Towards a coherent global framework for health financing: recommendations and recent developments.

Science.gov (United States)

Ottersen, Trygve; Elovainio, Riku; Evans, David B; McCoy, David; Mcintyre, Di; Meheus, Filip; Moon, Suerie; Ooms, Gorik; Røttingen, John-Arne

2017-04-01

The articles in this special issue have demonstrated how unprecedented transitions have come with both challenges and opportunities for health financing. Against the background of these challenges and opportunities, the Working Group on Health Financing at the Chatham House Centre on Global Health Security laid out, in 2014, a set of policy responses encapsulated in 20 recommendations for how to make progress towards a coherent global framework for health financing. These recommendations pertain to domestic financing of national health systems, global public goods for health, external financing for national health systems and the cross-cutting issues of accountability and agreement on a new global framework. Since the Working Group concluded its work, multiple events have reinforced the group's recommendations. Among these are the agreement on the Addis Ababa Action Agenda, the adoption of the Sustainable Development Goals, the outbreak of Ebola in West Africa and the release of the Panama Papers. These events also represent new stepping stones towards a new global framework.

Tobacco control, global health policy and development: towards policy coherence in global governance

Science.gov (United States)

Collin, Jeff

2015-01-01

The WHO Framework Convention on Tobacco Control (FCTC) demonstrates the international political will invested in combating the tobacco pandemic and a newfound prominence for tobacco control within the global health agenda. However, major difficulties exist in managing conflicts with foreign and trade policy priorities, and significant obstacles confront efforts to create synergies with development policy and avoid tensions with other health priorities. This paper uses the concept of policy coherence to explore congruence and inconsistencies in objectives, policy, and practice between tobacco control and trade, development and global health priorities. Following the inability of the FCTC negotiations to satisfactorily address the relationship between trade and health, several disputes highlight the challenges posed to tobacco control policies by multilateral and bilateral agreements. While the work of the World Bank has demonstrated the potential contribution of tobacco control to development, the absence of non-communicable diseases from the Millennium Development Goals has limited scope to offer developing countries support for FCTC implementation. Even within international health, tobacco control priorities may be hard to reconcile with other agendas. The paper concludes by discussing the extent to which tobacco control has been pursued via a model of governance very deliberately different from those used in other health issues, in what can be termed ‘tobacco exceptionalism’. The analysis developed here suggests that non-communicable disease (NCD) policies, global health, development and tobacco control would have much to gain from re-examining this presumption of difference. PMID:22345267

Studying text coherence in Czech – a corpus-based analysis

Directory of Open Access Journals (Sweden)

Rysová Magdaléna

2017-12-01

Full Text Available The paper deals with the field of Czech corpus linguistics and represents one of various current studies analysing text coherence through language interactions. It presents a corpusbased analysis of grammatical coreference and sentence information structure (in terms of contextual boundness in Czech. It focuses on examining the interaction of these two language phenomena and observes where they meet to participate in text structuring. Specifically, the paper analyses contextually bound and non-bound sentence items and examines whether (and how often they are involved in relations of grammatical coreference in Czech newspaper articles. The analysis is carried out on the language data of the Prague Dependency Treebank (PDT containing 3,165 Czech texts. The results of the analysis are helpful in automatic text annotation - the paper presents how (or to what extent the annotation of grammatical coreference may be used in automatic (pre-annotation of sentence information structure in Czech. It demonstrates how accurately we may (automatically assume the value of contextual boundness for the antecedent and anaphor (as the two participants of a grammatical coreference relation. The results of the paper demonstrate that the anaphor of grammatical coreference is automatically predictable - it is a non-contrastive contextually bound sentence item in 99.18% of cases. On the other hand, the value of contextual boundness of the antecedent is not so easy to estimate (according to the PDT, the antecedent is contextually non-bound in 37% of cases, non-contrastive contextually bound in 50% and contrastive contextually bound in 13% of cases.

Globally Stable Microresonator Turing Pattern Formation for Coherent High-Power THz Radiation On-Chip

Science.gov (United States)

Huang, Shu-Wei; Yang, Jinghui; Yang, Shang-Hua; Yu, Mingbin; Kwong, Dim-Lee; Zelevinsky, T.; Jarrahi, Mona; Wong, Chee Wei

2017-10-01

In nonlinear microresonators driven by continuous-wave (cw) lasers, Turing patterns have been studied in the formalism of the Lugiato-Lefever equation with emphasis on their high coherence and exceptional robustness against perturbations. Destabilization of Turing patterns and the transition to spatiotemporal chaos, however, limit the available energy carried in the Turing rolls and prevent further harvest of their high coherence and robustness to noise. Here, we report a novel scheme to circumvent such destabilization, by incorporating the effect of local mode hybridizations, and we attain globally stable Turing pattern formation in chip-scale nonlinear oscillators with significantly enlarged parameter space, achieving a record-high power-conversion efficiency of 45% and an elevated peak-to-valley contrast of 100. The stationary Turing pattern is discretely tunable across 430 GHz on a THz carrier, with a fractional frequency sideband nonuniformity measured at 7.3 ×10-14 . We demonstrate the simultaneous microwave and optical coherence of the Turing rolls at different evolution stages through ultrafast optical correlation techniques. The free-running Turing-roll coherence, 9 kHz in 200 ms and 160 kHz in 20 minutes, is transferred onto a plasmonic photomixer for one of the highest-power THz coherent generations at room temperature, with 1.1% optical-to-THz power conversion. Its long-term stability can be further improved by more than 2 orders of magnitude, reaching an Allan deviation of 6 ×10-10 at 100 s, with a simple computer-aided slow feedback control. The demonstrated on-chip coherent high-power Turing-THz system is promising to find applications in astrophysics, medical imaging, and wireless communications.

Correlations of sense of family coherence in adolescents

Directory of Open Access Journals (Sweden)

Minić Jelena Lj.

2016-01-01

Full Text Available Theoretical basis of the paper is a salutogenetic model of Aron Antonovski's model and belief that apart from the sense of coherence and sense of family coherence , as central sources of health, generalized and specific health sources are also important. The mentioned health sources Antonovski determines as different characteristics of an individual, group or environment which help mastering tension, which is caused by different stressors or serve for avoiding or suppress different stressors. The paper examines correlation of the sense of family coherence in adolescents with some variables which are included in the research as health sources (resistance sources. The aim of research was to examine the sense of family coherence in adolescents with: satisfaction with family (generally and globally, self-respect, family financial situation, educational level of their parents, success in education so far, number of family members and birth order. The sample consisted of adolescents of both sexes, aged 15 to 24 (N=360. Questionnaire of basic data, Scale for estimation of family coherence, Scale of family adaptation and Scale of self-respect are used for the research purposes. The data was processed by correlative analysis. Results obtained showed that there is a positive correlation of sense of family coherence in adolescents (both as a whole and as components with general and global satisfaction with family and self-respect, as well as correlation of components with family financial situation and school/academic success. Results obtained point to the conclusion that stronger feeling of family coherence is found in adolescents who are more satisfied with their families (generally and globally, those who posess higher self-respect, have better family financial situation and adolescents who have been more successful in their education. Total attitude of the adolescents towards their families is not in connection with the level of their parents education

Global genetic response in a cancer cell: self-organized coherent expression dynamics.

Directory of Open Access Journals (Sweden)

Masa Tsuchiya

Full Text Available Understanding the basic mechanism of the spatio-temporal self-control of genome-wide gene expression engaged with the complex epigenetic molecular assembly is one of major challenges in current biological science. In this study, the genome-wide dynamical profile of gene expression was analyzed for MCF-7 breast cancer cells induced by two distinct ErbB receptor ligands: epidermal growth factor (EGF and heregulin (HRG, which drive cell proliferation and differentiation, respectively. We focused our attention to elucidate how global genetic responses emerge and to decipher what is an underlying principle for dynamic self-control of genome-wide gene expression. The whole mRNA expression was classified into about a hundred groups according to the root mean square fluctuation (rmsf. These expression groups showed characteristic time-dependent correlations, indicating the existence of collective behaviors on the ensemble of genes with respect to mRNA expression and also to temporal changes in expression. All-or-none responses were observed for HRG and EGF (biphasic statistics at around 10-20 min. The emergence of time-dependent collective behaviors of expression occurred through bifurcation of a coherent expression state (CES. In the ensemble of mRNA expression, the self-organized CESs reveals distinct characteristic expression domains for biphasic statistics, which exhibits notably the presence of criticality in the expression profile as a route for genomic transition. In time-dependent changes in the expression domains, the dynamics of CES reveals that the temporal development of the characteristic domains is characterized as autonomous bistable switch, which exhibits dynamic criticality (the temporal development of criticality in the genome-wide coherent expression dynamics. It is expected that elucidation of the biophysical origin for such critical behavior sheds light on the underlying mechanism of the control of whole genome.

Salutogenesis, globalization, and communication.

Science.gov (United States)

Petzold, Theodor Dierk; Lehmann, Nadja

2011-12-01

Achieving successful communication in transcultural contexts means integrating emotional communication patterns into a global context. Professional, rational communication is characteristic of the cultural dimension, and emotions are characteristic of the direct, interpersonal dimension of human existence. Humans strive to achieve coherence in all dimensions of their lives; this goal is in the end the most essential aspect of psychophysical self-regulation. A major role in integrating emotional needs and cultural features in global coherence is played by the attractor 'global affinity'. The transitions from emotional coherence to cultural coherence, and likewise from cultural coherence to global coherence, can cause considerable insecurity as well as psychological problems, which previously went by the name 'adjustment disorders'. However, instead of pathologizing these processes, we should understand them in a salutogenic sense as challenges important for both individual and collective development. The development of more coherence is regulated by the neuropsychological approach and avoidance system. This system can be consciously fostered by directing our attention to the commonalities of all human beings. Such a global salutogenic orientation furthers both communication and creativity in teamwork. This article introduces a consequent salutogenic and evolutionary systemic view of transcultural communication and demonstrates its effectiveness in a number of case examples.

Canada's role in the global energy picture: making the case for a more coherent national energy approach

Energy Technology Data Exchange (ETDEWEB)

Gass, Philip; Drexhage, John [International Institute for Sustainable Development (Canada)

2010-07-01

Given Canada's position in the present global energy dynamic, there are opportunities for private sector economic actors to make large-scale investments in traditional energy resources such as oil, natural gas, hydropower and uranium. Canada, with so much to offer in terms of resources and potential for private investment, could play a leadership role in the push to develop clean energy. There is a need to articulate an overarching, coherent vision, not only in terms of Canada's stance on energy development but also in terms of national strategy. This is a critical moment, not only for Canada but for the whole world, when an effective, sustainable blueprint needs to be drawn up. If we can make a coherent case for a clean energy vision of the future, then Canada will make global progress in the energy field. Moreover, it seems clear that global governance with respect to energy issues will continue to be a topic of growing interest. Canada needs to give serious thought to what its position and its contribution will be with respect to a clean energy future.

Sentence connexion and global text structures: a case study of a political text, English leader article

OpenAIRE

Stein, Dieter; Mattei, Adriana

1993-01-01

The paper first gives a brief overview of the history and theoretical status of discourse analysis, or "text linguistics." The main body of the paper consists of a detailed analysis of sentence connexion, i.e. the logical relationship between sentences and larger chunks of text, performed on a newspaper leader article. The results of this local analysis are then related to the global organisation of text structure with components such as macro- and super-structure by way of int...

Averaging, not internal noise, limits the development of coherent motion processing

Directory of Open Access Journals (Sweden)

Catherine Manning

2014-10-01

Full Text Available The development of motion processing is a critical part of visual development, allowing children to interact with moving objects and navigate within a dynamic environment. However, global motion processing, which requires pooling motion information across space, develops late, reaching adult-like levels only by mid-to-late childhood. The reasons underlying this protracted development are not yet fully understood. In this study, we sought to determine whether the development of motion coherence sensitivity is limited by internal noise (i.e., imprecision in estimating the directions of individual elements and/or global pooling across local estimates. To this end, we presented equivalent noise direction discrimination tasks and motion coherence tasks at both slow (1.5°/s and fast (6°/s speeds to children aged 5, 7, 9 and 11 years, and adults. We show that, as children get older, their levels of internal noise reduce, and they are able to average across more local motion estimates. Regression analyses indicated, however, that age-related improvements in coherent motion perception are driven solely by improvements in averaging and not by reductions in internal noise. Our results suggest that the development of coherent motion sensitivity is primarily limited by developmental changes within brain regions involved in integrating motion signals (e.g., MT/V5.

Digital processing optical transmission and coherent receiving techniques

CERN Document Server

Binh, Le Nguyen

2013-01-01

With coherent mixing in the optical domain and processing in the digital domain, advanced receiving techniques employing ultra-high speed sampling rates have progressed tremendously over the last few years. These advances have brought coherent reception systems for lightwave-carried information to the next stage, resulting in ultra-high capacity global internetworking. Digital Processing: Optical Transmission and Coherent Receiving Techniques describes modern coherent receiving techniques for optical transmission and aspects of modern digital optical communications in the most basic lines. The

Globalization of consumer confidence

Directory of Open Access Journals (Sweden)

Çelik Sadullah

2017-01-01

Full Text Available The globalization of world economies and the importance of nowcasting analysis have been at the core of the recent literature. Nevertheless, these two strands of research are hardly coupled. This study aims to fill this gap through examining the globalization of the consumer confidence index (CCI by applying conventional and unconventional econometric methods. The US CCI is used as the benchmark in tests of comovement among the CCIs of several developing and developed countries, with the data sets divided into three sub-periods: global liquidity abundance, the Great Recession, and postcrisis. The existence and/or degree of globalization of the CCIs vary according to the period, whereas globalization in the form of coherence and similar paths is observed only during the Great Recession and, surprisingly, stronger in developing/emerging countries.

Inhibitory coherence in a heterogeneous population of subthreshold and suprathreshold type-I neurons

International Nuclear Information System (INIS)

Kim, Sang-Yoon; Hong, Duk-Geun; Kim, Jean; Lim, Woochang

2012-01-01

We study inhibitory coherence (i.e. collective coherence by synaptic inhibition) in a population of globally coupled type-I neurons, which can fire at arbitrarily low frequency. No inhibitory coherence is observed in a homogeneous population composed of only subthreshold neurons, which exhibit noise-induced firings. In addition to subthreshold neurons, there exist spontaneously firing suprathreshold neurons in a noisy environment of a real brain. To take into consideration the effect of suprathreshold neurons on inhibitory coherence, we consider a heterogeneous population of subthreshold and suprathreshold neurons and investigate the inhibitory coherence by increasing the fraction of suprathreshold neurons P supra . As P supra passes a threshold P* supra , suprathreshold neurons begin to synchronize and play the role of coherent inhibitors for the emergence of inhibitory coherence. Thus, regularly oscillating population-averaged global potential appears for P supra > P* supra . For this coherent case, suprathreshold neurons exhibit sparse spike synchronization (i.e. individual potentials of suprathreshold neurons consist of coherent sparse spikings and coherent subthreshold small-amplitude hoppings). By virtue of their coherent inhibition, sparsely synchronized suprathreshold neurons suppress the noisy activity of subthreshold neurons. Thus, subthreshold neurons exhibit hopping synchronization (i.e. only coherent subthreshold hopping oscillations without spikings appear in the individual potentials of subthreshold neurons). We also characterize the inhibitory coherence in terms of the ‘statistical-mechanical’ spike-based and correlation-based measures, which quantify the average contributions of the microscopic individual spikes and individual potentials to the macroscopic global potential. Finally, the effect of sparse randomness of synaptic connectivity on the inhibitory coherence is briefly discussed. (paper)

Direction-of-Arrival Estimation for Coherent Sources via Sparse Bayesian Learning

Directory of Open Access Journals (Sweden)

Zhang-Meng Liu

2014-01-01

Full Text Available A spatial filtering-based relevance vector machine (RVM is proposed in this paper to separate coherent sources and estimate their directions-of-arrival (DOA, with the filter parameters and DOA estimates initialized and refined via sparse Bayesian learning. The RVM is used to exploit the spatial sparsity of the incident signals and gain improved adaptability to much demanding scenarios, such as low signal-to-noise ratio (SNR, limited snapshots, and spatially adjacent sources, and the spatial filters are introduced to enhance global convergence of the original RVM in the case of coherent sources. The proposed method adapts to arbitrary array geometry, and simulation results show that it surpasses the existing methods in DOA estimation performance.

Why do adults with dyslexia have poor global motion sensitivity?

Directory of Open Access Journals (Sweden)

Elizabeth eConlon

2013-12-01

Full Text Available Two experiments aimed to determine why adults with dyslexia have higher global motion thresholds than typically reading controls. In Experiment 1, the dot density and number of animation frames presented in the dot stimulus were manipulated because of findings that use of a high dot density can normalise coherence thresholds in individuals with dyslexia. Dot densities were 14.15 dots/deg2 and 3.54 dots/deg2. These were presented for five (84ms or eight (134ms frames. The dyslexia group had higher coherence thresholds in all conditions than controls. However, in the high dot density, long duration condition, both reader groups had the lowest thresholds indicating normal temporal recruitment. These results indicated that the dyslexia group could sample the additional signals dots over space and then integrate these with the same efficiency as controls. In Experiment 2, we determined whether briefly presenting a fully coherent prime moving in either the same or opposite direction of motion to a partially coherent test stimulus would systematically increase and decrease global motion thresholds in the reader groups. When the direction of motion in the prime and test was the same, global motion thresholds increased for both reader groups. The increase in coherence thresholds was significantly greater for the dyslexia group. When the motion of the prime and test were presented in opposite directions, coherence thresholds were reduced in both groups. No group threshold differences were found. We concluded that the global motion processing deficit found in adults with dyslexia can be explained by undersampling of the target motion signals. This might occur because of difficulties directing attention to the relevant motion signals in the random dot pattern, and not a specific difficulty integrating global motion signals. These effects are most likely to occur in the group with dyslexia when more complex computational processes are required to process

Characterizing lifespan development of three aspects of coherence in life narratives: a cohort-sequential study.

Science.gov (United States)

Köber, Christin; Schmiedek, Florian; Habermas, Tilmann

2015-02-01

The ability to narrate stories and a synchronic self-concept develop in the pre- and primary school years. Life story theory proposes that both developments extend to an even later developmental stage, that is, to adolescents' acquisition of a coherent life story. Cross-sectional evidence supports the emergence of a life story in adolescence, but is mixed in terms of later life span development. The present study examines longitudinally the development of global coherence in life narratives across almost the entire life span. Starting in 2003, a total of 172 participants narrated their lives over the course of 8 years (aged 16, 20, 24, 28, 44, and 69 when last tested) resulting in up to 4 life narratives per person. Three aspects of global life narrative coherence--temporal, causal-motivational, and thematic coherence--were measured with global ratings and predicted by their respective textual indicators. Children lacked most aspects of global coherence. Almost all indicators of temporal and causal-motivational coherence increased substantially across adolescence up to early adulthood, as did thematic coherence, which continued to develop throughout middle adulthood. PsycINFO Database Record (c) 2015 APA, all rights reserved.

An integral, positive psychology paradigm for global coherence ...

African Journals Online (AJOL)

The article reviews research evidence in relation to psychophysiological coherence, which is characterised by a heart rhythm pattern of elevated amplitude in low frequency heart rate variability of around 0.1 Hz. This is associated with synchronisation between various physiological systems, positive emotions, athletes' ...

Effect of age on variability in the production of text-based global inferences.

Directory of Open Access Journals (Sweden)

Lynne J Williams

Full Text Available As we age, our differences in cognitive skills become more visible, an effect especially true for memory and problem solving skills (i.e., fluid intelligence. However, by contrast with fluid intelligence, few studies have examined variability in measures that rely on one's world knowledge (i.e., crystallized intelligence. The current study investigated whether age increased the variability in text based global inference generation--a measure of crystallized intelligence. Global inference generation requires the integration of textual information and world knowledge and can be expressed as a gist or lesson. Variability in generating two global inferences for a single text was examined in young-old (62 to 69 years, middle-old (70 to 76 years and old-old (77 to 94 years adults. The older two groups showed greater variability, with the middle elderly group being most variable. These findings suggest that variability may be a characteristic of both fluid and crystallized intelligence in aging.

Text-analytic Measurement of Effectuation and Causation Orientations among Small and Global Business Managers

DEFF Research Database (Denmark)

Mattsson, Jan; Helmersson, Helge

2012-01-01

We demonstrate how one can measure overall quality in texts gathered from interviews by means of PERTEX text analytic method. We compare text analytic measures and content for locally active Scandinavian small business managers and globally operating Indian IT managers when recapitulating......-components we are also able to display the degree of fragmentation, focus and integration in the text. We show how AFFI measures differ between managers with a causation or effectuation orientation irrespective of their role as small business manager or as an established global manager. Hence, we posit...... that effectuation and causation orientations may be generic characteristic of managers in general....

Progress in coherent laser radar

Science.gov (United States)

Vaughan, J. M.

1986-01-01

Considerable progress with coherent laser radar has been made over the last few years, most notably perhaps in the available range of high performance devices and components and the confidence with which systems may now be taken into the field for prolonged periods of operation. Some of this increasing maturity was evident at the 3rd Topical Meeting on Coherent Laser Radar: Technology and Applications. Topics included in discussions were: mesoscale wind fields, nocturnal valley drainage and clear air down bursts; airborne Doppler lidar studies and comparison of ground and airborne wind measurement; wind measurement over the sea for comparison with satellite borne microwave sensors; transport of wake vortices at airfield; coherent DIAL methods; a newly assembled Nd-YAG coherent lidar system; backscatter profiles in the atmosphere and wavelength dependence over the 9 to 11 micrometer region; beam propagation; rock and soil classification with an airborne 4-laser system; technology of a global wind profiling system; target calibration; ranging and imaging with coherent pulsed and CW system; signal fluctuations and speckle. Some of these activities are briefly reviewed.

Interocular suppression in amblyopia for global orientation processing.

Science.gov (United States)

Zhou, Jiawei; Huang, Pi-Chun; Hess, Robert F

2013-04-22

We developed a dichoptic global orientation coherence paradigm to quantify interocular suppression in amblyopia. This task is biased towards ventral processing and allows comparison with two other techniques-global motion processing, which is more dorsally biased, and binocular phase combination, which most likely reflects striate function. We found a similar pattern for the relationship between coherence threshold and interocular contrast curves (thresholds vs. interocular contrast ratios or TvRs) in our new paradigm compared with those of the previous dichoptic global motion coherence paradigm. The effective contrast ratios at balance point (where the signals from the two eyes have equal weighting) in our new paradigm were larger than those of the dichoptic global motion coherence paradigm but less than those of the binocular phase combination paradigm. The measured effective contrast ratios in the three paradigms were also positively correlated with each other, with the two global coherence paradigms having the highest correlation. We concluded that: (a) The dichoptic global orientation coherence paradigm is effective in quantifying interocular suppression in amblyopia; and (b) Interocular suppression, while sharing a common suppression mechanism at the early stage in the pathway (e.g., striate cortex), may have additional extra-striate contributions that affect both dorsal and ventral streams differentially.

Effect of age on variability in the production of text-based global inferences.

Science.gov (United States)

Williams, Lynne J; Dunlop, Joseph P; Abdi, Hervé

2012-01-01

As we age, our differences in cognitive skills become more visible, an effect especially true for memory and problem solving skills (i.e., fluid intelligence). However, by contrast with fluid intelligence, few studies have examined variability in measures that rely on one's world knowledge (i.e., crystallized intelligence). The current study investigated whether age increased the variability in text based global inference generation--a measure of crystallized intelligence. Global inference generation requires the integration of textual information and world knowledge and can be expressed as a gist or lesson. Variability in generating two global inferences for a single text was examined in young-old (62 to 69 years), middle-old (70 to 76 years) and old-old (77 to 94 years) adults. The older two groups showed greater variability, with the middle elderly group being most variable. These findings suggest that variability may be a characteristic of both fluid and crystallized intelligence in aging.

The Perfect Text.

Science.gov (United States)

Russo, Ruth

1998-01-01

A chemistry teacher describes the elements of the ideal chemistry textbook. The perfect text is focused and helps students draw a coherent whole out of the myriad fragments of information and interpretation. The text would show chemistry as the central science necessary for understanding other sciences and would also root chemistry firmly in the…

The global governance of crisis migration

Directory of Open Access Journals (Sweden)

Alexander Betts

2014-02-01

Full Text Available There is no coherent or unified global governance framework for the different areas that have been subsumed under the umbrella of ‘crisis migration’. This is not to say that when new challenges or labels arise new institution-building is necessarily required. Addressing emerging protection gaps such as those related to crisis migration requires creativity in making existing institutions work better across implementation, institutionalisation and international agreements.

Statistical text classifier to detect specific type of medical incidents.

Science.gov (United States)

Wong, Zoie Shui-Yee; Akiyama, Masanori

2013-01-01

WHO Patient Safety has put focus to increase the coherence and expressiveness of patient safety classification with the foundation of International Classification for Patient Safety (ICPS). Text classification and statistical approaches has showed to be successful to identifysafety problems in the Aviation industryusing incident text information. It has been challenging to comprehend the taxonomy of medical incidents in a structured manner. Independent reporting mechanisms for patient safety incidents have been established in the UK, Canada, Australia, Japan, Hong Kong etc. This research demonstrates the potential to construct statistical text classifiers to detect specific type of medical incidents using incident text data. An illustrative example for classifying look-alike sound-alike (LASA) medication incidents using structured text from 227 advisories related to medication errors from Global Patient Safety Alerts (GPSA) is shown in this poster presentation. The classifier was built using logistic regression model. ROC curve and the AUC value indicated that this is a satisfactory good model.

Volitional Control of Neuromagnetic Coherence

Directory of Open Access Journals (Sweden)

Matthew D Sacchet

2012-12-01

Full Text Available Coherence of neural activity between circumscribed brain regions has been implicated as an indicator of intracerebral communication in various cognitive processes. While neural activity can be volitionally controlled with neurofeedback, the volitional control of coherence has not yet been explored. Learned volitional control of coherence could elucidate mechanisms of associations between cortical areas and its cognitive correlates and may have clinical implications. Neural coherence may also provide a signal for brain-computer interfaces (BCI. In the present study we used the Weighted Overlapping Segment Averaging (WOSA method to assess coherence between bilateral magnetoencephalograph (MEG sensors during voluntary digit movement as a basis for BCI control. Participants controlled an onscreen cursor, with a success rate of 124 of 180 (68.9%, sign-test p < 0.001 and 84 out of 100 (84%, sign-test p < 0.001. The present findings suggest that neural coherence may be volitionally controlled and may have specific behavioral correlates.

Characterisation of dispersive systems using a coherer

Directory of Open Access Journals (Sweden)

Nikolić Pantelija M.

2002-01-01

Full Text Available The possibility of characterization of aluminium powders using a horizontal coherer has been considered. Al powders of known dimension were treated with a high frequency electromagnetic field or with a DC electric field, which were increased until a dielectric breakdown occurred. Using a multifunctional card PC-428 Electronic Design and a suitable interface between the coherer and PC, the activation time of the coherer was measured as a function of powder dimension and the distance between the coherer electrodes. It was also shown that the average dimension of powders of unknown size could be determined using the coherer.

Impaired coherence of life narratives of patients with schizophrenia.

Science.gov (United States)

Allé, Mélissa C; Potheegadoo, Jevita; Köber, Christin; Schneider, Priscille; Coutelle, Romain; Habermas, Tilmann; Danion, Jean-Marie; Berna, Fabrice

2015-08-10

Self-narratives of patients have received increasing interest in schizophrenia since they offer unique material to study patients' subjective experience related to their illness, in particular the alteration of self that accompanies schizophrenia. In this study, we investigated the life narratives and the ability to integrate and bind memories of personal events into a coherent narrative in 27 patients with schizophrenia and 26 controls. Four aspects of life narratives were analyzed: coherence with cultural concept of biography, temporal coherence, causal-motivational coherence and thematic coherence. Results showed that in patients cultural biographical knowledge is preserved, whereas temporal coherence is partially impaired. Furthermore, causal-motivational and thematic coherence are significantly impaired: patients have difficulties explaining how events have modeled their identity, and integrating different events along thematic lines. Impairment of global causal-motivational and thematic coherence was significantly correlated with patients' executive dysfunction, suggesting that cognitive impairment observed in patients could affect their ability to construct a coherent narrative of their life by binding important events to their self. This study provides new understanding of the cognitive deficits underlying self-disorders in patients with schizophrenia. Our findings suggest the potential usefulness of developing new therapeutic interventions to improve autobiographical reasoning skills.

Use of global context for handling noisy names in discussion texts of a homeopathy discussion forum

Directory of Open Access Journals (Sweden)

Mukta Majumder

2014-03-01

Full Text Available The task of identifying named entities from the discussion texts in Web forums faces the challenge of noisy names. As the names are often misspelled or abbreviated, the conventional techniques have failed to detect the noisy names properly. In this paper we propose a global context based framework for handling the noisy names. The framework is tested on a named entity recognition system designed to identify the names from the discussion texts in a homeopathy diagnosis discussion forum. The proposed global context-based framework is found to be effective in improving the accuracy of the named entity recognition system.

An Application of the Coherent Noise Model for the Prediction of Aftershock Magnitude Time Series

Directory of Open Access Journals (Sweden)

Stavros-Richard G. Christopoulos

2017-01-01

Full Text Available Recently, the study of the coherent noise model has led to a simple (binary prediction algorithm for the forthcoming earthquake magnitude in aftershock sequences. This algorithm is based on the concept of natural time and exploits the complexity exhibited by the coherent noise model. Here, using the relocated catalogue from Southern California Seismic Network for 1981 to June 2011, we evaluate the application of this algorithm for the aftershocks of strong earthquakes of magnitude M≥6. The study is also extended by using the Global Centroid Moment Tensor Project catalogue to the case of the six strongest earthquakes in the Earth during the last almost forty years. The predictor time series exhibits the ubiquitous 1/f noise behavior.

Coherent Anti-Stokes and Coherent Stokes in Raman Scattering by Superconducting Nanowire Single-Photon Detector for Temperature Measurement

Directory of Open Access Journals (Sweden)

Annepu Venkata Naga Vamsi

2016-01-01

Full Text Available We have reported the measurement of temperature by using coherent anti-Stroke and coherent Stroke Raman scattering using superconducting nano wire single-photon detector. The measured temperatures by both methods (Coherent Anti-Raman scattering & Coherent Stroke Raman scattering and TC 340 are in good accuracy of ± 5 K temperature range. The length of the pipe line under test can be increased by increasing the power of the pump laser. This methodology can be widely used to measure temperatures at instantaneous positions in test pipe line or the entire temperature of the pipe line under test.

Coherence and correspondence in engineering design

Directory of Open Access Journals (Sweden)

Konstantinos V. Katsikopoulos

2009-03-01

Full Text Available I show how the coherence/correspondence distinction can inform the conversation about decision methods for engineering design. Some engineers argue for the application of multi-attribute utility theory while others argue for what they call heuristics. To clarify the differences among methods, I first ask whether each method aims at achieving coherence or correspondence. By analyzing statements in the design literature, I argue that utility theory aims at achieving coherence and heuristics aim at achieving correspondence. Second, I ask if achieving coherence always implies achieving correspondence. It is important to provide an answer because while in design the objective is correspondence, it is difficult to assess it, and coherence that is easier to assess is used as a surrogate. I argue that coherence does not always imply correspondence in design and that this is also the case in problems studied in judgment and decision-making research. Uncovering the conditions under which coherence implies, or does not imply, correspondence is a topic where engineering design and judgment and decision-making research might connect.

Coherence and incoherence collective behavior in financial market

Science.gov (United States)

Zhao, Shangmei; Xie, Qiuchao; Lu, Qing; Jiang, Xin; Chen, Wei

2015-10-01

Financial markets have been extensively studied as highly complex evolving systems. In this paper, we quantify financial price fluctuations through a coupled dynamical system composed of phase oscillators. We find that a Financial Coherence and Incoherence (FCI) coexistence collective behavior emerges as the system evolves into the stable state, in which the stocks split into two groups: one is represented by coherent, phase-locked oscillators, the other is composed of incoherent, drifting oscillators. It is demonstrated that the size of the coherent stock groups fluctuates during the economic periods according to real-world financial instabilities or shocks. Further, we introduce the coherent characteristic matrix to characterize the involvement dynamics of stocks in the coherent groups. Clustering results on the matrix provides a novel manifestation of the correlations among stocks in the economic periods. Our analysis for components of the groups is consistent with the Global Industry Classification Standard (GICS) classification and can also figure out features for newly developed industries. These results can provide potentially implications on characterizing the inner dynamical structure of financial markets and making optimal investment into tragedies.

Multi-jet correlations and colour coherence phenomena

Directory of Open Access Journals (Sweden)

Lee Jason S.H.

2017-01-01

Full Text Available In multi-jet events, colour coherence was shown to play a important role in the topology of these events. In modern Monte Carlo generators, the colour coherence effect has become an inherent feature, such that the colour coherence effect can no longer be disentangled in a simple manner. This study looks at the multi-jet correlations by comparing Monte Carlo generators in Parton Shower dominant and Matrix Element dominant regions.

(NTIC et aides à la compréhension et à la production de textes explicatifs en langue seconde - Vers une didactique cognitive du texte en contexte plurilingue et pluriculturel (NICT and helps in second language comprehension and production of  explicative texts - Towards cognitive textual didactics in multilingual  and multicultural contexts

Directory of Open Access Journals (Sweden)

Med Makhlouf

2007-03-01

Full Text Available Les apprentis lecteurs et producteurs de textes en langue maternelle (L1 éprouvent des difficultés à élaborer la cohérence des significations locales (microstructure et globales (macrostructure du contenu sémantique des textes à comprendre et à produire. En langue seconde (L2, les difficultés sont encore plus grandes, car les apprenants doivent activer leurs connaissances non seulement sur la L2, mais aussi sur le monde évoqué par le texte et construites dans leur langue maternelle. Ce sont ces connaissances qui leur permettent de faire les inférences nécessaires à la construction de la cohérence de la signification des textes. Nous présentons deux recherches sur les aides en langue maternelle à la compréhension et à la production de textes en L2. Le but est de concevoir et de valider des systèmes hypertextes (closed hypertext systems et des systèmes de co-apprentissage à distance (open-ended internet environments en nous appuyant sur un même cadre théorique intégrateur permettant de rendre compte du fonctionnement de la mémoire dans les apprentissages en contexte plurilingue et diglossique. C'est à partir de ce cadre commun en effet qu'il est possible d'envisager de façon interdisciplinaire des développements cohérents et efficaces au niveau de la didactique et des systèmes d'aide.Learners in comprehension and production of texts in mother tongue (L1 have difficulties in working out the coherence of the local (microstructure and global (macrostructure meaning of the semantic contents of the texts to be understood and written. In second language (L2, these difficulties are even more important because students must activate linguistic knowledge about the second language, but also about representations evoked by the text and built in their mother tongue. These are the knowledge which enables learners to activate the necessary inferences for the construction of the coherence of the text. We present two researches on

Coherence and extensions of stochastic matrices

Directory of Open Access Journals (Sweden)

Angelo Gilio

1995-11-01

Full Text Available In this paper a review of some general results on coherence of conditional probability assessments is given. Then, a necessary and sufficient condition on coherence of two finite families of discrete conditianal probability distributions, represented by two stochastic matrices P and Q, is obtained. Moreover, the possible extensions of the assessment (P,Q to the marginal distributions are examined and explicit formulas for them are given in some special case. Finally, a general algorithm to check coherence of (P,Q and to derive its extensions is proposed.

Convex analysis and global optimization

CERN Document Server

Tuy, Hoang

2016-01-01

This book presents state-of-the-art results and methodologies in modern global optimization, and has been a staple reference for researchers, engineers, advanced students (also in applied mathematics), and practitioners in various fields of engineering. The second edition has been brought up to date and continues to develop a coherent and rigorous theory of deterministic global optimization, highlighting the essential role of convex analysis. The text has been revised and expanded to meet the needs of research, education, and applications for many years to come. Updates for this new edition include: · Discussion of modern approaches to minimax, fixed point, and equilibrium theorems, and to nonconvex optimization; · Increased focus on dealing more efficiently with ill-posed problems of global optimization, particularly those with hard constraints;

Entropy and Graph Based Modelling of Document Coherence using Discourse Entities

DEFF Research Database (Denmark)

Petersen, Casper; Lioma, Christina; Simonsen, Jakob Grue

2015-01-01

We present two novel models of document coherence and their application to information retrieval (IR). Both models approximate document coherence using discourse entities, e.g. the subject or object of a sentence. Our first model views text as a Markov process generating sequences of discourse...... entities (entity n-grams); we use the entropy of these entity n-grams to approximate the rate at which new information appears in text, reasoning that as more new words appear, the topic increasingly drifts and text coherence decreases. Our second model extends the work of Guinaudeau & Strube [28......] that represents text as a graph of discourse entities, linked by different relations, such as their distance or adjacency in text. We use several graph topology metrics to approximate different aspects of the discourse flow that can indicate coherence, such as the average clustering or betweenness of discourse...

Quantum Coherence, Time-Translation Symmetry, and Thermodynamics

Directory of Open Access Journals (Sweden)

Matteo Lostaglio

2015-04-01

Full Text Available The first law of thermodynamics imposes not just a constraint on the energy content of systems in extreme quantum regimes but also symmetry constraints related to the thermodynamic processing of quantum coherence. We show that this thermodynamic symmetry decomposes any quantum state into mode operators that quantify the coherence present in the state. We then establish general upper and lower bounds for the evolution of quantum coherence under arbitrary thermal operations, valid for any temperature. We identify primitive coherence manipulations and show that the transfer of coherence between energy levels manifests irreversibility not captured by free energy. Moreover, the recently developed thermomajorization relations on block-diagonal quantum states are observed to be special cases of this symmetry analysis.

