Orientation Selectivity

Three-dimensional (3D) electron microscopy (3DEM) aims at the determination of the spatial distribution of the Coulomb potential of macromolecular complexes. The 3D reconstruction of a macromolecule using single-particle techniques involves thousands of 2D projections. One of the key parameters required to perform such a 3D reconstruction is the orientation of each projection image as well as its in-plane orientation. This information is unknown experimentally and must be determined using image-processing techniques. We propose the use of wavelets to match the experimental projections with those obtained from a reference 3D model. The wavelet decomposition of the projection images provides a framework for a multiscale matching algorithm in which speed and robustness to noise are gained. Furthermore, this multiresolution approach is combined with a novel orientation selection strategy. Results obtained from computer simulations as well as experimental data encourage the use of this approach.

We applied suppression subtractive hybridization and mirror orientation selection to compare gene expression profiles of isolated Nicotiana tabacum cv SR1 zygotes and egg cells. Our results revealed that many differentially expressed genes in zygotes were transcribed de novo after fertilization. Some of these genes are critical to zygote polarity and pattern formation during early embryogenesis. This suggests that the transcriptome is restructed in zygote and that the maternal‐to‐zygotic transition happens before the first zygotic division, which is much earlier in higher plants than in animals. The expressed sequence tags used in this study provide a valuable resource for future research on fertilization and early embryogenesis.

Visual search for a line-element target differing sufficiently in orientation from a background of line elements can be performed rapidly, effortlessly, and without eye movements. There is, however, a response asymmetry: detection is better with an oblique target element in vertical or horizontal background elements than when these orientations are interchanged. If the underlying visual mechanisms also provide an input to the oculomotor system, then a similar asymmetry should be observed in eye-movement behaviour. To test this hypothesis, an experiment was undertaken in which eye movements were recorded while subjects searched for a line-element target in background of line elements; orientations were chosen from the range 0°, 30°, 60°, and 90°to the vertical. Data from three subjects showed that (1) latencies for the initial saccade, (2) angular errors in initial-saccade direction, and (3) manual response times depended similarly on the combination of target-and background-element orientations, performance being better for 30°or 60°targets in 0°or 90°backgrounds than vice-versa. The early orientation-selective mechanisms responsible for the rapid detection of oriented-line targets are probably the same as those providing signals for saccadic eye movements.

In the neocortex, inhibitory interneurons of the same subtype are electrically coupled with each other via dendritic gap junctions (GJs). The impact of multiple GJs on the biophysical properties of interneurons and thus on their input processing is unclear. The present experimentally based theoretical study examined GJs in L2/3 large basket cells (L2/3 LBCs) with 3 goals in mind: (1) To evaluate the errors due to GJs in estimating the cable properties of individual L2/3 LBCs and suggest ways to correct these errors when modeling these cells and the networks they form; (2) to bracket the GJ conductance value (0.05-0.25 nS) and membrane resistivity (10 000-40 000 Ω cm(2)) of L2/3 LBCs; these estimates are tightly constrained by in vitro input resistance (131 ± 18.5 MΩ) and the coupling coefficient (1-3.5%) of these cells; and (3) to explore the functional implications of GJs, and show that GJs: (i) dynamically modulate the effective time window for synaptic integration; (ii) improve t...

Inspired by optical recordings from visual cortex which show maps of orientation selectivity, and the finding that very similar patterns of population activity occur when the neurons fire spontaneously [T. Kenet, D. Bibitchkov, M. Tsodyks, A. Grinvald, A. Arieli, Spontaneously emerging cortical representations of visual attributes, Nature 425 (2003) 954-956], we approach the question of how the concept of cortical maps may be related to the concept of temporal coding. To this end we analyzed parallel spike recordings performed using a 10  10 electrode grid covering an area of 3:6 mm  3:6 mm of cat visual cortex for occurrence of spike correlation. We calculated all possible pairwise correlations between multi-unit activities (MUA) by cross-correlation and extracted significantly correlated pairs using a boot-strap procedure. The MUAs involved in correlated pairs were typically involved in more than a single correlated pair. Using methods of graph theory we found that the whole set of correlated MUAs decomposes into a small number of groups of MUAs that have a high degree of the overlap of mutually correlated pairs. Mapping these groups back onto the spatial arrangement of the recording electrodes revealed that these also correspond to spatially segregated clusters. The spatial scale of this correlation map is in agreement with the scale of orientation tuning maps found by optical imaging.

