. It is found that while for Gaussian correlation of the log-conductivity field all the methods perform well, in the exponential case their accuracy deteriorates and, for large variance and number of modes, the benchmark problems are practically not solvable with reasonably large computing resources, for all the methods considered in this study.

Distance and Direction Codes Underlie Navigation of a Novel Semantic Space in the Human Brain.

A recent proposal posits that humans might use the same neuronal machinery to support the representation of both spatial and nonspatial information, organizing concepts and memories using spatial codes. This view predicts that the same neuronal coding schemes characterizing navigation in the physical space (tuned to distance and direction) should underlie navigation of abstract semantic spaces, even if they are categorical and labeled by symbols. We constructed an artificial semantic environment by parsing a bidimensional audiovisual object space into four labeled categories. Before and after a nonspatial symbolic categorization training, 25 adults (15 females) were presented with pseudorandom sequences of objects and words during a functional MRI session. We reasoned that subsequent presentations of stimuli (either objects or words) referring to different categories implied implicit movements in the novel semantic space, and that such movements subtended specific distances and directions. Using whole-brain fMRI adaptation and searchlight model-based representational similarity analysis, we found evidence of both distance-based and direction-based responses in brain regions typically involved in spatial navigation: the medial prefrontal cortex and the right entorhinal cortex (EHC). After training, both regions encoded the distances between concepts, making it possible to recover a faithful bidimensional representation of the semantic space directly from their multivariate activity patterns, whereas the right EHC also exhibited a periodic modulation as a function of traveled direction. Our results indicate that the brain regions and coding schemes supporting relations and movements between spatial locations in mammals are "recycled" in humans to represent a bidimensional multisensory conceptual space during a symbolic categorization task.SIGNIFICANCE STATEMENT The hippocampal formation and the medial prefrontal cortex of mammals represent the surrounding physical space by encoding distances and directions between locations. Recent works suggested that humans use the same neural machinery to organize their memories as points of an internal map of experiences. We asked whether the same brain regions and neural codes supporting spatial navigation are recruited when humans use language to organize their knowledge of the world in categorical semantic representations. Using fMRI, we show that the medial prefrontal cortex and the entorhinal portion of the hippocampal formation represent the distances and the movement directions between concepts of a novel audiovisual semantic space, and that it was possible to reconstruct, from neural data, their relationships in memory.

An Unconstrained and Effective Approach of Script Identification for Online Bilingual Handwritten Text

A number of monolingual online handwriting recognition (OHR) systems were proposed by researchers for languages like English, Chinese, Japanese, Hindi, Punjabi, Tamil, Bangla, Arabic and many more. But very few researchers have worked on bilingual or multilingual OHR systems, as the challenging part of these systems is the identification of scripts during recognition of intermixed words. In this paper, a bilingual OHR system is proposed for the mixed text containing words, written by using two scripts Gurmukhi (for Punjabi language) and Roman (for English language). For converting handwritten intermixed text to digital text, two steps have been implemented: first, to identify the script of segmented handwritten word and second, to run the respective script recognition engine. Multilayered perceptron neural network classifier along with directional code feature has been implemented to identify the script of segmented handwritten word. Considerable results have been observed for the script identification process.

Age estimation in human face by fractal directional code method

This paper reveals various constraints in digital way of estimating the age of human facial image. The age estimation involves analyzing the facial features and classifying the age in accordance to the extracted feature values. The biometric features such as the facial parts (eye, mouth, chin, forehead, hair), texture, color and shape provide essential aging details. In the proposed method, the fractal features are extracted using fractal directional code method to retain the significant details present in the input image. The fractal features along with the local features are used to train the system. The deep neural network with three layers is used to train the system. The scaled conjugate gradient back propagation trains the system and the age is classified into seven age groups (0–10, 11–19, 20–29, 30–39, 40–49, 50–59 and 60–69). Higher accuracy is achieved by concocting the biometric features and the fractal features.

Design of Differential Spatial Modulation Cooperative System Based on Complementary Code

The traditional differential spatial modulation (DSM) cooperative system overcomes the interference between the antennas by the orthogonality of direct sequence-code division multiple access spreading code. But the spreading sequences they used have the following undesirable properties: the non-zero sidelobes of auto-correlation functions will result in severe multi-path interference, and the non-zero values of cross-correlation functions will result in serious multiple access interference. In this paper, we propose a novel DSM cooperative system scheme to overcome this limitation. In our proposed scheme, the anti-interference characteristic of the system is improved by replacing the traditional spreading codes with complementary codes (CCs) at the transmitter. The DSM signal system constructed by using a multi-symbol dispersion matrix at the transmission relay end can improve the system transmission efficiency and avoid the channel interference. At the receiver, in order to reduce the high computational complexity of traditional maximum likelihood detection algorithm, a low-complexity detection algorithm based on the column search is proposed. The simulation results show that the bit error rate performance of DSM cooperative system based on the CC is superior to the traditional DSM cooperative system based on spreading codes. Meanwhile, the system performance with complete CCs is superior to that with the other CCs, and its implementation complexity is lower.