Relationship between weak central coherence and mental states understanding in children with Autism and in children with ADHD.

Directory of Open Access Journals (Sweden)

Pina Filippello

2013-05-01

Full Text Available The central coherence involves the processes of perceptual coding and attention mechanisms, highly deficient in children with ADHD (Booth & Happé, 2010. According to this theory, also children with autism are overly focused on details to the expense of a global perspective, and this negatively affects their ability to integrate environmental stimuli into a coherent whole (Happé, Booth, Charlton, Hughes, 2006. The aim of this study was to determine differences in central coherence of children with high functioning autism (ASD; n=10, children with attention-deficit hyperactivity disorder (ADHD; n=10 and typically developing peers (n=10. Individuals with ADHD exhibit significant deficits in perceptual skills and problem solving, failing also in mental states understanding tasks. While the children with autism spectrum disorder show impairments in making pragmatic inferences. Future research should therefore concentrate on the investigation of the cognitive and psychological mechanisms underlying these effects.

DISRUPTING SHOCKS IN POSTWAR GLOBAL ECONOMIC EXPANSION

Directory of Open Access Journals (Sweden)

Dumitru FILIPEANU

2016-06-01

Full Text Available The coherence of the global economic system, created by its upswing in the first postwar decades, started to crumble in the ’70s. The destabilizing shocks affected the entire world, but in an uneven manner, in different geographical areas and at different times, being felt most acutely, with devastating economic and social effects, in Third World countries. Although the developed countries were affected as well, they always had means to combat or to diminish the adverse effects of the crises, leading to "gentler" consequences. This paper focuses on four main aspects in postwar global economic expansion, namely: the ’70s – the international monetary crisis and the oil shocks; the foreign debt crisis; the Latin American debt crisis, the Asian financial crises and the current global crisis.

Remote sensing observations of the coherent and non-coherent ring structures in the vicinity of Lesser Antilles

Directory of Open Access Journals (Sweden)

R. C. Cruz Gómez

2007-03-01

Full Text Available The North Brazil Current Rings (NBCR penetration into the Caribbean Sea is being investigated by employing a merged altimeter-derived sea height anomaly (TOPEX/Poseidon, Jason-1 and ERS-1, 2, the ocean surface color data (SeaWiFS and Global Drifter Program information. Four strategies are being applied to process the data: (1 calculations of the Okubo-Weiss parameter for NBCR identification, (2 longitude-time plots (also known as Hovmöller diagrams, (3 two-dimensional Radon transforms and (4 two-dimensional Fourier transforms.

A twofold NBCR structure has been detected in the region under investigation. The results have shown that NBC rings mainly propagate into the Caribbean Sea along two principal pathways (near 12° N and 17° N in the ring translation corridor. Thus, rings following the southern pathway in the fall-winter period can enter through very shallow southern straits as non-coherent structures. A different behavior is observed near the northern pathway (~17° N, where NBC rings are thought to have a coherent structure during their squeezing into the eastern Caribbean, i.e. conserving the principal characteristics of the incident rings. We attribute this difference in the rings' behavior to the vertical scales of the rings and to the bottom topography features in the vicinity of the Lesser Antilles.

Experimental tests of coherence and entanglement conservation under unitary evolutions

Science.gov (United States)

Černoch, Antonín; Bartkiewicz, Karol; Lemr, Karel; Soubusta, Jan

2018-04-01

We experimentally demonstrate the migration of coherence between composite quantum systems and their subsystems. The quantum systems are implemented using polarization states of photons in two experimental setups. The first setup is based on a linear optical controlled-phase quantum gate and the second scheme utilizes effects of nonlinear optics. Our experiment allows one to verify the relation between correlations of the subsystems and the coherence of the composite system, which was given in terms of a conservation law for maximal accessible coherence by Svozilík et al. [J. Svozilík et al., Phys. Rev. Lett. 115, 220501 (2015), 10.1103/PhysRevLett.115.220501]. We observe that the maximal accessible coherence is conserved for the implemented class of global evolutions of the composite system.

Extracting subsurface fingerprints using optical coherence tomography

CSIR Research Space (South Africa)

Akhoury, SS

2015-02-01

Full Text Available Subsurface Fingerprints using Optical Coherence Tomography Sharat Saurabh Akhoury, Luke Nicholas Darlow Modelling and Digital Science, Council for Scientific and Industrial Research, Pretoria, South Africa Abstract Physiologists have found... approach to extract the subsurface fingerprint representation using a high-resolution imaging technology known as Optical Coherence Tomography (OCT). ...

The Determination of Children's Knowledge of Global Lunar Patterns from Online Essays Using Text Mining Analysis

Science.gov (United States)

Cheon, Jongpil; Lee, Sangno; Smith, Walter; Song, Jaeki; Kim, Yongjin

2013-01-01

The purpose of this study was to use text mining analysis of early adolescents' online essays to determine their knowledge of global lunar patterns. Australian and American students in grades five to seven wrote about global lunar patterns they had discovered by sharing observations with each other via the Internet. These essays were analyzed for…

Coherent spectroscopies on ultrashort time and length scales

Directory of Open Access Journals (Sweden)

Schneider C.

2013-03-01

Full Text Available Three spectroscopic techniques are presented that provide simultaneous spatial and temporal resolution: modified confocal microscopy with heterodyne detection, space-time-resolved spectroscopy using coherent control concepts, and coherent two-dimensional nano-spectroscopy. Latest experimental results are discussed.

Coherent State Quantization and Moment Problem

Directory of Open Access Journals (Sweden)

J. P. Gazeau

2010-01-01

Full Text Available Berezin-Klauder-Toeplitz (“anti-Wick” or “coherent state” quantization of the complex plane, viewed as the phase space of a particle moving on the line, is derived from the resolution of the unity provided by the standard (or gaussian coherent states. The construction of these states and their attractive properties are essentially based on the energy spectrum of the harmonic oscillator, that is on natural numbers. We follow in this work the same path by considering sequences of non-negative numbers and their associated “non-linear” coherent states. We illustrate our approach with the 2-d motion of a charged particle in a uniform magnetic field. By solving the involved Stieltjes moment problem we construct a family of coherent states for this model. We then proceed with the corresponding coherent state quantization and we show that this procedure takes into account the circle topology of the classical motion.

Quantum Processes Which Do Not Use Coherence

Directory of Open Access Journals (Sweden)

Benjamin Yadin

2016-11-01

Full Text Available A major signature of quantum mechanics beyond classical physics is coherence, the existence of superposition states. The recently developed resource theory of quantum coherence allows the formalization of incoherent operations—those operations which cannot create coherence. We identify the set of operations which additionally do not use coherence. These are such that coherence cannot be exploited by a classical observer, who measures incoherent properties of the system, to go beyond classical dynamics. We give a physical interpretation in terms of interferometry and prove a dilation theorem, showing how these operations can always be constructed by the system interacting, in an incoherent way, with an ancilla. Such a physical justification is not known for the incoherent operations; thus, our results lead to a physically well-motivated resource theory of coherence. Next, we investigate the implications for coherence in multipartite systems. We show that quantum correlations can be defined naturally with respect to a fixed basis, providing a link between coherence and quantum discord. We demonstrate the interplay between these two quantities in the operations that we study and suggest implications for the theory of quantum discord by relating these operations to those which cannot create discord.

Why do adults with dyslexia have poor global motion sensitivity?

Science.gov (United States)

Conlon, Elizabeth G; Lilleskaret, Gry; Wright, Craig M; Stuksrud, Anne

2013-01-01

Two experiments aimed to determine why adults with dyslexia have higher global motion thresholds than typically reading controls. In Experiment 1, the dot density and number of animation frames presented in the dot stimulus were manipulated because of findings that use of a high dot density can normalize coherence thresholds in individuals with dyslexia. Dot densities were 14.15 and 3.54 dots/deg(2). These were presented for five (84 ms) or eight (134 ms) frames. The dyslexia group had higher coherence thresholds in all conditions than controls. However, in the high dot density, long duration condition, both reader groups had the lowest thresholds indicating normal temporal recruitment. These results indicated that the dyslexia group could sample the additional signals dots over space and then integrate these with the same efficiency as controls. In Experiment 2, we determined whether briefly presenting a fully coherent prime moving in either the same or opposite direction of motion to a partially coherent test stimulus would systematically increase and decrease global motion thresholds in the reader groups. When the direction of motion in the prime and test was the same, global motion thresholds increased for both reader groups. The increase in coherence thresholds was significantly greater for the dyslexia group. When the motion of the prime and test were presented in opposite directions, coherence thresholds were reduced in both groups. No group threshold differences were found. We concluded that the global motion processing deficit found in adults with dyslexia can be explained by undersampling of the target motion signals. This might occur because of difficulties directing attention to the relevant motion signals in the random dot pattern, and not a specific difficulty integrating global motion signals. These effects are most likely to occur in the group with dyslexia when more complex computational processes are required to process global motion.

Absence of auditory 'global interference' in autism.

Science.gov (United States)

Foxton, Jessica M; Stewart, Mary E; Barnard, Louise; Rodgers, Jacqui; Young, Allan H; O'Brien, Gregory; Griffiths, Timothy D

2003-12-01

There has been considerable recent interest in the cognitive style of individuals with Autism Spectrum Disorder (ASD). One theory, that of weak central coherence, concerns an inability to combine stimulus details into a coherent whole. Here we test this theory in the case of sound patterns, using a new definition of the details (local structure) and the coherent whole (global structure). Thirteen individuals with a diagnosis of autism or Asperger's syndrome and 15 control participants were administered auditory tests, where they were required to match local pitch direction changes between two auditory sequences. When the other local features of the sequence pairs were altered (the actual pitches and relative time points of pitch direction change), the control participants obtained lower scores compared with when these details were left unchanged. This can be attributed to interference from the global structure, defined as the combination of the local auditory details. In contrast, the participants with ASD did not obtain lower scores in the presence of such mismatches. This was attributed to the absence of interference from an auditory coherent whole. The results are consistent with the presence of abnormal interactions between local and global auditory perception in ASD.

Global warming policy: A coherent-sequential approach

International Nuclear Information System (INIS)

Manicke, R.L.

1996-01-01

This paper addresses these two closely related themes: (1) the need for structuring and evaluating global climate policy sequentially and (2) the need to incorporate the analysis of real options which may contribute significantly to global climate policy. This paper is organized into four sections. The first section deals with benefit-cost analysis and capital budgeting as they are generally practiced and discusses the reasons why the traditional benefit-cost formulation is inadequate. The second section then discusses the case of one financial option, namely, the European Call Option and discusses some important results. The third section of the paper addresses some of the important results or principles derived in the literature on real options, and while most of the mathematics is not easily transferred nor relevant to the global climate policy, there are many principles that can be applied. In the fourth section the author discusses the implications of a real option environment for the policy process

Genre-dependent interaction of coherence and lexical cohesion in written discourse

NARCIS (Netherlands)

Berzlánovich, I.; Redeker, G.

2012-01-01

We investigate the interaction between coherence and lexical cohesion in expository and persuasive texts using seven encyclopedia texts and seven fundraising letters. We describe genre structure in terms of genre-specific moves and coherence structure with Rhetorical Structure Theory. For lexical

SAR image effects on coherence and coherence estimation.

Energy Technology Data Exchange (ETDEWEB)

Bickel, Douglas Lloyd

2014-01-01

Radar coherence is an important concept for imaging radar systems such as synthetic aperture radar (SAR). This document quantifies some of the effects in SAR which modify the coherence. Although these effects can disrupt the coherence within a single SAR image, this report will focus on the coherence between separate images, such as for coherent change detection (CCD) processing. There have been other presentations on aspects of this material in the past. The intent of this report is to bring various issues that affect the coherence together in a single report to support radar engineers in making decisions about these matters.

Functions of Expressions of Futurality in Professional Economic Texts

Directory of Open Access Journals (Sweden)

Mikuláš Martin

2016-07-01

Full Text Available The aim of this corpus-based study is to identify the functions that selected expressions of futurality can express in professional economic texts. The classification of functions is established on the corpus of seven economic books. Excerpted instances of futural constructions are analysed with respect to textual and interpersonal functions as defined by Halliday. Futurality is interpreted broadly to include all lexical and grammatical means referring to the future. This approach makes it also possible to analyse futurality as a means of text coherence. Hence the core grammatical means are interpreted along with co-occurring lexical means under the two categories of functions to provide a comprehensive model of text coherence with regard to futurality. Frequency analysis shows that core futural expressions are not distributed equally throughout the corpus. While some expressions (e.g., will and the present simple tense dominate, others prove to be rather insignificant (e.g., be on the point/verge of, the present progressive tense. In addition, both lexical and grammatical constructions regularly co-occur in clusters, contributing to the coherence of the economic texts.

Maintaining Web Cache Coherency

Directory of Open Access Journals (Sweden)

2000-01-01

Full Text Available Document coherency is a challenging problem for Web caching. Once the documents are cached throughout the Internet, it is often difficult to keep them coherent with the origin document without generating a new traffic that could increase the traffic on the international backbone and overload the popular servers. Several solutions have been proposed to solve this problem, among them two categories have been widely discussed: the strong document coherency and the weak document coherency. The cost and the efficiency of the two categories are still a controversial issue, while in some studies the strong coherency is far too expensive to be used in the Web context, in other studies it could be maintained at a low cost. The accuracy of these analysis is depending very much on how the document updating process is approximated. In this study, we compare some of the coherence methods proposed for Web caching. Among other points, we study the side effects of these methods on the Internet traffic. The ultimate goal is to study the cache behavior under several conditions, which will cover some of the factors that play an important role in the Web cache performance evaluation and quantify their impact on the simulation accuracy. The results presented in this study show indeed some differences in the outcome of the simulation of a Web cache depending on the workload being used, and the probability distribution used to approximate updates on the cached documents. Each experiment shows two case studies that outline the impact of the considered parameter on the performance of the cache.

COHERENT enlightenment of the neutrino dark side

Science.gov (United States)

Coloma, Pilar; Gonzalez-Garcia, M. C.; Maltoni, Michele; Schwetz, Thomas

2017-12-01

In the presence of nonstandard neutrino interactions (NSI), oscillation data are affected by a degeneracy which allows the solar mixing angle to be in the second octant (also known as the dark side) and implies a sign flip of the atmospheric mass-squared difference. This leads to an ambiguity in the determination of the ordering of neutrino masses, one of the main goals of the current and future experimental neutrino program. We show that the recent observation of coherent neutrino-nucleus scattering by the COHERENT experiment, in combination with global oscillation data, excludes the NSI degeneracy at the 3.1 σ (3.6 σ ) C.L. for NSI with up (down) quarks.

Requirements and Technology Advances for Global Wind Measurement with a Coherent Lidar: A Shrinking Gap

Science.gov (United States)

Kavaya, Michael J.; Kavaya, Michael J.; Yu, Jirong; Koch, Grady J.; Amzajerdian, Farzin; Singh, Upendra N.; Emmitt, G. David

2007-01-01

Early concepts to globally measure vertical profiles of vector horizontal wind from space planned on an orbit height of 525 km, a single pulsed coherent Doppler lidar system to cover the full troposphere, and a continuously rotating telescope/scanner that mandated a vertical line of sight wind profile from each laser shot. Under these conditions system studies found that laser pulse energies of approximately 20 J at 10 Hz pulse repetition rate with a rotating telescope diameter of approximately 1.5 m was required. Further requirements to use solid state laser technology and an eyesafe wavelength led to the relatively new 2-micron solid state laser. With demonstrated pulse energies near 20 mJ at 5 Hz, and no demonstration of a rotating telescope maintaining diffraction limited performance in space, the technology gap between requirements and demonstration was formidable. Fortunately the involved scientists and engineers set out to reduce the gap, and through a combination of clever ideas and technology advances over the last 15 years, they have succeeded. This paper will detail the gap reducing factors and will present the current status.

Change Detection by Interferometric Coherence in Nasca Lines, Peru (1997-2004)

Science.gov (United States)

Ruescas, Ana B.; Delgado, J. Manuel; Costantini, Fabiano; Sarti, Francesco

2010-03-01

Two interferometric pairs of Synthetic Aperture Radar (SAR) images are used to generate coherence images of the Nasca Lines Pampa area. The first coherence image is based on a pair of ERS-2 SAR data from 1997 and 1999; the second one is computed from two ENVISAT-ASAR (Advanced SAR) images from 2003 and 2004. The main objective is to study the changes in the coherence values in different parts of the area. Several different decorrelation factors contributing to a loss of coherency in a radar pair can be distinguished, and these include the temporal change in the ground properties and nature between the two satellite passes. In order to do this discrimination and interpretation, some ancillary data can be used, such as optical data from the Advanced Land Observing Satellite (ALOS), and meteorological data from the Global Precipitation Climatology Center (GPCC).

Quantum learning of coherent states

Energy Technology Data Exchange (ETDEWEB)

Sentis, Gael [Universitat Autonoma de Barcelona, Fisica Teorica: Informacio i Fenomens Quantics, Barcelona (Spain); Guta, Madalin; Adesso, Gerardo [University of Nottingham, School of Mathematical Sciences, Nottingham (United Kingdom)

2015-12-15

We develop a quantum learning scheme for binary discrimination of coherent states of light. This is a problem of technological relevance for the reading of information stored in a digital memory. In our setting, a coherent light source is used to illuminate a memory cell and retrieve its encoded bit by determining the quantum state of the reflected signal. We consider a situation where the amplitude of the states produced by the source is not fully known, but instead this information is encoded in a large training set comprising many copies of the same coherent state. We show that an optimal global measurement, performed jointly over the signal and the training set, provides higher successful identification rates than any learning strategy based on first estimating the unknown amplitude by means of Gaussian measurements on the training set, followed by an adaptive discrimination procedure on the signal. By considering a simplified variant of the problem, we argue that this is the case even for non-Gaussian estimation measurements. Our results show that, even in absence of entanglement, collective quantum measurements yield an enhancement in the readout of classical information, which is particularly relevant in the operating regime of low-energy signals. (orig.)

Quantum learning of coherent states

International Nuclear Information System (INIS)

Sentis, Gael; Guta, Madalin; Adesso, Gerardo

2015-01-01

We develop a quantum learning scheme for binary discrimination of coherent states of light. This is a problem of technological relevance for the reading of information stored in a digital memory. In our setting, a coherent light source is used to illuminate a memory cell and retrieve its encoded bit by determining the quantum state of the reflected signal. We consider a situation where the amplitude of the states produced by the source is not fully known, but instead this information is encoded in a large training set comprising many copies of the same coherent state. We show that an optimal global measurement, performed jointly over the signal and the training set, provides higher successful identification rates than any learning strategy based on first estimating the unknown amplitude by means of Gaussian measurements on the training set, followed by an adaptive discrimination procedure on the signal. By considering a simplified variant of the problem, we argue that this is the case even for non-Gaussian estimation measurements. Our results show that, even in absence of entanglement, collective quantum measurements yield an enhancement in the readout of classical information, which is particularly relevant in the operating regime of low-energy signals. (orig.)

Fractals as macroscopic manifestation of squeezed coherent states and brain dynamics

International Nuclear Information System (INIS)

Vitiello, Giuseppe

2012-01-01

Recent results on the relation between self-similarity and squeezed coherent states are presented. I consider fractals which are generated iteratively according to a prescribed recipe, the so-called deterministic fractals. Fractal properties are incorporated in the framework of the theory of the entire analytical functions and deformed coherent states. Conversely, fractal properties of squeezed coherent states are recognized. This sheds some light on the understanding of the dynamical origin of fractals and their global nature emerging from local deformation processes. The self-similarity in brain background activity suggested by laboratory observations of power-law distributions of power spectral densities of electrocorticograms is also discussed and accounted in the frame of the dissipative many-body model of brain.

Detecting multiple moving objects in crowded environments with coherent motion regions

Science.gov (United States)

Cheriyadat, Anil M.; Radke, Richard J.

2013-06-11

Coherent motion regions extend in time as well as space, enforcing consistency in detected objects over long time periods and making the algorithm robust to noisy or short point tracks. As a result of enforcing the constraint that selected coherent motion regions contain disjoint sets of tracks defined in a three-dimensional space including a time dimension. An algorithm operates directly on raw, unconditioned low-level feature point tracks, and minimizes a global measure of the coherent motion regions. At least one discrete moving object is identified in a time series of video images based on the trajectory similarity factors, which is a measure of a maximum distance between a pair of feature point tracks.

Spectral coherent combination of ultrashort pulses

International Nuclear Information System (INIS)

Ursescu, D.; Banici, R.; Ionel, L.; Rusen, L.; Sandel, S.; Blanaru, C.

2010-01-01

Complete text of publication follows. The coherent beam combination was chosen in several laser systems, including ELI, as a solution to increase the final attainable intensity. However, the coherent beam combination it is also a difficult technique while it has to combine coherently in space and in time several beams amplified in different laser chains. That means in particular that the beams should be in phase in every point of the amplified beam so the spatial beam profiling techniques have to be mastered with high accuracy for all the combined beams. Here it is proposed an alternative coherent beam combination than the use of identical ultrashort pulses. The idea is to spectrally combine laser pulses with complementary spectra. Collinear and non-collinear approaches have been modelled. Ongoing experimental development, including the demonstration of the rephasing for two spectrally complementary ultrashort pulses will be presented. Acknowledgements. The research leading to these results has received funding from the EC's Seventh Framework Programme (LASERLAB-EUROPE, grant agreement no. 228334).

Coherent active polarization control without loss

Directory of Open Access Journals (Sweden)

Yuqian Ye

2017-11-01

Full Text Available We propose a lossless active polarization control mechanism utilizing an anisotropic dielectric medium with two coherent inputs. Using scattering matrix analysis, we derive analytically the required optical properties of the anisotropic medium that can behave as a switchable polarizing beam splitter. We also show that such a designed anisotropic medium can produce linearly polarized light at any azimuthal direction through coherent control of two inputs with a specific polarization state. Furthermore, we present a straightforward design-on-demand procedure of a subwavelength-thick metastructure that can possess the desired optical anisotropy at a flexible working wavelength. Our lossless coherent polarization control technique may lead to fast, broadband and integrated polarization control elements for applications in imaging, spectroscopy, and telecommunication.

Bosonic Confinement and Coherence in Disordered Nanodiamond Arrays.

Science.gov (United States)

Zhang, Gufei; Samuely, Tomas; Du, Hongchu; Xu, Zheng; Liu, Liwang; Onufriienko, Oleksandr; May, Paul W; Vanacken, Johan; Szabó, Pavol; Kačmarčík, Jozef; Yuan, Haifeng; Samuely, Peter; Dunin-Borkowski, Rafal E; Hofkens, Johan; Moshchalkov, Victor V

2017-11-28

In the presence of disorder, superconductivity exhibits short-range characteristics linked to localized Cooper pairs which are responsible for anomalous phase transitions and the emergence of quantum states such as the bosonic insulating state. Complementary to well-studied homogeneously disordered superconductors, superconductor-normal hybrid arrays provide tunable realizations of the degree of granular disorder for studying anomalous quantum phase transitions. Here, we investigate the superconductor-bosonic dirty metal transition in disordered nanodiamond arrays as a function of the dispersion of intergrain spacing, which ranges from angstroms to micrometers. By monitoring the evolved superconducting gaps and diminished coherence peaks in the single-quasiparticle density of states, we link the destruction of the superconducting state and the emergence of bosonic dirty metallic state to breaking of the global phase coherence and persistence of the localized Cooper pairs. The observed resistive bosonic phase transitions are well modeled using a series-parallel circuit in the framework of bosonic confinement and coherence.

Partially coherent imaging and spatial coherence wavelets

International Nuclear Information System (INIS)

Castaneda, Roman

2003-03-01

A description of spatially partially coherent imaging based on the propagation of second order spatial coherence wavelets and marginal power spectra (Wigner distribution functions) is presented. In this dynamics, the spatial coherence wavelets will be affected by the system through its elementary transfer function. The consistency of the model with the both extreme cases of full coherent and incoherent imaging was proved. In the last case we obtained the classical concept of optical transfer function as a simple integral of the elementary transfer function. Furthermore, the elementary incoherent response function was introduced as the Fourier transform of the elementary transfer function. It describes the propagation of spatial coherence wavelets form each object point to each image point through a specific point on the pupil planes. The point spread function of the system was obtained by a simple integral of the elementary incoherent response function. (author)

Connectives and Layout as Processing Signals: How Textual Features Affect Students' Processing and Text Representation

Science.gov (United States)

van Silfhout, Gerdineke; Evers-Vermeul, Jacqueline; Mak, Willem M.; Sanders, Ted J. M.

2014-01-01

When students read their school text, they may make a coherent mental representation of it that contains coherence relations between the text segments. The construction of such a representation is a prerequisite for learning from texts. This article focuses on the influence of connectives ("therefore," "furthermore") and layout…

Development of brain synchronisation within school-age--individual analysis of resting (α) coherence in a longitudinal data set.

Science.gov (United States)

Gmehlin, Dennis; Thomas, Christine; Weisbrod, Matthias; Walther, Stephan; Resch, Franz; Oelkers-Ax, Rieke

2011-10-01

Given evidence that synchronisation of neuronal activity may be a correlate of cognition, we examined EEG coherence as function of age and inter-electrode distance in healthy children and adolescents in order to elucidate basic information for a better understanding of developmental disorders associated with deficits in cognitive functions. Based on a 64-channel eyes closed resting EEG we combined local and global coherence measures in order to reduce volume conduction and reference effects. We used a two point longitudinal design in order to analyze intraindividual change during school-age (n=40; 6-18 years). Coherence was analyzed within individually adjusted frequency bands and around iPF (= individual alpha peak frequency). Both local and global resting coherence was largest in the alpha range and particularly around iPF. Local synchronisation was larger in the left compared with the right hemisphere. Controlling for increases in iPF, synchronisation increased with age, with global changes being most pronounced in the alpha range. Moreover age-related changes suggest an earlier development in girls. Our data provides evidence that both local and global functional integration increases during normal development within school-age. This general pattern - combined with more specific effects of sex and frequency - may help to specify deviations in developmental disorders. Copyright © 2011 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

Managerial level, managerial motivation and sense of coherence

Directory of Open Access Journals (Sweden)

MG Coetzee

2006-04-01

Full Text Available The first objective of the study was to assess whether the dimensions of Antonovsky’s Sense of Coherence (SOC scale correlated positively with those of the Managerial Motivation scale (MMQ. The second objective was to establish whether managers and supervisors differed with regard to sense of coherence and managerial motivation. The respondents were 124 employees of the Agricultural Research Council. None of the sense of coherence scales correlated with Attitude towards authority figures (MMQ. Also, Meaningfulness (SOC and Willingness to conduct administrative functions (MMQ did not correlate. However, the remainder of the correlations supported the hypothesis, indicating a strong positive relationship between managerial motivation and sense of coherence. Statistically significant differences between managers and supervisors were obtained for only two variables, namely Meaningfulness (SOC and Power motive (MMQ.

High-energy, 2µm laser transmitter for coherent wind LIDAR

Science.gov (United States)

Singh, Upendra N.; Yu, Jirong; Kavaya, Michael J.; Koch, Grady J.

2017-11-01

A coherent Doppler lidar at 2μm wavelength has been built with higher output energy (300 mJ) than previously available. The laser transmitter is based on the solid-state Ho:Tm:LuLiF, a NASA Langley Research Center invented laser material for higher extraction efficiency. This diode pumped injection seeded MOPA has a transform limited line width and diffraction limited beam quality. NASA Langley Research Center is developing coherent wind lidar transmitter technology at eye-safe wavelength for satellite-based observation of wind on a global scale. The ability to profile wind is a key measurement for understanding and predicting atmospheric dynamics and is a critical measurement for improving weather forecasting and climate modeling. We would describe the development and performance of an engineering hardened 2μm laser transmitter for coherent Doppler wind measurement from ground/aircraft/space platform.

Coherent regimes of globally coupled dynamical systems

DEFF Research Database (Denmark)

de Monte, Silvia; D'ovidio, Francesco; Mosekilde, Erik

2003-01-01

This Letter presents a method by which the mean field dynamics of a population of dynamical systems with parameter diversity and global coupling can be described in terms of a few macroscopic degrees of freedom. The method applies to populations of any size and functional form in the region...

Evidence of Reduced Global Processing in Autism Spectrum Disorder

Science.gov (United States)

Booth, Rhonda D. L.; Happé, Francesca G. E.

2018-01-01

Frith's original notion of 'weak central coherence' suggested that increased local processing in autism spectrum disorder (ASD) resulted from reduced global processing. More recent accounts have emphasised superior local perception and suggested intact global integration. However, tasks often place local and global processing in direct trade-off,…

Evaluating Extensions to Coherent Mortality Forecasting Models

Directory of Open Access Journals (Sweden)

Syazreen Shair

2017-03-01

Full Text Available Coherent models were developed recently to forecast the mortality of two or more sub-populations simultaneously and to ensure long-term non-divergent mortality forecasts of sub-populations. This paper evaluates the forecast accuracy of two recently-published coherent mortality models, the Poisson common factor and the product-ratio functional models. These models are compared to each other and the corresponding independent models, as well as the original Lee–Carter model. All models are applied to age-gender-specific mortality data for Australia and Malaysia and age-gender-ethnicity-specific data for Malaysia. The out-of-sample forecast error of log death rates, male-to-female death rate ratios and life expectancy at birth from each model are compared and examined across groups. The results show that, in terms of overall accuracy, the forecasts of both coherent models are consistently more accurate than those of the independent models for Australia and for Malaysia, but the relative performance differs by forecast horizon. Although the product-ratio functional model outperforms the Poisson common factor model for Australia, the Poisson common factor is more accurate for Malaysia. For the ethnic groups application, ethnic-coherence gives better results than gender-coherence. The results provide evidence that coherent models are preferable to independent models for forecasting sub-populations’ mortality.

Cohering power of quantum operations

Energy Technology Data Exchange (ETDEWEB)

Bu, Kaifeng, E-mail: bkf@zju.edu.cn [School of Mathematical Sciences, Zhejiang University, Hangzhou 310027 (China); Kumar, Asutosh, E-mail: asukumar@hri.res.in [Harish-Chandra Research Institute, Chhatnag Road, Jhunsi, Allahabad 211019 (India); Homi Bhabha National Institute, Anushaktinagar, Mumbai 400094 (India); Zhang, Lin, E-mail: linyz@zju.edu.cn [Institute of Mathematics, Hangzhou Dianzi University, Hangzhou 310018 (China); Wu, Junde, E-mail: wjd@zju.edu.cn [School of Mathematical Sciences, Zhejiang University, Hangzhou 310027 (China)

2017-05-18

Highlights: • Quantum coherence. • Cohering power: production of quantum coherence by quantum operations. • Study of cohering power and generalized cohering power, and their comparison for differentmeasures of quantum coherence. • Operational interpretation of cohering power. • Bound on cohering power of a generic quantum operation. - Abstract: Quantum coherence and entanglement, which play a crucial role in quantum information processing tasks, are usually fragile under decoherence. Therefore, the production of quantum coherence by quantum operations is important to preserve quantum correlations including entanglement. In this paper, we study cohering power–the ability of quantum operations to produce coherence. First, we provide an operational interpretation of cohering power. Then, we decompose a generic quantum operation into three basic operations, namely, unitary, appending and dismissal operations, and show that the cohering power of any quantum operation is upper bounded by the corresponding unitary operation. Furthermore, we compare cohering power and generalized cohering power of quantum operations for different measures of coherence.

Non-communicable diseases and global health governance: enhancing global processes to improve health development

Directory of Open Access Journals (Sweden)

Magnusson Roger S

2007-05-01

Full Text Available Abstract This paper assesses progress in the development of a global framework for responding to non-communicable diseases, as reflected in the policies and initiatives of the World Health Organization (WHO, World Bank and the UN: the institutions most capable of shaping a coherent global policy. Responding to the global burden of chronic disease requires a strategic assessment of the global processes that are likely to be most effective in generating commitment to policy change at country level, and in influencing industry behaviour. WHO has adopted a legal process with tobacco (the WHO Framework Convention on Tobacco Control, but a non-legal, advocacy-based approach with diet and physical activity (the Global Strategy on Diet, Physical Activity and Health. The paper assesses the merits of the Millennium Development Goals (MDGs and the FCTC as distinct global processes for advancing health development, before considering what lessons might be learned for enhancing the implementation of the Global Strategy on Diet. While global partnerships, economic incentives, and international legal instruments could each contribute to a more effective global response to chronic diseases, the paper makes a special case for the development of international legal standards in select areas of diet and nutrition, as a strategy for ensuring that the health of future generations does not become dependent on corporate charity and voluntary commitments. A broader frame of reference for lifestyle-related chronic diseases is needed: one that draws together WHO's work in tobacco, nutrition and physical activity, and that envisages selective use of international legal obligations, non-binding recommendations, advocacy and policy advice as tools of choice for promoting different elements of the strategy.

Strengthening the Global Refugee Protection System: Recommendations for the Global Compact on Refugees

Directory of Open Access Journals (Sweden)

Kevin Appleby

2017-12-01

• the adoption of coherent strategies, involving all sectors, to address large movements of refugees. This paper draws heavily, albeit not exclusively, from a series of papers published as a special collection in the Journal on Migration and Human Security[1] on strengthening the global system of refugee protection. [1] Rethinking the Global Refugee Protection System, Journal on Migration and Human Security, Center for Migration Studies, 2016-2017. See http://cmsny.org/cms_research/refugeeproject/.

Cross-coherent vector sensor processing for spatially distributed glider networks.

Science.gov (United States)

Nichols, Brendan; Sabra, Karim G

2015-09-01

Autonomous underwater gliders fitted with vector sensors can be used as a spatially distributed sensor array to passively locate underwater sources. However, to date, the positional accuracy required for robust array processing (especially coherent processing) is not achievable using dead-reckoning while the gliders remain submerged. To obtain such accuracy, the gliders can be temporarily surfaced to allow for global positioning system contact, but the acoustically active sea surface introduces locally additional sensor noise. This letter demonstrates that cross-coherent array processing, which inherently mitigates the effects of local noise, outperforms traditional incoherent processing source localization methods for this spatially distributed vector sensor network.

Mixed coherent states in coupled chaotic systems: Design of secure wireless communication

Science.gov (United States)

Vigneshwaran, M.; Dana, S. K.; Padmanaban, E.

2016-12-01

A general coupling design is proposed to realize a mixed coherent (MC) state: coexistence of complete synchronization, antisynchronization, and amplitude death in different pairs of similar state variables of the coupled chaotic system. The stability of coupled system is ensured by the Lyapunov function and a scaling of each variable is also separately taken care of. When heterogeneity as a parameter mismatch is introduced in the coupled system, the coupling function facilitates to retain its coherence and displays the global stability with renewed scaling factor. Robust synchronization features facilitated by a MC state enable to design a dual modulation scheme: binary phase shift key (BPSK) and parameter mismatch shift key (PMSK), for secure data transmission. Two classes of decoders (coherent and noncoherent) are discussed, the noncoherent decoder shows better performance over the coherent decoder, mostly a noncoherent demodulator is preferred in biological implant applications. Both the modulation schemes are demonstrated numerically by using the Lorenz oscillator and the BPSK scheme is demonstrated experimentally using radio signals.

Restricted Coherent Risk Measures and Actuarial Solvency

Directory of Open Access Journals (Sweden)

Christos E. Kountzakis

2012-01-01

Full Text Available We prove a general dual representation form for restricted coherent risk measures, and we apply it to a minimization problem of the required solvency capital for an insurance company.

Local and global limits on visual processing in schizophrenia.

Directory of Open Access Journals (Sweden)

Marc S Tibber

Full Text Available Schizophrenia has been linked to impaired performance on a range of visual processing tasks (e.g. detection of coherent motion and contour detection. It has been proposed that this is due to a general inability to integrate visual information at a global level. To test this theory, we assessed the performance of people with schizophrenia on a battery of tasks designed to probe voluntary averaging in different visual domains. Twenty-three outpatients with schizophrenia (mean age: 40±8 years; 3 female and 20 age-matched control participants (mean age 39±9 years; 3 female performed a motion coherence task and three equivalent noise (averaging tasks, the latter allowing independent quantification of local and global limits on visual processing of motion, orientation and size. All performance measures were indistinguishable between the two groups (ps>0.05, one-way ANCOVAs, with one exception: participants with schizophrenia pooled fewer estimates of local orientation than controls when estimating average orientation (p = 0.01, one-way ANCOVA. These data do not support the notion of a generalised visual integration deficit in schizophrenia. Instead, they suggest that distinct visual dimensions are differentially affected in schizophrenia, with a specific impairment in the integration of visual orientation information.

Regulatory Coherence and Standardization Mechanisms in the Trans-Pacific Partnership

Directory of Open Access Journals (Sweden)

Cai Phoenix X. F.

2016-12-01

Full Text Available This article posits a new taxonomy and framework for assessing regulatory coherence in the new generation of mega-regional, cross-cutting free trade agreements. Using the Trans-Pacific Partnership as the primary example, this article situates the rise of regulatory coherence within the current trade landscape, provides clear definitions of regulatory coherence, and argues that the real engine of regulatory coherence lies in the work of international standard setting organizations. This work has been little examined in the current literature. The article provides a detailed examination of the mechanics by which the Trans-Pacific Partnership promotes regulatory standardization and concludes with some normative implications and calls for future research.