We present a complete mean field theory for a balanced state of a simple model of an orientation hypercolumn. The theory is complemented by a description of a numerical procedure for solving the mean-field equations quantitatively. With our treatment, we can determine self-consistently both the firing rates and the firing correlations, without being restricted to specific neuron models. Here, we solve the analytically derived mean-field equations numerically for integrate-and-fire neurons. Several known key properties of orientation selective cortical neurons emerge naturally from the description: Irregular firing with statistics close to -but not restricted to -Poisson statistics; an almost linear gain function (firing frequency as a function of stimulus contrast) of the neurons within the network; and a contrast-invariant tuning width of the neuronal firing. We find that the irregularity in firing depends sensitively on synaptic strengths. If Fano factors are bigger than 1, then they are so for all stimulus orientations that elicit firing. We also find that the tuning of the noise in the input current is the same as the tuning of the external input, while that for the mean input current depends on both the external input and the intracortical connectivity.

This paper systematically reviews the literature on international human resource management (IHRM) policies and practices of South Korean multinational enterprises (MNEs). It reveals that South Korean MNEs adopt an ethnocentric staffing approach, but are increasingly using more host-country nationals (HCNs). Korean MNEs pay great attention to language training for expatriates, and there is an emphasis on international experience when selecting expatriates. South Korean MNEs tend to adopt home-oriented selection procedures and criteria, performance appraisal and rewardand-compensation schemes for HCNs. A range of training and development programmes are provided to HCNs in order to develop more local managers. However, studies concerning IHRM of South Korean MNEs are scarce and only a few expatriaterelated IHRM issues have been empirically examined. As a result, how South Korean MNEs manage IHRM and what is the rationale of their IHRM policies and practices remain largely unknown. This review paper calls for more empirical research and discusses the implications for future research.

inwardly rectifying K+ current. Rod horizontal cells are larger with a flatter soma composed of three to five broad, radiating parts. Rod horizontal cells have a passive resistance of 6 to 10 Gohm. They have a simpler mixture of voltage-activated currents and lack both the voltage-dependent Na+ current and the inward rectifier.

We present a novel optical method for edge enhancement in color images based on the polarization properties of liquid-crystal displays (LCD). In principle, a LCD generates simultaneously two colorcomplementary, orthogonally polarized replicas of the digital image used as input. The currently viewed image in standard LCD monitors and cell phone's screens-which we will refer as the "positive image or true-color image"-is the one obtained by placing an analyzer in front of the LCD, in cross configuration to the back polarizer of the display. The orthogonally polarized replica of this image-the "negative image or complementarycolor image"-is absorbed by the front polarizer. In order to generate the positive and negative replica with a slight displacement between them, we used a LCD monitor whose analyzer (originally a linear polarizer) was replaced by a calcite crystal acting as beam displacer. When both images are superimposed laterally displaced across the image plane, one obtains an image with enhanced first-order derivatives along a specific direction. The proposed technique works under incoherent illumination and does not require precise alignment, and thus, it could be potentially useful for processing large color images in real-time applications. Validation experiments are presented.

The aim of this study was to investigate the development of visual callosal transfer in the normally reared cat. Two‐ to nine‐week‐old kittens and adults (used as controls) underwent section of the optic chiasm. Three days later, the animals were placed under anaesthesia and paralysed; unit activities were recorded from visual cortical areas 17 and 18 and from the white matter in one hemisphere. The units were tested for their responses to visual stimulation of each eye successively. Out of 1036 recorded neurons, 185 could be activated through the eye contralateral to the explored cortex via callosal transfer. Most of them could also be driven through the ipsilateral eye via the ‘direct’ geniculo‐cortical pathway. For animals aged ≤2 weeks, virtually all of these units were located at the 17/18 border zone, with a majority in the supragranular layers. When activated through the corpus callosum, they displayed receptive fields located either on the central vertical meridian of the vi...

