Coherence Of Components Research Articles

UltraStat: Ultrafast Spectroscopy beyond the Fourier Limit Using Bayesian Inference.

The discrete Fourier transform (dFT) plays a central role in many ultrafast experiments, allowing the recovery of spectroscopic observables from time-domain measurements. In resonant experiments when population relaxation and coherence components of the signal coexist, the dFT is usually preceded by multiexponential fitting to remove the large population term. However, this procedure results in errors in both the recovered decay rates and the line shapes of the coherence spectral components. While other methods such as linear prediction singular value decomposition fit both terms simultaneously, they are limited to specific models that may not represent the true signal. These methods do not allow for systematic noise analysis or error estimation and require a priori knowledge of the signal rank. Here, we describe a general approach to parameter estimation in ultrafast spectroscopy─UltraStat─grounded in Bayesian analysis without the limitations set by Fourier theory. Using simulated, but realistic data, we demonstrate in a statistical sense how UltraStat provides accurate parameter estimation in the presence of many experimental constraints: noise, signal truncation, limited photon budget, and nonuniform sampling. UltraStat provides superior resolution compared to the dFT, up to an order of magnitude in cases where the line shapes are well-approximated. In these cases, we establish that primarily noise, not sampling, limits spectral resolution. Moreover, we show that subsampling may reduce the number of acquired points by 90% compared to the Nyquist-Shannon criteria. UltraStat greatly improves parameter estimation by providing statistically bound spectral and dynamics analysis, pushing the limits of ultrafast science.

Male graduates transitioning into the workplace: managing stress through the sense of coherence components.

Male graduates are faced with many challenges when transitioning into work life after graduation. This transition from university to the workplace is one of the most important developmental stages in a young adult's life. It has an important impact on their careers and causes increased stress levels. Often, young men are suffering from mental health challenges and feel as though they cannot seek the appropriate help. Thus, it is necessary to determine how young male graduates cope with the changes experienced in this period, especially relating to their sense of coherence and salutogenesis. The aim of the study is to investigate the transition from university to the workplace and to understand their stress and well-being experiences in terms of activating the three sense of coherence components for coping. A qualitative approach is employed through the use of semi-structured interviews with 10 male South African university graduates. A content analysis technique was used to analyse the qualitative data. The findings indicate that most of the young male graduates understand the transition from university to the workplace and the challenges that come with it (comprehensibility). They also have the necessary personal resources to cope with the stress (manageability) while experiencing this life phase as meaningful (meaningfulness). To understand the transition into the workforce was the most important aspect to stay health during the transition. However, male graduates mainly coped by applying their personal coping strategies and mechanisms and thereby managed their transition mainly by themselves, not based on organizational structures or integrative processes. Meaning applied to the transitional process mainly derived from their personal concepts of creating a meaningful life, not as such from the meaning applied to the work or position they held. The findings provide insights which can be used by higher education institutions to prepare graduates for the transition into the workforce and for organizations to develop programmes for graduates to improve their transition into the organization.

DISCO: Time-Compositional Cache Coherence for Multi-Core Real-Time Embedded Systems

Tasks in modern embedded systems share data and communicate among each other. Nonetheless, the majority of research in real-time systems either assumes that tasks do not share data or prohibits data sharing by design. Only recently, some works investigated solutions to address this limitation and enable data sharing. However, we find these works to suffer from severe limitations. In particular, proposed predictable cache coherence protocols increase the worst-case memory latency (WCL) quadratically due to coherence interference and breaks compositionality by coupling the design and timing analysis of the coherence with the underlying bus arbitration policy. In this paper, we argue that a protocol that distinguishes between non-modifying (read) and modifying (write) memory accesses is key towards reducing the effects of coherence interference on WCL. Accordingly, we propose DISCO, a discriminative coherence solution that capitalizes on this observation to 1) balance average-case performance and WCL, and 2) more importantly, achieves compositionality in the existing of coherence by enabling the decomposition of the effects from coherence and arbitration components. DISCO achieves 7.2× lower latency bounds compared to the state-of-the-art predictable coherence protocol. DISCO also achieves up to 11.4× (5.3× on average) better performance than private cache bypassing for the SPLASH-3 benchmarks.

