Second-order Patterns Research Articles

Anyon optics with time-of-flight two-particle interference of double-well-trapped interacting ultracold atoms

The subject of bianyon interference with ultracold atoms is introduced through theoretical investigations pertaining to the second-order momentum correlation maps of two anyons (built upon spinless and spin-1/2 bosonic, as well as spin-1/2 fermionic ultracold atoms) trapped in a double-well optical trap. The two-particle system is modeled according to the recently proposed protocols for emulating an anyonic Hubbard Hamiltonian in ultracold-atom one-dimensional lattices. Because the second-order momentum correlations are mirrored in the time-of-flight second-order interference patterns in space, our findings provide impetus for time-of-flight experimental protocols for detecting anyonic statistics via interferometry measurements of massive particles that broaden the scope of the biphoton interferometry of quantum optics.

Hourly time series model in drowning-induced mortality in Guilan and Mazandaran provinces

Background: Drowning is considered a major health problem in the world. According to World Health Organization statistics, drowning is one of the 10 main causes of death in the age range of 1-24 years in each region, and the third cause of death resulted from unintentional injuries in the world. The purpose of the study is to analyze drowning peak hours to help promote prevention policies. Methods: The present study used drowning data of Guilan and Mazandaran provinces in summer. The study model was estimated using a semi-panel non-linear Poisson regression model. The number of deaths was sorted according to the hours of drowning in three years 2014, 2015, and 2016. Finally, the predicted graphs of the hours of mortality and the regression model were estimated. Results: The regression model showed that the relationship between daytime hours and drowning mortality had a second-order pattern. The mortality increases during daytime hours, then it decreases. The IRR of time variable was 2.66 and significant, indicating a mean growth of 266% per pass of each hour of daytime. The hourly second-order IRR was 0.9689 and significant, indicating a decreasing hourly rate of drowning. The predicted peak point of drowning was at 15 o'clock. Conclusions: The study showed drowning peak time occurs at noon when it is warming and the swimmer may be neglected. Therefore, we can educate and made the society, especially parents, aware of the issue to help prevent and reduce the frequency of drowning.

Is the straddle effect in contrast perception limited to second-order spatial vision?

Previous work on the straddle effect in contrast perception (Foley, 2011; Graham & Wolfson, 2007; Wolfson & Graham, 2007, 2009) has used visual patterns and observer tasks of the type known as spatially second-order. After adaptation of about 1 s to a grid of Gabor patches all at one contrast, a second-order test pattern composed of two different test contrasts can be easy or difficult to perceive correctly. When the two test contrasts are both a bit less (or both a bit greater) than the adapt contrast, observers perform very well. However, when the two test contrasts straddle the adapt contrast (i.e., one of the test contrasts is greater than the adapt contrast and the other is less), performance drops dramatically. To explain this drop in performance—the straddle effect—we have suggested a contrast-comparison process. We began to wonder: Are second-order patterns necessary for the straddle effect? Here we show that the answer is “no”. We demonstrate the straddle effect using spatially first-order visual patterns and several different observer tasks. We also see the effect of contrast normalization using first-order visual patterns here, analogous to our prior findings with second-order visual patterns. We did find one difference between first- and second-order tasks: Performance in the first-order tasks was slightly lower. This slightly lower performance may be due to slightly greater memory load. For many visual scenes, the important quantity in human contrast processing may not be monotonic with physical contrast but may be something more like the unsigned difference between current contrast and recent average contrast.

Sucrose challenges to Streptococcus mutans biofilms and the curve fitting for the biofilm changes.

The relationship between sugar level and development of dental caries has long been a main topic in dentistry. However, as a ubiquitous component of the modern diet, sucrose is mainly derived from three meals a day, rather than a long time exposure. In this study, various concentrations of sucrose were provided to Streptococcus mutans biofilms for 1 h per exposure (three times per day) to imitate a human meal pattern. And then the relationship between sucrose concentration and changes in the treated biofilms was determined. The results indicated that the components and acid production of the treated biofilms changed in a second-order polynomial curve pattern with sucrose concentration increase, which were confirmed by CLSM and SEM analyses. However, gene expression related to extracellular polysaccharides (EPS) formation, acid production and tolerance was up-regulated with sucrose concentration increase, which might have been due to compensation for the decrease in EPS formation and acid production by the biofilms at higher concentrations of sucrose. These findings suggest that sucrose in the range of 1%-5% can support the highest acid production and accumulation of S. mutans biofilms, which may further increase its cariogenic potential. However, additional studies are required to confirm the relationships in human cariogenic biofilms.