Since the discovery of orientation selectivity by Hubel and Wiesel, the mechanisms responsible for this remarkable operation in the visual cortex have been controversial. Experimental studies over the past year have highlighted the contribution of feedforward thalamo-cortical afferents, as proposed originally by Hubel and Wiesel, but they have also indicated that this contribution alone is insufficient to account for the sharp orientation tuning observed in the visual cortex. Recent advances in understanding the functional architecture of local cortical circuitry have led to new proposals for the involvement of intracortical recurrent excitation and inhibition in orientation selectivity. Establishing how these two mechanisms work together remains an important experimental and theoretical challenge. no orientation selectivity [1,3-S]. Therefore, orientation selectivity must result either from the way the thalamic afferents connect to the cortical cells or from the cortico-cortical circuitry.

Simple cells in primary visual cortex are believed to extract local contour information from a visual scene. The 2D Gabor function (GF) model has gained particular popularity as a computational model of a simple cell. However, it shortcuts the LGN, it cannot reproduce a number of properties of real simple cells, and its effectiveness in contour detection tasks has never been compared with the effectiveness of alternative models. We propose a computational model that uses as afferent inputs the responses of model LGN cells with center-surround receptive fields (RFs) and we refer to it as a Combination of Receptive Fields (CORF) model. We use shifted gratings as test stimuli and simulated reverse correlation to explore the nature of the proposed model. We study its behavior regarding the effect of contrast on its response and orientation bandwidth as well as the effect of an orthogonal mask on the response to an optimally oriented stimulus. We also evaluate and compare the performances of the CORF and GF models regarding contour detection, using two public data sets of images of natural scenes with associated contour ground truths. The RF map of the proposed CORF model, determined with simulated reverse correlation, can be divided in elongated excitatory and inhibitory regions typical of simple cells. The modulated response to shifted gratings that this model shows is also characteristic of a simple cell. Furthermore, the CORF model exhibits cross orientation suppression, contrast invariant orientation tuning and response saturation. These properties are observed in real simple cells, but are not possessed by the GF model. The proposed CORF model outperforms the GF model in contour detection with high statistical confidence (RuG data set: p < 10 −4 , and

A 5-layer neuromorphic vision processor whose components communicate spike events asychronously using the address-eventrepresentation (AER) is demonstrated. The system includes a retina chip, two convolution chips, a 2D winner-take-all chip, a delay line chip, a learning classifier chip, and a set of PCBs for computer interfacing and address space remappings. The components use a mixture of analog and digital computation and will learn to classify trajectories of a moving object. A complete experimental setup and measurements results are shown.

Recent neurophysiological studies in alert monkeys have revealed that the parietal association cortex plays a crucial role in depth perception and visually guided hand movement.The following five classes of parietal neurons covering various aspects of these functions have been identified:(1) depth-selective visual-fixation (VF) neurons of the inferior parietal lobule (IPL), representing egocentric distance; (2) depth-movement sensitive (DMS) neurons of V5A and the ventral intraparietal (VIP) area representing direction of linear movement in 3-D space; (3) depth-rotation-sensitive (RS) neurons of V5A and the posterior parietal (PP) area representing direction of rotary movement in space; (4) visually responsive manipulation-related neurons (visual-dominant or visual-and-motor type) of the anterior intraparietal (AIP) area, representing 3-D shape or orientation (or both) of objects for manipulation; and (5) axis-orientation-selective (AOS) and surface-orientation-selective (SOS) neurons in the caudal intraparietal sulcus (cIPS) sensitive to binocular disparity and representing the 3-D orientation of the longitudinal axes and flat surfaces, respectively. Some AOS and SOS neurons are selective in both orientation and shape.Thus the dorsal visual pathway is divided into at least two subsystems,V5A, PP and VIP areas for motion vision and V6, LIP and cIPS areas for coding position and 3-D features.The cIPS sends the signals of 3-D features of objects to the AIP area, which is reciprocally connected to the ventral premotor (F5) area and plays an essential role in matching hand orientation and shaping with 3-D objects for manipulation.