Prioritizing flexible working memory representations through retrospective attentional strengthening

Previous work has proposed two potential benefits of retrospective attention on working memory (WM): target strengthening and non-target inhibition. It remains unknown which hypothesis contributes to the improved WM performance, yet the neural mechanisms responsible for this attentional benefit are unclear. Here, we recorded electroencephalography (EEG) signals while 33 participants performed a retrospective-cue WM task. Multivariate pattern classification analysis revealed that only representations of target features were enhanced by valid retrospective attention during retention, supporting the target strengthening hypothesis. Further univariate analysis found that mid-frontal theta inter-trial phase coherence (ITPC) and ERP components were modulated by valid retrospective attention and correlated with individual differences and moment-to-moment fluctuations on behavioral outcomes, suggesting that both trait- and state-level variability in attentional preparatory processes influence goal-directed behavior. Furthermore, task-irrelevant target spatial location could be decoded from EEG signals, indicating that enhanced spatial binding of target representation is vital to high WM precision. Importantly, frontoparietal theta-alpha phase-amplitude coupling was increased by valid retrospective attention and predicted the reduced random guessing rates. This long-range connection supported top-down information flow in the engagement of frontoparietal networks, which might organize attentional states to integrate target features. Altogether, these results provide neurophysiological bases that retrospective attention improves WM precision by enhancing flexible target representation and emphasize the critical role of the frontoparietal attentional network in the control of WM representations.

Coherence in (meta)community networks

In a general sense, a metacommunity can be considered as a network of communities, the coherence of which is based on characteristics that are shared by members of different communities, whatever forces were responsible (dispersal, migration, local adaptation, etc.). The purpose is to show that by basing the assessment of coherence on the degree of nestedness of one community within another with respect to the shared characteristics, coherence components can be identified within the network. To assess coherence, a measure of nestedness is developed, and its application to complex (variable) object differences (including multiple traits or characters) is investigated. A community network is then viewed as a graph in which the nodes represent the communities and the edges connecting nodes are weighted by the reverse of the degrees of nestedness between the corresponding communities. Given this framework, it is argued that a minimum requirement for a set of communities to be coherent is the existence of a spanning tree known from graph theory, i.e. a subgraph that connects all nodes through a cycle-free sequence of edges with positive weights. Of all spanning trees, minimum spanning trees (MST, or spanning trees with the minimum sum of edge weights) are most indicative of coherence. By expressing the degree of coherence as one minus the average weight of the edges of an MST, it is uniquely determined which communities form a coherent set at any given level of community distinctness. By this method, community networks can be broken down into coherence components that are separated at a specified distinctness level. This is illustrated in a worked example showing how to apply graph theoretical methods to distinguish coherence components at various threshold levels of object difference (resolution) and community distinctness. These results provide a basis for discussion of coherence gradients and coherence at various levels of distinctness in terms of MST-characteristics. As intuitively expected and analytically confirmed, coherence is a non-decreasing function of the object difference threshold, and the number of coherence components is a non-increasing function of both the object difference and the community distinctness thresholds.

‘The teacher makes us feel like we are a family’: students from refugee backgrounds’ perceptions of physical education in Swedish schools

ABSTRACT Background: Over the past five decades, the number of people from refugee backgrounds in developed countries has been on the constant rise. Although the field of refugee and forced migration studies in relation to education and sport has grown considerably in recent years, very little is known about refugee-background students’ perceptions of Physical Education (PE). Purpose: The aim of this study was to investigate refugee-background students’ perceptions of PE in Swedish high schools, using a salutogenic approach. Participants and settings: This qualitative study was conducted in two Swedish high schools and involved eleven students from refugee backgrounds aged 16–18 years (seven boys and four girls) who originated from a variety of countries including Afghanistan, Syria, Somalia, Ethiopia and Albania. Data collection/analysis: A total of 11 semi-structured interviews were conducted, and the interviews were systematically coded and analyzed using the sense of coherence (SOC) components as analytical tools. Findings: Three themes were identified that captured the students’ perceptions and experiences: (1) PE was perceived as more meaningful in Sweden than in their country of origin due to short-term benefits (e.g. social interaction with friends, and improving personal health and wellbeing) and long-term benefits (e.g. learning for the future); (2) understanding the rules and purpose of the activities helped students to better comprehend the experiences acquired in PE and communicate with others; and (3) constructive social relationships with teachers and classmates were an essential resource in order to make PE manageable. Implications: We suggest that strengths-based approaches should be recognized and incorporated into PE in order to facilitate health promoting factors and wellbeing among students from refugee backgrounds.