Hemispheric Coherence in ASD with and without Comorbid ADHD and Anxiety

Directory of Open Access Journals (Sweden)

A. Saunders

2016-01-01

Full Text Available There is a growing body of evidence suggesting that altered brain connectivity may be a defining feature of disorders such as autism spectrum disorder (ASD, anxiety, and ADHD. This study investigated whether resting state functional connectivity, measured by 128-channel EEG oscillation coherence, differs between developmental disorders. Analyses were conducted separately on groups with and without comorbid conditions. Analyses revealed increased coherence across central electrodes over the primary motor cortex and decreased coherence in the frontal lobe networks in those with ASD compared to neurotypical controls. There was increased coherence in occipital lobe networks in the ADHD group compared to other groups. Symptoms of generalised anxiety were positively correlated with both frontal-occipital intrahemispheric (alpha only coherence and occipital interhemispheric coherence (alpha, approaching theta band. The patterns of coherence in the ASD pure group were different when comorbid conditions were included in the analyses, suggesting that aberrant coherence in the frontal and central areas of the brain is specifically associated with ASD. Our findings support the idea that comorbid conditions are additive, rather than being symptoms of the same disorder.

The study of entanglement and teleportation of the harmonic oscillator bipartite coherent states

Directory of Open Access Journals (Sweden)

A Rabeie and

2015-01-01

Full Text Available In this paper, we reproduce the harmonic oscillator bipartite coherent states with imperfect cloning of coherent states. We show that if these entangled coherent states are embedded in a vacuum environment, their entanglement is degraded but not totally lost . Also, the optimal fidelity of these states is worked out for investigating their teleportation

Search and Coherence-Building in Intuition and Insight Problem Solving

Directory of Open Access Journals (Sweden)

Michael Öllinger

2017-05-01

Full Text Available Coherence-building is a key concept for a better understanding of the underlying mechanisms of intuition and insight problem solving. There are several accounts that address certain aspects of coherence-building. However, there is still no proper framework defining the general principles of coherence-building. We propose a four-stage model of coherence-building. The first stage starts with spreading activation restricted by constraints. This dynamic is a well-defined rule based process. The second stage is characterized by detecting a coherent state. We adopted a fluency account assuming that the ease of information processing indicates the realization of a coherent state. The third stage is designated to evaluate the result of the coherence-building process and assess whether the given problem is solved or not. If the coherent state does not fit the requirements of the task, the process re-enters at stage 1. These three stages characterize intuition. For insight problem solving a fourth stage is necessary, which restructures the given representation after repeated failure, so that a new search space results. The new search space enables new coherent states. We provide a review of the most important findings, outline our model, present a large number of examples, deduce potential new paradigms and measures that might help to decipher the underlying cognitive processes.

Optical Coherence Tomography Technology and Quality Improvement Methods for Optical Coherence Tomography Images of Skin: A Short Review

Directory of Open Access Journals (Sweden)

Saba Adabi

2017-06-01

Full Text Available Optical coherence tomography (OCT delivers 3-dimensional images of tissue microstructures. Although OCT imaging offers a promising high-resolution method, OCT images experience some artifacts that lead to misapprehension of tissue structures. Speckle, intensity decay, and blurring are 3 major artifacts in OCT images. Speckle is due to the low coherent light source used in the configuration of OCT. Intensity decay is a deterioration of light with respect to depth, and blurring is the consequence of deficiencies of optical components. In this short review, we summarize some of the image enhancement algorithms for OCT images which address the abovementioned artifacts.

Coherence optimization and its limitations for deformation monitoring in dynamic agricultural environments

CSIR Research Space (South Africa)

Eng, Jeanine

2016-12-01

Full Text Available the polInSAR technique for its ability to increase interferometric coherence and to detect surface movement in the areas of interest. Both fully polarimetric RADARSAT-2 and ALOS PALSAR data were subject to coherence optimization using the multiple...

Partial coherence with application to the monotonicity problem of coherence involving skew information

Science.gov (United States)

Luo, Shunlong; Sun, Yuan

2017-08-01

Quantifications of coherence are intensively studied in the context of completely decoherent operations (i.e., von Neuamnn measurements, or equivalently, orthonormal bases) in recent years. Here we investigate partial coherence (i.e., coherence in the context of partially decoherent operations such as Lüders measurements). A bona fide measure of partial coherence is introduced. As an application, we address the monotonicity problem of K -coherence (a quantifier for coherence in terms of Wigner-Yanase skew information) [Girolami, Phys. Rev. Lett. 113, 170401 (2014), 10.1103/PhysRevLett.113.170401], which is introduced to realize a measure of coherence as axiomatized by Baumgratz, Cramer, and Plenio [Phys. Rev. Lett. 113, 140401 (2014), 10.1103/PhysRevLett.113.140401]. Since K -coherence fails to meet the necessary requirement of monotonicity under incoherent operations, it is desirable to remedy this monotonicity problem. We show that if we modify the original measure by taking skew information with respect to the spectral decomposition of an observable, rather than the observable itself, as a measure of coherence, then the problem disappears, and the resultant coherence measure satisfies the monotonicity. Some concrete examples are discussed and related open issues are indicated.

Measuring coherence with entanglement concurrence

Science.gov (United States)

Qi, Xianfei; Gao, Ting; Yan, Fengli

2017-07-01

Quantum coherence is a fundamental manifestation of the quantum superposition principle. Recently, Baumgratz et al (2014 Phys. Rev. Lett. 113 140401) presented a rigorous framework to quantify coherence from the view of theory of physical resource. Here we propose a new valid quantum coherence measure which is a convex roof measure, for a quantum system of arbitrary dimension, essentially using the generalized Gell-Mann matrices. Rigorous proof shows that the proposed coherence measure, coherence concurrence, fulfills all the requirements dictated by the resource theory of quantum coherence measures. Moreover, strong links between the resource frameworks of coherence concurrence and entanglement concurrence is derived, which shows that any degree of coherence with respect to some reference basis can be converted to entanglement via incoherent operations. Our work provides a clear quantitative and operational connection between coherence and entanglement based on two kinds of concurrence. This new coherence measure, coherence concurrence, may also be beneficial to the study of quantum coherence.

Perceptual Integration Deficits in Autism Spectrum Disorders Are Associated with Reduced Interhemispheric Gamma-Band Coherence.

Science.gov (United States)

Peiker, Ina; David, Nicole; Schneider, Till R; Nolte, Guido; Schöttle, Daniel; Engel, Andreas K

2015-12-16

The integration of visual details into a holistic percept is essential for object recognition. This integration has been reported as a key deficit in patients with autism spectrum disorders (ASDs). The weak central coherence account posits an altered disposition to integrate features into a coherent whole in ASD. Here, we test the hypothesis that such weak perceptual coherence may be reflected in weak neural coherence across different cortical sites. We recorded magnetoencephalography from 20 adult human participants with ASD and 20 matched controls, who performed a slit-viewing paradigm, in which objects gradually passed behind a vertical or horizontal slit so that only fragments of the object were visible at any given moment. Object recognition thus required perceptual integration over time and, in case of the horizontal slit, also across visual hemifields. ASD participants were selectively impaired in the horizontal slit condition, indicating specific difficulties in long-range synchronization between the hemispheres. Specifically, the ASD group failed to show condition-related enhancement of imaginary coherence between the posterior superior temporal sulci in both hemispheres during horizontal slit-viewing in contrast to controls. Moreover, local synchronization reflected in occipitocerebellar beta-band power was selectively reduced for horizontal compared with vertical slit-viewing in ASD. Furthermore, we found disturbed connectivity between right posterior superior temporal sulcus and left cerebellum. Together, our results suggest that perceptual integration deficits co-occur with specific patterns of abnormal global and local synchronization in ASD. The weak central coherence account proposes a tendency of individuals with autism spectrum disorders (ASDs) to focus on details at the cost of an integrated coherent whole. Here, we provide evidence, at the behavioral and the neural level, that visual integration in object recognition is impaired in ASD, when

How might global health master deadly sins and strive for greater virtues?

Directory of Open Access Journals (Sweden)

Catherine Panter-Brick

2014-03-01

Full Text Available In the spirit of critical reflection, we examine how the field of global health might surmount current challenges and prioritize its ethical mandate, namely to achieve, for all people, equity in health. We use the parlance of mastering deadly sins and striving for greater virtues in an effort to review what is needed to transform global health action. Global health falls prey to four main temptations: coveting silo gains, lusting for technological solutions, leaving broad promises largely unfulfilled, and boasting of narrow successes. This necessitates a change of heart: to keep faith with the promise it made, global health requires a realignment of core values and a sharper focus on the primacy of relationships with the communities it serves. Based on the literature to date, we highlight six steps to re-orienting global health action. Articulating a coherent global health agenda will come from principled action, enacted through courage and prudence in decision-making to foster people-centered systems of care over the entire lifespan.

Global processing takes time: A meta-analysis on local-global visual processing in ASD

OpenAIRE

Van der Hallen, Ruth; Evers, Kris; Brewaeys, K.; Van Den Noortgate, Wim; Wagemans, Johan

2015-01-01

What does an individual with autism spectrum disorder (ASD) perceive first: the forest or the trees? In spite of 30 years of research and influential theories like the weak central coherence (WCC) theory and the enhanced perceptual functioning (EPF) account, the interplay of local and global visual processing in ASD remains only partly understood. Research findings vary in indicating a local processing bias or a global processing deficit, and often contradict each other. We have applied a for...

Influence of the Chemical Design on the Coherent Photoisomerization of Biomimetic Molecular Switches

Directory of Open Access Journals (Sweden)

Olivucci Massimo

2013-03-01

Full Text Available Ultrafast transient absorption spectroscopy reveals the effect of chemical substitutions on the photoreaction kinetics of biomimetic photoswitches displaying coherent dynamics. Ground state vibrational coherences are no longer observed when the excited state lifetime exceeds 300fs.

Towards an understanding of the mechanisms of weak central coherence effects: experiments in visual configural learning and auditory perception.

Science.gov (United States)

Plaisted, Kate; Saksida, Lisa; Alcántara, José; Weisblatt, Emma

2003-01-01

The weak central coherence hypothesis of Frith is one of the most prominent theories concerning the abnormal performance of individuals with autism on tasks that involve local and global processing. Individuals with autism often outperform matched nonautistic individuals on tasks in which success depends upon processing of local features, and underperform on tasks that require global processing. We review those studies that have been unable to identify the locus of the mechanisms that may be responsible for weak central coherence effects and those that show that local processing is enhanced in autism but not at the expense of global processing. In the light of these studies, we propose that the mechanisms which can give rise to 'weak central coherence' effects may be perceptual. More specifically, we propose that perception operates to enhance the representation of individual perceptual features but that this does not impact adversely on representations that involve integration of features. This proposal was supported in the two experiments we report on configural and feature discrimination learning in high-functioning children with autism. We also examined processes of perception directly, in an auditory filtering task which measured the width of auditory filters in individuals with autism and found that the width of auditory filters in autism were abnormally broad. We consider the implications of these findings for perceptual theories of the mechanisms underpinning weak central coherence effects. PMID:12639334

The semiclassical coherent state propagator in the Weyl representation

International Nuclear Information System (INIS)

Braun, Carol; Li, Feifei; Garg, Anupam; Stone, Michael

2015-01-01

It is shown that the semiclassical coherent state propagator takes its simplest form when the quantum mechanical Hamiltonian is replaced by its Weyl symbol in defining the classical action, in that there is then no need for a Solari-Kochetov correction. It is also shown that such a correction exists if a symbol other than the Weyl symbol is chosen and that its form is different depending on the symbol chosen. The various forms of the propagator based on different symbols are shown to be equivalent provided the correspondingly correct Solari-Kochetov correction is included. All these results are shown for both particle and spin coherent state propagators. The global anomaly in the fluctuation determinant is further elucidated by a study of the connection between the discrete fluctuation determinant and the discrete Jacobi equation

Coherent light squeezing states within a modified microring system

Directory of Open Access Journals (Sweden)

J. Ali

2018-06-01

Full Text Available We have proposed the simple method of the squeezed light generation in the modified microring resonator, which is known as the microring conjugate mirror (MCM. When the monochromatic light is input into the MCM, the general form of the squeezed coherent states for a quantum harmonic oscillator can be generated by controlling the additional two side rings, which are the phase modulators. By using the graphical method called the Optiwave program, the coherent squeezed states of coherent light within an MCM can be obtained and interpreted as the amplitude, phase, quadrature and photon number-squeezed states. This method has shown potentials for microring related device design, which can be used before practical applications.

Measurement of Spatial Coherence of Light Propagating in a Turbulent Atmosphere

Directory of Open Access Journals (Sweden)

P. Barcik

2013-04-01

Full Text Available A lot of issues have to be taken into account when designing a reliable free space optical communication link. Among these are e.g.,beam wander, fluctuation of optical intensity and loss of spatial coherence that are caused by atmospheric turbulence. This paper presents experimental measurements of spatial coherence of a laser beam. The experimental setup is based on Young's double pinhole experiment. Fringe patterns under atmospheric turbulence for four different pinhole separations are presented. From these fringe patterns, visibility is determined and the coherence radius is estimated.

Quantum coherence: Reciprocity and distribution

Energy Technology Data Exchange (ETDEWEB)

Kumar, Asutosh, E-mail: asukumar@hri.res.in [Harish-Chandra Research Institute, Allahabad-211019 (India); Homi Bhabha National Institute, Anushaktinagar, Mumbai 400094 (India)

2017-03-18

Quantum coherence is the outcome of the superposition principle. Recently, it has been theorized as a quantum resource, and is the premise of quantum correlations in multipartite systems. It is therefore interesting to study the coherence content and its distribution in a multipartite quantum system. In this work, we show analytically as well as numerically the reciprocity between coherence and mixedness of a quantum state. We find that this trade-off is a general feature in the sense that it is true for large spectra of measures of coherence and of mixedness. We also study the distribution of coherence in multipartite systems by looking at monogamy-type relation–which we refer to as additivity relation–between coherences of different parts of the system. We show that for the Dicke states, while the normalized measures of coherence violate the additivity relation, the unnormalized ones satisfy the same. - Highlights: • Quantum coherence. • Reciprocity between quantum coherence and mixedness. • Distribution of quantum coherence in multipartite quantum systems. • Additivity relation for distribution of quantum coherence in Dicke and “X” states.

Improved Visualization of Hydroacoustic Plumes Using the Split-Beam Aperture Coherence

Directory of Open Access Journals (Sweden)

Ann E. A. Blomberg

2018-06-01

Full Text Available Natural seepage of methane into the oceans is considerable, and plays a role in the global carbon cycle. Estimating the amount of this greenhouse gas entering the water column is important in order to understand their environmental impact. In addition, leakage from man-made structures such as gas pipelines may have environmental and economical consequences and should be promptly detected. Split beam echo sounders (SBES detect hydroacoustic plumes due to the significant contrast in acoustic impedance between water and free gas. SBES are also powerful tools for plume characterization, with the ability to provide absolute acoustic measurements, estimate bubble trajectories, and capture the frequency dependent response of bubbles. However, under challenging conditions such as deep water and considerable background noise, it can be difficult to detect the presence of gas seepage from the acoustic imagery alone. The spatial coherence of the wavefield measured across the split beam sectors, quantified by the coherence factor (CF, is a computationally simple, easily available quantity which complements the acoustic imagery and may ease the ability to automatically or visually detect bubbles in the water column. We demonstrate the benefits of CF processing using SBES data from the Hudson Canyon, acquired using the Simrad EK80 SBES. We observe that hydroacoustic plumes appear more clearly defined and are easier to detect in the CF imagery than in the acoustic backscatter images.

Coherence of brain electrical activity: a quality of life indicator in Alzheimer’s disease?Coerência da atividade elétrica cerebral: indicador da qualidade de vida na doença de Alzheimer?

Directory of Open Access Journals (Sweden)

Lineu Corrêa Fonseca

2015-05-01

Full Text Available Objective To investigate the relationships between quality of life (QOL and clinical and electroencephalogram (EEG aspects in patients with Alzheimer’s disease (AD. Method Twenty-eight patients with mild or moderate AD, 31 with Parkinson’s disease (PD, and 27 normal controls (NC were submitted to: CERAD neuropsychological battery, Hamilton Depression and Anxiety Rating Scales, Functional Activities Questionnaire, QOL scale for patients with AD, and quantitative EEG measures. Results AD and PD patients had similar QOL (31.0 ± 5.8; 31.7 ± 4.8, respectively, worse than that of NC (37.5 ± 6.3. AD patients had lower global interhemispheric theta coherence (0.49 ± 0.04; 0.52 ± 0.05; 0.52 ± 0.05; respectively than PD and NC. Multiple linear regression for QOL of AD patients revealed that global interhemispheric theta coherence, and Hamilton depression scores were significant factors (coefficients; 58.2 and -0.27, respectively; R2, 0.377. Conclusion Interhemispheric coherence correlates with QOL regardless of cognitive and functional variables and seems to be a neurophysiological indicator of QOL in AD patients.

Optical coherence tomography as a diagnostic tool

CSIR Research Space (South Africa)

Singh, A

2011-07-01

Full Text Available Optical Coherence Tomography (OCT) has been used in biomedical applications as a method to non-invasively detect changes occurring in tissue such as the detection of skin cancer. The effect of skin tone on detection of skin cancer has however...

The Weak Coherence Account: Detail-Focused Cognitive Style in Autism Spectrum Disorders

Science.gov (United States)

Happe, Francesca; Frith, Uta

2006-01-01

"Weak central coherence" refers to the detail-focused processing style proposed to characterise autism spectrum disorders (ASD). The original suggestion of a core deficit in central processing resulting in failure to extract global form/meaning, has been challenged in three ways. First, it may represent an outcome of superiority in local…

A comparison of central coherence skills between adolescents with an intellectual disability with and without comorbid autism spectrum disorder.

Science.gov (United States)

van Lang, Natasja D J; Bouma, Anke; Sytema, Sjoerd; Kraijer, Dirk W; Minderaa, Ruud B

2006-01-01

Central coherence theory hypothesizes individuals with autism process information in a detail-focused fashion. The present study examined whether adolescents with an intellectual disability and comorbid autism spectrum disorder showed a weaker central coherence than age- and IQ-matched controls. The central coherence skills of 43 adolescents from schools for students with severe learning problems were examined with two cognitive tasks. In these two tasks, detail-focused processing is beneficial to global processing to perform the tasks accurately and quickly. The group with autism spectrum disorder performed better than the control group. Adolescents with an intellectual disability and with comorbid autism spectrum disorder have a weaker central coherence than age- and IQ-matched controls. Partial support was also given for variability in weak central coherence within the autism spectrum.

Coherent hybrid electromagnetic field imaging

Science.gov (United States)

Cooke, Bradly J [Jemez Springs, NM; Guenther, David C [Los Alamos, NM

2008-08-26

An apparatus and corresponding method for coherent hybrid electromagnetic field imaging of a target, where an energy source is used to generate a propagating electromagnetic beam, an electromagnetic beam splitting means to split the beam into two or more coherently matched beams of about equal amplitude, and where the spatial and temporal self-coherence between each two or more coherently matched beams is preserved. Two or more differential modulation means are employed to modulate each two or more coherently matched beams with a time-varying polarization, frequency, phase, and amplitude signal. An electromagnetic beam combining means is used to coherently combine said two or more coherently matched beams into a coherent electromagnetic beam. One or more electromagnetic beam controlling means are used for collimating, guiding, or focusing the coherent electromagnetic beam. One or more apertures are used for transmitting and receiving the coherent electromagnetic beam to and from the target. A receiver is used that is capable of square-law detection of the coherent electromagnetic beam. A waveform generator is used that is capable of generation and control of time-varying polarization, frequency, phase, or amplitude modulation waveforms and sequences. A means of synchronizing time varying waveform is used between the energy source and the receiver. Finally, a means of displaying the images created by the interaction of the coherent electromagnetic beam with target is employed.

Le coordonnant en tant qu’outil de cohérence du texte : implications traductologiques

Directory of Open Access Journals (Sweden)

Brunon Bulikowski

2009-01-01

Full Text Available Co-ordinate connector as a tool for text coherence. The article shows the role of language mechanisms in respect of the co-ordination relation in the process of text coherence. The author considers the range of the phenomena studied and indicates that they go well beyond the boundaries of a complex sentence. Simultaneously, he shows their role in ensuring the isotopy of a text. In another place in the article, the author focuses his attention on the function of a co-ordinate conjunction at the inter-sentence level and, at the same time, shows the location of the phenomenon in the process of translation.

Ordering states with various coherence measures

Science.gov (United States)

Yang, Long-Mei; Chen, Bin; Fei, Shao-Ming; Wang, Zhi-Xi

2018-04-01

Quantum coherence is one of the most significant theories in quantum physics. Ordering states with various coherence measures is an intriguing task in quantification theory of coherence. In this paper, we study this problem by use of four important coherence measures—the l_1 norm of coherence, the relative entropy of coherence, the geometric measure of coherence and the modified trace distance measure of coherence. We show that each pair of these measures give a different ordering of qudit states when d≥3. However, for single-qubit states, the l_1 norm of coherence and the geometric coherence provide the same ordering. We also show that the relative entropy of coherence and the geometric coherence give a different ordering for single-qubit states. Then we partially answer the open question proposed in Liu et al. (Quantum Inf Process 15:4189, 2016) whether all the coherence measures give a different ordering of states.

Comprehension through explanation as the interaction of the brain’s coherence and cognitive control networks

Directory of Open Access Journals (Sweden)

Jarrod eMoss

2015-10-01

Full Text Available Discourse comprehension processes attempt to produce an elaborate and well-connected representation in the reader’s mind. A common network of regions including the angular gyrus, posterior cingulate, and dorsal frontal cortex appears to be involved in constructing coherent representations in a variety of tasks including social cognition tasks, narrative comprehension, and expository text comprehension. Reading strategies that require the construction of explicit inferences are used in the present research to examine how this coherence network interacts with other brain regions. A psychophysiological interaction analysis was used to examine regions showing changed functional connectivity with this coherence network when participants were engaged in either a non-inferencing reading strategy, paraphrasing, or a strategy requiring coherence-building inferences, self-explanation. Results of the analysis show that the coherence network increases in functional connectivity with a cognitive control network that may be specialized for the manipulation of semantic representations and the construction of new relations among these representations.

Central Coherence in Eating Disorders: A Synthesis of Studies Using the Rey Osterrieth Complex Figure Test.

Directory of Open Access Journals (Sweden)

Katie Lang

Full Text Available Large variability in tests and differences in scoring systems used to study central coherence in eating disorders may lead to different interpretations, inconsistent findings and between study discrepancies. This study aimed to address inconsistencies by collating data from several studies from the same research group that used the Rey Osterrieth Complex Figure Test (Rey Figure in order to produce norms to provide benchmark data for future studies.Data was collated from 984 participants in total. Anorexia Nervosa, Bulimia Nervosa, recovered Anorexia Nervosa, unaffected family members and healthy controls were compared using the Rey Figure.Poor global processing was observed across all current eating disorder sub-groups and in unaffected relatives. There was no difference in performance between recovered AN and HC groups.This is the largest dataset reported in the literature and supports previous studies implicating poor global processing across eating disorders using the Rey Figure. It provides robust normative data useful for future studies.

Scalable coherent interface

International Nuclear Information System (INIS)

Alnaes, K.; Kristiansen, E.H.; Gustavson, D.B.; James, D.V.

1990-01-01

The Scalable Coherent Interface (IEEE P1596) is establishing an interface standard for very high performance multiprocessors, supporting a cache-coherent-memory model scalable to systems with up to 64K nodes. This Scalable Coherent Interface (SCI) will supply a peak bandwidth per node of 1 GigaByte/second. The SCI standard should facilitate assembly of processor, memory, I/O and bus bridge cards from multiple vendors into massively parallel systems with throughput far above what is possible today. The SCI standard encompasses two levels of interface, a physical level and a logical level. The physical level specifies electrical, mechanical and thermal characteristics of connectors and cards that meet the standard. The logical level describes the address space, data transfer protocols, cache coherence mechanisms, synchronization primitives and error recovery. In this paper we address logical level issues such as packet formats, packet transmission, transaction handshake, flow control, and cache coherence. 11 refs., 10 figs

Coherent detectors

International Nuclear Information System (INIS)

Lawrence, C R; Church, S; Gaier, T; Lai, R; Ruf, C; Wollack, E

2009-01-01

Coherent systems offer significant advantages in simplicity, testability, control of systematics, and cost. Although quantum noise sets the fundamental limit to their performance at high frequencies, recent breakthroughs suggest that near-quantum-limited noise up to 150 or even 200 GHz could be realized within a few years. If the demands of component separation can be met with frequencies below 200 GHz, coherent systems will be strong competitors for a space CMB polarization mission. The rapid development of digital correlator capability now makes space interferometers with many hundreds of elements possible. Given the advantages of coherent interferometers in suppressing systematic effects, such systems deserve serious study.

Coherent detectors

Energy Technology Data Exchange (ETDEWEB)

Lawrence, C R [M/C 169-327, Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Church, S [Room 324 Varian Physics Bldg, 382 Via Pueblo Mall, Stanford, CA 94305-4060 (United States); Gaier, T [M/C 168-314, Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Lai, R [Northrop Grumman Corporation, Redondo Beach, CA 90278 (United States); Ruf, C [1533 Space Research Building, The University of Michigan, Ann Arbor, MI 48109-2143 (United States); Wollack, E, E-mail: charles.lawrence@jpl.nasa.go [NASA/GSFC, Code 665, Observational Cosmology Laboratory, Greenbelt, MD 20771 (United States)

2009-03-01

Coherent systems offer significant advantages in simplicity, testability, control of systematics, and cost. Although quantum noise sets the fundamental limit to their performance at high frequencies, recent breakthroughs suggest that near-quantum-limited noise up to 150 or even 200 GHz could be realized within a few years. If the demands of component separation can be met with frequencies below 200 GHz, coherent systems will be strong competitors for a space CMB polarization mission. The rapid development of digital correlator capability now makes space interferometers with many hundreds of elements possible. Given the advantages of coherent interferometers in suppressing systematic effects, such systems deserve serious study.

Teleportation of a Coherent Superposition State Via a nonmaximally Entangled Coherent Xhannel

Institute of Scientific and Technical Information of China (English)

无

2002-01-01

@@ We investigate the problemm of teleportation of a superposition coherent state with nonmaximally entangled coherent channel. Two strategies are considered to complete the task. The first one uses entanglement concentration to purify the channel to a maximally entangled one. The second one teleports the state through the nonmaximally entangled coherent channel directly. We find that the probabilities of successful teleportations for the two strategies are depend on the amplitudes of the coherent states and the mean fidelity of teleportation using the first strategy is always less than that of the second strategy.

Sevoflurane Induces Coherent Slow-Delta Oscillations in Rats

Directory of Open Access Journals (Sweden)

Jennifer A. Guidera

2017-07-01

Full Text Available Although general anesthetics are routinely administered to surgical patients to induce loss of consciousness, the mechanisms underlying anesthetic-induced unconsciousness are not fully understood. In rats, we characterized changes in the extradural EEG and intracranial local field potentials (LFPs within the prefrontal cortex (PFC, parietal cortex (PC, and central thalamus (CT in response to progressively higher doses of the inhaled anesthetic sevoflurane. During induction with a low dose of sevoflurane, beta/low gamma (12–40 Hz power increased in the frontal EEG and PFC, PC and CT LFPs, and PFC–CT and PFC–PFC LFP beta/low gamma coherence increased. Loss of movement (LOM coincided with an abrupt decrease in beta/low gamma PFC–CT LFP coherence. Following LOM, cortically coherent slow-delta (0.1–4 Hz oscillations were observed in the frontal EEG and PFC, PC and CT LFPs. At higher doses of sevoflurane sufficient to induce loss of the righting reflex, coherent slow-delta oscillations were dominant in the frontal EEG and PFC, PC and CT LFPs. Dynamics similar to those observed during induction were observed as animals emerged from sevoflurane anesthesia. We conclude that the rat is a useful animal model for sevoflurane-induced EEG oscillations in humans, and that coherent slow-delta oscillations are a correlate of sevoflurane-induced behavioral arrest and loss of righting in rats.

q-deformed charged fermion coherent states and SU(3) charged, Hyper-charged fermion coherent states

International Nuclear Information System (INIS)

Hao Sanru; Li Guanghua; Long Junyan

1994-01-01

By virtue of the algebra of the q-deformed fermion oscillators, the q-deformed charged fermion coherent states and SU(3) charged, hyper-charged fermion coherent states are discussed. The explicit forms of the two kinds of coherent states mentioned above are obtained by making use of the completeness of base vectors in the q-fermion Fock space. By comparing the q-deformed results with the ordinary results, it is found that the q-deformed charged fermion coherent states and SU(3) charged, hyper-charged fermion coherent states are automatically reduced to the ordinary charged fermion coherent states and SU(3) charged hyper-charged fermion coherent states if the deformed parameter q→1

Global status of hydrogen research

Energy Technology Data Exchange (ETDEWEB)

Lakeman, J.B.; Browning, D.J.

2001-07-01

This report surveys the global status of hydrogen research and identifies technological barriers to the implementation of a global hydrogen economy. It is concluded that there will be a 30 year transition phase to the full implementation of the hydrogen economy. In this period, hydrogen will be largely produced by the reformation of hydrocarbons, particularly methane. It will be necessary to ensure that any carbonaceous oxides (and other unwanted species) formed as by-products will be trapped and not released into the atmosphere. Following the transition phase, hydrogen should be largely produced from renewable energy sources using some form of water cracking, largely electrolysis. Target performances and costs are identified for key technologies. The status of hydrogen research in the UK is reviews and it is concluded that the UK does not have a strategy for the adoption of the hydrogen economy, nor does it have a coherent and co-ordinated research and development strategy addressing barriers to the hydrogen economy. Despite this fact, because of the long transition phase, it is still possible for the UK to formulate a coherent strategy and make a significant contribution to the global implementation of the hydrogen economy, as there are still unresolved technology issues. The report concludes with a number of recommendations. (Author)

Compiler-Enforced Cache Coherence Using a Functional Language

Directory of Open Access Journals (Sweden)

Rich Wolski

1996-01-01

Full Text Available The cost of hardware cache coherence, both in terms of execution delay and operational cost, is substantial for scalable systems. Fortunately, compiler-generated cache management can reduce program serialization due to cache contention; increase execution performance; and reduce the cost of parallel systems by eliminating the need for more expensive hardware support. In this article, we use the Sisal functional language system as a vehicle to implement and investigate automatic, compiler-based cache management. We describe our implementation of Sisal for the IBM Power/4. The Power/4, briefly available as a product, represents an early attempt to build a shared memory machine that relies strictly on the language system for cache coherence. We discuss the issues associated with deterministic execution and program correctness on a system without hardware coherence, and demonstrate how Sisal (as a functional language is able to address those issues.

An Enhanced Non-Coherent Pre-Filter Design for Tracking Error Estimation in GNSS Receivers.

Science.gov (United States)

Luo, Zhibin; Ding, Jicheng; Zhao, Lin; Wu, Mouyan

2017-11-18

Tracking error estimation is of great importance in global navigation satellite system (GNSS) receivers. Any inaccurate estimation for tracking error will decrease the signal tracking ability of signal tracking loops and the accuracies of position fixing, velocity determination, and timing. Tracking error estimation can be done by traditional discriminator, or Kalman filter-based pre-filter. The pre-filter can be divided into two categories: coherent and non-coherent. This paper focuses on the performance improvements of non-coherent pre-filter. Firstly, the signal characteristics of coherent and non-coherent integration-which are the basis of tracking error estimation-are analyzed in detail. After that, the probability distribution of estimation noise of four-quadrant arctangent (ATAN2) discriminator is derived according to the mathematical model of coherent integration. Secondly, the statistical property of observation noise of non-coherent pre-filter is studied through Monte Carlo simulation to set the observation noise variance matrix correctly. Thirdly, a simple fault detection and exclusion (FDE) structure is introduced to the non-coherent pre-filter design, and thus its effective working range for carrier phase error estimation extends from (-0.25 cycle, 0.25 cycle) to (-0.5 cycle, 0.5 cycle). Finally, the estimation accuracies of discriminator, coherent pre-filter, and the enhanced non-coherent pre-filter are evaluated comprehensively through the carefully designed experiment scenario. The pre-filter outperforms traditional discriminator in estimation accuracy. In a highly dynamic scenario, the enhanced non-coherent pre-filter provides accuracy improvements of 41.6%, 46.4%, and 50.36% for carrier phase error, carrier frequency error, and code phase error estimation, respectively, when compared with coherent pre-filter. The enhanced non-coherent pre-filter outperforms the coherent pre-filter in code phase error estimation when carrier-to-noise density ratio

Revisiting the Global Software Engineering Terminology

DEFF Research Database (Denmark)

Tell, Paolo; Giuffrida, Rosalba; Shah, Hina

2013-01-01

Even though Global Software Engineering (GSE) has been a research topic of interest for many years, some of its ground terminology is still lacking a unified, coherent, and shared definition and/or classification. The purpose of this report is to collect, outline, and relate several fundamental...

Topological Properties of Spatial Coherence Function

International Nuclear Information System (INIS)

Ji-Rong, Ren; Tao, Zhu; Yi-Shi, Duan

2008-01-01

The topological properties of the spatial coherence function are investigated rigorously. The phase singular structures (coherence vortices) of coherence function can be naturally deduced from the topological current, which is an abstract mathematical object studied previously. We find that coherence vortices are characterized by the Hopf index and Brouwer degree in topology. The coherence flux quantization and the linking of the closed coherence vortices are also studied from the topological properties of the spatial coherence function

Lexical Processing in Toddlers with ASD: Does Weak Central Coherence Play a Role?

Science.gov (United States)

Ellis Weismer, Susan; Haebig, Eileen; Edwards, Jan; Saffran, Jenny; Venker, Courtney E.

2016-01-01

This study investigated whether vocabulary delays in toddlers with autism spectrum disorders (ASD) can be explained by a cognitive style that prioritizes processing of detailed, local features of input over global contextual integration--as claimed by the weak central coherence (WCC) theory. Thirty toddlers with ASD and 30 younger,…

Tunnel splitting in biaxial spin models investigated with spin-coherent-state path integrals

International Nuclear Information System (INIS)

Chen Zhide; Liang, J.-Q.; Pu, F.-C.

2003-01-01

Tunnel splitting in biaxial spin models is investigated with a full evaluation of the fluctuation functional integrals of the Euclidean kernel in the framework of spin-coherent-state path integrals which leads to a magnitude of tunnel splitting quantitatively comparable with the numerical results in terms of diagonalization of the Hamilton operator. An additional factor resulted from a global time transformation converting the position-dependent mass to a constant one seems to be equivalent to the semiclassical correction of the Lagrangian proposed by Enz and Schilling. A long standing question whether the spin-coherent-state representation of path integrals can result in an accurate tunnel splitting is therefore resolved

Coherently combining data between detectors for all-sky semi-coherent continuous gravitational wave searches

International Nuclear Information System (INIS)

Goetz, E; Riles, K

2016-01-01

We present a method for coherently combining short data segments from gravitational-wave detectors to improve the sensitivity of semi-coherent searches for continuous gravitational waves. All-sky searches for continuous gravitational waves from unknown sources are computationally limited. The semi-coherent approach reduces the computational cost by dividing the entire observation timespan into short segments to be analyzed coherently, then combined together incoherently. Semi-coherent analyses that attempt to improve sensitivity by coherently combining data from multiple detectors face a computational challenge in accounting for uncertainties in signal parameters. In this article, we lay out a technique to meet this challenge using summed Fourier transform coefficients. Applying this technique to one all-sky search algorithm called TwoSpect, we confirm that the sensitivity of all-sky, semi-coherent searches can be improved by coherently combining the short data segments, e.g., by up to 42% over a single detector for an all-sky search. For misaligned detectors, however, this improvement requires careful attention when marginalizing over unknown polarization parameters. In addition, care must be taken in correcting for differential detector velocity due to the Earth’s rotation for high signal frequencies and widely separated detectors. (paper)

Self-Mixing Demodulation for Coherent Phase-Sensitive OTDR System

Directory of Open Access Journals (Sweden)

Haijun He

2016-05-01

Full Text Available Phase-sensitive optical time domain reflectometry (Ф-OTDR attracts much attention due to its capability of telling the type and position of an intrusion simultaneously. In recent decades, coherent Ф-OTDR has been demonstrated to realize long-distance detection. For coherent Ф-OTDR, there are three typical demodulation schemes in the reported studies. However, they still cannot realize real-time monitoring to satisfy practical demands. A simple and effective demodulation method based on self-mixing has been put forward to demodulate the beat signal in coherent Ф-OTDR. It not only saves a local electrical oscillator and frequency locked loop, but also demodulates the beat signal without residual frequency. Several vibrations with different frequency were separately applied at the same location of a 42.5 km fiber. The spatial resolution of 10 m and frequency response range from 8 Hz to 980 Hz have been achieved. The precise location with signal-to-noise ratio of 21.4 dB and broadband measurement demonstrate the self-mixing scheme can demodulate the coherent Ф-OTDR signal effectively.