The role of consolidation in learning context-dependent phonotactic patterns in speech and digital sequence production

Speakers implicitly learn novel phonotactic patterns by producing strings of syllables. The learning is revealed in their speech errors. First-order patterns, such as "/f/ must be a syllable onset," can be distinguished from contingent, or second-order, patterns, such as "/f/ must be an onset if the vowel is /a/, but a coda if the vowel is /o/." A metaanalysis of 19 experiments clearly demonstrated that first-order patterns affect speech errors to a very great extent in a single experimental session, but second-order vowel-contingent patterns only affect errors on the second day of testing, suggesting the need for a consolidation period. Two experiments tested an analogue to these studies involving sequences of button pushes, with fingers as "consonants" and thumbs as "vowels." The button-push errors revealed two of the key speech-error findings: first-order patterns are learned quickly, but second-order thumb-contingent patterns are only strongly revealed in the errors on the second day of testing. The influence of computational complexity on the implicit learning of phonotactic patterns in speech production may be a general feature of sequence production.

Analysis of Second-Order Pattern of Proton NMR Spectrum of 1,3-Dichloro-2-nitrobenzene

Abstract The analysis of a second-order pattern on a proton NMR spectrum is proposed using a multi field NMR measurement, a spectral simulation, a DFT calculation and a solvent effect study. The ordinary 9.4 T proton NMR measurement of 1,3-dichloro-2-nitrobenzene in organic solvents gave the AB2 spectrum showing the second-order pattern. The higher field, 14.1 T proton NMR measurement gave the spectrum close to the AX2 showing the first-order pattern with a little roofing. Then the peak assignments were confirmed by the spectral simulation using the NMR parameters obtained from each experimental spectra. Finally, the NMR parameters are discussed from the results of the DFT calculation and the solvent effect study.

Jumping and Refined Local Pattern for Texture Classification

The local binary pattern (LBP) model is a simple and effective method of texture classification, but it is sensitive to rotational and noisy images. Although many variants of LBP are proposed by scholars, there are still several urgent problems, such as poor noise and rotation immunity. In this paper, we propose a robust texture descriptor, jumping and refined local pattern (JRLP) for texture classification. In particular, we first extract jumping local difference count pattern (JLDCP) consisting of second-order difference count pattern and diagonal difference count pattern to represent the jumping information in a local domain. To capture the detail information left by JLDCP, we extract a refined completed LBP (RCLBP). By concatenating the JLDCP and RCLBP, we build a JRLP-based robust texture descriptor for classification. Experimental results on four representative texture databases (Brodatz, CUReT, UIUC, and VisTex) reveal that our proposed texture classification method is effective and robust for noise, rotation, scale, and illumination variants and outperforms six representative methods.

Physical and biogeochemical controls on soil respiration along a topographical gradient in a semiarid forest

Soil respiration is a dynamic and fundamental process across all terrestrial ecosystems. However, how physical and biogeochemical factors control seasonal variation and annual rates of soil respiration remains poorly understood. A topographical gradient in a semiarid forest was chosen as the study site to assess how both biogeochemical and physical factors control respiration rates. Parameters measured include soil respiration, litterfall, fine root biomass, soil physical and chemical properties, soil bacteria and archaea gene abundance, ectomycorrhizal fungi abundance and richness, and soil carbon isotope signatures. The results showed that increases in soil temperature and moisture exponentially and linearly promoted root activity, driving seasonal variation of total soil respiration. Seasonal variation of heterotrophic respiration was driven by soil moisture in a second-order polynomial pattern. Autotrophic respiration only contributed to 20% of the total soil respiration, and seasonal variation in the soil respiration rate was driven by heterotrophic respiration. Utilizing soil moisture as a scalar, the values of Q10 and R10 in different poisons on the slope indicated soil respiration was controlled by interaction of soil temperature and moisture, and a new transformation of the R10 function inducing soil moisture was proposed. Along the topographical gradient, the long-term average soil temperature and moisture significantly varied from the top to the bottom of a slope. This variation in physical processes induced differences in plant productivity and biomass accumulation, leading to varying organic matter accumulation across the gradient. The topographical position also induced differences in the size of the soil organic matter aggregates, archaea and bacteria gene abundances, and ectomycorrhizal fungi abundance and richness. The aforementioned parameters are interrelated due to their association with the long-term average soil temperature and moisture, and the interrelation of these parameters ultimately affects annual rates of soil respiration.

Local derivative pattern for action recognition in depth images

This paper proposes a new local descriptor for action recognition in depth images using second-order directional Local Derivative Patterns (LDPs). LDP relies on local derivative direction variations to capture local patterns contained in an image region. Our proposed local descriptor combines different directional LDPs computed from three depth maps obtained by representing depth sequences in three orthogonal views and is able to jointly encode the shape and motion cues. Moreover, we suggest the use of Sparse Coding-based Fisher Vector (SCFVC) for encoding local descriptors into a global representation of depth sequences. SCFVC has been proven effective for object recognition but has not gained much attention for action recognition. We perform action recognition using Extreme Learning Machine (ELM). Experimental results on three public benchmark datasets show the effectiveness of the proposed approach.