This paper examines the interaction between first-and second-order contours in the orientation domain. Using the simultaneous tilt illusion (TI), we show that the apparent rotation of a vertical test grating away from that of a surrounding inducing grating (repulsion effect) occurs when both the inducing and test grating are either first-or second-order. Furthermore, a significant repulsion effect is obtained when a first-order inducing grating surrounds a second-order test. If lateral inhibitory interactions between populations of orientation selective neurons provides a plausible explanation for orientation repulsion effects [Blakemore, C. B. Carpenter, R. H. S. & Georgeson, M. A. (1970) Nature, 228, 37-39], it is likely that the cue-invariant mechanisms that encodes the orientation of first-and second-order contours also exhibit inhibitory interactions. A two-channel computational model of orientation encoding is presented where one channel encodes only first-order stimuli while the second channel encodes both first-and second-order contours. In addition to predicting the orientation repulsion effects we observed, the model also provides a functional account of orientation attraction effects in terms of the responses of populations of orientation-tuned neurons.

Motion in the visual scene is processed by direction-selective neurons in primary visual cortex. These cells receive inputs that differ in space and time. What are these inputs? A previous single-unit recording study in anesthetized monkey V1 proposed that the two major streams arising in the primate retina, the M and P pathways, differed in space and time as required to create direction selectivity. We confirmed that cortical cells driven by P inputs tend to have sustained responses. The M pathway, however, as assessed by recordings in layer 4C␣ and from cells with high contrast sensitivity, is not purely transient. The diversity of timing in the M stream suggests that combinations of M inputs, as well as of M and P inputs, create direction selectivity.

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This article was published in an Elsevier journal. The attached copy is furnished to the author for non-commercial research and education use, including for instruction at the author's institution, sharing with colleagues and providing to institution administration. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit:

Objectives This study evaluated factors associated with vertical root fracture in endodontically treated teeth, using a cone-beam computed tomography (CBCT) image database. Materials and methods The sample for this case-control study consisted of 81 CBCT scans of teeth with vertical root fracture (VRF) and 81 CBCT scans of non-fractured teeth, matched by age, sex, and tooth position. The analyzed variables included dentin thickness, an intraradicular post, an adjacent implant, and a missing adjacent tooth. Student's t test test was used to compare the quantitative variables. The chi-square test was used to compare the categorical variables. Logistic regression was performed to evaluate the association between the presence of VRF and the independent factors assessed. Results The mean dentin thickness of fractured teeth was 1.3 mm, whereas that of non-fractured ones was 1.5 mm (p < 0.001). There was no difference between the fractured and non-fractured groups, regarding implant frequency or missing adjacent tooth (p > 0.05). There were a significantly larger number of teeth with posts in the fractured versus non-fractured group (p = 0.007). However, dentin thickness ≤ 1.3 mm was the only factor associated with VRF in the multiple regression model (OR = 3.60, 95%CI = 1.76-7.37). Conclusions Dentin thickness may influence the development of VRF. Dentin thickness ≤ 1.3 mm is associated with a greater likelihood of fracture than ≥ 1.4 mm. Clinical relevance This study suggests there may be a minimum amount of safe dentin thickness that should be preserved after endodontic instrumentation.

In normal observers preadaptation to a parallel grating increases the contrast threshold for a line whereas a perpendicular grating has no effect. Such orientation selectivity was not found in the amblyopic eye of two out of five squinters. Only a weak after-effect produced with a grating parallel to the line was obtained in the good eye of four of the amblyopes while all of them show an abnormal threshold reduction following adaptation to a perpendicular grating. This suggests a relationship between abnormal binocular interaction during visual development and the organization of orientational mechanisms but does not explain the loss of visual acuity in amblyopia.

Curvelet transform is a promising tool for multi-resolution analysis on images. This paper explains a new approach for facial expression recognition based on curvelet features extracted using curvelet transform. Curvelet transform is applied on the database images and curvelet coefficients are obtained for selected scale for image analysis. Facial curvelet features are compressed using singular value decomposition (SVD) approach. Back propagation neural network (BPNN) and Adaptive Neuro-Fuzzy Inference System (ANFIS) are used as classifiers for classifying expressions into one of the seven categories like angry, disgust, fear, happy, neutral, sad and surprise. Experimentation is carried out on JAFFE database. The experimental results show that the novel approach is a better option for extracting feature values and classifying facial expressions.