Chronic stress disrupts neural coherence between cortico-limbic structures

Directory of Open Access Journals (Sweden)

João Filipe Oliveira

2013-02-01

Full Text Available Chronic stress impairs cognitive function, namely on tasks that rely on the integrity of cortico-limbic networks. To unravel the functional impact of progressive stress in cortico-limbic networks we measured neural activity and spectral coherences between the ventral hippocampus (vHIP and the medial prefrontal cortex (mPFC in rats subjected to short term (STS and chronic unpredictable stress (CUS. CUS exposure consistently disrupted the spectral coherence between both areas for a wide range of frequencies, whereas STS exposure failed to trigger such effect. The chronic stress-induced coherence decrease correlated inversely with the vHIP power spectrum, but not with the mPFC power spectrum, which supports the view that hippocampal dysfunction is the primary event after stress exposure. Importantly, we additionally show that the variations in vHIP-to-mPFC coherence and power spectrum in the vHIP correlated with stress-induced behavioral deficits in a spatial reference memory task. Altogether, these findings result in an innovative readout to measure, and follow, the functional events that underlie the stress-induced reference memory impairments.

Spectral coherence in windturbine wakes

Energy Technology Data Exchange (ETDEWEB)

Hojstrup, J. [Riso National Lab., Roskilde (Denmark)

1996-12-31

This paper describes an experiment at a Danish wind farm to investigate the lateral and vertical coherences in the nonequilibrium turbulence of a wind turbine wake. Two meteorological masts were instrumented for measuring profiles of mean speed, turbulence, and temperature. Results are provided graphically for turbulence intensities, velocity spectra, lateral coherence, and vertical coherence. The turbulence was somewhat influenced by the wake, or possibly from aggregated wakes further upstream, even at 14.5 diameters. Lateral coherence (separation 5m) seemed to be unaffected by the wake at 7.5 diameters, but the flow was less coherent in the near wake. The wake appeared to have little influence on vertical coherence (separation 13m). Simple, conventional models for coherence appeared to be adequate descriptions for wake turbulence except for the near wake situation. 3 refs., 7 figs., 1 tab.

[On-line processing mechanisms in text comprehension: a theoretical review on constructing situation models].

Science.gov (United States)

Iseki, Ryuta

2004-12-01

This article reviewed research on construction of situation models during reading. To position variety of research in overall process appropriately, an unitary framework was devised in terms of three theories for on-line processing: resonance process, event-indexing model, and constructionist theory. Resonance process was treated as a basic activation mechanism in the framework. Event-indexing model was regarded as a screening system which selected and encoded activated information in situation models along with situational dimensions. Constructionist theory was considered to have a supervisory role based on coherence and explanation. From a view of the unitary framework, some problems concerning each theory were examined and possible interpretations were given. Finally, it was pointed out that there were little theoretical arguments on associative processing at global level and encoding text- and inference-information into long-term memory.

A Direct Comparison of Local-Global Integration in Autism and other Developmental Disorders: Implications for the Central Coherence Hypothesis

OpenAIRE

Bernardiono, I; Mouga, S; Almeida, J; van Asselen, M; Oliveira, G

2012-01-01

The weak central coherence hypothesis represents one of the current explanatory models in Autism Spectrum Disorders (ASD). Several experimental paradigms based on hierarchical figures have been used to test this controversial account. We addressed this hypothesis by testing central coherence in ASD (n = 19 with intellectual disability and n = 20 without intellectual disability), Williams syndrome (WS, n = 18), matched controls with intellectual disability (n = 20) and chronological age-matche...

Coherent, Short-Pulse X-ray Generation via Relativistic Flying Mirrors

Directory of Open Access Journals (Sweden)

Masaki Kando

2018-04-01

Full Text Available Coherent, Short X-ray pulses are demanded in material science and biology for the study of micro-structures. Currently, large-sized free-electron lasers are used; however, the available beam lines are limited because of the large construction cost. Here we review a novel method to downsize the system as well as providing fully (spatially and temporally coherent pulses. The method is based on the reflection of coherent laser light by a relativistically moving mirror (flying mirror. Due to the double Doppler effect, the reflected pulses are upshifted in frequency and compressed in time. Such mirrors are formed when an intense short laser pulse excites a strongly nonlinear plasma wave in tenuous plasma. Theory, proof-of-principle, experiments, and possible applications are addressed.

Linear algebraic theory of partial coherence: discrete fields and measures of partial coherence.

Science.gov (United States)

Ozaktas, Haldun M; Yüksel, Serdar; Kutay, M Alper

2002-08-01

A linear algebraic theory of partial coherence is presented that allows precise mathematical definitions of concepts such as coherence and incoherence. This not only provides new perspectives and insights but also allows us to employ the conceptual and algebraic tools of linear algebra in applications. We define several scalar measures of the degree of partial coherence of an optical field that are zero for full incoherence and unity for full coherence. The mathematical definitions are related to our physical understanding of the corresponding concepts by considering them in the context of Young's experiment.

Coherent Performance Analysis of the HJ-1-C Synthetic Aperture Radar

Directory of Open Access Journals (Sweden)

Li Hai-ying

2014-06-01

Full Text Available Synthetic Aperture Radar (SAR is a coherent imaging radar. Hence, coherence is critical in SAR imaging. In a coherent system, several sources can degrade performance. Based on the HJ-1-C SAR system implementation and sensor characteristics, this study evaluates the effect of frequency stability and pulse-to-pulse timing jitter on the SAR coherent performance. A stable crystal oscillator with short-term stability of 10×1.0−10 / 5 ms is used to generate the reference frequency by using a direct multiplier and divider. Azimuth ISLR degradation owing to the crystal oscillator phase noise is negligible. The standard deviation of the pulse-to-pulse timing jitter of HJ-1-C SAR is lower than 2ns (rms and the azimuth random phase error in the synthetic aperture time slightly degrades the side lobe of the azimuth impulse response. The mathematical expressions and simulation results are presented and suggest that the coherent performance of the HJ-1-C SAR system meets the requirements of synthetic aperture radar imaging.

Optical Coherence and Quantum Optics

CERN Document Server

Mandel, Leonard

1995-01-01

This book presents a systematic account of optical coherence theory within the framework of classical optics, as applied to such topics as radiation from sources of different states of coherence, foundations of radiometry, effects of source coherence on the spectra of radiated fields, coherence theory of laser modes, and scattering of partially coherent light by random media. The book starts with a full mathematical introduction to the subject area and each chapter concludes with a set of exercises. The authors are renowned scientists and have made substantial contributions to many of the topi

Global variation of meteor trail plasma turbulence

Directory of Open Access Journals (Sweden)

L. P. Dyrud

2011-12-01

Full Text Available We present the first global simulations on the occurrence of meteor trail plasma irregularities. These results seek to answer the following questions: when a meteoroid disintegrates in the atmosphere, will the resulting trail become plasma turbulent? What are the factors influencing the development of turbulence? and how do these trails vary on a global scale? Understanding meteor trail plasma turbulence is important because turbulent meteor trails are visible as non-specular trails to coherent radars. Turbulence also influences the evolution of specular radar meteor trails; this fact is important for the inference of mesospheric temperatures from the trail diffusion rates, and their usage for meteor burst communication. We provide evidence of the significant effect that neutral atmospheric winds and ionospheric plasma density have on the variability of meteor trail evolution and on the observation of non-specular meteor trails. We demonstrate that trails are far less likely to become and remain turbulent in daylight, explaining several observational trends for non-specular and specular meteor trails.

On Longitudinal Spectral Coherence

DEFF Research Database (Denmark)

Kristensen, Leif

1979-01-01

It is demonstrated that the longitudinal spectral coherence differs significantly from the transversal spectral coherence in its dependence on displacement and frequency. An expression for the longitudinal coherence is derived and it is shown how the scale of turbulence, the displacement between ...... observation sites and the turbulence intensity influence the results. The limitations of the theory are discussed....

Store operations to maintain cache coherence

Energy Technology Data Exchange (ETDEWEB)

Evangelinos, Constantinos; Nair, Ravi; Ohmacht, Martin

2017-08-01

In one embodiment, a computer-implemented method includes encountering a store operation during a compile-time of a program, where the store operation is applicable to a memory line. It is determined, by a computer processor, that no cache coherence action is necessary for the store operation. A store-without-coherence-action instruction is generated for the store operation, responsive to determining that no cache coherence action is necessary. The store-without-coherence-action instruction specifies that the store operation is to be performed without a cache coherence action, and cache coherence is maintained upon execution of the store-without-coherence-action instruction.

Store operations to maintain cache coherence

Energy Technology Data Exchange (ETDEWEB)

Evangelinos, Constantinos; Nair, Ravi; Ohmacht, Martin

2017-09-12

In one embodiment, a computer-implemented method includes encountering a store operation during a compile-time of a program, where the store operation is applicable to a memory line. It is determined, by a computer processor, that no cache coherence action is necessary for the store operation. A store-without-coherence-action instruction is generated for the store operation, responsive to determining that no cache coherence action is necessary. The store-without-coherence-action instruction specifies that the store operation is to be performed without a cache coherence action, and cache coherence is maintained upon execution of the store-without-coherence-action instruction.

Novel Direction Of Arrival Estimation Method Based on Coherent Accumulation Matrix Reconstruction

Directory of Open Access Journals (Sweden)

Li Lei

2015-04-01

Full Text Available Based on coherent accumulation matrix reconstruction, a novel Direction Of Arrival (DOA estimation decorrelation method of coherent signals is proposed using a small sample. First, the Signal to Noise Ratio (SNR is improved by performing coherent accumulation operation on an array of observed data. Then, according to the structure characteristics of the accumulated snapshot vector, the equivalent covariance matrix, whose rank is the same as the number of array elements, is constructed. The rank of this matrix is proved to be determined just by the number of incident signals, which realize the decorrelation of coherent signals. Compared with spatial smoothing method, the proposed method performs better by effectively avoiding aperture loss with high-resolution characteristics and low computational complexity. Simulation results demonstrate the efficiency of the proposed method.

Research on the space-borne coherent wind lidar technique and the prototype experiment

Science.gov (United States)

Gao, Long; Tao, Yuliang; An, Chao; Yang, Jukui; Du, Guojun; Zheng, Yongchao

2016-10-01

Space-borne coherent wind lidar technique is considered as one of the most promising and appropriate remote Sensing methods for successfully measuring the whole global vector wind profile between the lower atmosphere and the middle atmosphere. Compared with other traditional methods, the space-borne coherent wind lidar has some advantages, such as, the all-day operation; many lidar systems can be integrated into the same satellite because of the light-weight and the small size, eye-safe wavelength, and being insensitive to the background light. Therefore, this coherent lidar could be widely applied into the earth climate research, disaster monitoring, numerical weather forecast, environment protection. In this paper, the 2μm space-borne coherent wind lidar system for measuring the vector wind profile is proposed. And the technical parameters about the sub-system of the coherent wind lidar are simulated and the all sub-system schemes are proposed. For sake of validating the technical parameters of the space-borne coherent wind lidar system and the optical off-axis telescope, the weak laser signal detection technique, etc. The proto-type coherent wind lidar is produced and the experiments for checking the performance of this proto-type coherent wind lidar are finished with the hard-target and the soft target, and the horizontal wind and the vertical wind profile are measured and calibrated, respectively. For this proto-type coherent wind lidar, the wavelength is 1.54μm, the pulse energy 80μJ, the pulse width 300ns, the diameter of the off-axis telescope 120mm, the single wedge for cone scanning with the 40°angle, and the two dualbalanced InGaAs detector modules are used. The experiment results are well consisted with the simulation process, and these results show that the wind profile between the vertical altitude 4km can be measured, the accuracy of the wind velocity and the wind direction are better than 1m/s and +/-10°, respectively.

On P-coherent endomorphism rings

Indian Academy of Sciences (India)

A ring is called right -coherent if every principal right ideal is finitely presented. Let M R be a right -module. We study the -coherence of the endomorphism ring of M R . It is shown that is a right -coherent ring if and only if every endomorphism of M R has a pseudokernel in add M R ; S is a left -coherent ring if and ...

Optical Coherence Tomography

DEFF Research Database (Denmark)

Fercher, A.F.; Andersen, Peter E.

2017-01-01

Optical coherence tomography (OCT) is a technique that is used to peer inside a body noninvasively. Tissue structure defined by tissue absorption and scattering coefficients, and the speed of blood flow, are derived from the characteristics of light remitted by the body. Singly backscattered light...... detected by partial coherence interferometry (PCI) is used to synthesize the tomographic image coded in false colors. A prerequisite of this technique is a low time-coherent but high space-coherent light source, for example, a superluminescent diode or a supercontinuum source. Alternatively, the imaging...... technique can be realized by using ultrafast wavelength scanning light sources. For tissue imaging, the light source wavelengths are restricted to the red and near-infrared (NIR) region from about 600 to 1300 nm, the so-called therapeutic window, where absorption (μa ≈ 0.01 mm−1) is small enough. Transverse...

Progress of recent experimental research on the J-TEXT tokamak

Science.gov (United States)

Zhuang, G.; Gentle, K. W.; Chen, Z. Y.; Chen, Z. P.; Yang, Z. J.; Zheng, Wei; Hu, Q. M.; Chen, J.; Rao, B.; Zhong, W. L.; Zhao, K. J.; Gao, L.; Cheng, Z. F.; Zhang, X. Q.; Wang, L.; Jiang, Z. H.; Xu, T.; Zhang, M.; Wang, Z. J.; Ding, Y. H.; Yu, K. X.; Hu, X. W.; Pan, Y.; Huang, H.; the J-TEXT Team

2017-10-01

The progress of experimental research over the last two years on the J-TEXT tokamak is reviewed and reported in this paper, including: investigations of resonant magnetic perturbations (RMPs) on the J-TEXT operation region show that moderate amplitude of applied RMPs either increases the density limit from less than 0.7n G to 0.85n G (n G is the Greenwald density, {{n}\\text{G}}={{I}\\text{p}}/π {{a}2} ) or lowers edge safety factor q a from 2.15 to nearly 2.0; observations of influence of RMPs with a large m/n  =  3/1 dominant component (where m and n are the toroidal and poloidal mode numbers respectively) on electron density indicate electron density first increases (decreases) inside (around/outside) of the 3/1 rational surface, and it is increased globally later together with enhanced edge recycling; investigations of the effect of RMPs on the behavior of runaway electrons/current show that application of RMPs with m/n  =  2/1 dominant component during disruptions can reduce runaway production. Furthermore, its application before the disruption can reduce both the amplitude and the length of runaway current; experimental results in the high-density disruption plasmas confirm that local current shrinkage during a multifaceted asymmetric radiation from the edge can directly terminate the discharge; measurements by a multi-channel Doppler reflectometer show that the quasi-coherent modes in the electron diamagnetic direction occur in the J-TEXT ohmic confinement regime in a large plasma region (r/a ~ 0.3-0.8) with frequency of 30-140 kHz.

Tevatron global radius and 0s system

International Nuclear Information System (INIS)

Bristol, S.; Kerns, C.; Kerns, Q.; Miller, H.W.

1985-06-01

It has been found to be practical to extract a turn-average measurement of bunch beam phase relative to cavity gap voltage. This 0s signal shows the bunch position on the rf wave throughout injection, acceleration and extraction, including coherent synchrotron oscillations when present. In turn, the time derivative of 0s is a direct measure of global radial position error. We use the 0s signal, driving a phase shifter in the rf low-level system, to damp coherent synchrotron oscillations. Design and operation will be discussed including single beam bunch operation if available. 8 refs., 5 figs

Electromagnetic spatial coherence wavelets

International Nuclear Information System (INIS)

Castaneda, R.; Garcia-Sucerquia, J.

2005-10-01

The recently introduced concept of spatial coherence wavelets is generalized for describing the propagation of electromagnetic fields in the free space. For this aim, the spatial coherence wavelet tensor is introduced as an elementary amount, in terms of which the formerly known quantities for this domain can be expressed. It allows analyzing the relationship between the spatial coherence properties and the polarization state of the electromagnetic wave. This approach is completely consistent with the recently introduced unified theory of coherence and polarization for random electromagnetic beams, but it provides a further insight about the causal relationship between the polarization states at different planes along the propagation path. (author)

Coherent states in quantum mechanics

CERN Document Server

Rodrigues, R D L; Fernandes, D

2001-01-01

We present a review work on the coherent states is non-relativistic quantum mechanics analysing the quantum oscillators in the coherent states. The coherent states obtained via a displacement operator that act on the wave function of ground state of the oscillator and the connection with Quantum Optics which were implemented by Glauber have also been considered. A possible generalization to the construction of new coherent states it is point out.

Photoinduced Coherent Spin Fluctuation in Primary Dynamics of Insulator to Metal Transition in Perovskite Cobalt Oxide

Directory of Open Access Journals (Sweden)

Arima T.

2013-03-01

Full Text Available Coherent spin fluctuation was detected in the photoinduced Mott insulator-metal transition in perovskite cobalt oxide by using 3 optical-cycle infrared pulse. Such coherent spin fluctuation is driven by the perovskite distortion changing orbital gap.

From quantum coherence to quantum correlations

Science.gov (United States)

Sun, Yuan; Mao, Yuanyuan; Luo, Shunlong

2017-06-01

In quantum mechanics, quantum coherence of a state relative to a quantum measurement can be identified with the quantumness that has to be destroyed by the measurement. In particular, quantum coherence of a bipartite state relative to a local quantum measurement encodes quantum correlations in the state. If one takes minimization with respect to the local measurements, then one is led to quantifiers which capture quantum correlations from the perspective of coherence. In this vein, quantum discord, which quantifies the minimal correlations that have to be destroyed by quantum measurements, can be identified as the minimal coherence, with the coherence measured by the relative entropy of coherence. To advocate and formulate this idea in a general context, we first review coherence relative to Lüders measurements which extends the notion of coherence relative to von Neumann measurements (or equivalently, orthonomal bases), and highlight the observation that quantum discord arises as minimal coherence through two prototypical examples. Then, we introduce some novel measures of quantum correlations in terms of coherence, illustrate them through examples, investigate their fundamental properties and implications, and indicate their applications to quantum metrology.

Entropic cohering power in quantum operations

Science.gov (United States)

Xi, Zhengjun; Hu, Ming-Liang; Li, Yongming; Fan, Heng

2018-02-01

Coherence is a basic feature of quantum systems and a common necessary condition for quantum correlations. It is also an important physical resource in quantum information processing. In this paper, using relative entropy, we consider a more general definition of the cohering power of quantum operations. First, we calculate the cohering power of unitary quantum operations and show that the amount of distributed coherence caused by non-unitary quantum operations cannot exceed the quantum-incoherent relative entropy between system of interest and its environment. We then find that the difference between the distributed coherence and the cohering power is larger than the quantum-incoherent relative entropy. As an application, we consider the distributed coherence caused by purification.

Quantum Coherence and Random Fields at Mesoscopic Scales

International Nuclear Information System (INIS)

Rosenbaum, Thomas F.

2016-01-01

We seek to explore and exploit model, disordered and geometrically frustrated magnets where coherent spin clusters stably detach themselves from their surroundings, leading to extreme sensitivity to finite frequency excitations and the ability to encode information. Global changes in either the spin concentration or the quantum tunneling probability via the application of an external magnetic field can tune the relative weights of quantum entanglement and random field effects on the mesoscopic scale. These same parameters can be harnessed to manipulate domain wall dynamics in the ferromagnetic state, with technological possibilities for magnetic information storage. Finally, extensions from quantum ferromagnets to antiferromagnets promise new insights into the physics of quantum fluctuations and effective dimensional reduction. A combination of ac susceptometry, dc magnetometry, noise measurements, hole burning, non-linear Fano experiments, and neutron diffraction as functions of temperature, magnetic field, frequency, excitation amplitude, dipole concentration, and disorder address issues of stability, overlap, coherence, and control. We have been especially interested in probing the evolution of the local order in the progression from spin liquid to spin glass to long-range-ordered magnet.

Quantum Coherence and Random Fields at Mesoscopic Scales

Energy Technology Data Exchange (ETDEWEB)

Rosenbaum, Thomas F. [Univ. of Chicago, IL (United States)

2016-03-01

We seek to explore and exploit model, disordered and geometrically frustrated magnets where coherent spin clusters stably detach themselves from their surroundings, leading to extreme sensitivity to finite frequency excitations and the ability to encode information. Global changes in either the spin concentration or the quantum tunneling probability via the application of an external magnetic field can tune the relative weights of quantum entanglement and random field effects on the mesoscopic scale. These same parameters can be harnessed to manipulate domain wall dynamics in the ferromagnetic state, with technological possibilities for magnetic information storage. Finally, extensions from quantum ferromagnets to antiferromagnets promise new insights into the physics of quantum fluctuations and effective dimensional reduction. A combination of ac susceptometry, dc magnetometry, noise measurements, hole burning, non-linear Fano experiments, and neutron diffraction as functions of temperature, magnetic field, frequency, excitation amplitude, dipole concentration, and disorder address issues of stability, overlap, coherence, and control. We have been especially interested in probing the evolution of the local order in the progression from spin liquid to spin glass to long-range-ordered magnet.

Experimental generation of optical coherence lattices

Energy Technology Data Exchange (ETDEWEB)

Chen, Yahong; Cai, Yangjian, E-mail: serpo@dal.ca, E-mail: yangjiancai@suda.edu.cn [College of Physics, Optoelectronics and Energy and Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215006 (China); Key Lab of Advanced Optical Manufacturing Technologies of Jiangsu Province and Key Lab of Modern Optical Technologies of Education Ministry of China, Soochow University, Suzhou 215006 (China); Ponomarenko, Sergey A., E-mail: serpo@dal.ca, E-mail: yangjiancai@suda.edu.cn [Department of Electrical and Computer Engineering, Dalhousie University, Halifax, Nova Scotia B3J 2X4 (Canada)

2016-08-08

We report experimental generation and measurement of recently introduced optical coherence lattices. The presented optical coherence lattice realization technique hinges on a superposition of mutually uncorrelated partially coherent Schell-model beams with tailored coherence properties. We show theoretically that information can be encoded into and, in principle, recovered from the lattice degree of coherence. Our results can find applications to image transmission and optical encryption.

Localization of Cortical Oscillations Induced by SCS Using Coherence

Directory of Open Access Journals (Sweden)

P. Sovka

2007-12-01

Full Text Available This paper suggests a method based on coherence analysis and scalp mapping of coherence suitable for more accurate localization of cortical oscillations induced by electric stimulation of the dorsal spinal cord (SCS, which were previously detected using spectral analysis. While power spectral density shows the increase of power during SCS only at small number of electrodes, coherence extends this area and sharpens its boundary simultaneously. Parameters of the method were experimentally optimized to maximize its reliability. SCS is applied to suppress chronic, intractable pain by patients, whom pharmacotherapy does not relieve. In our study, the pain developed in lower back and lower extremity as the result of unsuccessful vertebral discotomy, which is called failed-back surgery syndrome (FBSS. Our method replicated the results of previous analysis using PSD and extended them with more accurate localization of the area influenced by SCS.

Collective stochastic coherence in recurrent neuronal networks

Science.gov (United States)

Sancristóbal, Belén; Rebollo, Beatriz; Boada, Pol; Sanchez-Vives, Maria V.; Garcia-Ojalvo, Jordi

2016-09-01

Recurrent networks of dynamic elements frequently exhibit emergent collective oscillations, which can show substantial regularity even when the individual elements are considerably noisy. How noise-induced dynamics at the local level coexists with regular oscillations at the global level is still unclear. Here we show that a combination of stochastic recurrence-based initiation with deterministic refractoriness in an excitable network can reconcile these two features, leading to maximum collective coherence for an intermediate noise level. We report this behaviour in the slow oscillation regime exhibited by a cerebral cortex network under dynamical conditions resembling slow-wave sleep and anaesthesia. Computational analysis of a biologically realistic network model reveals that an intermediate level of background noise leads to quasi-regular dynamics. We verify this prediction experimentally in cortical slices subject to varying amounts of extracellular potassium, which modulates neuronal excitability and thus synaptic noise. The model also predicts that this effectively regular state should exhibit noise-induced memory of the spatial propagation profile of the collective oscillations, which is also verified experimentally. Taken together, these results allow us to construe the high regularity observed experimentally in the brain as an instance of collective stochastic coherence.

Coherent states in quantum mechanics

International Nuclear Information System (INIS)

Rodrigues, R. de Lima; Fernandes Junior, Damasio; Batista, Sheyla Marques

2001-12-01

We present a review work on the coherent states is non-relativistic quantum mechanics analysing the quantum oscillators in the coherent states. The coherent states obtained via a displacement operator that act on the wave function of ground state of the oscillator and the connection with Quantum Optics which were implemented by Glauber have also been considered. A possible generalization to the construction of new coherent states it is point out. (author)

Coherency Identification of Generators Using a PAM Algorithm for Dynamic Reduction of Power Systems

Directory of Open Access Journals (Sweden)

Seung-Il Moon

2012-11-01

Full Text Available This paper presents a new coherency identification method for dynamic reduction of a power system. To achieve dynamic reduction, coherency-based equivalence techniques divide generators into groups according to coherency, and then aggregate them. In order to minimize the changes in the dynamic response of the reduced equivalent system, coherency identification of the generators should be clearly defined. The objective of the proposed coherency identification method is to determine the optimal coherent groups of generators with respect to the dynamic response, using the Partitioning Around Medoids (PAM algorithm. For this purpose, the coherency between generators is first evaluated from the dynamic simulation time response, and in the proposed method this result is then used to define a dissimilarity index. Based on the PAM algorithm, the coherent generator groups are then determined so that the sum of the index in each group is minimized. This approach ensures that the dynamic characteristics of the original system are preserved, by providing the optimized coherency identification. To validate the effectiveness of the technique, simulated cases with an IEEE 39-bus test system are evaluated using PSS/E. The proposed method is compared with an existing coherency identification method, which uses the K-means algorithm, and is found to provide a better estimate of the original system. 

MODEL ACCURACY COMPARISON FOR HIGH RESOLUTION INSAR COHERENCE STATISTICS OVER URBAN AREAS

Directory of Open Access Journals (Sweden)

Y. Zhang

2016-06-01

Full Text Available The interferometric coherence map derived from the cross-correlation of two complex registered synthetic aperture radar (SAR images is the reflection of imaged targets. In many applications, it can act as an independent information source, or give additional information complementary to the intensity image. Specially, the statistical properties of the coherence are of great importance in land cover classification, segmentation and change detection. However, compared to the amount of work on the statistical characters of SAR intensity, there are quite fewer researches on interferometric SAR (InSAR coherence statistics. And to our knowledge, all of the existing work that focuses on InSAR coherence statistics, models the coherence with Gaussian distribution with no discrimination on data resolutions or scene types. But the properties of coherence may be different for different data resolutions and scene types. In this paper, we investigate on the coherence statistics for high resolution data over urban areas, by making a comparison of the accuracy of several typical statistical models. Four typical land classes including buildings, trees, shadow and roads are selected as the representatives of urban areas. Firstly, several regions are selected from the coherence map manually and labelled with their corresponding classes respectively. Then we try to model the statistics of the pixel coherence for each type of region, with different models including Gaussian, Rayleigh, Weibull, Beta and Nakagami. Finally, we evaluate the model accuracy for each type of region. The experiments on TanDEM-X data show that the Beta model has a better performance than other distributions.

Responsibility, God and society: The cry of the Other in the sacred texts as a challenge towards responsible global citizenship

Directory of Open Access Journals (Sweden)

Johann-Albrecht Meylahn

2009-04-01

Full Text Available The article seeks to respond to the question: What role can the sacred texts play in the construction of a Christian identity that is responsible to the Other in a pluralistic global world? The sacred texts of the Judaic-Christian tradition offer not only an understanding of the wholly otherness of God, but also form the basis of our understanding and perception of humanity (anthropology, the world and ourselves (personhood/identity. This understanding is constructed in the context of responding to the call of the wholly Other and the others. Identities are traditionally constructed through the identification and exclusion of differences (otherness, thus leading to an ethic of exclusion and responsibility only to oneself/ourselves. Yet these identity-forming texts harbour a persistent otherness, which challenges these traditional identities by interrupting them with a call to responsibility toward the other. The otherness harboured in these texts takes various forms, namely: The otherness of the ancient world to our world, the otherness of the transcendental Other, and the otherness of the text itself, as there is always a différance that has not yet been heard. These various forms of otherness, of our identity-forming texts, deconstruct our identity constructions, thus calling us to a continuous responsibility towards the other. This call could form the basis of a Christian identity and ethic of global cosmopolitan citizenship that is always responding to the eschatological interruption by the other, who is not yet present or who has not been offered presence.

Aircraft Wake Vortex Measurement with Coherent Doppler Lidar

Directory of Open Access Journals (Sweden)

Wu Songhua

2016-01-01

Full Text Available Aircraft vortices are generated by the lift-producing surfaces of the aircraft. The variability of near-surface conditions can change the drop rate and cause the cell of the wake vortex to twist and contort unpredictably. The pulsed Coherent Doppler Lidar Detection and Ranging is an indispensable access to real aircraft vortices behavior which transmitting a laser beam and detecting the radiation backscattered by atmospheric aerosol particles. Experiments for Coherent Doppler Lidar measurement of aircraft wake vortices has been successfully carried out at the Beijing Capital International Airport (BCIA. In this paper, the authors discuss the Lidar system, the observation modes carried out in the measurements at BCIA and the characteristics of vortices.

Towards Resource Theory of Coherence in Distributed Scenarios

Directory of Open Access Journals (Sweden)

Alexander Streltsov

2017-03-01

Full Text Available The search for a simple description of fundamental physical processes is an important part of quantum theory. One example for such an abstraction can be found in the distance lab paradigm: if two separated parties are connected via a classical channel, it is notoriously difficult to characterize all possible operations these parties can perform. This class of operations is widely known as local operations and classical communication. Surprisingly, the situation becomes comparably simple if the more general class of separable operations is considered, a finding that has been extensively used in quantum information theory for many years. Here, we propose a related approach for the resource theory of quantum coherence, where two distant parties can perform only measurements that do not create coherence and can communicate their outcomes via a classical channel. We call this class local incoherent operations and classical communication. While the characterization of this class is also difficult in general, we show that the larger class of separable incoherent operations has a simple mathematical form, yet still preserves the main features of local incoherent operations and classical communication. We demonstrate the relevance of our approach by applying it to three different tasks: assisted coherence distillation, quantum teleportation, and single-shot quantum state merging. We expect that the results we obtain in this work also transfer to other concepts of coherence that are discussed in recent literature. The approach we present here opens new ways to study the resource theory of coherence in distributed scenarios.

Experimental study of coherence vortices: Local properties of phase singularities in a spatial coherence function

DEFF Research Database (Denmark)

Wang, W.; Duan, Z.H.; Hanson, Steen Grüner

2006-01-01

By controlling the irradiance of an extended quasimonochromatic, spatially incoherent source, an optical field is generated that exhibits spatial coherence with phase singularities, called coherence vortices. A simple optical geometry for direct visualization of coherence vortices is proposed, an...

Partially coherent isodiffracting pulsed beams

Science.gov (United States)

Koivurova, Matias; Ding, Chaoliang; Turunen, Jari; Pan, Liuzhan

2018-02-01

We investigate a class of isodiffracting pulsed beams, which are superpositions of transverse modes supported by spherical-mirror laser resonators. By employing modal weights that, for stationary light, produce a Gaussian Schell-model beam, we extend this standard model to pulsed beams. We first construct the two-frequency cross-spectral density function that characterizes the spatial coherence in the space-frequency domain. By assuming a power-exponential spectral profile, we then employ the generalized Wiener-Khintchine theorem for nonstationary light to derive the two-time mutual coherence function that describes the space-time coherence of the ensuing beams. The isodiffracting nature of the laser resonator modes permits all (paraxial-domain) calculations at any propagation distance to be performed analytically. Significant spatiotemporal coupling is revealed in subcycle, single-cycle, and few-cycle domains, where the partial spatial coherence also leads to reduced temporal coherence even though full spectral coherence is assumed.

Coherent diffractive imaging using randomly coded masks

Energy Technology Data Exchange (ETDEWEB)

Seaberg, Matthew H., E-mail: seaberg@slac.stanford.edu [CNRS and D.I., UMR 8548, École Normale Supérieure, 45 Rue d' Ulm, 75005 Paris (France); Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); D' Aspremont, Alexandre [CNRS and D.I., UMR 8548, École Normale Supérieure, 45 Rue d' Ulm, 75005 Paris (France); Turner, Joshua J. [Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States)

2015-12-07

We experimentally demonstrate an extension to coherent diffractive imaging that encodes additional information through the use of a series of randomly coded masks, removing the need for typical object-domain constraints while guaranteeing a unique solution to the phase retrieval problem. Phase retrieval is performed using a numerical convex relaxation routine known as “PhaseCut,” an iterative algorithm known for its stability and for its ability to find the global solution, which can be found efficiently and which is robust to noise. The experiment is performed using a laser diode at 532.2 nm, enabling rapid prototyping for future X-ray synchrotron and even free electron laser experiments.

The use of the partial coherence function technique for the investigation of BWR noise dynamics

International Nuclear Information System (INIS)

Kostic, Lj.

1983-01-01

The extensive experimental investigations, at the last time, indicate that the partial coherence function technique can be a powerful method of the investigation of BWR noise dynamics. Symple BWR noise dynamics model for the global noise study, based on different noise phenomena, is proposed in this paper. (author)

The Coherent Structure of Hafez's Ghazals (Sonnets

Directory of Open Access Journals (Sweden)

Dr. Teimour Malmir

2010-01-01

Full Text Available Hafez's poetry, despite its structural coherence, appears to be incoherent and fragmented. Some opponents, then, based on this surface appearance have criticized Hafez since each line of his ghazals contains an independent point; some have also used this quality as a pretext to invalidate his main themes; or they have separated the lines to diminish and neutralize the stinging bitterness of his critical comments. However, today, regardless of such controversial views, this independence of the lines has been considered as Hafez's craft and art. The present article, after discussing the roots of emergence of such diverse criticism, has dealt with the vital structural coherence of Hafez' ghazals interpretively posing one example from each of his mystic, witty love ghazals and clarifying the co-relationship among those lines.

Identification of individual coherent sets associated with flow trajectories using coherent structure coloring

Science.gov (United States)

Schlueter-Kuck, Kristy L.; Dabiri, John O.

2017-09-01

We present a method for identifying the coherent structures associated with individual Lagrangian flow trajectories even where only sparse particle trajectory data are available. The method, based on techniques in spectral graph theory, uses the Coherent Structure Coloring vector and associated eigenvectors to analyze the distance in higher-dimensional eigenspace between a selected reference trajectory and other tracer trajectories in the flow. By analyzing this distance metric in a hierarchical clustering, the coherent structure of which the reference particle is a member can be identified. This algorithm is proven successful in identifying coherent structures of varying complexities in canonical unsteady flows. Additionally, the method is able to assess the relative coherence of the associated structure in comparison to the surrounding flow. Although the method is demonstrated here in the context of fluid flow kinematics, the generality of the approach allows for its potential application to other unsupervised clustering problems in dynamical systems such as neuronal activity, gene expression, or social networks.

Average intensity and coherence properties of a partially coherent Lorentz-Gauss beam propagating through oceanic turbulence

Science.gov (United States)

Liu, Dajun; Wang, Guiqiu; Wang, Yaochuan

2018-01-01

Based on the Huygens-Fresnel integral and the relationship of Lorentz distribution and Hermite-Gauss function, the average intensity and coherence properties of a partially coherent Lorentz-Gauss beam propagating through oceanic turbulence have been investigated by using numerical examples. The influences of beam parameters and oceanic turbulence on the propagation properties are also discussed in details. It is shown that the partially coherent Lorentz-Gauss beam with smaller coherence length will spread faster in oceanic turbulence, and the stronger oceanic turbulence will accelerate the spreading of partially coherent Lorentz-Gauss beam in oceanic turbulence.

Rhetorical structure theory and text analysis

Science.gov (United States)

Mann, William C.; Matthiessen, Christian M. I. M.; Thompson, Sandra A.

1989-11-01

Recent research on text generation has shown that there is a need for stronger linguistic theories that tell in detail how texts communicate. The prevailing theories are very difficult to compare, and it is also very difficult to see how they might be combined into stronger theories. To make comparison and combination a bit more approachable, we have created a book which is designed to encourage comparison. A dozen different authors or teams, all experienced in discourse research, are given exactly the same text to analyze. The text is an appeal for money by a lobbying organization in Washington, DC. It informs, stimulates and manipulates the reader in a fascinating way. The joint analysis is far more insightful than any one team's analysis alone. This paper is our contribution to the book. Rhetorical Structure Theory (RST), the focus of this paper, is a way to account for the functional potential of text, its capacity to achieve the purposes of speakers and produce effects in hearers. It also shows a way to distinguish coherent texts from incoherent ones, and identifies consequences of text structure.

Coherent communication with continuous quantum variables

Science.gov (United States)

Wilde, Mark M.; Krovi, Hari; Brun, Todd A.

2007-06-01

The coherent bit (cobit) channel is a resource intermediate between classical and quantum communication. It produces coherent versions of teleportation and superdense coding. We extend the cobit channel to continuous variables by providing a definition of the coherent nat (conat) channel. We construct several coherent protocols that use both a position-quadrature and a momentum-quadrature conat channel with finite squeezing. Finally, we show that the quality of squeezing diminishes through successive compositions of coherent teleportation and superdense coding.

Estimation of Time-Varying Coherence and Its Application in Understanding Brain Functional Connectivity

Directory of Open Access Journals (Sweden)

Cheng Liu

2010-01-01

Full Text Available Time-varying coherence is a powerful tool for revealing functional dynamics between different regions in the brain. In this paper, we address ways of estimating evolutionary spectrum and coherence using the general Cohen's class distributions. We show that the intimate connection between the Cohen's class-based spectra and the evolutionary spectra defined on the locally stationary time series can be linked by the kernel functions of the Cohen's class distributions. The time-varying spectra and coherence are further generalized with the Stockwell transform, a multiscale time-frequency representation. The Stockwell measures can be studied in the framework of the Cohen's class distributions with a generalized frequency-dependent kernel function. A magnetoencephalography study using the Stockwell coherence reveals an interesting temporal interaction between contralateral and ipsilateral motor cortices under the multisource interference task.