Experimental realization and characterization of an electronic Lieb lattice.

Geometry, whether on the atomic or nanoscale, is a key factor for the electronic band structure of materials. Some specific geometries give rise to novel and potentially useful electronic bands. For example, a honeycomb lattice leads to Dirac-type bands where the charge carriers behave as massless particles [1]. Theoretical predictions are triggering the exploration of novel 2D geometries [2–10], such as graphynes, Kagomé and the Lieb lattice. The latter is the 2D analogue of the 3D lattice exhibited by perovskites [2]; it is a square-depleted lattice, which is characterised by a band structure featuring Dirac cones intersected by a flat band. Whereas photonic and cold-atom Lieb lattices have been demonstrated [11–17], an electronic equivalent in 2D is difficult to realize in an existing material. Here, we report an electronic Lieb lattice formed by the surface state electrons of Cu(111) confined by an array of CO molecules positioned with a scanning tunneling microscope (STM). Using scanning tunneling microscopy, spectroscopy and wave-function mapping, we confirm the predicted characteristic electronic structure of the Lieb lattice. The experimental findings are corroborated by muffin-tin and tight-binding calculations. At higher energies, second-order electronic patterns are observed, which are equivalent to a super-Lieb lattice.

Second-order temporal interference of two independent light beams at an asymmetrical beam splitter**Project supported by the National Natural Science Foundation of China (Grant No. 11404255), the Doctor Foundation of Education Ministry of China (Grant No. 20130201120013), the Programme of Introducing Talents of Discipline to Universities, China (Grant No. B14040), and the Fundamental Research Funds for the Central Universities, China.

The second-order temporal interference of classical and nonclassical light at an asymmetrical beam splitter is discussed based on two-photon interference in Feynman’s path integral theory. The visibility of the second-order interference pattern is determined by the properties of the superposed light beams, the ratio between the intensities of these two light beams, and the reflectivity of the asymmetrical beam splitter. Some requirements about the asymmetrical beam splitter have to be satisfied in order to ensure that the visibility of the second-order interference pattern of nonclassical light beams exceeds the classical limit. The visibility of the second-order interference pattern of photons emitted by two independent single-photon sources is independent of the ratio between the intensities. These conclusions are important for the researches and applications in quantum optics and quantum information when an asymmetrical beam splitter is employed.

Phase-Dependent Interactions in Visual Cortex to Combinations of First- and Second-Order Stimuli.

Many visual cortex neurons exhibit orientation-selective responses to boundaries defined by differences either in luminance or in texture contrast. Previous studies have examined responses to either type of boundary in isolation, but here we measured systematically responses of cortical neurons to the spatial relationship between superimposed periodic luminance-modulated (LM) and contrast-modulated (CM) stimuli with contrasts adjusted to give equated responses. We demonstrate that neuronal responses to these compound stimuli are highly dependent on the relative phase between the LM and CM components. Diversity in the degree of such phase dependence could help to disambiguate different kinds of boundaries in natural scenes, for example, those arising from surface reflectance changes or from illumination gradients such as shading or shadows.

BSD: Blind image quality assessment based on structural degradation

Research in biological vision and neurology has evidenced that there are separate mechanisms in human visual cortex to process the first- and second-order patterns. Image structures detected by a linear filter are the first-order patterns which describe luminance changes, while patterns that are invisible to linear filters are often referred as the second-order structures. In this paper, we propose a general-purpose blind image quality assessment (BIQA) method by taking account of both the first- and second-order image structures. Specifically, the Prewitt linear filters are used to extract first-order image structures and the local contrast normalization is employed to extract second-order image structures. Perceptual features are extracted from these two image structural maps and used as the input to a support vector regression to model the nonlinear relationship between feature space to human opinion score. Extensive experiments on five image databases manifest the outstanding performance of the proposed method compared to the relevant state-of-the-art BIQA methods.

Second-order interference of two independent and tunable single-mode continuous-wave lasers**Project supported by the National Natural Science Foundation of China (Grant No. 11404255) and the Doctor Foundation of Education Ministry of China (Grant No. 20130201120013).

The second-order temporal interference of two independent single-mode continuous-wave lasers is discussed by employing two-photon interference in Feynman’s path integral theory. It is concluded that whether the second-order temporal interference pattern can or cannot be retrieved via two-photon coincidence counting rate is dependent on the resolution time of the detection system and the frequency difference between these two lasers. Two identical and tunable single-mode continuous-wave diode lasers are employed to verify the predictions. These studies are helpful to understand the physics of two-photon interference with photons of different spectra.