There are inadequate data or reviews to confirm the reliability and efficacy of cone-beam computed tomography (CBCT) in evaluation of vertical root fractures (VRFs). Thus, the aim of this mini review is to discover the reliability and efficacy of CBCT in the evaluation of VRFs and prove CBCT as a picturing addition in the different aspects of VRFs.

Simultaneous presentation of multiple stimuli can reduce the firing rates of neurons in extrastriate visual cortex below the rate elicited by a single preferred stimulus. We describe computational results suggesting how this remarkable effect may arise from strong excitatory drive to a substantial local population of fast-spiking inhibitory interneurons, which can lead to a loss of coherence in that population and thereby raise the effectiveness of inhibition. We propose that in attentional states fast-spiking interneurons may be subject to a bath of inhibition resulting from cholinergic activation of a second class of inhibitory interneurons, restoring conditions needed for gamma rhythmicity. Oscillations and coherence are emergent features, not assumptions, in our model. The gamma oscillations in turn support stimulus competition. The mechanism is a form of “oscillatory selection,” in which neural interactions change phase relationships that regulate firing rates, and attention sh...

Purpose: This study compared the diagnostic accuracy of cone-beam computed tomography (CBCT) scans obtained with 2 CBCT systems with high-and low-resolution modes for the detection of root perforations in endodontically treated mandibular molars. Materials and Methods: The root canals of 72 mandibular molars were cleaned and shaped. Perforations measuring 0.2, 0.3, and 0.4 mm in diameter were created at the furcation area of 48 roots, simulating strip perforations, or on the external surfaces of 48 roots, simulating root perforations. Forty-eight roots remained intact (control group). The roots were filled using gutta-percha (Gapadent, Tianjin, China) and AH26 sealer (Dentsply Maillefer, Ballaigues, Switzerland). The CBCT scans were obtained using the NewTom 3G (QR srl, Verona, Italy) and Cranex 3D (Soredex, Helsinki, Finland) CBCT systems in high-and low-resolution modes, and were evaluated by 2 observers. The chisquare test was used to assess the nominal variables. results: In strip perforations, the accuracies of low-and high-resolution modes were 75% and 83% for NewTom 3G and 67% and 69% for Cranex 3D. In root perforations, the accuracies of low-and high-resolution modes were 79% and 83% for NewTom 3G and was 56% and 73% for Cranex 3D. conclusion: The accuracy of the 2 CBCT systems was different for the detection of strip and root perforations. The Cranex 3D had non-significantly higher accuracy than the NewTom 3G. In both scanners, the high-resolution mode yielded significantly higher accuracy than the low-resolution mode. The diagnostic accuracy of CBCT scans was not affected by the perforation diameter.

Several researchers have used image enhancement methods to reduce detection errors and increase verification accuracy in palmprint identification. Divergent opinions exist among experts regarding the best method of image filtering to improve image palmprint recognition. Because of the unique characteristics of palmprints and the difficulties in preventing counterfeiting, image-filtering techniques are the subject of this current research. Researchers hope to create the best biometric system possible by utilizing various techniques. These techniques include image enhancement, Gabor orientation scales, dimension reduction techniques, and appropriate matching strategies. This study investigates how different filtering approaches might be combined to improve images. The palmprint identification system uses a 3W filter, which combines wavelet, Wiener, and weighted filters. Optimizing results entails coordinating the 3W filter with Gabor orientation scales, matching processes, and dimension reduction methods. The research shows that accuracy may be considerably increased using a 3W filter with a Gabor orientation scale of [8 × 7], the kernel principal component analysis (KPCA) dimension reduction methodology, and a cosine matching method. Specifically, a value of 99.722% can be achieved. These results highlight the importance of selecting appropriate settings and techniques for palmprint recognition systems. This is an open access article under the CC BY-SA license.

Classic models of primary visual cortex (V1) reproduce orientation selectivity with sufficiently high accuracy. However, they are unable to explain phenomena that are widely studied experimentally: a single cell carry additional information in response waveform and oscillations. Among the other effects not reproduced by the classic models are changes in the peak orientation during the response time course and shifts induced by inhibition blockage. We suppose that the main reason for such a failure is assumption that spatial distribution of short-range horizontal connections in V1 is symmetric. In the present study, we provide an experimental evidence that such symmetry is not the case in higher mammals. Based on this evidence we improved the classical model of V1 by replacing the symmetric spatial distribution to another one revealed from experiments. The improved model is able to reproduce orientation shifts and transmission of additional information. This means that the asymmetry shall take into consideration when simulating V1.