Operational resource theory of total quantum coherence

Science.gov (United States)

Yang, Si-ren; Yu, Chang-shui

2018-01-01

Quantum coherence is an essential feature of quantum mechanics and is an important physical resource in quantum information. Recently, the resource theory of quantum coherence has been established parallel with that of entanglement. In the resource theory, a resource can be well defined if given three ingredients: the free states, the resource, the (restricted) free operations. In this paper, we study the resource theory of coherence in a different light, that is, we consider the total coherence defined by the basis-free coherence maximized among all potential basis. We define the distillable total coherence and the total coherence cost and in both the asymptotic regime and the single-copy regime show the reversible transformation between a state with certain total coherence and the state with the unit reference total coherence. Extensively, we demonstrate that the total coherence can also be completely converted to the total correlation with the equal amount by the free operations. We also provide the alternative understanding of the total coherence, respectively, based on the entanglement and the total correlation in a different way.

Self-organisation and intermittent coherent oscillations in the EXTRAP T2 reversed field pinch

International Nuclear Information System (INIS)

Cecconello, M.; Malmberg, J.A.; Sallander, E.; Drake, J.R.

2002-01-01

Many reversed-field pinch (RFP) experiments exhibit a coherent oscillatory behaviour that is characteristic of discrete dynamo events and is associated with intermittent current profile self-organisation phenomena. However, in the vast majority of the discharges in the resistive shell RFP experiment EXTRAP T2, the dynamo activity does not show global, coherent oscillatory behaviour. The internally resonant tearing modes are phase-aligned and wall-locked resulting in a large localised magnetic perturbation. Equilibrium and plasma parameters have a level of high frequency fluctuations but the average values are quasi-steady. For some discharges, however, the equilibrium parameters exhibit the oscillatory behaviour characteristic of the discrete dynamo events. For these discharges, the trend observed in the tearing mode spectra, associated with the onset of the discrete relaxation event behaviour, is a relative higher amplitude of m = 0 mode activity and relative lower amplitude of the m = 1 mode activity compared with their average values. Global plasma parameters and model profile calculations for sample discharges representing the two types of relaxation dynamics are presented

Self-Organisation and Intermittent Coherent Oscillations in the EXTRAP T2 Reversed Field Pinch

Science.gov (United States)

Cecconello, M.; Malmberg, J.-A.; Sallander, E.; Drake, J. R.

Many reversed-field pinch (RFP) experiments exhibit a coherent oscillatory behaviour that is characteristic of discrete dynamo events and is associated with intermittent current profile self-organisation phenomena. However, in the vast majority of the discharges in the resistive shell RFP experiment EXTRAP T2, the dynamo activity does not show global, coherent oscillatory behaviour. The internally resonant tearing modes are phase-aligned and wall-locked resulting in a large localised magnetic perturbation. Equilibrium and plasma parameters have a level of high frequency fluctuations but the average values are quasi-steady. For some discharges, however, the equilibrium parameters exhibit the oscillatory behaviour characteristic of the discrete dynamo events. For these discharges, the trend observed in the tearing mode spectra, associated with the onset of the discrete relaxation event behaviour, is a relative higher amplitude of m = 0 mode activity and relative lower amplitude of the m = 1 mode activity compared with their average values. Global plasma parameters and model profile calculations for sample discharges representing the two types of relaxation dynamics are presented.

Stimulated coherent transition radiation

International Nuclear Information System (INIS)

Hung-chi Lihn.

1996-03-01

Coherent radiation emitted from a relativistic electron bunch consists of wavelengths longer than or comparable to the bunch length. The intensity of this radiation out-numbers that of its incoherent counterpart, which extends to wavelengths shorter than the bunch length, by a factor equal to the number of electrons in the bunch. In typical accelerators, this factor is about 8 to 11 orders of magnitude. The spectrum of the coherent radiation is determined by the Fourier transform of the electron bunch distribution and, therefore, contains information of the bunch distribution. Coherent transition radiation emitted from subpicosecond electron bunches at the Stanford SUNSHINE facility is observed in the far-infrared regime through a room-temperature pyroelectric bolometer and characterized through the electron bunch-length study. To measure the bunch length, a new frequency-resolved subpicosecond bunch-length measuring system is developed. This system uses a far-infrared Michelson interferometer to measure the spectrum of coherent transition radiation through optical autocorrelation with resolution far better than existing time-resolved methods. Hence, the radiation spectrum and the bunch length are deduced from the autocorrelation measurement. To study the stimulation of coherent transition radiation, a special cavity named BRAICER is invented. Far-infrared light pulses of coherent transition radiation emitted from electron bunches are delayed and circulated in the cavity to coincide with subsequent incoming electron bunches. This coincidence of light pulses with electron bunches enables the light to do work on electrons, and thus stimulates more radiated energy. The possibilities of extending the bunch-length measuring system to measure the three-dimensional bunch distribution and making the BRAICER cavity a broadband, high-intensity, coherent, far-infrared light source are also discussed

Coherence in electron energy loss spectrometry

International Nuclear Information System (INIS)

Schattschneider, P.; Werner, W.S.M.

2005-01-01

Coherence effects in electron energy loss spectrometry (EELS) and in energy filtering are largely neglected although they occur frequently due to Bragg scattering in crystals. We discuss how coherence in the inelastically scattered wave field can be described by the mixed dynamic form factor (MDFF), and how it relates to the density matrix of the scattered electrons. Among the many aspects of 'inelastic coherence' are filtered high-resolution images, dipole-forbidden transitions, coherence in plasma excitations, errors in chemical microanalysis, coherent double plasmons, and circular dichroism

Coherent x-rays from PEP

International Nuclear Information System (INIS)

Baird, S.; Nuhn, H.-D.; Tatchyn, R.; Winick, H.; Fisher, A.S.; Gallardo, J.C.; Pellegrini, C.

1991-01-01

This paper explores the use of a large-circumference, high-energy, electron-positron collider such as PEP to drive a free-electron laser (FEL), producing high levels of coherent power at short wavelengths. The author consider Self-Amplified Spontaneous Emission (SASE), in which electron bunches with low emittance, high peak current and small energy spread radiate coherently in a single passthrough a long undulator. As the electron beam passes down the undulator, its interaction with the increasingly intense spontaneous radiation causes a bunch density modulation at the optical wavelength, resulting in stimulated emissional growth of coherent power in a single pass. The need for optical-cavity mirrors, which place a lower limit on the wavelength of a conventional FEL oscillator, is avoided. The authors explore various combinations of electron-beam and undulator parameters, as well as special undulator designs and optical klystrons (OK), to reach high average or peak coherent power at wavelengths around 40 angstrom by achieving significant exponential gain or full saturation. Examples are presented for devices that achieve high peak coherent power (up to about 400 MW) with lower average coherent power (about 20 mW) and other devices which produce a few watts of average coherent power

Temporal coherence among tropical coastal lagoons: a search for patterns and mechanisms

Directory of Open Access Journals (Sweden)

A. Caliman

Full Text Available Temporal coherence (i.e., the degree of synchronicity of a given variable among ecological units within a predefined space has been shown for several limnological features among temperate lakes, allowing predictions about the structure and function of ecosystems. However, there is little evidence of temporal coherence among tropical aquatic systems, where the climatic variability among seasons is less pronounced. Here, we used data from long-term monitoring of physical, chemical and biological variables to test the degree of temporal coherence among 18 tropical coastal lagoons. The water temperature and chlorophyll-a concentration had the highest and lowest temporal coherence among the lagoons, respectively, whereas the salinity and water colour had intermediate temporal coherence. The regional climactic factors were the main factors responsible for the coherence patterns in the water temperature and water colour, whereas the landscape position and morphometric characteristics explained much of the variation of the salinity and water colour among the lagoons. These results indicate that both local (lagoon morphometry and regional (precipitation, air temperature factors regulate the physical and chemical conditions of coastal lagoons by adjusting the terrestrial and marine subsidies at a landscape-scale. On the other hand, the chlorophyll-a concentration appears to be primarily regulated by specific local conditions resulting in a weak temporal coherence among the ecosystems. We concluded that temporal coherence in tropical ecosystems is possible, at least for some environmental features, and should be evaluated for other tropical ecosystems. Our results also reinforce that aquatic ecosystems should be studied more broadly to accomplish a full understanding of their structure and function.

Methods for Examining Electrophysiological Coherence in Epileptic Networks

Directory of Open Access Journals (Sweden)

Jasmine eSong

2013-05-01

Full Text Available Epilepsy may reflect a focal abnormality of cerebral tissue, but the generation of seizures typically involves propagation of abnormal activity through cerebral networks. We examined epileptiform discharges (spikes with dense array electroencephalography (dEEG in five patients to search for the possible engagement of pathological networks. Source analysis was conducted with individual electrical head models for each patient, including sensor position measurement for registration with MRI with geodesic photogrammetry; tissue segmentation and skull conductivity modeling with an atlas skull CT warped to each patient’s MRI; cortical surface extraction and tessellation into 1 square cm equivalent dipole patches; inverse source estimation with either minimum norm or cortical surface Laplacian constraints; and spectral coherence computed among equivalent dipoles aggregated within Brodmann areas with 1 Hz resolution from 1 to 70 Hz. These analyses revealed characteristic source coherence patterns in each patient during the pre-spike, spike, and post-spike intervals. For one patient with both spikes and seizure onset localized to a single temporal lobe, we observed a cluster of apparently abnormal coherences over the involved temporal lobe. For the other patients, there were apparently characteristic coherence patterns associated with the discharges, and in some cases these appeared to reflect abnormal temporal lobe synchronization, but the coherence patterns for these patients were not easily related to an unequivocal epileptogenic zone. In contrast, simple localization of the site of onset of the spike discharge, and/or the site of onset of the seizure, with noninvasive 256 dEEG was useful in predicting the characteristic site of seizure onset for those cases that were verified by intracranial EEG and/or by surgical outcome.

On the Importance of Audiovisual Coherence for the Perceived Quality of Synthesized Visual Speech

Directory of Open Access Journals (Sweden)

Wesley Mattheyses

2009-01-01

Full Text Available Audiovisual text-to-speech systems convert a written text into an audiovisual speech signal. Typically, the visual mode of the synthetic speech is synthesized separately from the audio, the latter being either natural or synthesized speech. However, the perception of mismatches between these two information streams requires experimental exploration since it could degrade the quality of the output. In order to increase the intermodal coherence in synthetic 2D photorealistic speech, we extended the well-known unit selection audio synthesis technique to work with multimodal segments containing original combinations of audio and video. Subjective experiments confirm that the audiovisual signals created by our multimodal synthesis strategy are indeed perceived as being more synchronous than those of systems in which both modes are not intrinsically coherent. Furthermore, it is shown that the degree of coherence between the auditory mode and the visual mode has an influence on the perceived quality of the synthetic visual speech fragment. In addition, the audio quality was found to have only a minor influence on the perceived visual signal's quality.

SAR COHERENCE CHANGE DETECTION OF URBAN AREAS AFFECTED BY DISASTERS USING SENTINEL-1 IMAGERY

Directory of Open Access Journals (Sweden)

P. Washaya

2018-04-01

Full Text Available The study focuses on two study areas: San Juan in Puerto Rico, which was affected by Hurricane Maria in September 2017, and Sarpol Zahab in Iran, which was one of the towns affected by an earthquake in November 2017. In our study, we generate coherence images, and classify them into areas of ‘change’ and ‘no-change’. A statistical analysis is made by converting the coherence results into point data, creating street blocks for the study areas and integrating the point data into the street blocks to calculate the standard deviation over the whole stack of images. Additionally, Landsat imagery is used to create land-use classes, convert them to polygons and integrate the polygon classes to the coherence maps to determine the average coherence loss per class for each disaster. Results show 65 % loss in coherence after the earthquake in Sarpol-e-Zahab and 75 % loss in Puerto Rico after the Hurricane. Land-use classes show coherence losses to below 0.5 for each disaster.

Global Knowledge Futures: Articulating the Emergence of a New Meta-level Field

Directory of Open Access Journals (Sweden)

Jennifer M. Gidley

2013-06-01

Full Text Available In this paper I articulate a new meta-level field of studies that I call global knowledge futures—a field through which other emerging transdisciplinary fields can be integrated to cohere knowledge at a higher level. I contrast this with the current dominant knowledge paradigm of the global knowledge economy with its fragmentation, commodification and instrumentalism based on neoliberal knowledge capitalism. I take a big-picture, macrohistorical lens to the new thinking and new knowledge patterns that are emerging within the evolution of consciousness discourse. I explore three discourses: postformal studies, integral studies and planetary studies—using a fourth discourse, futures studies, to provide a macro-temporal framing. By extending the meta-fields of postformal, integral and planetary studies into a prospective future dimension, I locate areas of development where these leading-edge discourses can be brought into closer dialogue with each other. In this meeting point of four boundary-spanning discourses I identify the new meta-level field of global knowledge futures, grounded in human thinking capacities, such as creativity, imagination, dialogue and collaboration.

Morpho-functional evaluation of torpedo maculopathy with optical coherence tomography angiography and microperimetry

Directory of Open Access Journals (Sweden)

Gabriela Grimaldi

2018-06-01

Full Text Available Purpose: To report the case of a 13-year-old girl with torpedo maculopathy, evaluated with multimodal morpho-functional retinal imaging, including fundus photography, infra-red and blue fundus autofluorescence, swept-source optical coherence tomography (OCT, en face OCT, OCT angiography and microperimetry (MP. Observations: On fundus examination, a torpedo-like hypopigmented lesion was observed temporal to the fovea in the left eye. OCT showed disruption of outer retinal layers and the presence of a subretinal cleft. On OCTA, a diffuse attenuation of signal from choriocapillaris was observed along the lesion. Functional analysis with MP revealed a reduction of retinal sensitivity over the lesion. Conclusions: and importance: On OCTA, torpedo maculopathy is characterized by vascular alterations of the choriocapillaris along the lesion. Keywords: Optical coherence tomography angiography, Torpedo maculopathy, Microperimetry, Swept-source optical coherence tomography, En face optical coherence tomography

Coherence and Sense of Coherence

DEFF Research Database (Denmark)

Dau, Susanne

2014-01-01

Constraints in the implementation of models of blended learning can be explained by several causes, but in this paper, it is illustrated that lack of sense of coherence is a major factor of these constraints along with the referential whole of the perceived learning environments. The question exa...

Coherent states and rational surfaces

International Nuclear Information System (INIS)

Brody, Dorje C; Graefe, Eva-Maria

2010-01-01

The state spaces of generalized coherent states associated with special unitary groups are shown to form rational curves and surfaces in the space of pure states. These curves and surfaces are generated by the various Veronese embeddings of the underlying state space into higher dimensional state spaces. This construction is applied to the parameterization of generalized coherent states, which is useful for practical calculations, and provides an elementary combinatorial approach to the geometry of the coherent state space. The results are extended to Hilbert spaces with indefinite inner products, leading to the introduction of a new kind of generalized coherent states.

Higher coherent x-ray laser

International Nuclear Information System (INIS)

Hasegawa, Noboru; Nagashima, Keisuke; Kawachi, Tetsuya

2001-01-01

X-ray lasers generated by an ultra short pulse laser have advantages such as monochromatic, short pulse duration, small beam divergence, high intensity, and coherence. Spatial coherence is most important for applications, we have investigated the transient collisional excitation (TCE) scheme x-ray laser lasing from Ne-like titanium (31.6 nm), Ne-like silver (13.9 nm) and tin (11.9 nm). However, the spatial coherence was not so good with this scheme. We have been studying to improve the spatial coherence of the x-ray laser and have proposed to use coherent seed light tuned to the x-ray laser wavelength generated from higher harmonics generation (HHG), which is introduced to the x-ray laser medium (Ne-like titanium, Ni-like silver plasmas). We present about the theoretical study of the coupling efficiency HHG light with x-ray laser medium. (author)

Echo questions as a means of building coherence in conversational discourse

Directory of Open Access Journals (Sweden)

Strelchenko Natalia

2017-06-01

Full Text Available The study focuses on the cognitive-communicative characteristics of echo questions in English conversational discourse. Drawing on van Dijk's sociocognitive (mental model theory and cognitive discourse analysis, the paper suggests viewing echo questions as a means of building/updating a mental context model of a communicative situation. As discourse comprehension presupposes building its coherent mental model, echo questions resolving misunderstanding are regarded as an instrument for increasing coherence in conversational discourse. Based on the mental model theory, the study offers a typology of misunderstandings corrected by echo questions.

Long-lived coherence in carotenoids

Energy Technology Data Exchange (ETDEWEB)

Davis, J A; Cannon, E; Van Dao, L; Hannaford, P [ARC Centre of Excellence for Coherent X-ray Science, Centre for Atom Optics and Ultrafast Spectroscopy, Swinburne University of Technology, Victoria 3122 (Australia); Quiney, H M; Nugent, K A, E-mail: jdavis@swin.edu.a [ARC Centre of Excellence for Coherent X-ray Science, School of Physics, University of Melbourne, Victoria 3010 (Australia)

2010-08-15

We use two-colour vibronic coherence spectroscopy to observe long-lived vibrational coherences in the ground electronic state of carotenoid molecules, with decoherence times in excess of 1 ps. Lycopene and spheroidene were studied isolated in solution, and within the LH2 light-harvesting complex extracted from purple bacteria. The vibrational coherence time is shown to increase significantly for the carotenoid in the complex, providing further support to previous assertions that long-lived electronic coherences in light-harvesting complexes are facilitated by in-phase motion of the chromophores and surrounding proteins. Using this technique, we are also able to follow the evolution of excited state coherences and find that for carotenoids in the light-harvesting complex the (S{sub 2}|S{sub 0}) superposition remains coherent for more than 70 fs. In addition to the implications of this long electronic decoherence time, the extended coherence allows us to observe the evolution of the excited state wavepacket. These experiments reveal an enhancement of the vibronic coupling to the first vibrational level of the C-C stretching mode and/or methyl-rocking mode in the ground electronic state 70 fs after the initial excitation. These observations open the door to future experiments and modelling that may be able to resolve the relaxation dynamics of carotenoids in solution and in natural light-harvesting systems.

Long-lived coherence in carotenoids

International Nuclear Information System (INIS)

Davis, J A; Cannon, E; Van Dao, L; Hannaford, P; Quiney, H M; Nugent, K A

2010-01-01

We use two-colour vibronic coherence spectroscopy to observe long-lived vibrational coherences in the ground electronic state of carotenoid molecules, with decoherence times in excess of 1 ps. Lycopene and spheroidene were studied isolated in solution, and within the LH2 light-harvesting complex extracted from purple bacteria. The vibrational coherence time is shown to increase significantly for the carotenoid in the complex, providing further support to previous assertions that long-lived electronic coherences in light-harvesting complexes are facilitated by in-phase motion of the chromophores and surrounding proteins. Using this technique, we are also able to follow the evolution of excited state coherences and find that for carotenoids in the light-harvesting complex the (S 2 |S 0 ) superposition remains coherent for more than 70 fs. In addition to the implications of this long electronic decoherence time, the extended coherence allows us to observe the evolution of the excited state wavepacket. These experiments reveal an enhancement of the vibronic coupling to the first vibrational level of the C-C stretching mode and/or methyl-rocking mode in the ground electronic state 70 fs after the initial excitation. These observations open the door to future experiments and modelling that may be able to resolve the relaxation dynamics of carotenoids in solution and in natural light-harvesting systems.

Gain with and without population inversion via vacuum-induced coherence in a V-type atom without external coherent driving

International Nuclear Information System (INIS)

Xu Weihua; Wu Jinhui; Gao Jinyue

2006-01-01

In a three-level V-type atomic system without any external coherent driving, owing to the coherence that results from the vacuum of the radiation field, both the probe gain with and without population inversion can be achieved with very weak incoherent pumping. The gain is achieved in the absence of any external coherent driving field, so it is different from the gain without inversion in ordinary laser-driven schemes where a coherent driving field is necessary to create the coherence. The gain is also different from the conventional lasing gain because the population inversion is achieved via vacuum-induced coherence, which is dependent on the atomic coherence

VCSEL Based Coherent PONs

DEFF Research Database (Denmark)

Jensen, Jesper Bevensee; Rodes, Roberto; Caballero Jambrina, Antonio

2014-01-01

We present a review of research performed in the area of coherent access technologies employing vertical cavity surface emitting lasers (VCSELs). Experimental demonstrations of optical transmission over a passive fiber link with coherent detection using VCSEL local oscillators and directly modula...

Sequential Coherence in Sentence Pairs Enhances Imagery during Comprehension: An Individual Differences Study.

Directory of Open Access Journals (Sweden)

Carol Madden-Lombardi

Full Text Available The present study investigates how sequential coherence in sentence pairs (events in sequence vs. unrelated events affects the perceived ability to form a mental image of the sentences for both auditory and visual presentations. In addition, we investigated how the ease of event imagery affected online comprehension (word reading times in the case of sequentially coherent and incoherent sentence pairs. Two groups of comprehenders were identified based on their self-reported ability to form vivid mental images of described events. Imageability ratings were higher and faster for pairs of sentences that described events in coherent sequences rather than non-sequential events, especially for high imagers. Furthermore, reading times on individual words suggested different comprehension patterns with respect to sequence coherence for the two groups of imagers, with high imagers activating richer mental images earlier than low imagers. The present results offer a novel link between research on imagery and discourse coherence, with specific contributions to our understanding of comprehension patterns for high and low imagers.

La coherence conceptuelle d'etudiants collegiaux en mecanique Newtonienne et en metrologie

Science.gov (United States)

Periard, Martin

This thesis evaluates the coherence of the conceptual network demonstrated by college students in life and applied sciences. This evaluation was based on the analysis of Burt tables issuing from multiple choice questionnaires, on the creation and careful examination of a novel tool, the matrix of specific discrimination coefficients, which will be described in the main text, and on the qualitative analysis of actual laboratory work of students doing an experimentation. At the completion of this project, four research axis have been explored. (1) What is the conceptual coherence demonstrated in Newtonian mechanics? (2) Is the mastery of uncertainty quantification related to the development of logical thinking or to mathematical competency? (3) What is the conceptual coherence demonstrated in the quantification of experimental uncertainty? (4) What are the concrete procedures utilized by students to quantify experimental uncertainty in a semi-directed laboratory context? The main conclusions that emerged from each axis of research can be summerized as follow. (1) The most prevalent erroneous conceptions are not solidly set in a rigid conceptual network. For example, a student successful in a question about Newton's third law (the most difficult subject of the Force Concept Inventory) is just slightly more likely to succeed in another related question than the other participants. Many pairs of questions displays a negative specific discrimination coefficient demonstrating a weak conceptual coherence in pre-test and a somewhat ameliorated conceptual coherence in post-test. (2) If a small proportion of students has demonstrated marked deficiencies in questions related with control of variable and in those related to the relationship between the graphical display of experimental data and a mathematical model, the majority of students can be considered as adequately mastering those subjects. However, almost every student demonstrated a lack of mastery of concepts

Tropical forest policies for the global climate

International Nuclear Information System (INIS)

De Groot, W.T.; Kamminga, E.M.

1995-01-01

A summary is given of the approach and findings of the NRP project 'Local Actors and Global Tree Cover Policies'. The aim of this project was to identify the most effective and efficient options for global climate policies focusing on the tropical forest. Tropical deforestation is a process with very complex and variable causes. In the project's conclusions, therefore, much care has been given to arrive at a coherent image of what really counts most in the myriad of factors, actors, policy levels and policy options. 5 refs

Multi-channel coherent perfect absorbers

KAUST Repository

Bai, Ping

2016-05-18

The absorption efficiency of a coherent perfect absorber usually depends on the phase coherence of the incident waves on the surfaces. Here, we present a scheme to create a multi-channel coherent perfect absorber in which the constraint of phase coherence is loosened. The scheme has a multi-layer structure such that incident waves in different channels with different angular momenta can be simultaneously and perfectly absorbed. This absorber is robust in achieving high absorption efficiency even if the incident waves become "incoherent" and possess "random" wave fronts. Our work demonstrates a unique approach to designing highly efficient metamaterial absorbers. © CopyrightEPLA, 2016.

Multi-channel coherent perfect absorbers

KAUST Repository

Bai, Ping; Wu, Ying; Lai, Yun

2016-01-01

The absorption efficiency of a coherent perfect absorber usually depends on the phase coherence of the incident waves on the surfaces. Here, we present a scheme to create a multi-channel coherent perfect absorber in which the constraint of phase coherence is loosened. The scheme has a multi-layer structure such that incident waves in different channels with different angular momenta can be simultaneously and perfectly absorbed. This absorber is robust in achieving high absorption efficiency even if the incident waves become "incoherent" and possess "random" wave fronts. Our work demonstrates a unique approach to designing highly efficient metamaterial absorbers. © CopyrightEPLA, 2016.

Coherent Multistatic ISAR Imaging

NARCIS (Netherlands)

Dorp, Ph. van; Otten, M.P.G.; Verzeilberg, J.M.M.

2012-01-01

This paper presents methods for Coherent Multistatic Radar Imaging for Non Cooperative Target Recognition (NCTR) with a network of radar sensors. Coherent Multistatic Radar Imaging is based on an extension of existing monostatic ISAR algorithms to the multistatic environment. The paper describes the

?Hunting with a knife and ? fork?: Examining central coherence in autism, attention deficit/hyperactivity disorder, and typical development with a linguistic task

OpenAIRE

Booth, Rhonda; Happ?, Francesca

2010-01-01

A local processing bias, referred to as ?weak central coherence,? has been postulated to underlie key aspects of autism spectrum disorder (ASD). Little research has examined whether individual differences in this cognitive style can be found in typical development, independent of intelligence, and how local processing relates to executive control. We present a brief and easy-to-administer test of coherence requiring global sentence completions. We report results from three studies assessing (...

Theory of coherent resonance energy transfer

International Nuclear Information System (INIS)

Jang, Seogjoo; Cheng, Y.-C.; Reichman, David R.; Eaves, Joel D.

2008-01-01

A theory of coherent resonance energy transfer is developed combining the polaron transformation and a time-local quantum master equation formulation, which is valid for arbitrary spectral densities including common modes. The theory contains inhomogeneous terms accounting for nonequilibrium initial preparation effects and elucidates how quantum coherence and nonequilibrium effects manifest themselves in the coherent energy transfer dynamics beyond the weak resonance coupling limit of the Foerster and Dexter (FD) theory. Numerical tests show that quantum coherence can cause significant changes in steady state donor/acceptor populations from those predicted by the FD theory and illustrate delicate cooperation of nonequilibrium and quantum coherence effects on the transient population dynamics.

Governing Global Climate Change: Past Achievements, Future Prospects

Directory of Open Access Journals (Sweden)

Ella Kokotsis

2014-11-01

Full Text Available The cumulative effects of a significantly changing climate are projected to have disastrous implications on the world’s natural habitats, and along with that, are projected to drastically increase the rate and likelihood of violent conflict globally, particularly in high-density, urban, poverty hotspots. Limiting the effects of a changing climate is thus critical in influencing multiple societal goals including equitable sustainable development, human health, biodiversity, food security and access to reliable energy sources. This paper argues that the G7/8 has led global climate governance in ways other international environmental institu­tions have largely failed to do. It has done so largely by placing climate protection at the forefront of its policy objectives, alongside economic, health, energy and security goals, and reaching consensus repeatedly amongst its leaders on the impor­tance of stabilizing emissions through energy efficiency, conservation, investment and technological innovation. Moreover, this chapter argues that the summit’s predominant capability, its constricted participation, democratic convergence and political cohesion – as well as the combined effects of global shocks – have all had positive impacts on the G7/8’s success in mitigating climate change. Following a detailed process-tracing exercise over the summit’s 40-year history in which clear surges and retreats on global climate governance are outlined, this paper concludes by assessing the G7/8’s accountability record on climate mitigation and outlines a set of prescriptive recommendations, allowing for the delivery of a more tangible, coherent, results-driven accountability process for global climate governance.

Wavelet coherence analysis of dynamic cerebral autoregulation in neonatal hypoxic–ischemic encephalopathy

Directory of Open Access Journals (Sweden)

Fenghua Tian

2016-01-01

Full Text Available Cerebral autoregulation represents the physiological mechanisms that keep brain perfusion relatively constant in the face of changes in blood pressure and thus plays an essential role in normal brain function. This study assessed cerebral autoregulation in nine newborns with moderate-to-severe hypoxic–ischemic encephalopathy (HIE. These neonates received hypothermic therapy during the first 72 h of life while mean arterial pressure (MAP and cerebral tissue oxygenation saturation (SctO2 were continuously recorded. Wavelet coherence analysis, which is a time-frequency domain approach, was used to characterize the dynamic relationship between spontaneous oscillations in MAP and SctO2. Wavelet-based metrics of phase, coherence and gain were derived for quantitative evaluation of cerebral autoregulation. We found cerebral autoregulation in neonates with HIE was time-scale-dependent in nature. Specifically, the spontaneous changes in MAP and SctO2 had in-phase coherence at time scales of less than 80 min (<0.0002 Hz in frequency, whereas they showed anti-phase coherence at time scales of around 2.5 h (~0.0001 Hz in frequency. Both the in-phase and anti-phase coherence appeared to be related to worse clinical outcomes. These findings suggest the potential clinical use of wavelet coherence analysis to assess dynamic cerebral autoregulation in neonatal HIE during hypothermia.

Global processing takes time: A meta-analysis on local-global visual processing in ASD.

Science.gov (United States)

Van der Hallen, Ruth; Evers, Kris; Brewaeys, Katrien; Van den Noortgate, Wim; Wagemans, Johan

2015-05-01

What does an individual with autism spectrum disorder (ASD) perceive first: the forest or the trees? In spite of 30 years of research and influential theories like the weak central coherence (WCC) theory and the enhanced perceptual functioning (EPF) account, the interplay of local and global visual processing in ASD remains only partly understood. Research findings vary in indicating a local processing bias or a global processing deficit, and often contradict each other. We have applied a formal meta-analytic approach and combined 56 articles that tested about 1,000 ASD participants and used a wide range of stimuli and tasks to investigate local and global visual processing in ASD. Overall, results show no enhanced local visual processing nor a deficit in global visual processing. Detailed analysis reveals a difference in the temporal pattern of the local-global balance, that is, slow global processing in individuals with ASD. Whereas task-dependent interaction effects are obtained, gender, age, and IQ of either participant groups seem to have no direct influence on performance. Based on the overview of the literature, suggestions are made for future research. (c) 2015 APA, all rights reserved).

Entanglement of Grassmannian Coherent States for Multi-Partite n-Level Systems

Directory of Open Access Journals (Sweden)

Ghader Najarbashi

2011-01-01

Full Text Available In this paper, we investigate the entanglement of multi-partite Grassmannian coherent states (GCSs described by Grassmann numbers for n>2 degree of nilpotency. Choosing an appropriate weight function, we show that it is possible to construct some well-known entangled pure states, consisting of GHZ, W, Bell, cluster type and bi-separable states, which are obtained by integrating over tensor product of GCSs. It is shown that for three level systems, the Grassmann creation and annihilation operators b and b^† together with bz form a closed deformed algebra, i.e., SU_q(2 with q=e^{2πi/3}, which is useful to construct entangled qutrit-states. The same argument holds for three level squeezed states. Moreover combining the Grassmann and bosonic coherent states we construct maximal entangled super coherent states.

Physics-Based Predictions for Coherent Change Detection Using X-Band Synthetic Aperture Radar

Directory of Open Access Journals (Sweden)

Mark Preiss

2005-12-01

Full Text Available A theoretical model is developed to describe the interferometric coherency between pairs of SAR images of rough soil surfaces. The model is derived using a dyadic form for surface reflectivity in the Kirchhoff approximation. This permits the combination of Kirchhoff theory and spotlight synthetic aperture radar (SAR image formation theory. The resulting model is used to describe the interferometric coherency between pairs of SAR images of rough soil surfaces. The theoretical model is applied to SAR images formed before and after surface changes observed by a repeat-pass SAR system. The change in surface associated with a tyre track following vehicle passage is modelled and SAR coherency estimates are obtained. Predicted coherency distributions for both the change and no-change scenarios are used to estimate receiver operator curves for the detection of the changes using a high-resolution, X-band SAR system.

Optimization of a coherent soft x-ray beamline for coherent scattering experiments at NSLS-II

Energy Technology Data Exchange (ETDEWEB)

Shapiro D.; Chubar, O.; Kaznatcheev, K.; Reininger, R.; Sanchez-Hanke, C.; Wang, S.

2011-08-21

The coherent soft x-ray and full polarization control (CSX) beamline at the National Synchrotron Light Source - II (NSLS-II) will deliver 1013 coherent photons per second in the energy range of 0.2-2 keV with a resolving power of 2000. The source, a dual elliptically polarizing undulator (EPU), and beamline optics should be optimized to deliver the highest possible coherent flux in a 10-30 {micro}m spot for use in coherent scattering experiments. Using the computer code Synchrotron Radiation Workshop (SRW), we simulate the photon source and focusing optics in order to investigate the conditions which provide the highest usable coherent intensity on the sample. In particular, we find that an intermediate phasing magnet is needed to correct for the relative phase between the two EPUs and that the optimum phase setting produces a spectrum in which the desired wavelength is slightly red-shifted thus requiring a larger aperture than originally anticipated. This setting is distinct from that which produces an on-axis spectrum similar to a single long undulator. Furthermore, partial coherence calculations, utilizing a multiple electron approach, indicate that a high degree of spatial coherence is still obtained at the sample location when such an aperture is used. The aperture size which maximizes the signal-to-noise ratio of a double-slit experiment is explored. This combination of high coherence and intensity is ideally suited for x-ray ptychography experiments which reconstruct the scattering density from micro-diffraction patterns. This technique is briefly reviewed and the effects on the image quality of proximity to the beamline focus are explored.

A Study on PolInSAR Coherence Based Regression Analysis of Forest Biomass (BARKOT Reserve Forest India), Using RADARSAT-2 Datasets

Science.gov (United States)

Singh, J.; Kumar, S.; Kushwaha, S. P. S.

2015-04-01

Forests cover 30% of the world's land surface, and are home to around 90% of the world's flora and fauna. They serve as one of the world's largest carbon sinks, absorbing 2.4 million tons of CO2 each year and storing billions more in form of biomass. Around 6 million hectares of forest is lost or changed each year and as much as a fifth of global emissions are estimated to come from deforestation. Hence accurate estimation of forest biophysical variables is necessary as it is a key parameter in determination of forest inventories, vegetation modeling and global carbon cycle. SAR Remote sensing technique is capable of providing accurate and reliable information about forest parameters. The present work aims to explore the potential of C-band Radarsat-2 Polarimetric Interferometric Synthetic Aperture Radar (PolinSAR) technique for developing a relationship between complex coherence and forest aboveground biomass (t/ha). In order to attain our objective Radarsat-2 satellite interferometric pair of 4th March 2013(master image) and 28th March 2013(slave image) were acquired for Barkot Reserve Forest, Dehradun, India. Field inventory was done for 30 plots (31.62m x 31.62m) and tree height and stem diameter were procured for each plot which were later utilized in calculation of aboveground biomass(AGB).Work emphasizes on the application of PolinSAR coherence instead of using SAR backscatter which saturates after a certain value of biomass content. Complex coherence values for different polarization channels were computed with the help of polarimetric interferometric coherence matrix. Retrieved complex coherences were investigated individually and then regression analysis was carried with the field estimated aboveground biomass. R2 value of HV+VH complex coherence component was found to be relatively higher than other polarization channel components

Coherent states on Hilbert modules

International Nuclear Information System (INIS)

Ali, S Twareque; Bhattacharyya, T; Roy, S S

2011-01-01

We generalize the concept of coherent states, traditionally defined as special families of vectors on Hilbert spaces, to Hilbert modules. We show that Hilbert modules over C*-algebras are the natural settings for a generalization of coherent states defined on Hilbert spaces. We consider those Hilbert C*-modules which have a natural left action from another C*-algebra, say A. The coherent states are well defined in this case and they behave well with respect to the left action by A. Certain classical objects like the Cuntz algebra are related to specific examples of coherent states. Finally we show that coherent states on modules give rise to a completely positive definite kernel between two C*-algebras, in complete analogy to the Hilbert space situation. Related to this, there is a dilation result for positive operator-valued measures, in the sense of Naimark. A number of examples are worked out to illustrate the theory. Some possible physical applications are also mentioned.

Integrated coherent matter wave circuits

International Nuclear Information System (INIS)

Ryu, C.; Boshier, M. G.