SAR Backscatter and InSAR Coherence for Monitoring Wetland Extent, Flood Pulse and Vegetation: A Study of the Amazon Lowland

Synthetic aperture radar (SAR) data have been identified as a potential source of information for monitoring surface water, including open water and flooded vegetation, in frequent time intervals, which is very significant for flood mapping applications. The SAR specular reflectance separates open water and land surface, and its canopy penetration capability allows enhanced backscatter from flooded vegetation. Further, under certain conditions, the SAR signal from flooded vegetation may remain coherent between two acquisitions, which can be exploited using the InSAR technique. With these SAR capabilities in mind, this study examines the use of multi-temporal RADARSAT-2 C band SAR intensity and coherence components to monitor wetland extent, inundation and vegetation of a tropical wetland, such as Amazon lowland. For this study, 22 multi-temporal RADARSAT-2 images (21 pairs) were used for InSAR processing and the pairs in the low water stage (November, December) showed high coherence over the wetland areas. The three-year intensity stack was used for assessing wetland boundary, inundation extent, flood pulse, hydroperiod, and wetland vegetation. In addition to the intensity, derived coherence was used for classifying wetland vegetation. Wetland vegetation types were successfully classified with 86% accuracy using the statistical parameters derived from the multi-temporal intensity and coherence data stacks. We have found that in addition to SAR intensity, coherence provided information about wetland vegetation. In the next year, the Canadian RADARSAT Constellation Mission (RCM), will provide more data with frequent revisits, enhancing the application of SAR intensity and coherence for monitoring these types of wetlands at large scales.

Sense of Coherence, Disability, and Health-Related Quality of Life: A Cross-Sectional Study of Rehabilitation Patients in Norway

ObjectiveTo study relations between sense of coherence (SOC), disability, and mental and physical components of health-related quality of life (HRQOL) among rehabilitation patients. DesignSurvey. SettingRehabilitation centers in secondary care. ParticipantsPatients (N=975) from the Western Norway Health Region consented to participate and had valid data of the main outcome measures. InterventionsNot applicable. Main Outcome MeasuresSOC was measured with the sense of coherence questionnaire (13-item SOC scale [SOC-13]), disability with the World Health Organization Disability Assessment Schedule 2.0 (WHODAS 2.0), and HRQOL with the Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36). ResultsMean scores ± SD were 62.9±12.3 for SOC-13, 30.8±16.2 for WHODAS 2.0, 32.8±9.6 for SF-36 physical component score, and 43.6±11.8 for SF-36 mental component score. Linear regression analysis showed that increased SOC score was associated with reduced disability scores in the following domains with estimated regression coefficients (95% confidence interval) cognition –0.20 (–0.32 to –0.08), getting along –0.36 (–0.52 to –0.25), and participation –0.23 (–0.36 to –0.11). The fit of 2 structural models with the association from SOC to HRQOL and disability or with disability as a mediator was better for the mental versus the physical component of HRQOL. High SOC increased the mental component of HRQOL, consistent for all diagnostic groups. For both models, good fit was reported for circulatory and less good fit for musculoskeletal diseases. ConclusionsThe results indicate that higher SOC decreases disability in mental domains. The effect of SOC on disability and HRQOL might vary between diagnostic groups. SOC could be a target in rehabilitation, especially among patients with circulatory diseases, but prospective studies are needed.

Numerical simulations of spectral shifts in the far-field spectrum of light due to source correlations

We discuss how to simulate numerically the far-field propagation of the spectrum of light by propagating the cross-spectral density for a planar light source with a given coherence model. To test our approach, we performed simulations for two source models: a Gaussian Schell-model source and a nonuniformly Gaussian-correlated source. We show that our algorithm correctly reproduces the theoretical solutions by Emil Wolf for planar Gaussian Schell-model source, namely, the spectral shifts of spectral lines due to source correlations. Our approach can be used for two-dimensional source models in which the spatial coherence components are frequency independent. It can also be used for nonhomogeneous extended sources of partial coherent light.