Prolonged exposure to an oriented line shifts the perceived orientation of a subsequently observed line in the opposite direction, a phenomenon known as the tilt aftereffect (TAE). Here we consider whether the TAE for line stimuli is mediated by a mechanism that integrates the local parts of the line into a single global entity prior to the site of adaptation, or the result of the sum of local TAEs acting separately on the parts of the line. To test between these two alternatives we used the fact the TAE transfers almost completely across luminance contrast polarity [1]. We measured the TAE using adaptor and test lines that (1) either alternated in luminance polarity or were of a single polarity, and (2) either alternated in local orientation or were of a single orientation. We reasoned that if the TAE was agnostic to luminance polarity and was partsbased, we should obtain large TAEs using alternating-polarity adaptors with single-polarity tests. However we found that (i) TAEs using one-alternating-polarity adaptors with all-white tests were relatively small, increased slightly for two-alternatingpolarity adaptors, and were largest with all-white or all-black adaptors. (ii) however TAEs were relatively large when the test was one-alternating polarity, irrespective of the adaptor type. (iii) The results with orientation closely mirrored those obtained with polarity with the difference that the TAE transfer across orthogonal orientations was weak. Taken together, our results demonstrate that the TAE for lines is mediated by a global shape mechanism that integrates the parts of lines into whole prior to the site of orientation adaptation. The asymmetry in the magnitude of TAE depending on whether the alternating-polarity lines was the adaptor or test can be explained by an imbalance in the population of neurons sensitive to 1 stand 2 nd-order lines, with the 2 nd-order lines being encoded by a subset of the mechanisms sensitive to 1 st-order lines.

The present study reports the microstructure evolution in multicomponent Al-Ni-X (X = Fe, Cr) alloys. The X-ray diffraction characterization technique and electron microscope attached with energy-dispersive spectroscopic analysis have been used to understand the structural and microstructural evolution in the present multicomponent Al-Ni-X (X = Fe, Cr) alloys. Al 98.6-Ni 0.5 Fe 0.9 alloy shows the presence of (Al) ss , Al 3 Fe and Al 9 FeNi phases. It is observed that the microstructure of Al-Ni-Fe alloy shows the existence of primary dendritic phase of (Al) ss and two eutectics (i.e. globular eutectic: L ? (Al) ss ? Al 3 Fe and lamellar eutectic: L ? (Al) ss-? Al 9 FeNi). Al-Ni-Fe alloy shows superb compressive strength (* 200 MPa) and plasticity (* 70%) at room temperature, while the microstructure of multicomponent Al 92 Ni 4 Cr 4 alloy exhibits the presence of dendritic phases of Al 7 Cr and Al 3 Ni plus ternary eutectic (i.e. L ? (Al) ss-? Al 3 Ni ? Al 7 Cr). Al-Ni-Cr alloy shows good room temperature ultimate compressive strength (* 300 MPa) and plasticity (* 50%). It is important to note that there is no fracture during mechanical testing of investigated Al-Ni-X (X = Fe, Cr) alloys. Keywords Al-based alloys Á SEM Á XRD Á Microstructural evolution Á Mechanical properties & Sandeep Jain

Crystal growth has been recognized as a paradigm for non-equilibrium pattern formation for decades. Scientific interest in this field has focused on the growth rates and curvature of branches in snowflake-like structures patterned after a solid's crystallographic orientations. In reality, there exists a much richer variety of crystal patterns in nature. Investigations of dendritically solidifying alloys reveals structures that continuously change orientation between different growth directions, some of which are not along preferred crystallographic directions. The selection mechanism of such patterns is poorly understood. In this paper we demonstrate computationally and experimentally that a material's surface tension anisotropy can compete with anisotropies present in processing conditions during solidification to produce a continuous transition from dendritic to seaweed and fractal-like structures. The phase space of such morphologies is characterized and the selection principles of the various morphologies explored are explained. These results have direct relevance to microstructure formation in commercial lightweight metal castings.