2015-01-01

An integrated coherent matter wave circuit is a single device, analogous to an integrated optical circuit, in which coherent de Broglie waves are created and then launched into waveguides where they can be switched, divided, recombined, and detected as they propagate. Applications of such circuits include guided atom interferometers, atomtronic circuits, and precisely controlled delivery of atoms. We report experiments demonstrating integrated circuits for guided coherent matter waves. The circuit elements are created with the painted potential technique, a form of time-averaged optical dipole potential in which a rapidly moving, tightly focused laser beam exerts forces on atoms through their electric polarizability. Moreover, the source of coherent matter waves is a Bose-Einstein condensate (BEC). Finally, we launch BECs into painted waveguides that guide them around bends and form switches, phase coherent beamsplitters, and closed circuits. These are the basic elements that are needed to engineer arbitrarily complex matter wave circuitry

Coherent states in quantum physics

CERN Document Server

Gazeau, Jean-Pierre

2009-01-01

This self-contained introduction discusses the evolution of the notion of coherent states, from the early works of Schrödinger to the most recent advances, including signal analysis. An integrated and modern approach to the utility of coherent states in many different branches of physics, it strikes a balance between mathematical and physical descriptions.Split into two parts, the first introduces readers to the most familiar coherent states, their origin, their construction, and their application and relevance to various selected domains of physics. Part II, mostly based on recent original results, is devoted to the question of quantization of various sets through coherent states, and shows the link to procedures in signal analysis. Title: Coherent States in Quantum Physics Print ISBN: 9783527407095 Author(s): Gazeau, Jean-Pierre eISBN: 9783527628292 Publisher: Wiley-VCH Dewey: 530.12 Publication Date: 23 Sep, 2009 Pages: 360 Category: Science, Science: Physics LCCN: Language: English Edition: N/A LCSH:

Personality, sense of coherence and the coping of working mothers

Directory of Open Access Journals (Sweden)

Lettie Herbst

2007-02-01

Full Text Available The purpose of the study was to examine the relationships between personality dimensions, sense of coherence and coping styles among working mothers. The OPQ, OLQ and COPE questionnaires were administered to 120 married, working mothers. In view of contrasting results obtained by other researchers regarding the dimensionality of the COPE, its factorial validity and internal consistency were assessed. Exploratory factor analysis indicated that the COPE measured five factors with high degrees of internal consistency. Several personality dimensions and sense of coherence variables correlated significantly with the dependent variables (coping styles. It appeared that these independent variables predicted substantial percentages of the variability in the coping styles.

Coherent Coupled Qubits for Quantum Annealing

Science.gov (United States)

Weber, Steven J.; Samach, Gabriel O.; Hover, David; Gustavsson, Simon; Kim, David K.; Melville, Alexander; Rosenberg, Danna; Sears, Adam P.; Yan, Fei; Yoder, Jonilyn L.; Oliver, William D.; Kerman, Andrew J.

2017-07-01

Quantum annealing is an optimization technique which potentially leverages quantum tunneling to enhance computational performance. Existing quantum annealers use superconducting flux qubits with short coherence times limited primarily by the use of large persistent currents Ip. Here, we examine an alternative approach using qubits with smaller Ip and longer coherence times. We demonstrate tunable coupling, a basic building block for quantum annealing, between two flux qubits with small (approximately 50-nA) persistent currents. Furthermore, we characterize qubit coherence as a function of coupler setting and investigate the effect of flux noise in the coupler loop on qubit coherence. Our results provide insight into the available design space for next-generation quantum annealers with improved coherence.

Optical coherent tomography in diagnoses of peripheral retinal degenarations

Directory of Open Access Journals (Sweden)

O. G. Pozdeyeva

2013-01-01

Full Text Available Purpose: Studying the capabilities of optical coherence tomography (RTVue-100, OPTOVUE, USA in evaluation of peripheral retinal degenerations, vitreoretinal adhesions, adjacent vitreous body as well as measurement of morphometric data.Methods: The study included 189 patients (239 eyes with peripheral retinal degeneration. 77 men and 112 women aged 18 to 84 underwent an ophthalmologic examination since November 2012 until October 2013. The peripheral retina was visualized with the help of optical coherence tomography («RTVue-100,» USA. The fundography was carried out using a Nikon NF505‑AF (Japan fundus camera. All patients were examined with a Goldmann lens.Results: Optical coherence tomography was used to evaluate different kinds of peripheral retinal degenerations, such as lattice and snail track degeneration, isolated retinal tears, cystoid retinal degeneration, pathological hyperpigmentation, retinoschisis and cobblestone degeneration. The following morphometric data were studied: dimensions of the lesion (average length, retinal thickness along the edge of the lesion, retinal thickness at the base of the lesion and the vitreoretinal interface.Conclusion: Optical coherence tomography is a promising in vivo visualization method which is useful in evaluation of peripheral retinal degenerations, vitreoretinal adhesions and tractions. It also provides a comprehensive protocolling system and monitoring. It will enable ophthalmologists to better define laser and surgical treatment indications and evaluate therapy effectiveness.

Optical coherent tomography in diagnoses of peripheral retinal degenarations

Directory of Open Access Journals (Sweden)

O. G. Pozdeyeva

2014-07-01

Full Text Available Purpose: Studying the capabilities of optical coherence tomography (RTVue-100, OPTOVUE, USA in evaluation of peripheral retinal degenerations, vitreoretinal adhesions, adjacent vitreous body as well as measurement of morphometric data.Methods: The study included 189 patients (239 eyes with peripheral retinal degeneration. 77 men and 112 women aged 18 to 84 underwent an ophthalmologic examination since November 2012 until October 2013. The peripheral retina was visualized with the help of optical coherence tomography («RTVue-100,» USA. The fundography was carried out using a Nikon NF505‑AF (Japan fundus camera. All patients were examined with a Goldmann lens.Results: Optical coherence tomography was used to evaluate different kinds of peripheral retinal degenerations, such as lattice and snail track degeneration, isolated retinal tears, cystoid retinal degeneration, pathological hyperpigmentation, retinoschisis and cobblestone degeneration. The following morphometric data were studied: dimensions of the lesion (average length, retinal thickness along the edge of the lesion, retinal thickness at the base of the lesion and the vitreoretinal interface.Conclusion: Optical coherence tomography is a promising in vivo visualization method which is useful in evaluation of peripheral retinal degenerations, vitreoretinal adhesions and tractions. It also provides a comprehensive protocolling system and monitoring. It will enable ophthalmologists to better define laser and surgical treatment indications and evaluate therapy effectiveness.

sLORETA intracortical lagged coherence during breath counting in meditation-naïve participants

Directory of Open Access Journals (Sweden)

Patricia eMilz

2014-05-01

Full Text Available We investigated brain functional connectivity comparing no-task resting to breath counting (a meditation exercise but given as task without referring to meditation. Functional connectivity computed as EEG coherence between head-surface data suffers from localization ambiguity, reference dependence, and overestimation due to volume conduction. Lagged coherence between intracortical model sources addresses these criticisms. With this analysis approach, experienced meditators reportedly showed reduced coherence during meditation, meditation-naïve participants have not yet been investigated. 58-channel EEG from 23 healthy, right-handed, meditation-naïve males during resting [3 runs] and breath counting [2 runs] was computed into sLORETA time series of intracortical electrical activity in 19 regions of interest corresponding to the cortex underlying 19 scalp electrode sites, for each of the 8 independent EEG frequency bands covering 1.5-44 Hz. Intracortical lagged coherences and head-surface conventional coherences were computed between the 19 regions/sites. During breath counting compared to resting, paired t-tests corrected for multiple testing revealed 4 significantly lower intracortical lagged coherences, but 4 significantly higher head-surface conventional coherences. Lowered intracortical lagged coherences involved left BA 10 and right BAs 3, 10, 17, 40. In conclusion, intracortical lagged coherence can yield results that are inverted to those of head-surface conventional coherence. The lowered functional connectivity between cognitive control areas and sensory perception areas during meditation-type breath counting compared to resting conceivably reflects the attention to a bodily percept without cognitive reasoning. The reductions in functional connectivity were similar but not as widespread as the reductions reported during meditation in experienced meditators.

Coherence Generalises Duality: A Logical Explanation of Multiparty Session Types

DEFF Research Database (Denmark)

Carbone, Marco; Lindley, Sam; Montesi, Fabrizio

2016-01-01

the duality of classical linear logic (relating two types) with a more general notion of coherence (relating an arbitrary number of types). This paper introduces variants of CP and MCP, plus a new intermediate calculus of Globally-governed Classical Processes (GCP). We show a tight relation between......Wadler introduced Classical Processes (CP), a calculus based on a propositions-as-types correspondence between propositions of classical linear logic and session types. Carbone et al. introduced Multiparty Classical Processes, a calculus that generalises CP to multiparty session types, by replacing...

Asymmetry and coherence weight of quantum states

Science.gov (United States)

Bu, Kaifeng; Anand, Namit; Singh, Uttam

2018-03-01

The asymmetry of quantum states is an important resource in quantum information processing tasks such as quantum metrology and quantum communication. In this paper, we introduce the notion of asymmetry weight—an operationally motivated asymmetry quantifier in the resource theory of asymmetry. We study the convexity and monotonicity properties of asymmetry weight and focus on its interplay with the corresponding semidefinite programming (SDP) forms along with its connection to other asymmetry measures. Since the SDP form of asymmetry weight is closely related to asymmetry witnesses, we find that the asymmetry weight can be regarded as a (state-dependent) asymmetry witness. Moreover, some specific entanglement witnesses can be viewed as a special case of an asymmetry witness—which indicates a potential connection between asymmetry and entanglement. We also provide an operationally meaningful coherence measure, which we term coherence weight, and investigate its relationship to other coherence measures like the robustness of coherence and the l1 norm of coherence. In particular, we show that for Werner states in any dimension d all three coherence quantifiers, namely, the coherence weight, the robustness of coherence, and the l1 norm of coherence, are equal and are given by a single letter formula.

Coherent systems with multistate components

International Nuclear Information System (INIS)

Caldarola, L.

1980-01-01

The basic rules of the Boolean algebra with restrictions on variables are briefly recalled. This special type of Boolean algebra allows one to handle fault trees of systems made of multistate (two or more than two states) components. Coherent systems are defined in the case of multistate components. This definition is consistent with that originally suggested by Barlow in the case of binary (two states) components. The basic properties of coherence are described and discussed. Coherent Boolean functions are also defined. It is shown that these functions are irredundant, that is they have only one base which is at the same time complete and irredundant. However, irredundant functions are not necessarily coherent. Finally a simplified algorithm for the calculation of the base of a coherent function is described. In the case that the function is not coherent, the algorithm can be used to reduce the size of the normal disjunctive form of the function. This in turn eases the application of the Nelson algorithm to calculate the complete base of the function. The simplified algorithm has been built in the computer program MUSTAFA-1. In a sample case the use of this algorithm caused a reduction of the CPU time by a factor of about 20. (orig.)

Identification of individual coherent sets associated with flow trajectories using Coherent Structure Coloring

Science.gov (United States)

Schlueter-Kuck, Kristy; Dabiri, John

2017-11-01

In recent years, there has been a proliferation of techniques that aim to characterize fluid flow kinematics on the basis of Lagrangian trajectories of collections of tracer particles. Most of these techniques depend on presence of tracer particles that are initially closely-spaced, in order to compute local gradients of their trajectories. In many applications, the requirement of close tracer spacing cannot be satisfied, especially when the tracers are naturally occurring and their distribution is dictated by the underlying flow. Moreover, current methods often focus on determination of the boundaries of coherent sets, whereas in practice it is often valuable to identify the complete set of trajectories that are coherent with an individual trajectory of interest. We extend the concept of Coherent Structure Coloring to achieve identification of the coherent set associated with individual Lagrangian trajectories. This algorithm is proven successful in identifying coherent structures of varying complexities in canonical unsteady flows. Importantly, although the method is demonstrated here in the context of fluid flow kinematics, the generality of the approach allows for its potential application to other unsupervised clustering problems in dynamical systems. This work was supported by the Department of Defense (DoD) through the National Defense Science & Engineering Graduate Fellowship (NDSEG) Program.

Coherent Waves in Seismic Researches

Science.gov (United States)

Emanov, A.; Seleznev, V. S.

2013-05-01

Development of digital processing algorithms of seismic wave fields for the purpose of useful event picking to study environment and other objects is the basis for the establishment of new seismic techniques. In the submitted paper a fundamental property of seismic wave field coherence is used. The authors extended conception of coherence types of observed wave fields and devised a technique of coherent component selection from observed wave field. Time coherence and space coherence are widely known. In this paper conception "parameter coherence" has been added. The parameter by which wave field is coherent can be the most manifold. The reason is that the wave field is a multivariate process described by a set of parameters. Coherence in the first place means independence of linear connection in wave field of parameter. In seismic wave fields, recorded in confined space, in building-blocks and stratified mediums time coherent standing waves are formed. In prospecting seismology at observation systems with multiple overlapping head waves are coherent by parallel correlation course or, in other words, by one measurement on generalized plane of observation system. For detail prospecting seismology at observation systems with multiple overlapping on basis of coherence property by one measurement of area algorithms have been developed, permitting seismic records to be converted to head wave time sections which have neither reflected nor other types of waves. Conversion in time section is executed on any specified observation base. Energy storage of head waves relative to noise on basis of multiplicity of observation system is realized within area of head wave recording. Conversion on base below the area of wave tracking is performed with lack of signal/noise ratio relative to maximum of this ratio, fit to observation system. Construction of head wave time section and dynamic plots a basis of automatic processing have been developed, similar to CDP procedure in method of

COHERENT Experiment: current status

International Nuclear Information System (INIS)

Akimov, D; Belov, V; Bolozdynya, A; Burenkov, A; Albert, J B; Del Valle Coello, M; D’Onofrio, M; Awe, C; Barbeau, P S; Cervantes, M; Becker, B; Cabrera-Palmer, B; Collar, J I; Cooper, R J; Cooper, R L; Cuesta, C; Detwiler, J; Eberhardt, A; Dean, D; Dolgolenko, A G

2017-01-01

The COHERENT Collaboration is realizing a long term neutrino physics research program. The main goals of the program are to detect and study elastic neutrino-nucleus scattering (CEνNS). This process is predicted by Standard Model but it has never been observed experimentally because of the very low energy of the recoil nucleus. COHERENT is using different detector technologies: CsI[Na] and NaI scintillator crystals, a single-phase liquid Ar and a Ge detectors. The placement of all the detector setups is in the basement of the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL). The current status of the COHERENT experimental program is presented. (paper)

Coherence-driven argumentation to norm consensus

NARCIS (Netherlands)

Joseph, S.; Prakken, H.

2009-01-01

In this paper coherence-based models are proposed as an alternative to logic-based BDI and argumentation models for the reasoning of normative agents. A model is provided for how two coherence-based agents can deliberate on how to regulate a domain of interest. First a deductive coherence model

Coherent and Incoherent Neutral Current Scattering for Supernova Detection

Directory of Open Access Journals (Sweden)

P. C. Divari

2012-01-01

Full Text Available The total cross sections as well as the neutrino event rates are calculated in the neutral current neutrino scattering off 40Ar and 132Xe isotopes at neutrino energies (Ev<100 MeV. The individual contribution coming from coherent and incoherent channels is taking into account. An enhancement of the neutral current component is achieved via the coherent (0gs+→0gs+ channel which is dominant with respect to incoherent (0gs+→Jf one. The response of the above isotopes as a supernova neutrino detection has been considered, assuming a two parameter Fermi-Dirac distribution for the supernova neutrino energy spectra. The calculated total cross sections are tested on a gaseous spherical TPC detector dedicated for supernova neutrino detection.

Magnons coherent transmission and its heat transport at ultrathin insulating ferromagnetic nanojunctions

Directory of Open Access Journals (Sweden)

Ghantous M. Abou

2012-06-01

Full Text Available A model calculation is presented for the magnons coherent transmission and corresponding heat transport at magnetic insulating nanojunctions. The system consists of a ferromagnetically ordered ultrathin insulating junction between two semi-infinite ferromagnetically ordered leads. Spin dynamics are analyzed using the equations of motion for the spin precession displacements, valid for the range of temperatures of interest. Coherent scattering cross-sections at the junction boundary are calculated using the phase field matching theory, for all the incidence angles on the boundary from the lead bands, for arbitrary angles of incidence, at variable temperatures, and for different nano thicknesses of the ultrathin junction. The model is general; it is applied in particular to the Fe/Gd/Fe system with a sandwiched ferromagnetic Gd junction. It yields also the thermal conductivity due to the magnons coherent transmission between the two leads when these are maintained at slightly different temperatures. The calculation is carried out for state of the art values of the exchange constants, and elucidates the relation between the coherent scattering transmission of magnons and their thermal conductivity, for different thicknesses.

Novelty detection-based internal fingerprint segmentation in optical coherence tomography images

CSIR Research Space (South Africa)

Khutlang, R

2014-12-01

Full Text Available present an automatic segmentation of the papillary layer method, in 3-D swept source optical coherence tomography (SS-OCT) images. The papillary contour represents the internal fingerprint, which does not suffer external skin problems. The slices composing...

Novelty detection-based internal fingerprint segmentation in optical coherence tomography images

CSIR Research Space (South Africa)

Khutlang, Rethabile

2017-08-01

Full Text Available present an automatic segmentation of the papillary layer method, from images acquired using contact-less 3-D swept source optical coherence tomography (OCT). The papillary contour represents the internal fingerprint, which does not suffer from the external...

In vivo sweat film layer thickness measured with Fourier-domain optical coherence tomography

CSIR Research Space (South Africa)

Jonathan, E

2008-01-01

Full Text Available s Centre form the f th s pr t fi d id Keywords: Fourier-domain optical coherence tomography; Human sweat secretion; Sweat gland; Sweat duct; Hyperhidrosis growing list of triggers include cancer, glucose control disorder, mental stress, social..., that is, the gland, duct and pore(s). However, due to a slow imaging time, COCT is largely restricted to morphometry of human tissue and thickness measurement of biologic and biologic samples [12,13]. ARTICLE IN PRESS Fourier-domain optical coherence...

Effect of quantum lattice fluctuations on quantum coherent oscillations in a coherently driven quantum dot-cavity system

International Nuclear Information System (INIS)

Zhu, Ka-Di; Li, Wai-Sang

2003-01-01

The quantum coherent oscillations in a coherently driven quantum dot-cavity system with the presence of strong exciton-phonon interactions are investigated theoretically in a fully quantum treatment. It is shown that even at zero temperature, the strong exciton-phonon interactions still affect the quantum coherent oscillations significantly

Quantum coherence and correlations in quantum system

Science.gov (United States)

Xi, Zhengjun; Li, Yongming; Fan, Heng

2015-01-01

Criteria of measure quantifying quantum coherence, a unique property of quantum system, are proposed recently. In this paper, we first give an uncertainty-like expression relating the coherence and the entropy of quantum system. This finding allows us to discuss the relations between the entanglement and the coherence. Further, we discuss in detail the relations among the coherence, the discord and the deficit in the bipartite quantum system. We show that, the one-way quantum deficit is equal to the sum between quantum discord and the relative entropy of coherence of measured subsystem. PMID:26094795

Exergy of partially coherent thermal radiation

International Nuclear Information System (INIS)

Wijewardane, S.; Goswami, Yogi

2012-01-01

Exergy of electromagnetic radiation has been studied by a number of researchers for well over four decades in order to estimate the maximum conversion efficiencies of thermal radiation. As these researchers primarily dealt with solar and blackbody radiation, which have a low degree of coherence, they did not consider the partial coherence properties of thermal radiation. With the recent development of surface structures, which can emit radiation with high degree of coherence, the importance of considering the partial coherent properties in exergy calculation has become a necessity as the coherence properties directly influence the entropy of the wave field. Here in this paper we derive an expression for the exergy of quasi-monochromatic radiation using statistical thermodynamics and show that it is identical with the expressions derived using classical thermodynamics. We also present a method to calculate the entropy, thereby the exergy of partially coherent radiation using statistical thermodynamics and a method called matrix treatment of wave field. -- Highlights: ► Considered partial coherence of radiation for the first time to calculate exergy. ► The importance of this method is emphasized with energy conversion examples. ► Derived an expression for the exergy of radiation using statistical thermodynamics. ► Adopted a method to calculate intensity of statistically independent principle wave.

Painlevé IV coherent states

Energy Technology Data Exchange (ETDEWEB)

Bermudez, David, E-mail: david.bermudez@weizmann.ac.il [Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot 76100 (Israel); Departamento de Física, Cinvestav, A.P. 14-740, 07000 México D.F. (Mexico); Contreras-Astorga, Alonso, E-mail: aloncont@iun.edu [Department of Mathematics and Actuarial Science, Indiana University Northwest, 3400 Broadway, Gary IN 46408 (United States); Departamento de Física, Cinvestav, A.P. 14-740, 07000 México D.F. (Mexico); Fernández C, David J., E-mail: david@fis.cinvestav.mx [Departamento de Física, Cinvestav, A.P. 14-740, 07000 México D.F. (Mexico)

2014-11-15

A simple way to find solutions of the Painlevé IV equation is by identifying Hamiltonian systems with third-order differential ladder operators. Some of these systems can be obtained by applying supersymmetric quantum mechanics (SUSY QM) to the harmonic oscillator. In this work, we will construct families of coherent states for such subset of SUSY partner Hamiltonians which are connected with the Painlevé IV equation. First, these coherent states are built up as eigenstates of the annihilation operator, then as displaced versions of the extremal states, both involving the related third-order ladder operators, and finally as extremal states which are also displaced but now using the so called linearized ladder operators. To each SUSY partner Hamiltonian corresponds two families of coherent states: one inside the infinite subspace associated with the isospectral part of the spectrum and another one in the finite subspace generated by the states created through the SUSY technique. - Highlights: • We use SUSY QM to obtain Hamiltonians with third-order differential ladder operators. • We show that these systems are related with the Painlevé IV equation. • We apply different definitions of coherent states to these Hamiltonians using the third-order ladder operators and some linearized ones. • We construct families of coherent states for such systems, which we called Painlevé IV coherent states.

Painlevé IV coherent states

International Nuclear Information System (INIS)

Bermudez, David; Contreras-Astorga, Alonso; Fernández C, David J.

2014-01-01

A simple way to find solutions of the Painlevé IV equation is by identifying Hamiltonian systems with third-order differential ladder operators. Some of these systems can be obtained by applying supersymmetric quantum mechanics (SUSY QM) to the harmonic oscillator. In this work, we will construct families of coherent states for such subset of SUSY partner Hamiltonians which are connected with the Painlevé IV equation. First, these coherent states are built up as eigenstates of the annihilation operator, then as displaced versions of the extremal states, both involving the related third-order ladder operators, and finally as extremal states which are also displaced but now using the so called linearized ladder operators. To each SUSY partner Hamiltonian corresponds two families of coherent states: one inside the infinite subspace associated with the isospectral part of the spectrum and another one in the finite subspace generated by the states created through the SUSY technique. - Highlights: • We use SUSY QM to obtain Hamiltonians with third-order differential ladder operators. • We show that these systems are related with the Painlevé IV equation. • We apply different definitions of coherent states to these Hamiltonians using the third-order ladder operators and some linearized ones. • We construct families of coherent states for such systems, which we called Painlevé IV coherent states

Sense of Coherence and Gambling: Exploring the Relationship Between Sense of Coherence, Gambling Behaviour and Gambling-Related Harm.

Science.gov (United States)

Langham, Erika; Russell, Alex M T; Hing, Nerilee; Gainsbury, Sally M

2017-06-01

Understanding why some people experience problems with gambling whilst others are able to restrict gambling to recreational levels is still largely unexplained. One potential explanation is through salutogenesis, which is a health promotion approach of understanding factors which move people towards health rather than disease. An important aspect of salutogenesis is sense of coherence. Individuals with stronger sense of coherence perceive their environment as comprehensible, manageable and meaningful. The present study examined the relationship of individuals' sense of coherence on their gambling behaviour and experience of gambling related harm. This exploratory study utilised an archival dataset (n = 1236) from an online, cross sectional survey of people who had experienced negative consequences from gambling. In general, a stronger sense of coherence was related to lower problem gambling severity. When gambling behaviour was controlled for, sense of coherence was significantly related to the experience of individual gambling harms. A strong sense of coherence can be seen as a protective factor against problematic gambling behaviour, and subsequent gambling related harms. These findings support the value of both primary and tertiary prevention strategies that strengthen sense of coherence as a harm minimisation strategy. The present study demonstrates the potential value of, and provides clear direction for, considering sense of coherence in order to understand gambling-related issues.

Coherence in the Argumentative Essays of First Year College of Liberal Arts Students at De La Salle University

Directory of Open Access Journals (Sweden)

Alphie G. Garing

2013-12-01

Full Text Available The study investigates five textual features of coherence in the students’ argumentative essays for text comprehensibility and overall writing quality. Specifically, it examines how comprehensible the students’ argumentative essays considering the following: focus, organization, cohesion, support and elaboration, and conventions; and the relationship between the textual features and the comprehensibility of the students’ argumentative essays. The data consists of 13 argumentative essays written in ENGLCOM class first year College of Liberal Arts students of De La Salle University. Two techniques were used to analyze the data. First, an analytic and holistic scorings using a four-point writing rubric were used to evaluate each of the textual features of coherence and comprehensibility, respectively. Second, correlation analysis was performed to determine the relationship between the coherence features and the comprehensibility of the students’ texts and between the comprehensibility of the students’ argumentative essays.

Health in All (Foreign) Policy: challenges in achieving coherence.

Science.gov (United States)

Labonté, Ronald

2014-06-01

Health in All Policies (HiAP) approach is generally perceived as an intersectoral approach to national or sub-national public policy development, such that health outcomes are given full consideration by non-health sectors. Globalization, however, has created numerous 'inherently global health issues' with cross-border causes and consequences, requiring new forms of global governance for health. Although such governance often includes both state and non-state (private, civil society) actors in agenda setting and influence, different actors have differing degrees of power and authority and, ultimately, it is states that ratify intergovernmental covenants or normative declarations that directly or indirectly affect health. This requires public health and health promotion practitioners working within countries to give increased attention to the foreign policies of their national governments. These foreign policies include those governing national security, foreign aid, trade and investment as well as the traditional forms of diplomacy. A new term has been coined to describe how health is coming to be positioned in governments' foreign policies: global health diplomacy. To become adept at this nuanced diplomatic practice requires familiarity with the different policy frames by which health might be inserted into the foreign policy deliberations, and thence intergovernmental/global governance negotiations. This article discusses six such frames (security, trade, development, global public goods, human rights, ethical/moral reasoning) that have been analytically useful in assessing the potential for greater and more health-promoting foreign policy coherence: a 'Health in All (Foreign) Policies' approach. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Coherence-generating power of quantum dephasing processes

Science.gov (United States)

Styliaris, Georgios; Campos Venuti, Lorenzo; Zanardi, Paolo

2018-03-01

We provide a quantification of the capability of various quantum dephasing processes to generate coherence out of incoherent states. The measures defined, admitting computable expressions for any finite Hilbert-space dimension, are based on probabilistic averages and arise naturally from the viewpoint of coherence as a resource. We investigate how the capability of a dephasing process (e.g., a nonselective orthogonal measurement) to generate coherence depends on the relevant bases of the Hilbert space over which coherence is quantified and the dephasing process occurs, respectively. We extend our analysis to include those Lindblad time evolutions which, in the infinite-time limit, dephase the system under consideration and calculate their coherence-generating power as a function of time. We further identify specific families of such time evolutions that, although dephasing, have optimal (over all quantum processes) coherence-generating power for some intermediate time. Finally, we investigate the coherence-generating capability of random dephasing channels.

Effects of quantum coherence on work statistics

Science.gov (United States)

Xu, Bao-Ming; Zou, Jian; Guo, Li-Sha; Kong, Xiang-Mu

2018-05-01

In the conventional two-point measurement scheme of quantum thermodynamics, quantum coherence is destroyed by the first measurement. But as we know the coherence really plays an important role in the quantum thermodynamics process, and how to describe the work statistics for a quantum coherent process is still an open question. In this paper, we use the full counting statistics method to investigate the effects of quantum coherence on work statistics. First, we give a general discussion and show that for a quantum coherent process, work statistics is very different from that of the two-point measurement scheme, specifically the average work is increased or decreased and the work fluctuation can be decreased by quantum coherence, which strongly depends on the relative phase, the energy level structure, and the external protocol. Then, we concretely consider a quenched one-dimensional transverse Ising model and show that quantum coherence has a more significant influence on work statistics in the ferromagnetism regime compared with that in the paramagnetism regime, so that due to the presence of quantum coherence the work statistics can exhibit the critical phenomenon even at high temperature.

Coherent Code Tracking for Spatial Transmit Diversity DS-CDMA Systems

Directory of Open Access Journals (Sweden)

R. W. Stewart

2005-09-01

Full Text Available Spatial transmit diversity schemes are now well integrated into third-generation cellular mobile communication system specifications. When DS-CDMA-based technology is deployed in typical macro- and microcell environments, multipath diversity and spatial diversity may be exploited simultaneously by a 2D RAKE receiver. The work presented in this paper focuses on taking advantage of spatial transmit diversity in synchronising the 2D RAKE structure. We investigate the use of coherent and noncoherent techniques for tracking the timing parameters of each multipath component. It is shown that both noncoherent and coherent techniques benefit from transmit diversity. Additionally the performance gap between these two techniques increases with the number of antennas.

Simultaneous measurements of global vibrational spectra and dephasing times of molecular vibrational modes by broadband time-resolved coherent anti-Stokes Raman scattering spectrography

International Nuclear Information System (INIS)

Yin Jun; Yu Ling-Yao; Liu Xing; Wan Hui; Lin Zi-Yang; Niu Han-Ben

2011-01-01

In broadband coherent anti-Stokes Raman scattering (CARS) spectroscopy with supercontinuum (SC), the simultaneously detectable spectral coverage is limited by the spectral continuity and the simultaneity of various spectral components of SC in an enough bandwidth. By numerical simulations, the optimal experimental conditions for improving the SC are obtained. The broadband time-resolved CARS spectrography based on the SC with required temporal and spectral distributions is realised. The global molecular vibrational spectrum with well suppressed nonresonant background noise can be obtained in a single measurement. At the same time, the measurements of dephasing times of various molecular vibrational modes can be conveniently achieved from intensities of a sequence of time-resolved CARS signals. It will be more helpful to provide a complete picture of molecular vibrations, and to exhibit a potential to understand not only both the solvent dynamics and the solute-solvent interactions, but also the mechanisms of chemical reactions in the fields of biology, chemistry and material science. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

[The sense of coherence among nurses].

Science.gov (United States)

Malagón-Aguilera, M Carmen; Fuentes-Pumarola, Concepció; Suñer-Soler, Rosa; Bonmatí-Tomàs, Anna; Fernández-Peña, Roser; Bosch-Farré, Cristina

2012-01-01

Through the construct "The sense of coherence" (SOC), the salutogenic model explains why people subjected to stressors are able to maintain good health. The SOC was defined by Antonovsky as a global orientation that expresses the extent to which a person has a highly internalized, permanent - but at the same time dynamic - feeling of confidence; this feeling of confidence is predictable and leads to a high probability that events will turn out well. The present article reviews the literature on the SOC in the nursing profession. The results show that the SOC is a protective factor against stressors in the work environment and in the work-life balance. Low SOC levels are associated with health problems such as burnout or depression, as well as certain personality traits. Copyright © 2012 Elsevier España, S.L. All rights reserved.

The quantum coherence of disordered dipolar bosonic gas

International Nuclear Information System (INIS)

Wang Jiguo; Zhang Aixia; Tang Rongan; Gao Jimin; Xue Jukui

2013-01-01

We investigate the coherence of correlated dipolar gas in the presence of disorder within a three-site Bose–Hubbard model. We show that the interplay between the on-site interaction, the inter-site dipole–dipole interactions (DDI) and the disorder exhibits new and interesting coherence characters that cannot take place in a non-dipolar system. The ratio between the on-site interaction and DDI plays a dominant role in the phase coherence. The resonance character of the coherence against both disorder and interactions emerges. DDI can enhance the coherence at certain values of the disorder and on-site interaction. In the coherence region, the enhancement of the coherence by disorder in a dipolar system is more significant than that in a non-dipolar system. In particular, the on-site interaction and DDI together can enhance the coherence even in the clean dipolar system (i.e. a dipolar system without disorder). However, without the on-site interaction, disorder, DDI or both together suppress the coherence. Furthermore, the relationship between the coherence and the energy gap and the compressibility of the system is also discussed. (paper)

FABRICATION OF TISSUE-SIMULATIVE PHANTOMS AND CAPILLARIES AND THEIR INVESTIGATION BY OPTICAL COHERENCE TOMOGRAPHY TECHNIQUES

Directory of Open Access Journals (Sweden)

A. V. Bykov

2013-03-01

Full Text Available Methods of tissue-simulative phantoms and capillaries fabrication from PVC-plastisol and silicone for application as test-objects in optical coherence tomography (OCT and skin and capillary emulation are considered. Comparison characteristics of these materials and recommendations for their application are given. Examples of phantoms visualization by optical coherence tomography method are given. Possibility of information using from B-scans for refractive index evaluation is shown.

Checklist for One Health Epidemiological Reporting of Evidence (COHERE

Directory of Open Access Journals (Sweden)

Meghan F. Davis

2017-12-01

Full Text Available One Health is defined as the intersection and integration of knowledge regarding humans, animals, and the environment, yet as the One Health scientific literature expands, there is considerable heterogeneity of approach and quality of reporting in One Health studies. In addition, many researchers who publish such studies do not include or integrate data from all three domains of human, animal, and environmental health. This points to a critical need to unify guidelines for One Health studies. This report details the Checklist for One Health Epidemiological Reporting of Evidence (COHERE to guide the design and publication format of future One Health studies. COHERE was developed by a core writing team and international expert review group that represents multiple disciplines, including human medicine, veterinary medicine, public health, allied professionals, clinical laboratory science, epidemiology, the social sciences, ecohealth and environmental health. The twin aims of the COHERE standards are to 1 improve the quality of reporting of observational or interventional epidemiological studies that collect and integrate data from humans, animals and/or vectors, and their environments; and 2 promote the concept that One Health studies should integrate knowledge from these three domains. The 19 standards in the COHERE checklist address descriptions of human populations, animal populations, environmental assessment, spatial and temporal relationships of data from the three domains, integration of analyses and interpretation, and inclusion of expertise in the research team from disciplines related to human health, animal health, and environmental health.

Donor disc attachment assessment with intraoperative spectral optical coherence tomography during descemet stripping automated endothelial keratoplasty

Directory of Open Access Journals (Sweden)

Edward Wylegala

2013-01-01

Full Text Available Optical coherence tomography has already been proven to be useful for pre- and post-surgical anterior eye segment assessment, especially in lamellar keratoplasty procedures. There is no evidence for intraoperative usefulness of optical coherence tomography (OCT. We present a case report of the intraoperative donor disc attachment assessment with spectral-domain optical coherence tomography in case of Descemet stripping automated endothelial keratoplasty (DSAEK surgery combined with corneal incisions. The effectiveness of the performed corneal stab incisions was visualized directly by OCT scan analysis. OCT assisted DSAEK allows the assessment of the accuracy of the Descemet stripping and donor disc attachment.

Electron beam instrumentation techniques using coherent radiation

International Nuclear Information System (INIS)

Wang, D.X.

1997-01-01

Much progress has been made on coherent radiation research since coherent synchrotron radiation was first observed in 1989. The use of coherent radiation as a bunch length diagnostic tool has been studied by several groups. In this paper, brief introductions to coherent radiation and far-infrared measurement are given, the progress and status of their beam diagnostic application are reviewed, different techniques are described, and their advantages and limitations are discussed

Autofluorescence and spectral-domain optical coherence tomography of optic disk melanocytoma

Directory of Open Access Journals (Sweden)

Ricardo Luz Leitão Guerra

2014-12-01

Full Text Available The authors report fundus autofluorescence (FAF and spectral-domain optical coherence tomography (OCT findings of two consecutive patients who presented with optic disk melanocytoma (ODM. A retrospective study was performed by reviewing medical records and ophthalmic imaging examinations. Optical coherence tomography findings were sloped and brightly reflective anterior tumor surface, adjacent retinal desorganization and abrupt posterior optical shadowing. Vitreous seeds were found in one patient. Fundus autofluorescence revealed outstanding hypoautofluorescence at the tumor area and isoautofluorescence at the remaining retina. Optical coherence tomography findings of the reported cases are consistent with those reported in the reviewed literature. Fundus autofluorescence has been used in the assessment of choroidal melanocytic tumors, but not yet in melanocytomas. We assume that this is the first report of these findings and believe that when its pattern has become clearly defined, fundus autofluorescence will be a useful tool to avoid misdiagnosis in suspicious cases and for follow-up.

Benign familial fleck retina: multimodal imaging including optical coherence tomography angiography

Directory of Open Access Journals (Sweden)

Jose Mauricio Botto de Barros Garcia

Full Text Available ABSTRACT This report presents multimodal imaging of a 27-year-old woman diagnosed with benign familial fleck retina (OMIM 228980, an uncommon disorder. Fundus photographs revealed retinal flecks that affected her post-equatorial retina but spared the macular area. Fundus autofluorescence and infrared imaging demonstrated a symmetrical pattern of yellow-white fleck lesions that affected both eyes. Her full-field electroretinogram and electrooculogram were normal. An optical coherence tomography B-scan was performed for both eyes, revealing increased thickness of the retinal pigmented epithelium leading to multiple small pigmented epithelium detachments. The outer retina remained intact in both eyes. Spectral-domain optical coherence tomography angiography with split-spectrum amplitude decorrelation algorithm and 3 × 3 mm structural en face optical coherence tomography did not show macular lesions. Benign familial fleck retina belongs to a heterogenous group of so-called flecked retina syndromes, and should be considered in patients with yellowish-white retinal lesions without involvement of the macula.

Relaxation Mechanisms, Structure and Properties of Semi-Coherent Interfaces

Directory of Open Access Journals (Sweden)

Shuai Shao

2015-10-01

Full Text Available In this work, using the Cu–Ni (111 semi-coherent interface as a model system, we combine atomistic simulations and defect theory to reveal the relaxation mechanisms, structure, and properties of semi-coherent interfaces. By calculating the generalized stacking fault energy (GSFE profile of the interface, two stable structures and a high-energy structure are located. During the relaxation, the regions that possess the stable structures expand and develop into coherent regions; the regions with high-energy structure shrink into the intersection of misfit dislocations (nodes. This process reduces the interface excess potential energy but increases the core energy of the misfit dislocations and nodes. The core width is dependent on the GSFE of the interface. The high-energy structure relaxes by relative rotation and dilatation between the crystals. The relative rotation is responsible for the spiral pattern at nodes. The relative dilatation is responsible for the creation of free volume at nodes, which facilitates the nodes’ structural transformation. Several node structures have been observed and analyzed. The various structures have significant impact on the plastic deformation in terms of lattice dislocation nucleation, as well as the point defect formation energies.