Studying the optical second-order interference pattern formation process with classical light in the photon counting regime.

The formation process of the second-order interference pattern is studied experimentally in the photon counting regime by superposing two independent single-mode continuous-wave lasers. Two-photon interference based on the superposition principle in Feynman's path integral theory is employed to interpret the experimental results. The second-order interference pattern of classical light can be formulated when, with high probability, there are only two photons in the interferometer at one time. The studies are helpful in understanding the second-order interference of classical light in the language of photons. The method and conclusions can be generalized to the third- and higher-order interference of light and interference of massive particles.

First- and Second-Order Stimuli Reaction Time Measures Are Highly Sensitive to Mild Traumatic Brain Injuries.

Mild traumatic brain injury (mTBI) has subtle effects on several brain functions that can be difficult to assess and follow up. We investigated the impact of mTBI on the perception of sine-wave gratings defined by first- and second-order characteristics. Fifteen adults diagnosed with mTBI were assessed at 15 days, 3 months, and 12 months postinjury. Fifteen matched controls followed the same testing schedule. Reaction times (RTs) for flicker detection and motion direction discrimination were measured. Stimulus contrast of first- and second-order patterns was equated to control for visibility, and correct-response RT means, standard deviations (SDs), medians, and interquartile ranges (IQRs) were calculated. The level of symptoms was also evaluated to compare it to RT data. In general in mTBI, RTs were longer, and SDs as well as IQRs larger, than those of controls. In addition, mTBI participants' RTs to first-order stimuli were shorter than those to second-order stimuli, and SDs as well as IQRs larger for first- than for second-order stimuli in the motion condition. All these observations were made over the three sessions. The level of symptoms observed in mTBI was higher than that of control participants, and this difference did also persist up to 1 year after the brain injury, despite an improvement. The combination of RT measures with particular stimulus properties is a highly sensitive method for measuring mTBI-induced visuomotor anomalies and provides a fine probe of the underlying mechanisms when the brain is exposed to mild trauma.

Two-photon interference with non-identical photons

Two-photon interference with non-identical photons is studied based on the superposition principle in Feynman's path integral theory. The second-order temporal interference pattern is observed by superposing laser and pseudothermal light beams with different spectra. The reason why there is two-photon interference for photons of different spectra is that non-identical photons can be indistinguishable for the detection system when Heisenberg's uncertainty principle is taken into account. These studies are helpful to understand the second-order interference of light in the language of photons.

The first- and second-order temporal interference between thermal and laser light.

The first- and second-order temporal interference between two independent thermal and laser light beams is discussed by employing the superposition principle in Feynman's path integral theory. It is concluded that the first-order temporal interference pattern can not be observed by superposing two independent thermal and laser light beams, while the second-order temporal interference pattern can be observed in the same condition. These predictions are experimentally verified by employing pseudothermal light to simulate thermal light. The relationship between the indistinguishability of alternatives and photons is analyzed. The conclusions are helpful to understand the interference of different kinds of light and the difference between the coherence properties of thermal and laser light.

The second-order interference of two independent single-mode He–Ne lasers

The second-order spatial and temporal interference patterns with two independent single-mode continuous-wave He–Ne lasers are observed when these two lasers are incident to two adjacent input ports of a 1:1 non-polarizing beam splitter, respectively. Two-photon interference based on the superposition principle in Feynman's path integral theory is employed to interpret the experimental results. The conditions to observe the second-order interference pattern with two independent single-mode continuous-wave lasers are discussed. It is concluded that frequency stability is important to observe the second-order interference pattern with two independent light beams.

LEARNING NONADJACENT DEPENDENCIES IN PHONOLOGY: TRANSPARENT VOWELS IN VOWEL HARMONY.

Nonadjacent dependencies are an important part of the structure of language. While the majority of syntactic and phonological processes occur at a local domain, there are several processes that appear to apply at a distance, posing a challenge for theories of linguistic structure. This article addresses one of the most common nonadjacent phenomena in phonology: transparent vowels in vowel harmony. Vowel harmony occurs when adjacent vowels are required to share the same phonological feature value (e.g. V+F C V+F). However, transparent vowels create a second-order nonadjacent pattern because agreement between two vowels can 'skip' the transparent neutral vowel in addition to consonants (e.g. V+F C VT-F C V+F). Adults are shown to display initial learning biases against second-order nonadjacency in experiments that use an artificial grammar learning paradigm. Experiments 1-3 show that adult learners fail to learn the second-order long-distance dependency created by the transparent vowel (as compared to a control condition). In experiments 4-5, training in terms of overall exposure as well as the frequency of relevant transparent items was increased. With adequate exposure, learners reliably generalize to novel words containing transparent vowels. The experiments suggest that learners are sensitive to the structure of phonological representations, even when learning occurs at a relatively rapid pace.