Times Varying Spectral Coherence Investigation of Cardiovascular Signals Based on Energy Concentration in Healthy Young and Elderly Subjects by the Adaptive Continuous Morlet Wavelet Transform

ObjectiveThe aims of this study, to investigate the interaction among heart rate variability (HRV), respiratory, systolic arterial blood pressure variability (SABPV) and systolic arterial pressure interval variability (APIV) signals for understanding of cardiovascular control. MethodsIn this study, three methods referred as adaptive continuous Morlet wavelet transform (ADCMWT), adaptive Stockwell transform (ADST) and adaptive modified Stockwell transform (ADMST) was used to assess the accuracy (AC) of time-varying spectral coherence (TVSC). The adaptation of these estimators was based on maximum energy concentration measurement. The capability to correct temporal localization of time–frequency regions was validated on synthetic time series data modeled as dynamic characteristics of cardiovascular signals. ResultsThe results on synthetic simulated data show that the ADCMWT method allows for the temporal localization of the time–frequency regions with higher accuracy (AC > 96.074% for SNR ≥ 0 dB), compared to ADST (AC > 90.71% for SNR ≥ 0 dB) and ADMST (AC > 84.45% for SNR ≥ 5 dB). Further, the ADCMWT was applied to real cardiovascular data obtained from Fantasia standard data base and grouped as, 8 young subjects (4M + 4F, age range 23–32) and 8 elderly subjects (4M + 4F, age range 70–82) for estimating the TVSC in low frequency (LF) band (0.04 Hz–0.15 Hz) and high frequency (HF) band (0.15 Hz–0.4 Hz) of HRV spectrum. The global result depict that the median value of interquartile range of coherency between HRV-SABPV and HRV-APIV signals in LF and HF band were significantly (p=0.00001) lower in elderly group subjects compared to young group subjects. The coupling between HRV-Respiratory signals in LF band was not significantly affected with the aging of healthy subjects. However, this coupling in HF band significantly reduced in elderly compare to young group subjects (p=0.0125). ConclusionThe comparative study shows that the time-varying spectra and accurate localization of coupling between two physiological signals can be affected by energy concentration. The ADCMWT at w0=6, could be an alternative, possibly more suitable and highly accurate method for assessment and detection of time varying spectral and coherence components of cardiovascular time series.

Correlation between Mindfulness, Coherence and Wisdom in Sample of Different Age Groups in Adulthood

<p><em>There are two different researches has been explain in this article. There is common idea of those two researches (Svence, Mihailova, Bebre, 2014)- does age as correlate statistical significant differ scores of mindfulness, wisdom and coherence.</em></p><p><em>The aim of the first research (Svence, Mihailova, 2014) is to make theoretical and practical analysis of correllations between sense of coherence, mindfulness and wellbeing among 25-45 year old women, as also make qualitative analysis in order to explore one of the sense of coherence categories – meaningfulness. Reserach has shown that there exists positive correlation between wellbeing and sense of coherence and between wellbeing and mindfulness, as aslo it has been shown that higher scores of sense of meaning in life is related to higher scores of wellbeing, yet there are nearly no research where the correlations between mindfulness and sense of coherece and/or meaningfulness would be explored. Yet there are enough research where the realaton of these concepts with other concepts such as self-efficacy, anxiety, stressreactivity is confirmed. Considering the above mentioned it is valuable to explore relations between sense of coherence, mindfulness and wellbeing. </em></p><p><em>Principal question of the research was to investigate if there is an association between sense of coherence, mindfulness and wellbeing, as also to make qualitative and quantitative analysis and acquire the broader understanding of this association. There were 36 participants in the research who were asked to fill three questionnaires via internet and to particiapate in the interview. Quantative methods were used in the research (Fife Facet Mindfulness Questionnaire, Orientation to Life Questionnaire to measure sense of coherence, Scales of Psychological Well-Being), as well as statistical methods (Pearson correlation) and qualitative method (content analysis of narratives). </em></p><p><em>Quantitative analysis confirmed the question of the research, since there were significant positive correlations discovered between all three concepts – sense of coherence, mindfulness and wellbeing. Content analysis of narratives was made and several typical content units were discovered whish are related to age appropriate meaningful life tasks, and to the processes of sense of coherence. Therefore the associatio between meaningfulness and other sense of coherence components was confirmed. </em></p><p><em>There is other research (Svence, Bebre,2014) about wisdom and meaningfulness scores- how they correlates and differes in different age subgroups in adulthood.</em></p><p><em>There are some results show- scores of wisdom and meaningfulness are not significant differ in different age groups- early adulthood (20-35), middle age (40-55) mathematical statistical significant, but differences has been finded about wisdom in early adulthood and middle age – according scores – wisdom is more higher in middle age as in early adulthood.</em></p><p> </p>

Three-photon electromagnetically induced absorption in a ladder-type atomic system

We report on three-photon electromagnetically induced absorption (TPEIA) due to three-photon coherence in ladder-type atomic systems for the $5{S}_{1/2}$-$5{P}_{3/2}$-$5{D}_{5/2}$ transition in Rb atoms. When a counterpropagating coupling field was added to the typical ladder-type electromagnetically induced transparency (EIT) experiment, both EIT and two-photon absorption (TPA) switched to TPEIA. Considering three-photon coherence in a Doppler-broadened three-level ladder-type atomic system, the spectrum of the switch from EIT and TPA to TPEIA was numerically calculated and could be understood by decomposing the calculated spectrum into two-photon coherence and three-photon coherence components.