Structure Transformation and Coherent Interface in Large Lattice-Mismatched Nanoscale Multilayers

Directory of Open Access Journals (Sweden)

J. Y. Xie

2013-01-01

Full Text Available Nanoscale Al/W multilayers were fabricated by DC magnetron sputtering and characterized by transmission electron microscopy and high-resolution electron microscopy. Despite the large lattice mismatch and significantly different lattice structures between Al and W, a structural transition from face-centered cubic to body-centered cubic in Al layers was observed when the individual layer thickness was reduced from 5 nm to 1 nm, forming coherent Al/W interfaces. For potential mechanisms underlying the observed structure transition and forming of coherent interfaces, it was suggested that the reduction of interfacial energy and high stresses induced by large lattice-mismatch play a crucial role.

Some remarks on quantum coherence theory

International Nuclear Information System (INIS)

Burzynski, A.

1982-01-01

This paper is devoted to the basic topics connected with coherence in quantum mechanics and quantum theory of radiation. In particular the formalism of the normal ordered coherence functions in cases of one and many degrees of freedom is described in detail. A few examples illustrate the analysis of the coherence properties of the various quantum states of the field of radiation. (author)

Optical Coherence Tomography

DEFF Research Database (Denmark)

Mogensen, Mette; Themstrup, Lotte; Banzhaf, Christina

2014-01-01

Optical coherence tomography (OCT) has developed rapidly since its first realisation in medicine and is currently an emerging technology in the diagnosis of skin disease. OCT is an interferometric technique that detects reflected and backscattered light from tissue and is often described as the o......Optical coherence tomography (OCT) has developed rapidly since its first realisation in medicine and is currently an emerging technology in the diagnosis of skin disease. OCT is an interferometric technique that detects reflected and backscattered light from tissue and is often described...

Coherence of light. 2. ed.

International Nuclear Information System (INIS)

Perina, J.

1985-01-01

This book puts the theory of coherence of light on a rigorous mathematical footing. It deals with the classical and quantum theories and with their inter-relationships, including many results from the author's own research. Particular attention is paid to the detection of optical fields, using the correlation functions, photocount statistics and coherent state. Radiometry with light fields of arbitrary states of coherence is discussed and the coherent state methods are demonstrated by photon statistics of radiation in random and nonlinear media, using the Heisenberg-Langevin and Fokker-Planck approaches to the interaction of radiation with matter. Many experimental and theoretical results are compared. A full list of references to theoretical and experimental literature is provided. The book is intended for researchers and postgraduate students in the fields of quantum optics, quantum electronics, statistical optics, nonlinear optics, optical communication and optoelectronics. (Auth.)

Perturbative coherence in field theory

International Nuclear Information System (INIS)

Aldrovandi, R.; Kraenkel, R.A.

1987-01-01

A general condition for coherent quantization by perturbative methods is given, because the basic field equations of a fild theory are not always derivable from a Lagrangian. It's seen that non-lagrangian models way have well defined vertices, provided they satisfy what they call the 'coherence condition', which is less stringent than the condition for the existence of a Lagrangian. They note that Lagrangian theories are perturbatively coherent, in the sense that they have well defined vertices, and that they satisfy automatically that condition. (G.D.F.) [pt

Models of coherent exciton condensation

International Nuclear Information System (INIS)

Littlewood, P B; Eastham, P R; Keeling, J M J; Marchetti, F M; Simons, B D; Szymanska, M H

2004-01-01

That excitons in solids might condense into a phase-coherent ground state was proposed about 40 years ago, and has been attracting experimental and theoretical attention ever since. Although experimental confirmation has been hard to come by, the concepts released by this phenomenon have been widely influential. This tutorial review discusses general aspects of the theory of exciton and polariton condensates, focusing on the reasons for coherence in the ground state wavefunction, the BCS to Bose crossover(s) for excitons and for polaritons, and the relationship of the coherent condensates to standard lasers

Models of coherent exciton condensation

Energy Technology Data Exchange (ETDEWEB)

Littlewood, P B [Theory of Condensed Matter, Cavendish Laboratory, Cambridge CB3 0HE (United Kingdom); Eastham, P R [Theory of Condensed Matter, Cavendish Laboratory, Cambridge CB3 0HE (United Kingdom); Keeling, J M J [Theory of Condensed Matter, Cavendish Laboratory, Cambridge CB3 0HE (United Kingdom); Marchetti, F M [Theory of Condensed Matter, Cavendish Laboratory, Cambridge CB3 0HE (United Kingdom); Simons, B D [Theory of Condensed Matter, Cavendish Laboratory, Cambridge CB3 0HE (United Kingdom); Szymanska, M H [Theory of Condensed Matter, Cavendish Laboratory, Cambridge CB3 0HE (United Kingdom)

2004-09-08

That excitons in solids might condense into a phase-coherent ground state was proposed about 40 years ago, and has been attracting experimental and theoretical attention ever since. Although experimental confirmation has been hard to come by, the concepts released by this phenomenon have been widely influential. This tutorial review discusses general aspects of the theory of exciton and polariton condensates, focusing on the reasons for coherence in the ground state wavefunction, the BCS to Bose crossover(s) for excitons and for polaritons, and the relationship of the coherent condensates to standard lasers.

Optimally cloned binary coherent states

Science.gov (United States)

Müller, C. R.; Leuchs, G.; Marquardt, Ch.; Andersen, U. L.

2017-10-01

Binary coherent state alphabets can be represented in a two-dimensional Hilbert space. We capitalize this formal connection between the otherwise distinct domains of qubits and continuous variable states to map binary phase-shift keyed coherent states onto the Bloch sphere and to derive their quantum-optimal clones. We analyze the Wigner function and the cumulants of the clones, and we conclude that optimal cloning of binary coherent states requires a nonlinearity above second order. We propose several practical and near-optimal cloning schemes and compare their cloning fidelity to the optimal cloner.

High resolution feature extraction from optical coherence tomography acquired internal fingerprint

CSIR Research Space (South Africa)

Khutlang, Rethabile

2016-05-01

Full Text Available coherence tomography (OCT) can be used to scan the internal skin features, up to the depth of the papillary layer. OCT is contactless and scans in three dimensions. The papillary contour represents an internal fingerprint, which does not suffer external skin...

Interference due to coherence swapping

Indian Academy of Sciences (India)

particle is, its interaction with the beam splitter does not reveal this information .... If one shines a strong linearly polarised monochromatic laser beam, or a quasi .... to be a hindrance to coherence, can be suitably designed to create coherence.

Coherent states and covariant semi-spectral measures

International Nuclear Information System (INIS)

Scutaru, H.

1976-01-01

The close connection between Mackey's theory of imprimitivity systems and the so called generalized coherent states introduced by Perelomov is established. Coherent states give a covariant description of the ''localization'' of a quantum system in the phase space in a similar way as the imprimitivity systems give a covariant description of the localization of a quantum system in the configuration space. The observation that for any system of coherent states one can define a covariant semi-spectral measure made possible a rigurous formulation of this idea. A generalization of the notion of coherent states is given. Covariant semi-spectral measures associated with systems of coherent states are defined and characterized. Necessary and sufficient conditions for a unitary representation of a Lie group to be i) a subrepresentation of an induced one and ii) a representation with coherent states are given (author)

Seasonal distributions of diabatic heating during the First GARP Global Experiment

OpenAIRE

Ying Wei, Ming; Johnson, Donald R.; Townsend, Ronald D.

2011-01-01

The seasonal and annual global distributions of diabatic heating during the First GARP Global Experiment (FGGE) are estimated using the isentropic mass continuity equation. The data used are from the FGGE Level IIIa analyses generated by the United States National Meteorological Center. Spatially and temporally coherent diabatic heating distributions are obtained from the isentropic planetary scale mass circulation that is forced by large-scale heat sources and sinks. The diabatic heating in...

Geometry of spin coherent states

Science.gov (United States)

Chryssomalakos, C.; Guzmán-González, E.; Serrano-Ensástiga, E.

2018-04-01

Spin states of maximal projection along some direction in space are called (spin) coherent, and are, in many respects, the ‘most classical’ available. For any spin s, the spin coherent states form a 2-sphere in the projective Hilbert space \

Experimental studies on coherent synchrotron radiation at an emittance exchange beam line

Directory of Open Access Journals (Sweden)

J. C. T. Thangaraj

2012-11-01

Full Text Available One of the goals of the Fermilab A0 photoinjector is to investigate experimentally the transverse to longitudinal emittance exchange (EEX principle. Coherent synchrotron radiation in the emittance exchange line could limit the performance of the emittance exchanger at short bunch lengths. In this paper, we present experimental and simulation studies of the coherent synchrotron radiation (CSR in the emittance exchange line at the A0 photoinjector. We report on time-resolved CSR studies using a skew-quadrupole technique. We also demonstrate the advantages of running the EEX with an energy-chirped beam.

Designing a view for visually representing information coherence in a document set

CSIR Research Space (South Africa)

Engelbrecht, L

2015-11-01

Full Text Available Knowledge Management System (NIKMAS) system to capture and preserve indigenous knowledge, it was discovered that there was sometimes a coherence between the descriptions of the knowledge. It is proposed by the paper that a visual representation...

Constructing “petal” modes from the coherent superposition of Laguerre-Gaussian modes

CSIR Research Space (South Africa)

Naidoo, Darryl

2011-01-01

Full Text Available An experimental approach in generating Petal-like transverse modes, which are similar to what is seen in porro-prism resonators, has been successfully demonstrated. We hypothesize that the petal-like structures are generated from a coherent...

Coherent light microscopy

CERN Document Server

Ferraro, Pietro; Zalevsky, Zeev

2011-01-01

This book deals with the latest achievements in the field of optical coherent microscopy. While many other books exist on microscopy and imaging, this book provides a unique resource dedicated solely to this subject. Similarly, many books describe applications of holography, interferometry and speckle to metrology but do not focus on their use for microscopy. The coherent light microscopy reference provided here does not focus on the experimental mechanics of such techniques but instead is meant to provide a users manual to illustrate the strengths and capabilities of developing techniques. Th

Entropy coherent and entropy convex measures of risk

NARCIS (Netherlands)

Laeven, R.J.A.; Stadje, M.

2013-01-01

We introduce two subclasses of convex measures of risk, referred to as entropy coherent and entropy convex measures of risk. Entropy coherent and entropy convex measures of risk are special cases of φ-coherent and φ-convex measures of risk. Contrary to the classical use of coherent and convex

Ultra-wide-band accumulation of coherent undulator synchrotron radiation in a resonating cavity

Directory of Open Access Journals (Sweden)

Y. H. Seo

2011-06-01

Full Text Available Cavity accumulation of coherent undulator synchrotron radiation emitted by a train of periodic electron bunches is investigated. Phase-matching conditions for accumulation of radiation emitted by successive bunches are analyzed and numerically confirmed. While the coherent emission of a single bunch is optimal at grazing resonance, the accumulated radiation targeted at the upper resonant frequency of the waveguide mode is found to have much broader bandwidth and higher efficiency as the resonance steps away from the grazing condition. Numerical results confirm that stimulated superradiance is responsible for the accumulated radiation.

Optical coherence tomography findings of quinine poisoning

Directory of Open Access Journals (Sweden)

John Christoforidis

2011-01-01

Full Text Available John Christoforidis, Robert Ricketts, Theodore Loizos, Susie ChangThe Ohio State University College of Medicine, Columbus, OH, USAPurpose: To report a case of acute quinine poisoning, document acute and chronic macular changes with optical coherence tomography imaging and fluorescein angiography (FA, and to review the literature on ocular toxicity of quinine.Methods: A 32-year-old white female presented to our Emergency Department after ingesting over 7.5 g of quinine. She underwent a complete ophthalmologic examination, fluorescein angiography, Stratus time-domain optical coherence tomography (OCT, and electroretinography at 72 hours and 15 months postingestion. Stratus time-domain and Cirrus spectral-domain OCT, fundus autofluorescence, and FA were obtained at 28 months postingestion.Results: Fluorescein angiography at 72 hours postingestion revealed normal filling times and vasculature. OCT showed marked thickening of the inner retina bilaterally. At 15 and 28 months follow-up, fundus photography and fluorescein angiography demonstrated optic nerve pallor, severely attenuated retinal vessels while OCT showed inner retinal atrophy. Fundus autofluorescence did not reveal any retinal pigmentary abnormalities.Conclusions: Quinine toxicity as seen by OCT reveals increased thickness with inner retinal hyperreflectivity acutely with development of significant retinal atrophy in the long-term. Fundus autofluorescence reveals an intact retinal pigment epithelial layer at 28 months. These findings suggest that quinine poisoning may produce a direct toxic effect on the inner retina in the acute phase resulting in long-term retinal atrophy.Keywords: retinal, optical coherence tomography, quinine toxicity 

Coherent quantum cascade laser micro-stripe arrays

Directory of Open Access Journals (Sweden)

G. M. de Naurois

2011-09-01

Full Text Available We have fabricated InP-based coherent quantum cascade laser micro-stripe arrays. Phase-locking is provided by evanescent coupling between adjacent stripes. Stripes are buried into semi-insulating iron doped InP. Lasing at room temperature is obtained at 8.4μm for stripe arrays comprising up to 16 emitters. Pure supermode emission is demonstrated via farfield measurements and simulations. The farfield pattern shows a dual-lobe emission, corroborating the predicted phase-locked antisymmetric supermode emission.

Sense of coherence: A distinct perspective on financial well-being

Directory of Open Access Journals (Sweden)

Antoni Barnard

2016-11-01

Full Text Available With the ongoing financial challenges being faced in the economic environment, research exploring financial and psychological well-being is of significant value because employees’ socio-economic behaviour affects productivity. Research emphasises mainly the effect of income level on psychological well-being, and its orientation to psychological well-being is narrowly derived from a focus on subjective well-being constructs. This study addresses the research gap by exploring the relationship dynamics between sense of coherence, income level and financial well-being. Secondary data were obtained from a cross-sectional online employee-wellness survey (n=7 185. The sample distribution included 66 per cent females and 34 per cent males from various age groups, with 46 per cent of the sample comprising single-household earners and 54 per cent sharing household income. Analysis of variance was conducted to examine the relationship dynamics between sense of coherence, level of income and financial well-being. Demographic variables that formed part of the survey results were included in the analysis. The relationships between sense of coherence and identified significant income level, financial well-being and demographic effects were further explored in Bonferroni multiple comparisons of means test and cross reference frequency tables that included Pearson’s chi-square and/or Cochran–Armitage trend tests. Detail results indicate that high-income employees exhibit a significantly stronger sense of coherence than low-income employees, and that, despite level of income, financial wellbeing is nevertheless positively related to sense of coherence. Results indicate important implications for managing a financially healthy workforce. Limitations are discussed and recommendations for future research are highlighted.

Laser diode technology for coherent communications

Science.gov (United States)

Channin, D. J.; Palfrey, S. L.; Toda, M.

1989-01-01

The effect of diode laser characteristics on the overall performance capabilities of coherent communication systems is discussed. In particular, attention is given to optical performance issues for diode lasers in coherent systems, measurements of key performance parameters, and optical requirements for coherent single-channel and multichannel communication systems. The discussion also covers limitations imposed by diode laser optical performance on multichannel system capabilities and implications for future developments.

Towards a coherent picture of excitonic coherence in the Fenna–Matthews–Olson complex

International Nuclear Information System (INIS)

Fidler, Andrew F; Caram, Justin R; Hayes, Dugan; Engel, Gregory S

2012-01-01

Observations of long-lived coherence between excited states in several photosynthetic antenna complexes has motivated interest in developing a more detailed understanding of the role of the protein matrix in guiding the underlying dynamics of the system. These experiments suggest that classical rate laws may not provide an adequate description of the energy transfer process and that quantum effects must be taken into account to describe the near unity transfer efficiency in these systems. Recently, it has been shown that coherences between different pairs of excitons dephase at different rates. These details should provide some insight about the underlying electronic structure of the complex and its coupling to the protein bath. Here we show that a simple model can account for the different dephasing rates as well as the most current available experimental evidence of excitonic coherences in the Fenna–Matthews–Olson complex. The differences in dephasing rates can be understood as arising largely from differences in the delocalization and shared character between the underlying electronic states. We also suggest that the anomalously low dephasing rate of the exciton 1–2 coherence is enhanced by non-secular effects. (paper)

Quantum State Engineering Via Coherent-State Superpositions

Science.gov (United States)

Janszky, Jozsef; Adam, P.; Szabo, S.; Domokos, P.

1996-01-01

The quantum interference between the two parts of the optical Schrodinger-cat state makes possible to construct a wide class of quantum states via discrete superpositions of coherent states. Even a small number of coherent states can approximate the given quantum states at a high accuracy when the distance between the coherent states is optimized, e. g. nearly perfect Fock state can be constructed by discrete superpositions of n + 1 coherent states lying in the vicinity of the vacuum state.

Regulating Emotions during Difficult Multiattribute Decision Making: The Role of Pre-Decisional Coherence Shifting.

Directory of Open Access Journals (Sweden)

Stephanie M Carpenter

Full Text Available Almost all real-life decisions entail attribute conflict; every serious choice alternative is better than its competitors on some attribute dimensions but worse on others. In pre-decisional "coherence shifting," the decision maker gradually softens that conflict psychologically to the point where one alternative is seen as dominant over its competitors, or nearly so. Specifically, weaknesses of the eventually chosen alternative come to be perceived as less severe and less important while its strengths seem more desirable and significant. The research described here demonstrates that difficult multiattribute decision problems are aversive and that pre-decisional coherence shifting aids individuals in regulating that emotional discomfort. Across three studies, attribute conflict was confirmed to be aversive (Study 1, and skin conductance responses and ratings of decision difficulty both decreased in participants who coherence shifted (Study 2. Coherence shifting was also diminished among decision makers who were depleted of regulatory resources, known to be required for common emotion regulation mechanisms. Further, coherence shifting was shown to be relatively common among people who reported strong suppression tendencies in everyday emotion regulation (Study 3. Overall, the data suggest that, at least in part, coherence shifting serves as a tool that helps decision makers manage the pre-decisional discomfort generated by attribute conflict. Theoretical and practical implications are discussed.

Collision-induced coherence

International Nuclear Information System (INIS)

Bloembergen, N.

1985-01-01

Collision-induced coherence is based on the elimination of phase correlations between coherent Feynman-type pathways which happen to interfere destructively in the absence of damping for certain nonlinear processes. One consequence is the appearance of the extra resonances in four-wave light mixing experiments, for which the intensity increases with increasing buffer gas pressure. These resonances may occur between a pair of initially unpopulated excited states, or between a pair of initially equally populated ground states. The pair of levels may be Zeeman substrates which became degenerate in zero magnetic field. The resulting collision-enhanced Hanle resonances can lead to very sharp variations in the four-wave light mixing signal as the external magnetic field passes through zero. The theoretical description in terms of a coherence grating between Zeeman substrates is equivalent to a description in terms of a spin polarization grating obtained by collision-enhanced transverse optical pumping. The axis of quantization in the former case is taken perpendicular to the direction of the light beams; in the latter case is taken parallel to this direction

Evidence on a link between the intensity of Schumann resonance and global surface temperature

Directory of Open Access Journals (Sweden)

M. Sekiguchi

2006-08-01

Full Text Available A correlation is investigated between the intensity of the global electromagnetic oscillations (Schumann resonance with the planetary surface temperature. The electromagnetic signal was monitored at Moshiri (Japan, and temperature data were taken from surface meteorological observations. The series covers the period from November 1998 to May 2002. The Schumann resonance intensity is found to vary coherently with the global ground temperature in the latitude interval from 45° S to 45° N: the relevant cross-correlation coefficient reaches the value of 0.9. It slightly increases when the high-latitude temperature is incorporated. Correspondence among the data decreases when we reduce the latitude interval, which indicates the important role of the middle-latitude lightning in the Schumann resonance oscillations. We apply the principal component (or singular spectral analysis to the electromagnetic and temperature records to extract annual, semiannual, and interannual variations. The principal component analysis (PCA clarifies the links between electromagnetic records and meteorological data.

Depression and a sense of coherence in case of people with anxiety disorders

Directory of Open Access Journals (Sweden)

Krystyna Kurowska

2013-03-01

Full Text Available Introduction: Anxiety and depressive disorders belong to the most prevalent mental diseases. Concomitance of anx‑ iety and depression is very strongly correlated with increased sense of guilt, low self-esteem and hopelessness, which significantly contributes to worse social functioning. The sense of coherence (SOC is a factor which influences the ability to cope with stress and is inseparably related with health. A high level of SOC makes people more self-confi‑ dent and gives them strength to fight with the disease. Aim: Defining the correlation between the level of the sense of coherence and the level of depression in people treated for anxiety disorders, as a determinant having an influence on maintaining the optimal health. Material and methods: The research was carried out among 96 patients treated in the Anxiety and Affective Disorders Ward in Bydgoszcz. The sense of coherence was assessed using Antonovsky’s Orientation to Life Questionnaire (SOC-29 and the level of depression was assessed using the Beck Depression Inventory. Results: People suffering from anxiety disorders have a low level of the sense of coherence and a high level of depression. A strong negative correlation was found between the level of the sense of coherence and the level of depression: with a lower level of the sense of coherence the level of depression grows and vice versa. Conclusions: The obtained results may significantly affect the level of understanding and accepting the people with anxiety disor‑ ders. Determining the level of the sense of coherence and the level of depression may have a significant impact on therapy and may be used as a determinant in prediction and planning of the care for the patient.

Emerging ‘Donor’, Geopolitical Actor: South Africa in the Global Terrain

Directory of Open Access Journals (Sweden)

Elizabeth Sidiropoulos

2012-03-01

Full Text Available Published by Palgrave MacmillanAn active participant in the various global debates and motivated by a desire to address global inequalities and power imbalances in rule-making, South Africa seeks to balance its domestic imperatives with an enlightened developmentally-minded foreign policy where Africa is the priority. Since 1994 South Africa has initiated many activities that may be described as development cooperation. However, with the exception of the African Renaissance Fund (ARF, it has lacked an overarching architecture for its assistance, which has been fragmented among various departments and agencies with very little coherence, bar their focus on Africa. The establishment of the South African Development Partnership Agency (SADPA within the Department of International Relations and Cooperation (DIRCO by the first half of 2012 is poised to address many of these shortcomings, ensuring greater intragovernmental coordination and evaluation. In embarking on this path, South Africa will engage more in the future structure of international development, arguing for a broader definition of development cooperation and a framework that has evolved with input from the South. The fluidity in global development provides an opportunity for South Africa to help bridge the divide between North and South, and encourage policy innovation in the aid debate.

Phase synchronization in inhomogeneous globally coupled map lattices

International Nuclear Information System (INIS)

Ho Mingchung; Hung Yaochen; Jiang, I-M.

2004-01-01

The study of inhomogeneous-coupled chaotic systems has attracted a lot of attention recently. With simple definition of phase, we present the phase-locking behavior in ensembles of globally coupled non-identical maps. The inhomogeneous globally coupled maps consist of logistic map and tent map simultaneously. Average phase synchronization ratios, which are used to characterize the phase coherent phenomena, depend on different coupling coefficients and chaotic parameters. By using interdependence, the relationship between a single unit and the mean field is illustrated. Moreover, we take the effect of external noise and parameter mismatch into consideration and present the results by numerical simulation

Coherent states in quaternionic quantum mechanics

Science.gov (United States)

Adler, Stephen L.; Millard, Andrew C.

1997-05-01

We develop Perelomov's coherent states formalism to include the case of a quaternionic Hilbert space. We find that, because of the closure requirement, an attempted quaternionic generalization of the special nilpotent or Weyl group reduces to the normal complex case. For the case of the compact group SU(2), however, coherent states can be formulated using the quaternionic half-integer spin matrices of Finkelstein, Jauch, and Speiser, giving a nontrivial quaternionic analog of coherent states.

Quantum oscillators in the canonical coherent states

Energy Technology Data Exchange (ETDEWEB)

Rodrigues, R. de Lima [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil); Lima, A.F. de; Ferreira, K. de Araujo [Paraiba Univ., Campina Grande, PB (Brazil). Dept. de Fisica; Vaidya, A.N. [Universidade Federal, Rio de Janeiro, RJ (Brazil). Inst. de Fisica

2001-11-01

The main characteristics of the quantum oscillator coherent states including the two-particle Calogero interaction are investigated. We show that these Calogero coherent states are the eigenstates of the second-order differential annihilation operator which is deduced via Wigner-Heisenberg algebraic technique and correspond exactly to the pure uncharged-bosonic states. They posses the important properties of non-orthogonality and completeness. The minimum uncertainty relation for the Wigner oscillator coherent states are investigated. New sets of even and odd coherent states are point out. (author)

EFFECTS OF LIGHT WAVELENGTHS AND COHERENCE ON BASIDIOSPORES GERMINATION

Directory of Open Access Journals (Sweden)

Natalia Poyedinok

2015-02-01

Full Text Available The effects of light wavelengths and coherence on basidiospore germination of Agaricus bisporus, Flammulina velutipes, Ganoderma applanatum, Ganoderma lucidum, Hericium erinaceus, Lentinus edodes and Pleurotus ostreatus have been studied. Short-term low-intensity irradiation by coherent (laser light wavelength 488.0 nm and 632.8 nm at doses 45 and 230 mJ/cm2 has significantly increased the number of germinated basidiospores. It has established that there are differences in the photosensitivity not only between species but also between strains. Spores irradiation by 514.5 nm light has been either neutral or inhibitory. A comparative analysis of basidiospores sensitivity to laser and LED light has also been conducted. To stimulate germination of basidiospores and growth of monokaryons the most suitable solution was to use red coherent and incoherent light of 632.8 nm and 660,0 nm for A. bisporus, G. applanatum and P. ostreatus, red and blue coherent light of 632.8 nm and 488,0 nm for F. velutipes, and both red and blue laser and LED light G. lucidum and H. erinaceus and for L. edodes. No essential difference of a continuous wave mode and intermittent mode light effect at the same doses and wavelength on spore germination were revealed. Light influence has reduced germination time and formation of aerial mycelium on agar medium as compared to the original value and increased the growth rate of monosporous isolates. Characterization of basidiospores photosensitivity and development of environmentally friendly stimulating methods of their germination is important for creating highly effective technologies of mushrooms selection and cultivation.

Speckles generated by skewed, short-coherence light beams

International Nuclear Information System (INIS)

Brogioli, D; Salerno, D; Ziano, R; Mantegazza, F; Croccolo, F

2011-01-01

When a coherent laser beam impinges on a random sample (e.g. a colloidal suspension), the scattered light exhibits characteristic speckles. If the temporal coherence of the light source is too short, then the speckles disappear, along with the possibility of performing homodyne or heterodyne scattering detection or photon correlation spectroscopy. Here we investigate the scattering of a so-called ‘skewed coherence beam’, i.e. a short-coherence beam modified such that the field is coherent within slabs that are skewed with respect to the wave fronts. We show that such a beam generates speckles and can be used for heterodyne scattering detection, despite its short temporal coherence. Moreover, we show that the heterodyne signal is not affected by multiple scattering. We suggest that the phenomenon presented here can be used as a means of carrying out heterodyne scattering measurement with any short-coherence radiation, including x-rays. (paper)

From conceptual pluralism to practical agreement on policy: global responsibility for global health.

Science.gov (United States)

Ruger, Jennifer Prah; Hammonds, Rachel; Ooms, Gorik; Barry, Donna; Chapman, Audrey; Van Damme, Wim

2015-10-28

conceptual level into policies and practice that advance global health. The issues of shared responsibility and mutual accountability feature widely in the post-2015 discussions and need to be addressed in a coherent manner. Our article argues why and how a Global Fund for Health effectuates this, thus advancing global responsibility for global health.

Coherent and non-coherent processing of multiband radar sensor data

Directory of Open Access Journals (Sweden)

S. Tejero

2006-01-01

Full Text Available Increasing resolution is an attractive goal for all types of radar sensor applications. Obtaining high radar resolution is strongly related to the signal bandwidth which can be used. The currently available frequency bands however, restrict the available bandwidth and consequently the achievable range resolution. As nowadays more sensors become available e.g. on automotive platforms, methods of combining sensor information stemming from sensors operating in different and not necessarily overlapping frequency bands are of concern. It will be shown that it is possible to derive benefit from perceiving the same radar scenery with two or more sensors in distinct frequency bands. Beyond ordinary sensor fusion methods, radar information can be combined more effectively if one compensates for the lack of mutual coherence, thus taking advantage of phase information. At high frequencies, complex scatterers can be approximately modeled as a group of single scattering centers with constant delay and slowly varying amplitude, i.e. a set of complex exponentials buried in noise. The eigenanalysis algorithms are well known for their capability to better resolve complex exponentials as compared to the classical spectral analysis methods. These methods exploit the statistical properties of those signals to estimate their frequencies. Here, two main approaches to extend the statistical analysis for the case of data collected at two different subbands are presented. One method relies on the use of the band gap information (and therefore, coherent data collection is needed and achieves an increased resolution capability compared with the single-band case. On the other hand, the second approach does not use the band gap information and represents a robust way to process radar data collected with incoherent sensors. Combining the information obtained with these two approaches a robust estimator of the target locations with increased resolution can be built.

Globalization

Directory of Open Access Journals (Sweden)

Tulio Rosembuj

2006-12-01

Full Text Available There is no singular globalization, nor is the result of an individual agent. We could start by saying that global action has different angles and subjects who perform it are different, as well as its objectives. The global is an invisible invasion of materials and immediate effects.

Coherent states for polynomial su(2) algebra

International Nuclear Information System (INIS)

Sadiq, Muhammad; Inomata, Akira

2007-01-01

A class of generalized coherent states is constructed for a polynomial su(2) algebra in a group-free manner. As a special case, the coherent states for the cubic su(2) algebra are discussed. The states so constructed reduce to the usual SU(2) coherent states in the linear limit

Common volume coherent and incoherent scatter radar observations of mid-latitude sporadic E-layers and QP echoes

Directory of Open Access Journals (Sweden)

D. L. Hysell

2004-09-01

Full Text Available Common-volume observations of sporadic E-layers made on 14-15 June 2002 with the Arecibo incoherent scatter radar and a 30MHz coherent scatter radar imager located on St. Croix are described. Operating in dual-beam mode, the Arecibo radar detected a slowly descending sporadic E-layer accompanied by a series of dense E-region plasma clouds at a time when the coherent scatter radar was detecting quasi-periodic (QP echoes. Using coherent radar imaging, we collocate the sources of the coherent scatter with the plasma clouds observed by Arecibo. In addition to patchy, polarized scattering regions drifting through the radar illuminated volume, which have been observed in previous imaging experiments, the 30MHz radar also detected large-scale electrostatic waves in the E-region over Puerto Rico, with a wavelength of about 30km and a period of about 10min, propagating to the southwest. Both the intensity and the Doppler shifts of the coherent echoes were modulated by the wave.

Anatomy of a digital coherent receiver

DEFF Research Database (Denmark)

Borkowski, Robert; Zibar, Darko; Tafur Monroy, Idelfonso

2014-01-01

, orthonormaliation, chromatic dispersion compensation/nonlinear compensation, resampling a nd timing recovery, polarization demultiplexing and equalization, frequency and phase recovery, digital demodulation. We also describe novel subsystems of a digital coherent receiver: modulation format recognition......Digital coherent receivers have gained significant attention in the last decade. The reason for this is that coherent detection, along with digital signal processing (DSP) allows for substantial increase of the channel capacity by employing advanced detection techniques. In this paper, we first...

Modeling coherent errors in quantum error correction

Science.gov (United States)

Greenbaum, Daniel; Dutton, Zachary

2018-01-01

Analysis of quantum error correcting codes is typically done using a stochastic, Pauli channel error model for describing the noise on physical qubits. However, it was recently found that coherent errors (systematic rotations) on physical data qubits result in both physical and logical error rates that differ significantly from those predicted by a Pauli model. Here we examine the accuracy of the Pauli approximation for noise containing coherent errors (characterized by a rotation angle ɛ) under the repetition code. We derive an analytic expression for the logical error channel as a function of arbitrary code distance d and concatenation level n, in the small error limit. We find that coherent physical errors result in logical errors that are partially coherent and therefore non-Pauli. However, the coherent part of the logical error is negligible at fewer than {ε }-({dn-1)} error correction cycles when the decoder is optimized for independent Pauli errors, thus providing a regime of validity for the Pauli approximation. Above this number of correction cycles, the persistent coherent logical error will cause logical failure more quickly than the Pauli model would predict, and this may need to be combated with coherent suppression methods at the physical level or larger codes.

Coherent imaging at FLASH

International Nuclear Information System (INIS)

Chapman, H N; Bajt, S; Duesterer, S; Treusch, R; Barty, A; Benner, W H; Bogan, M J; Frank, M; Hau-Riege, S P; Woods, B W; Boutet, S; Cavalleri, A; Hajdu, J; Iwan, B; Seibert, M M; Timneanu, N; Marchesini, S; Sakdinawat, A; Sokolowski-Tinten, K

2009-01-01

We have carried out high-resolution single-pulse coherent diffractive imaging at the FLASH free-electron laser. The intense focused FEL pulse gives a high-resolution low-noise coherent diffraction pattern of an object before that object turns into a plasma and explodes. In particular we are developing imaging of biological specimens beyond conventional radiation damage resolution limits, developing imaging of ultrafast processes, and testing methods to characterize and perform single-particle imaging.

Alzheimer's disease: relationship between cognitive aspects and power and coherence EEG measures

Directory of Open Access Journals (Sweden)

Lineu C. Fonseca

2011-12-01

Full Text Available OBJECTIVE: To evaluate the relationship between specific cognitive aspects and quantitative EEG measures, in patients with mild or moderate Alzheimer's disease (AD. METHOD: Thirty-eight AD patients and 31 controls were assessed by CERAD neuropsychological battery (Consortium to Establish a Registry for AD and the electroencephalogram (EEG. The absolute power and coherences EEG measures were calculated at rest. The correlations between the cognitive variables and the EEG were evaluated. RESULTS: In the AD group there were significant correlations between different coherence EEG measures and Mini-Mental State Examination, verbal fluency, modified Boston naming, word list memory with repetition, word list recall and recognition, and constructional praxis (p<0.01. These correlations were all negative for the delta and theta bands and positive for alpha and beta. There were no correlations between cognitive aspects and absolute EEG power. CONCLUSION: The coherence EEG measures reflect different forms in the relationship between regions related to various cognitive dysfunctions.

Coherent control of photoelectron wavepacket angular interferograms

International Nuclear Information System (INIS)

Hockett, P; Wollenhaupt, M; Baumert, T

2015-01-01

Coherent control over photoelectron wavepackets, via the use of polarization-shaped laser pulses, can be understood as a time and polarization-multiplexed process, where the final (time-integrated) observable coherently samples all instantaneous states of the light–matter interaction. In this work, we investigate this multiplexing via computation of the observable photoelectron angular interferograms resulting from multi-photon atomic ionization with polarization-shaped laser pulses. We consider the polarization sensitivity of both the instantaneous and cumulative continuum wavefunction; the nature of the coherent control over the resultant photoelectron interferogram is thus explored in detail. Based on this understanding, the use of coherent control with polarization-shaped pulses as a methodology for a highly multiplexed coherent quantum metrology is also investigated, and defined in terms of the information content of the observable. (paper)

Coherent control of photoelectron wavepacket angular interferograms

Science.gov (United States)

Hockett, P.; Wollenhaupt, M.; Baumert, T.

2015-11-01

Coherent control over photoelectron wavepackets, via the use of polarization-shaped laser pulses, can be understood as a time and polarization-multiplexed process, where the final (time-integrated) observable coherently samples all instantaneous states of the light-matter interaction. In this work, we investigate this multiplexing via computation of the observable photoelectron angular interferograms resulting from multi-photon atomic ionization with polarization-shaped laser pulses. We consider the polarization sensitivity of both the instantaneous and cumulative continuum wavefunction; the nature of the coherent control over the resultant photoelectron interferogram is thus explored in detail. Based on this understanding, the use of coherent control with polarization-shaped pulses as a methodology for a highly multiplexed coherent quantum metrology is also investigated, and defined in terms of the information content of the observable.

Polarization Sensitive Coherent Raman Measurements of DCVJ

Science.gov (United States)

Anderson, Josiah; Cooper, Nathan; Lawhead, Carlos; Shiver, Tegan; Ujj, Laszlo

2014-03-01

Coherent Raman spectroscopy which recently developed into coherent Raman microscopy has been used to produce label free imaging of thin layers of material and find the spatial distributions of certain chemicals within samples, e.g. cancer cells.(1) Not all aspects of coherent scattering have been used for imaging. Among those for example are special polarization sensitive measurements. Therefore we have investigated the properties of polarization sensitive CARS spectra of a highly fluorescent molecule, DCVJ.(2) Spectra has been recorded by using parallel polarized and perpendicular polarized excitations. A special polarization arrangement was developed to suppress the non-resonant background scattering from the sample. These results can be used to improve the imaging properties of a coherent Raman microscope in the future. This is the first time coherent Raman polarization sensitive measurements have been used to characterize the vibrational modes of DCVJ. 1: K. I. Gutkowski, et al., ``Fluorescence of dicyanovinyl julolidine in a room temperature ionic liquid '' Chemical Physics Letters 426 (2006) 329 - 333 2: Fouad El-Diasty, ``Coherent anti-Stokes Raman scattering: Spectroscopy and microscopy'' Vibrational Spectroscopy 55 (2011) 1-37

A highly unscientific guide to civil-military coherence

DEFF Research Database (Denmark)

Zartsdahl, Peter Horne

2017-01-01

Coordinating external instruments is easy. In this EU-CIVCAP newsletter editorial, we provide a highly unscientific guide to succesful civil-military coherence. A User's Guide to Coherence; and extensive collection of buzzwords.......Coordinating external instruments is easy. In this EU-CIVCAP newsletter editorial, we provide a highly unscientific guide to succesful civil-military coherence. A User's Guide to Coherence; and extensive collection of buzzwords....