proposed in 1980 simultaneously by Daugman (9) in two-dimensional form and by Marcelja (lo) in one- This paper describes a neural network which detects dimensional form. the edges of different orientation and spatial frequency Watson (ll) proposed a cortex transform which in an image. The proposed neural network is useful for maps an image into a set of image that

The high surface area and porosity, and limitless compound and network combinations between the metal ions and organic ligands making up metal–organic frameworks (MOFs) offer tremendous opportunities for their use in many applications. While numerous methods have been proposed for the synthesis of MOF powders, it is often difficult to obtain oriented crystals with these techniques. Further, the need for additional post-synthesis steps to activate the crystals and release them from the substrate presents a considerable production challenge. Here, we report an acoustically-driven microcentrifugation platform that facilitates fast convective solutal transport, allowing the synthesis of MOF crystals in as short as five minutes. The crystals are not only oriented due to long-range out-of-plane superlattice ordering aided by molecular dipole polarization under the acoustoelectric coupling, but also simultaneously activated during the synthesis process.

1. Eleven kittens were deprived of vision in one eye until the age of between 5 and 14 weeks. Their eyes were then reverse‐sutured, they were allowed to survive for a further 3‐63 days, and their brains were then examined histologically. 2. Measurement of the cross‐sectional area of cells in the lateral geniculate nucleus (LGN) showed that when the reversal of lid suture was performed at the age of 8 or 14 weeks, the mean cell size was smaller in laminae connected to the initially closed right eye than it was in other laminae. 3. When the reversal of lid suture took place at 5 or 6 weeks of age there was a reversal of interlaminar size differences: the initially deprived eye was then connected to laminae containing larger cells. Even within 3 days after the reversal of lid suture, most of the morphological effects of the initial suture had been abolished, and they were fully reversed within 12 days. 4. These results are compared with physiological changes in the visual cortex of the...

To combat retinal degeneration, healthy fetal retinal sheets have been successfully transplanted into both rodent models and humans, with synaptic connectivity between transplant and degenerated host retina having been confirmed. In rodent studies, transplants have been shown to restore responses to flashes of light in a region of the superior colliculus corresponding to the location of the transplant in the host retina. To determine the quality and detail of visual information provided by the transplant, visual responsivity was studied here at the level of visual cortex where higher visual perception is processed. For our model, we used the transgenicRho-S334ter line-3rat (both sexes), which loses photoreceptors at an early age and is effectively blind at postnatal day 30. These rats received fetal retinal sheet transplants in one eye between 24 and 40 d of age. Three to 10 months following surgery, visually responsive neurons were found in regions of primary visual cortex matching...

In the presented paper, the face images modeling in different circumstances such as occlusion, poses, and illumination was investigated. A novel research based on a new combination of the discrete wavelet transform (DWT) and wavelet packet (WP) methods in conjunction with log energy and sure entropies is proposed. Probabilistic neural network (PNN) was used for classification. The performance of the proposed method was investigated using a collection of experiments with different challenges ORL face database and extended Yale face database was conducted. For testing the proposed face recognition system on the ORL database, many classification scores were calculated for different training/testing sets. The comparative results obtained on the ORL database for different published methods based on the efficiency were performed and showed that our method was superior with rate reached 98.5% and relatively small, elapsed time about 4.4 sec was found. For the extended Yale face database B,...

We present a series of calculations for the scattering of an oriented NO beam from a silver surface. The potential energy surface chosen was empirically determined to reproduce the scattering of non-oriented beams and has been used in several previous theoretical studies. Surface motion is included in the calculation by coupling this potential to an Einstein oscillator representing a surface atom. Scattering simulations are presented using (i) the split operator method for fully quantum dynamics, (ii) the semiclassical Gaussian method and (iii) classical mechanics. Results obtained using the various methods are contrasted. The main effect occurring as a consequence of including surface motion is an overall downshifting of the features in the rotational distributions to lower energies. This occurs for oriented and non-oriented beams. The previously found anticorrelation between the energy transferred into molecular rotation and that put into the surface is found and discussed in the light of these new calculations.