A Salutogenic Analysis of the Well-Being Paradox in Older Age

Following Antonovsky’s salutogenic perspective, we investigate to what extent the sense of coherence and psychological resources mediate the physical health-mental health relationship, assuming that these resilience factors mutually influence each other. In our questionnaire study, 387 older persons at the mean age of 73.8 years volunteered. We assessed physical health appraisals, sense of coherence components (comprehensibility, manageability, and meaningfulness), psychological resources (self-efficacy and self-esteem) and mental health (subjective well-being, depressive mood, and psychological health). We used structural equation modeling with latent variables and a bootstrapping method to test hypothesized mediation chains. We found (a) a significant direct effect of physical health on mental health, (b) two significant specific indirect effects of physical health on mental health, substantiating that the sense of coherence was a stronger mediator than psychological resources, and (c) two significant 3-path mediated effects. Physical health is profoundly associated with mental health. However, resilience factors such as the sense of coherence and psychological resources enable older people to maintain mental health when confronted with chronic physical health problems.

Three-pion correlations for studying partial coherence in nuclear collisions

Use of three-particle correlations provides a unique tool for studying partial coherence in relativistic heavy-ion collisions. Here a theory is presented for multiple coherent source components of partially coherent pion radiation. Results are given for the relative probabilities of emission of one, two, or three pions. The calculations on the relation between two- and three-pion correlators give some evidence, when compared with available experimental data, for the existence of partial coherence and multiple coherent components in heavy-ion collisions.

Stationary light pulses in cold thermal atomic clouds

Fourier-expanded Maxwell-Liouville equations are employed to study the light pulse dynamics in atomic samples coherently driven by a standing-wave light field. Solutions are obtained by a suitable truncation of the Maxwell-Liouville equations that contain the number of spin and optical Fourier coherence components appropriate to the sample temperature. This approach is examined here for cold but thermal atoms where the Doppler broadening is still not negligible and familiar secular approximations no longer hold. In this temperature regime higher-order momentum Fourier coherence components are shown to be important for achieving excellent agreement with a recent experiment done in cold $^{87}\mathrm{Rb}$ clouds at several hundred microkelvins.

Dynamic functional connectivity between contralateral and ipsilateral motor cortices observed using the Multi-Source Interference Task

Event Abstract Back to Event Dynamic functional connectivity between contralateral and ipsilateral motor cortices observed using the Multi-Source Interference Task William Gaetz1*, Cheng Liu2, Hongmei Zhu2 and Timothy Roberts1 1 The Children's Hospital of Philadelphia, United States 2 York University, Department of Mathematics and Statistics, Canada Previous studies demonstrated activity of ipsilateral motor cortex and coupling at 8 -12 Hz between bilateral motor cortices during the execution of simple motor tasks [1]. In this study, we investigate the dynamic functional connectivity of brain motor areas under the Multi-Source Interference Task (MSIT) [1] using time-varying coherence analysis. The coherence function measures the linear interactions of signals from different brain areas and therefore reveals information about brain functional connectivity. However, the conventional coherence analysis assumes the stationarity of the analyzed signals, which has limited use to investigate the dynamic and transient features of brain functional activities. To better capture temporal information, we extend the definition of coherence function from the Fourier domain to the time-frequency plane using the Stockwell transform [2]. We apply this time-varying coherence analysis to a set of MEG data where a differential beamformer (dual state SAM) was used to identify contralateral (MIc) and ipsilateral motor cortices (MIi). Fifteen right-handed adult subjects (7 male, 8 female; mean ages: 31) performed the MSIT task [1] using the right hand only. For the response interference condition, we observed that subjects with significant coherence components have relatively longer response time, compared to those with almost no significant coherence. A statistical test indicates that these two groups (‘slow’ responders vs. ‘fast’) are significantly different (permutation test p<0.01). For the slow responders, the identified coupling between the MIc and MIi is concentrated in the 8-12 Hz band. Meanwhile, the Stockwell coherence also provides the time information of the onset and duration of this coupling. Our findings suggest that basic performance measures such as RT are important for observing and interpreting bi-hemispheric motor cortical interactions. Conference: Biomag 2010 - 17th International Conference on Biomagnetism , Dubrovnik, Croatia, 28 Mar - 1 Apr, 2010. Presentation Type: Poster Presentation Topic: Sensory Processing and Functional Connectivity Citation: Gaetz W, Liu C, Zhu H and Roberts T (2010). Dynamic functional connectivity between contralateral and ipsilateral motor cortices observed using the Multi-Source Interference Task. Front. Neurosci. Conference Abstract: Biomag 2010 - 17th International Conference on Biomagnetism . doi: 10.3389/conf.fnins.2010.06.00157 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 26 Mar 2010; Published Online: 26 Mar 2010. * Correspondence: William Gaetz, The Children's Hospital of Philadelphia, Philadelphia, United States, bill.gaetz@gmail.com Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers William Gaetz Cheng Liu Hongmei Zhu Timothy Roberts Google William Gaetz Cheng Liu Hongmei Zhu Timothy Roberts Google Scholar William Gaetz Cheng Liu Hongmei Zhu Timothy Roberts PubMed William Gaetz Cheng Liu Hongmei Zhu Timothy Roberts Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Examining Curricular Coherence in an Exemplary Elementary School Program

A coherent curriculum is characterized by visible connections between purposes and experiences so that students acknowledge the content's immediate value. This study examined an exemplary elementary physical education curriculum for coherence components. Research questions examined the role of coherence in connecting and engaging students meaningfully in physical education. Observations and interviews were conducted to collect qualitative data in one program for 22 weeks. Data were analyzed using open, axial, and selective coding. Results described two units, Balls Skills, leading to modified basketball, and Scooter City, a theme-based unit emphasizing student choice and responsibility. Students reported that both units were enjoyable. Although the Balls Skills unit was well planned, taught, and managed, some students commented that the skill and games content was valuable only in basketball. In the Scooter City unit, students identified numerous connections to out-of-school activities that enhanced content value. Comparisons with Beane's coherence criteria suggested that students valued Scooter City based on concrete connections to their lived experiences.

Thermalized displaced squeezed thermal states

In the coordinate representation of thermofield dynamics, we investigate the thermalized displaced squeezed thermal state which involves two temperatures successively. We give the wavefunction and the matrix element of the density operator at any time, and accordingly calculate some quantities related to the position, momentum and particle number operator, special cases of which are consistent with the results in the literature. The two temperatures have diffenent correlations with the squeeze and coherence components. Moreover, different from the properties of the position and momentum, the average value and variance of the particle number operator as well as the second-order correlation function are time-independent.

Signal processing algorithm for sound source localization with discretionarily distributed multiple receiving sensors

The deployment of strategically placed multiple receiving sensors has many practical ways to detect, localize, and classify a sound source in situations such as monitoring an isolated street disturbance in an urban environment with posted microphones or identifying a submerged object in the ocean with air-dropped sonobuoys. A simple processsing algorithm based on signals received from multiple sensors is derived from the information contained in the cross-spectrum matrix formed from the receiving sensors. Using the magnitude distribution of eigenvalues across the frequency bandwidth as the indication for the strength of signal excess in the frequency domain, their corresponding eigenvectors provide the required complex number weightings to select the related coherence components of the signal. By examining the phase angle data from each sensor’s weighting factor, a set of simultaneous algebra equations can be formulated to estimate the location of the sound source. The computation procedure of this approach is uncomplicated in comparison with the traditional triangulation method. Furthermore, the additional accompanied computed eigenvalues can be utilized for the characterization of the detected sound source, thereby establishing its identification reference. Simulated examples are used to test out the effectiveness of this multiple sensor sound source evaluation methodology at various operational scenarios.

Geometrical representation of coherent-excitation methods using delayed and detuned lasers

A precessing vector model has been developed for the geometrical interpretation of the adiabatic following and the optimal detuning methods, which play a decisive role in coherent population transfer in a three-level system. In our model, the Bloch vector defined by a population inversion and two-photon coherence components precesses about the torque vector consisting of an effective Rabi frequency and detuning components. The Bloch vector traces out different routes depending on combinations of the time delay of two laser pulses and detunings from the resonant frequencies. For the extreme cases where the optimal detuning with zero delay and the optimal delay with zero detunings are taken, our vector model with analytical solutions is compared with numerical solutions.