Transport processes around phase interfaces, together with thermodynamic properties and kinetic phenomena, control the formation of dendritic patterns. Using the thermodynamic and kinetic data of phase interfaces obtained on the atomic scale, one can analyse the formation of a single dendrite and the growth of a dendritic ensemble. This is the result of recent progress in theoretical methods and computational algorithms calculated using powerful computer clusters. Great benefits can be attained from the development of micro-, meso- and macro-levels of analysis when investigating the dynamics of interfaces, interpreting experimental data and designing the macrostructure of samples. The review and research articles in this theme issue cover the spectrum of scales (from nano- to macro-length scales) in order to exhibit recently developing trends in the theoretical analysis and computational modelling of dendrite pattern formation. Atomistic modelling, the flow effect on interface dynam...

Purpose: This study compared the accuracy of detection of incomplete vertical root fractures (VRFs) in filled and unfilled teeth on cone-beam computed tomography images with and without a metal artefact reduction (MAR) algorithm. Materials and Methods: Forty single-rooted maxillary premolars were selected and, after endodontic instrumentation, were categorized as unfilled teeth without fractures, filled teeth without fractures, unfilled teeth with fractures, or filled teeth with fractures. Each VRF was artificially created and confirmed by operative microscopy. The teeth were randomly arranged, and images were acquired with and without the MAR algorithm. The images were evaluated with OnDemand software (Cybermed Inc., Seoul, Korea). After training, 2 blinded observers each assessed the images for the presence and absence of VRFs 2 times separated by a 1-week interval. P-values<0.05 were considered to indicate significance. Results: Of the 4 protocols, unfilled teeth analysed with the MAR algorithm had the highest accuracy of incomplete VRF diagnosis (0.65), while unfilled teeth reviewed without MAR were associated with the least accurate diagnosis (0.55). With MAR, an unfilled tooth with an incomplete VRF was 4 times more likely to be identified as having an incomplete VRF than an unfilled tooth without this condition, while without MAR, an unfilled tooth with an incomplete VRF was 2.28 times more likely to be identified as having an incomplete VRF than an unfilled tooth without this condition. Conclusion: The use of the MAR algorithm increased the diagnostic accuracy in the detection of incomplete VRF on images of unfilled teeth.

Human observers are exquisitely sensitive to tilt in the orientation of a line. We can detect rotations away from the vertical of 0.5°. It has been suggested [1,2] that this accuracy is a result of the orientation-selectivity of simple cells in the primary visual cortex (V1), many of which have receptive fields with an elliptical shape [3]. However, it is possible to sense the tilt of many stimuli that are unlikely to have their tilt directly encoded by such cells. For example, a garment such as a tie with diagonal stripes would predominantly stimulate cells in V1 tuned to an orientation of the stripes; yet we could tell whether or not the garment as a whole was tilted from the vertical. The perception of oriented textures is subject to systematic errors, however. A striking example is the Fraser 'twisted cord' illusion (Figure 1) in which we see the global orientation of the horizontal texture-defined lines as being tilted in the direction of its locally tilted segments. If the component segments are at a larger angle (30°) to the global orientation, on the other hand, the perceived shift is in the opposite direction. We have measured these effects psychophysically, and we propose a model in which second-order orientation units receive excitation from V1 units of similar orientation, but inhibition from V1 units of dissimilar orientation. Our model correctly predicts that making the textures different in average brightness from the background will reduce the illusions.

Offprint requests to. M.G.P. Rosa bution of neurons with different degrees of OD in V1 is qualitatively similar in New-and Old World monkeys of similar sizes and suggest that common ancestry, rather than parallel evolution, may account for the OD phenotypes of contemporaneous simians.

Responses of neurons in the superior colticuli and visual cortex of rabbits to a black and white boundary moving in different directions were investigated. Neurons responding clearly to presentation of the black and white boundary moving in one direction (movement in the opposite direction led to inhibition of spontaneous activity) and neurons giving well-defined maximal responses to movement of this boundary in 2 or 3 directions were found in the superior colliculi. Neurons with a marked maximal response to the stimulus moving in 1 or 2 directions were found in the visual cortex. Nembutal has a powerful effect on the quantitative detector properties of visual cortical neurons and sometimes may completely inhibit unit activity.