Coherent matter wave optics on an atom chip

DEFF Research Database (Denmark)

Krüger, Peter; Hofferberth, S.; Schumm, Thorsten

2006-01-01

Coherent manipulation of matter waves in microscopic trapping potentials facilitates both fundamental and technological applications. Here we focus on experiments with a microscopic integrated interferometer that demonstrate coherent operation on an atom chip.......Coherent manipulation of matter waves in microscopic trapping potentials facilitates both fundamental and technological applications. Here we focus on experiments with a microscopic integrated interferometer that demonstrate coherent operation on an atom chip....

Quantifying Neural Oscillatory Synchronization: A Comparison between Spectral Coherence and Phase-Locking Value Approaches.

Directory of Open Access Journals (Sweden)

Eric Lowet

Full Text Available Synchronization or phase-locking between oscillating neuronal groups is considered to be important for coordination of information among cortical networks. Spectral coherence is a commonly used approach to quantify phase locking between neural signals. We systematically explored the validity of spectral coherence measures for quantifying synchronization among neural oscillators. To that aim, we simulated coupled oscillatory signals that exhibited synchronization dynamics using an abstract phase-oscillator model as well as interacting gamma-generating spiking neural networks. We found that, within a large parameter range, the spectral coherence measure deviated substantially from the expected phase-locking. Moreover, spectral coherence did not converge to the expected value with increasing signal-to-noise ratio. We found that spectral coherence particularly failed when oscillators were in the partially (intermittent synchronized state, which we expect to be the most likely state for neural synchronization. The failure was due to the fast frequency and amplitude changes induced by synchronization forces. We then investigated whether spectral coherence reflected the information flow among networks measured by transfer entropy (TE of spike trains. We found that spectral coherence failed to robustly reflect changes in synchrony-mediated information flow between neural networks in many instances. As an alternative approach we explored a phase-locking value (PLV method based on the reconstruction of the instantaneous phase. As one approach for reconstructing instantaneous phase, we used the Hilbert Transform (HT preceded by Singular Spectrum Decomposition (SSD of the signal. PLV estimates have broad applicability as they do not rely on stationarity, and, unlike spectral coherence, they enable more accurate estimations of oscillatory synchronization across a wide range of different synchronization regimes, and better tracking of synchronization

Coherent Lagrangian swirls among submesoscale motions.

Science.gov (United States)

Beron-Vera, F J; Hadjighasem, A; Xia, Q; Olascoaga, M J; Haller, G

2018-03-05

The emergence of coherent Lagrangian swirls (CLSs) among submesoscale motions in the ocean is illustrated. This is done by applying recent nonlinear dynamics tools for Lagrangian coherence detection on a surface flow realization produced by a data-assimilative submesoscale-permitting ocean general circulation model simulation of the Gulf of Mexico. Both mesoscale and submesoscale CLSs are extracted. These extractions prove the relevance of coherent Lagrangian eddies detected in satellite-altimetry-based geostrophic flow data for the arguably more realistic ageostrophic multiscale flow.

Sense of coherence as a predictor of physical and psychosocial health among cardiac patients

Directory of Open Access Journals (Sweden)

Janusz Kocjan

2015-06-01

Summary   INTRODUCTION: According to salutogenic concept, a strong sense of coherence is associated with physical and psychological health. Global life orientation is a measure of an individual’s ability to balance needs and resources of the body in confrontation with stress. AIM OF THE STUDY: The aim of the present study was to assess relationship between sense of coherence (SOC with health-related quality of life (HRQoL, especially with physical (PC and mental (MC component of health in patients undergoing cardiac treatment. MATERIAL AND METHODS: 144 patients in age of 40-84 (mean age: 63,35 ± 10,71 years were examined. The following scale were used: SOC-29 (Sense of Coherence and SF-36 (Short Form Health Survey. Statistical analyses included perform descriptive statistics, calculate correlation between variables and comparision in groups. Levels of p<0,05 were accepted as being statistically significant values. RESULTS: The median score for SOC and its individuals components were as follows: SOC: 121,50; sense of  comprehensibility: 46,00; sense of meaningfulness: 40,00; sense of manageability: 39,00. Correlation between SOC and all components with MC were noted (0,20Coherence has an impact both for MC as well as PC. Strong SOC is associated with better HRQoL. KEY WORDS: Sense of coherence, SOC-29,  health-related quality of life, cardiac patients.

Managing coherence via put/get windows

Science.gov (United States)

Blumrich, Matthias A [Ridgefield, CT; Chen, Dong [Croton on Hudson, NY; Coteus, Paul W [Yorktown Heights, NY; Gara, Alan G [Mount Kisco, NY; Giampapa, Mark E [Irvington, NY; Heidelberger, Philip [Cortlandt Manor, NY; Hoenicke, Dirk [Ossining, NY; Ohmacht, Martin [Yorktown Heights, NY

2011-01-11

A method and apparatus for managing coherence between two processors of a two processor node of a multi-processor computer system. Generally the present invention relates to a software algorithm that simplifies and significantly speeds the management of cache coherence in a message passing parallel computer, and to hardware apparatus that assists this cache coherence algorithm. The software algorithm uses the opening and closing of put/get windows to coordinate the activated required to achieve cache coherence. The hardware apparatus may be an extension to the hardware address decode, that creates, in the physical memory address space of the node, an area of virtual memory that (a) does not actually exist, and (b) is therefore able to respond instantly to read and write requests from the processing elements.

Coherence Phenomena in Coupled Optical Resonators

Science.gov (United States)

Smith, D. D.; Chang, H.

2004-01-01

We predict a variety of photonic coherence phenomena in passive and active coupled ring resonators. Specifically, the effective dispersive and absorptive steady-state response of coupled resonators is derived, and used to determine the conditions for coupled-resonator-induced transparency and absorption, lasing without gain, and cooperative cavity emission. These effects rely on coherent photon trapping, in direct analogy with coherent population trapping phenomena in atomic systems. We also demonstrate that the coupled-mode equations are formally identical to the two-level atom Schrodinger equation in the rotating-wave approximation, and use this result for the analysis of coupled-resonator photon dynamics. Notably, because these effects are predicted directly from coupled-mode theory, they are not unique to atoms, but rather are fundamental to systems of coherently coupled resonators.

Managing coherence via put/get windows

Science.gov (United States)

Blumrich, Matthias A [Ridgefield, CT; Chen, Dong [Croton on Hudson, NY; Coteus, Paul W [Yorktown Heights, NY; Gara, Alan G [Mount Kisco, NY; Giampapa, Mark E [Irvington, NY; Heidelberger, Philip [Cortlandt Manor, NY; Hoenicke, Dirk [Ossining, NY; Ohmacht, Martin [Yorktown Heights, NY

2012-02-21

A method and apparatus for managing coherence between two processors of a two processor node of a multi-processor computer system. Generally the present invention relates to a software algorithm that simplifies and significantly speeds the management of cache coherence in a message passing parallel computer, and to hardware apparatus that assists this cache coherence algorithm. The software algorithm uses the opening and closing of put/get windows to coordinate the activated required to achieve cache coherence. The hardware apparatus may be an extension to the hardware address decode, that creates, in the physical memory address space of the node, an area of virtual memory that (a) does not actually exist, and (b) is therefore able to respond instantly to read and write requests from the processing elements.

Generating high-brightness and coherent soft x-ray pulses in the water window with a seeded free-electron laser

Directory of Open Access Journals (Sweden)

Kaishang Zhou

2017-01-01

Full Text Available We propose a new scheme to generate high-brightness and temporal coherent soft x-ray radiation in a seeded free-electron laser. The proposed scheme is based on the coherent harmonic generation (CHG and superradiant principles. A CHG scheme is first used to generate a coherent signal at ultrahigh harmonics of the seed. This coherent signal is then amplified by a series of chicane-undulator modules via the fresh bunch and superradiant processes in the following radiator. Using a representative of a realistic set of parameters, three-dimensional simulations have been carried out and the simulations results demonstrated that 10 GW-level ultrashort (∼20  fs coherent radiation pulses in the water window can be achieved by using a 1.6 GeV electron beam based on the proposed technique.

Dynamic coherent backscattering mirror

Energy Technology Data Exchange (ETDEWEB)

Zeylikovich, I.; Xu, M., E-mail: mxu@fairfield.edu [Physics Department, Fairfield University, Fairfield, CT 06824 (United States)

2016-02-15

The phase of multiply scattered light has recently attracted considerable interest. Coherent backscattering is a striking phenomenon of multiple scattered light in which the coherence of light survives multiple scattering in a random medium and is observable in the direction space as an enhancement of the intensity of backscattered light within a cone around the retroreflection direction. Reciprocity also leads to enhancement of backscattering light in the spatial space. The random medium behaves as a reciprocity mirror which robustly converts a diverging incident beam into a converging backscattering one focusing at a conjugate spot in space. Here we first analyze theoretically this coherent backscattering mirror (CBM) phenomenon and then demonstrate the capability of CBM compensating and correcting both static and dynamic phase distortions occurring along the optical path. CBM may offer novel approaches for high speed dynamic phase corrections in optical systems and find applications in sensing and navigation.

Connectives as processing signals : How students benefit in processing narrative and expository texts

NARCIS (Netherlands)

van Silfhout, Gerdineke; Evers-Vermeul, Jacqueline; Sanders, Ted

2015-01-01

Many young readers fail to construct a proper mental text representation, often due to a lack of higher-order skills such as making integrative and inferential links. In an eye-tracking experiment among 141 Dutch eighth graders, we tested whether coherence markers (moreover, after, because) improve

Coherent electron cooling

Energy Technology Data Exchange (ETDEWEB)

Litvinenko,V.

2009-05-04

Cooling intense high-energy hadron beams remains a major challenge in modern accelerator physics. Synchrotron radiation is still too feeble, while the efficiency of two other cooling methods, stochastic and electron, falls rapidly either at high bunch intensities (i.e. stochastic of protons) or at high energies (e-cooling). In this talk a specific scheme of a unique cooling technique, Coherent Electron Cooling, will be discussed. The idea of coherent electron cooling using electron beam instabilities was suggested by Derbenev in the early 1980s, but the scheme presented in this talk, with cooling times under an hour for 7 TeV protons in the LHC, would be possible only with present-day accelerator technology. This talk will discuss the principles and the main limitations of the Coherent Electron Cooling process. The talk will describe the main system components, based on a high-gain free electron laser driven by an energy recovery linac, and will present some numerical examples for ions and protons in RHIC and the LHC and for electron-hadron options for these colliders. BNL plans a demonstration of the idea in the near future.

Retrieval of Sentence Sequences for an Image Stream via Coherence Recurrent Convolutional Networks.

Science.gov (United States)

Park, Cesc Chunseong; Kim, Youngjin; Kim, Gunhee

2018-04-01

We propose an approach for retrieving a sequence of natural sentences for an image stream. Since general users often take a series of pictures on their experiences, much online visual information exists in the form of image streams, for which it would better take into consideration of the whole image stream to produce natural language descriptions. While almost all previous studies have dealt with the relation between a single image and a single natural sentence, our work extends both input and output dimension to a sequence of images and a sequence of sentences. For retrieving a coherent flow of multiple sentences for a photo stream, we propose a multimodal neural architecture called coherence recurrent convolutional network (CRCN), which consists of convolutional neural networks, bidirectional long short-term memory (LSTM) networks, and an entity-based local coherence model. Our approach directly learns from vast user-generated resource of blog posts as text-image parallel training data. We collect more than 22 K unique blog posts with 170 K associated images for the travel topics of NYC, Disneyland , Australia, and Hawaii. We demonstrate that our approach outperforms other state-of-the-art image captioning methods for text sequence generation, using both quantitative measures and user studies via Amazon Mechanical Turk.

Global motion perception is associated with motor function in 2-year-old children.

Science.gov (United States)

Thompson, Benjamin; McKinlay, Christopher J D; Chakraborty, Arijit; Anstice, Nicola S; Jacobs, Robert J; Paudel, Nabin; Yu, Tzu-Ying; Ansell, Judith M; Wouldes, Trecia A; Harding, Jane E

2017-09-29

The dorsal visual processing stream that includes V1, motion sensitive area V5 and the posterior parietal lobe, supports visually guided motor function. Two recent studies have reported associations between global motion perception, a behavioural measure of processing in V5, and motor function in pre-school and school aged children. This indicates a relationship between visual and motor development and also supports the use of global motion perception to assess overall dorsal stream function in studies of human neurodevelopment. We investigated whether associations between vision and motor function were present at 2 years of age, a substantially earlier stage of development. The Bayley III test of Infant and Toddler Development and measures of vision including visual acuity (Cardiff Acuity Cards), stereopsis (Lang stereotest) and global motion perception were attempted in 404 2-year-old children (±4 weeks). Global motion perception (quantified as a motion coherence threshold) was assessed by observing optokinetic nystagmus in response to random dot kinematograms of varying coherence. Linear regression revealed that global motion perception was modestly, but statistically significantly associated with Bayley III composite motor (r 2 =0.06, Pmotor scores (r 2 =0.06, pmotor and fine motor scores, but unaided visual acuity was not statistically significantly associated with any of the motor scores. These results demonstrate that global motion perception and binocular vision are associated with motor function at an early stage of development. Global motion perception can be used as a partial measure of dorsal stream function from early childhood. Copyright © 2017 Elsevier B.V. All rights reserved.

Optical Coherence Tomography of the Aging Kidney.

Science.gov (United States)

Andrews, Peter M; Wang, Hsing-Wen; Guo, Hengchang; Anderson, Erik; Falola, Reuben; Chen, Yu

2016-12-01

The aging kidney exhibits a progressive decline in renal function with characteristic histopathologic changes and is a risk factor for renal transplant. However, the degree to which the kidney exhibits this decline depends on several factors that vary from one individual to the next. Optical coherence tomography is an evolving noninvasive imaging technology that has recently been used to evaluate acute tubular necrosis of living-human donor kidneys before their transplant. With the increasing use of kidneys from older individuals, it is important to determine whether optical coherence tomography also can distinguish the histopathology associated with aging. In this investigation, we used Munich-Wistar rats to evaluate the ability of optical coherence tomography to detect histopathologic changes associated with aging. Optical coherence tomography observations were correlated with renal function and conventional light microscopic evaluation of these same kidneys. With the onset of severe proteinuria at 10 to 12 months of age, optical coherence tomography revealed tubular necrosis/atrophy, interstitial fibrosis, tubular dilation, and glomerulosclerosis. With a further deterioration in kidney function at 16 to 18 months of age (as indicated by rising creatinine levels), optical coherence tomography revealed more extensive interstitial fibrosis and tubular atrophy, increased tubular dilation with cyst formation and more sclerotic glomeruli. The foregoing observations suggest that optical coherence tomography can be used to detect the histopathology of progressive nephropathy associated with aging.

Coherent states in quaternionic quantum mechanics

International Nuclear Information System (INIS)

Adler, S.L.; Millard, A.C.

1997-01-01

We develop Perelomov close-quote s coherent states formalism to include the case of a quaternionic Hilbert space. We find that, because of the closure requirement, an attempted quaternionic generalization of the special nilpotent or Weyl group reduces to the normal complex case. For the case of the compact group SU(2), however, coherent states can be formulated using the quaternionic half-integer spin matrices of Finkelstein, Jauch, and Speiser, giving a nontrivial quaternionic analog of coherent states. copyright 1997 American Institute of Physics

Seamlessly and Coherently Locating Interesting Mirrors on the Web

Directory of Open Access Journals (Sweden)

Neilze Dorta

2003-06-01

Full Text Available Nowadays, the World Wide Web is used mostly as a common medium for information sharing. Therefore, locating an object on this large scale dynamic medium tends to be more and more difficult. Content Distribution Networks, e.g. Akamai, and global naming services, e.g. Globe, do more or less than what is required by most users. In this paper, we are interested in discovering, advertising, and transparently locating interesting mirrors of interest to a group of users. Our solution, AR , is user-centric; it uses cooperation among organizations to discover, publicize and locate coherently new mirrors that are of interest to them. Access transparency is achieved through a naming service that manages the different aliases for the same replica. Consistency guarantees are given to each user that no document delivered would be older than the one viewed before. The system scales geographically due to the epidemic and asynchronous nature of the cooperation protocol. We propose a methodology for creating homogeneous groups with common interests, using collected Web traces, then give a glimpse of the potential benefits made by using AR . It opens a path towards making mirroring ubiquitous, hence fostering a better use of the Internet and its resources. A prototype has been implemented in Java and will be used, in the future, in real-world tests for more accurate and realistic results.

Influence of HeartMath quick coherence technique on ...

African Journals Online (AJOL)

... of high psychophysiological coherence, decreased feelings of sadness and increased feelings of peacefulness. Psychophysiological and emotional state findings are discussed in relation to health and sport psychology, theory and practice. Keywords: Biofeedback, physiological coherence, Quick Coherence Technique, ...

Atom lasers, coherent states, and coherence II. Maximally robust ensembles of pure states

International Nuclear Information System (INIS)

Wiseman, H.M.; Vaccaro, John A.

2002-01-01

As discussed in the preceding paper [Wiseman and Vaccaro, preceding paper, Phys. Rev. A 65, 043605 (2002)], the stationary state of an optical or atom laser far above threshold is a mixture of coherent field states with random phase, or, equivalently, a Poissonian mixture of number states. We are interested in which, if either, of these descriptions of ρ ss as a stationary ensemble of pure states, is more natural. In the preceding paper we concentrated upon the question of whether descriptions such as these are physically realizable (PR). In this paper we investigate another relevant aspect of these ensembles, their robustness. A robust ensemble is one for which the pure states that comprise it survive relatively unchanged for a long time under the system evolution. We determine numerically the most robust ensembles as a function of the parameters in the laser model: the self-energy χ of the bosons in the laser mode, and the excess phase noise ν. We find that these most robust ensembles are PR ensembles, or similar to PR ensembles, for all values of these parameters. In the ideal laser limit (ν=χ=0), the most robust states are coherent states. As the phase noise or phase dispersion is increased through ν or the self-interaction of the bosons χ, respectively, the most robust states become more and more amplitude squeezed. We find scaling laws for these states, and give analytical derivations for them. As the phase diffusion or dispersion becomes so large that the laser output is no longer quantum coherent, the most robust states become so squeezed that they cease to have a well-defined coherent amplitude. That is, the quantum coherence of the laser output is manifest in the most robust PR ensemble being an ensemble of states with a well-defined coherent amplitude. This lends support to our approach of regarding robust PR ensembles as the most natural description of the state of the laser mode. It also has interesting implications for atom lasers in particular

Application of optical coherence tomography angiography for diabetic retinopathy

Directory of Open Access Journals (Sweden)

Qing Liu

2016-04-01

Full Text Available Optical coherence tomography angiography(OCTAis a new emerging technology of the optical coherence tomography(OCTin recent years. It's a noninvasive and fast retinal vascular imaging technology with high resolution, and has been gradually applied to make diagnosis, gives treatment and follow-up for various types of retinal vascular diseases, such as diabetic retinopathy, choroid neovascularization, etc. OCTA has the unique advantages of layered observing the structure and shape of the chorioretinal vascular at different levels, and quantifying the blood flow index of designated scope and the flow area of lesions. However, OCTA requires high solid vision and good cooperation of patients, even has the limitations to observe the retinal scope and retinal vascular barrier function. With overcoming these limitations, it's helpful for us to improve the understanding of retinal vascular diseases, consummate the diagnosis and treatment and observation of retinal vascular diseases.

On Radar Resolution in Coherent Change Detection.

Energy Technology Data Exchange (ETDEWEB)

Bickel, Douglas L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2015-11-01

It is commonly observed that resolution plays a role in coherent change detection. Although this is the case, the relationship of the resolution in coherent change detection is not yet defined . In this document, we present an analytical method of evaluating this relationship using detection theory. Specifically we examine the effect of resolution on receiver operating characteristic curves for coherent change detection.

Representations of coherent states in non-orthogonal bases

International Nuclear Information System (INIS)

Ali, S Twareque; Roknizadeh, R; Tavassoly, M K

2004-01-01

Starting with the canonical coherent states, we demonstrate that all the so-called nonlinear coherent states, used in the physical literature, as well as large classes of other generalized coherent states, can be obtained by changes of bases in the underlying Hilbert space. This observation leads to an interesting duality between pairs of generalized coherent states, bringing into play a Gelfand triple of (rigged) Hilbert spaces. Moreover, it is shown that in each dual pair of families of nonlinear coherent states, at least one family is related to a (generally) non-unitary projective representation of the Weyl-Heisenberg group, which can then be thought of as characterizing the dual pair

The Not-So-Global Blood Oxygen Level-Dependent Signal.

Science.gov (United States)

Billings, Jacob; Keilholz, Shella

2018-04-01

Global signal regression is a controversial processing step for resting-state functional magnetic resonance imaging, partly because the source of the global blood oxygen level-dependent (BOLD) signal remains unclear. On the one hand, nuisance factors such as motion can readily introduce coherent BOLD changes across the whole brain. On the other hand, the global signal has been linked to neural activity and vigilance levels, suggesting that it contains important neurophysiological information and should not be discarded. Any widespread pattern of coordinated activity is likely to contribute appreciably to the global signal. Such patterns may include large-scale quasiperiodic spatiotemporal patterns, known also to be tied to performance on vigilance tasks. This uncertainty surrounding the separability of the global BOLD signal from concurrent neurological processes motivated an examination of the global BOLD signal's spatial distribution. The results clarify that although the global signal collects information from all tissue classes, a diverse subset of the BOLD signal's independent components contribute the most to the global signal. Further, the timing of each network's contribution to the global signal is not consistent across volunteers, confirming the independence of a constituent process that comprises the global signal.

Transition to Coherence in Populations of Coupled Chaotic Oscillators: A Linear Response Approach

International Nuclear Information System (INIS)

Topaj, Dmitri; Kye, Won-Ho; Pikovsky, Arkady

2001-01-01

We consider the collective dynamics in an ensemble of globally coupled chaotic maps. The transition to the coherent state with a macroscopic mean field is analyzed in the framework of the linear response theory. The linear response function for the chaotic system is obtained using the perturbation approach to the Frobenius-Perron operator. The transition point is defined from this function by virtue of the self-excitation condition for the feedback loop. Analytical results for the coupled Bernoulli maps are confirmed by the numerics

Coherence Length and Vibrations of the Coherence Beamline I13 at the Diamond Light Source

International Nuclear Information System (INIS)

Wagner, U.H.; Parson, A.; Rau, C.

2017-01-01

I13 is a 250 m long hard x-ray beamline for imaging and coherent diffraction at the Diamond Light Source. The beamline (6 keV to 35 keV) comprises two independent experimental endstations: one for imaging in direct space using x-ray microscopy and one for imaging in reciprocal space using coherent diffraction based imaging techniques [1]. In particular the coherence experiments pose very high demands on the performance on the beamline instrumentation, requiring extensive testing and optimisation of each component, even during the assembly phase. Various aspects like the quality of optical components, the mechanical design concept, vibrations, drifts, thermal influences and the performance of motion systems are of particular importance. In this paper we study the impact of the front-end slit size (FE slit size), which determines the horizontal source size, onto the coherence length and the detrimental impact of monochromator vibrations using in-situ x-ray metrology in conjunction with fringe visibility measurements and vibration measurements, based on centroid tracking of an x-ray pencil beam with a photon-counting detector. (paper)

Coherence Length and Vibrations of the Coherence Beamline I13 at the Diamond Light Source

Science.gov (United States)

Wagner, U. H.; Parson, A.; Rau, C.

2017-06-01

I13 is a 250 m long hard x-ray beamline for imaging and coherent diffraction at the Diamond Light Source. The beamline (6 keV to 35 keV) comprises two independent experimental endstations: one for imaging in direct space using x-ray microscopy and one for imaging in reciprocal space using coherent diffraction based imaging techniques [1]. In particular the coherence experiments pose very high demands on the performance on the beamline instrumentation, requiring extensive testing and optimisation of each component, even during the assembly phase. Various aspects like the quality of optical components, the mechanical design concept, vibrations, drifts, thermal influences and the performance of motion systems are of particular importance. In this paper we study the impact of the front-end slit size (FE slit size), which determines the horizontal source size, onto the coherence length and the detrimental impact of monochromator vibrations using in-situ x-ray metrology in conjunction with fringe visibility measurements and vibration measurements, based on centroid tracking of an x-ray pencil beam with a photon-counting detector.

Global implications of China's healthcare reform.

Science.gov (United States)

Yan, Fei; Tang, Shenglan; Zhang, Jian

2016-01-01

The ongoing healthcare reform in China has a powerful spillover effect beyond the health sector and the borders of China. A successful completion of the Chinese reform will offer a new model for social justice development, shift the global economy toward sustainability and create a new hub for science and technology in medical and health science. However, reforming the healthcare system in the most populated country is a daunting task. China will not live up to its promise, and all the potentials may end with hype not hope if coherent national strategies are not constructed and state-of-the-art navigation is not achieved with staggering domestic and global challenges. The cost of failure will be immensely high, socioeconomic costs for Chinese and an opportunity cost for the world as a whole. A full appreciation of the global implications of China's healthcare reform is crucial in keeping China receptive toward good practices evidence-approved elsewhere and open minded to fulfill its international obligations. More critically, the appreciation yields constructive engagements from global community toward a joint development and global prosperity. The current report provides a multiple disciplinary assessment on the global implications of the healthcare reform in China. Copyright © 2014 John Wiley & Sons, Ltd.

Coherence for vectorial waves and majorization

OpenAIRE

Luis, Alfredo

2016-01-01

We show that majorization provides a powerful approach to the coherence conveyed by partially polarized transversal electromagnetic waves. Here we present the formalism, provide some examples and compare with standard measures of polarization and coherence of vectorial waves.

Meta-Structures: The Search of Coherence in Collective Behaviours (without Physics

Directory of Open Access Journals (Sweden)

Eliano Pessa

2013-09-01

Full Text Available This contribution shortly outlines and reviews a theoretical and computational approach for a theory of change concerning systems where it is not possible to apply the laws of motion ab initio. The concept of meta-structure relates to the emergence of forms of spatiotemporal coherences in collective behaviours intended as coherent sequences of multiple structures. The essential difference compared with traditional methods is the role of the cognitive design by the observer when identifying multiple mesoscopic variables. The goal is both to study the "change without physics" of the dynamics of change and to design non-catastrophic interventions having the purpose to induce, change, keep or restore collective behaviours by influencing -at the mesoscopic level -and not prescribing explicit rules and changes.

Method to generate a pulse train of few-cycle coherent radiation

Directory of Open Access Journals (Sweden)

Bryant Garcia

2016-09-01

Full Text Available We develop a method to generate a long pulse train of few-cycle coherent radiation by modulating an electron beam with a high power laser. The large energy modulation disperses the beam in a radiating undulator and leads to the production of phase-locked few-cycle coherent radiation pulses. These pulses are produced at a high harmonic of the modulating laser, and are longitudinally separated by the modulating laser wavelength. We discuss an analytical model for this scheme and investigate the temporal and spectral properties of this radiation. This model is compared with numerical simulation results using the unaveraged code Puffin. We examine various harmful effects and how they might be avoided, as well as a possible experimental realization of this scheme.

Mismatch removal via coherent spatial relations

Science.gov (United States)

Chen, Jun; Ma, Jiayi; Yang, Changcai; Tian, Jinwen

2014-07-01

We propose a method for removing mismatches from the given putative point correspondences in image pairs based on "coherent spatial relations." Under the Bayesian framework, we formulate our approach as a maximum likelihood problem and solve a coherent spatial relation between the putative point correspondences using an expectation-maximization (EM) algorithm. Our approach associates each point correspondence with a latent variable indicating it as being either an inlier or an outlier, and alternatively estimates the inlier set and recovers the coherent spatial relation. It can handle not only the case of image pairs with rigid motions but also the case of image pairs with nonrigid motions. To parameterize the coherent spatial relation, we choose two-view geometry and thin-plate spline as models for rigid and nonrigid cases, respectively. The mismatches could be successfully removed via the coherent spatial relations after the EM algorithm converges. The quantitative results on various experimental data demonstrate that our method outperforms many state-of-the-art methods, it is not affected by low initial correct match percentages, and is robust to most geometric transformations including a large viewing angle, image rotation, and affine transformation.

Coherent structures in tokamak plasmas workshop: Proceedings

International Nuclear Information System (INIS)

Koniges, A.E.; Craddock, G.G.

1992-08-01

Coherent structures have the potential to impact a variety of theoretical and experimental aspects of tokamak plasma confinement. This includes the basic processes controlling plasma transport, propagation and efficiency of external mechanisms such as wave heating and the accuracy of plasma diagnostics. While the role of coherent structures in fluid dynamics is better understood, this is a new topic for consideration by plasma physicists. This informal workshop arose out of the need to identify the magnitude of structures in tokamaks and in doing so, to bring together for the first time the surprisingly large number of plasma researchers currently involved in work relating to coherent structures. The primary purpose of the workshop, in addition to the dissemination of information, was to develop formal and informal collaborations, set the stage for future formation of a coherent structures working group or focus area under the heading of the Tokamak Transport Task Force, and to evaluate the need for future workshops on coherent structures. The workshop was concentrated in four basic areas with a keynote talk in each area as well as 10 additional presentations. The issues of discussion in each of these areas was as follows: Theory - Develop a definition of structures and coherent as it applies to plasmas. Experiment - Review current experiments looking for structures in tokamaks, discuss experimental procedures for finding structures, discuss new experiments and techniques. Fluids - Determine how best to utilize the resource of information available from the fluids community both on the theoretical and experimental issues pertaining to coherent structures in plasmas. Computation - Discuss computational aspects of studying coherent structures in plasmas as they relate to both experimental detection and theoretical modeling

Symmetric discrete coherent states for n-qubits

International Nuclear Information System (INIS)

Muñoz, C; Klimov, A B; Sánchez-Soto, L L

2012-01-01

We put forward a method of constructing discrete coherent states for n qubits. After establishing appropriate displacement operators, the coherent states appear as displaced versions of a fiducial vector that is fixed by imposing a number of natural symmetry requirements on its Q-function. Using these coherent states, we establish a partial order in the discrete phase space, which allows us to picture some n-qubit states as apparent distributions. We also analyze correlations in terms of sums of squared Q-functions. This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical devoted to ‘Coherent states: mathematical and physical aspects’. (paper)

Self-Organized Complexity and Coherent Infomax from the Viewpoint of Jaynes’s Probability Theory

Directory of Open Access Journals (Sweden)

William A. Phillips

2012-01-01

Full Text Available This paper discusses concepts of self-organized complexity and the theory of Coherent Infomax in the light of Jaynes’s probability theory. Coherent Infomax, shows, in principle, how adaptively self-organized complexity can be preserved and improved by using probabilistic inference that is context-sensitive. It argues that neural systems do this by combining local reliability with flexible, holistic, context-sensitivity. Jaynes argued that the logic of probabilistic inference shows it to be based upon Bayesian and Maximum Entropy methods or special cases of them. He presented his probability theory as the logic of science; here it is considered as the logic of life. It is concluded that the theory of Coherent Infomax specifies a general objective for probabilistic inference, and that contextual interactions in neural systems perform functions required of the scientist within Jaynes’s theory.

Coherence and entanglement measures based on Rényi relative entropies

International Nuclear Information System (INIS)

Zhu, Huangjun; Hayashi, Masahito; Chen, Lin

2017-01-01

We study systematically resource measures of coherence and entanglement based on Rényi relative entropies, which include the logarithmic robustness of coherence, geometric coherence, and conventional relative entropy of coherence together with their entanglement analogues. First, we show that each Rényi relative entropy of coherence is equal to the corresponding Rényi relative entropy of entanglement for any maximally correlated state. By virtue of this observation, we establish a simple operational connection between entanglement measures and coherence measures based on Rényi relative entropies. We then prove that all these coherence measures, including the logarithmic robustness of coherence, are additive. Accordingly, all these entanglement measures are additive for maximally correlated states. In addition, we derive analytical formulas for Rényi relative entropies of entanglement of maximally correlated states and bipartite pure states, which reproduce a number of classic results on the relative entropy of entanglement and logarithmic robustness of entanglement in a unified framework. Several nontrivial bounds for Rényi relative entropies of coherence (entanglement) are further derived, which improve over results known previously. Moreover, we determine all states whose relative entropy of coherence is equal to the logarithmic robustness of coherence. As an application, we provide an upper bound for the exact coherence distillation rate, which is saturated for pure states. (paper)

Coherent radiation from pulsars

International Nuclear Information System (INIS)

Cox, J.L. Jr.

1979-01-01

Interaction between a relativistic electrom stream and a plasma under conditions believed to exist in pulsar magnetospheres is shown to result in the simultaneous emission of coherent curvature radiation at radio wavelengths and incoherent curvature radiation at X-ray wavelengths from the same spatial volume. It is found that such a stream can propagate through a plasma parallel to a very strong magnetic field only if its length is less than a critical length L/sub asterisk/ic. Charge induced in the plasma by the stream co-moves with the stream and has the same limitation in longitudinal extent. The resultant charge bunching is sufficient to cause the relatively low energy plasma particles to radiate at radio wavelengths coherently while the relatively high energy stream particles radiate at X-ray wavelengths incoherently as the stream-plasma system moves along curved magnetic field lines. The effective number of coherently radiating particles per bunch is estimated to be approx.10 14 --10 15 for a tupical pulsar

Coherent Raman scattering: Applications in imaging and sensing

Science.gov (United States)

Cui, Meng

In this thesis, I discuss the theory, implementation and applications of coherent Raman scattering to imaging and sensing. A time domain interferometric method has been developed to collect high resolution shot-noise-limited Raman spectra over the Raman fingerprint regime and completely remove the electronic background signal in coherent Raman scattering. Compared with other existing coherent Raman microscopy methods, this time domain approach is proved to be simpler and more robust in rejecting background signal. We apply this method to image polymers and biological samples and demonstrate that the same setup can be used to collect two photon fluorescence and self phase modulation signals. A signal to noise ratio analysis is performed to show that this time domain method has a comparable signal to noise ratio to spectral domain methods, which we confirm experimentally. The coherent Raman method is also compared with spontaneous Raman scattering. The conditions under which coherent methods provide signal enhancement are discussed and experiments are performed to compare coherent Raman scattering with spontaneous Raman scattering under typical biological imaging conditions. A critical power, above which coherent Raman scattering is more sensitive than spontaneous Raman scattering, is experimentally determined to be ˜1mW in samples of high molecule concentration with a 75MHz laser system. This finding is contrary to claims that coherent methods provide many orders of magnitude enhancement under comparable conditions. In addition to the far field applications, I also discuss the combination of our time domain coherent Raman method with near field enhancement to explore the possibility of sensing and near field imaging. We report the first direct time-resolved coherent Raman measurement performed on a nanostructured substrate for molecule sensing. The preliminary results demonstrate that sub 20 fs pulses can be used to obtain coherent Raman spectra from a small number

Multiple-Symbol, Partially Coherent Detection of MPSK

Science.gov (United States)

Simon, Marvin K.; Divsalar, Dariush

1994-01-01

Proposed method of reception of multiple-phase-shift-keyed (MPSK) radio signals involves multiple-symbol, partially coherent detection. Instead of attempting to determine phase of transmitted signal during each symbol period as in coherent detection, receiver acquires signal data during multiple-symbol observation interval, then produces maximum-likelihood-sequence estimate of phases transmitted during interval. Combination of coherent-reception and incoherent-reception decision rules are used.

Gaussian cloning of coherent states with known phases

International Nuclear Information System (INIS)

Alexanian, Moorad

2006-01-01

The fidelity for cloning coherent states is improved over that provided by optimal Gaussian and non-Gaussian cloners for the subset of coherent states that are prepared with known phases. Gaussian quantum cloning duplicates all coherent states with an optimal fidelity of 2/3. Non-Gaussian cloners give optimal single-clone fidelity for a symmetric 1-to-2 cloner of 0.6826. Coherent states that have known phases can be cloned with a fidelity of 4/5. The latter is realized by a combination of two beam splitters and a four-wave mixer operated in the nonlinear regime, all of which are realized by interaction Hamiltonians that are quadratic in the photon operators. Therefore, the known Gaussian devices for cloning coherent states are extended when cloning coherent states with known phases by considering a nonbalanced beam splitter at the input side of the amplifier

Construction of classical and non-classical coherent photon states

International Nuclear Information System (INIS)

Honegger, Reinhard; Rieckers, Alfred

2001-01-01

It is well known that the diagonal matrix elements of all-order coherent states for the quantized electromagnetic field have to constitute a Poisson distribution with respect to the photon number. The present work gives first the summary of a constructive scheme, developed previously, which determines in terms of an auxiliary Hilbert space all possible off-diagonal elements for the all-order coherent density operators in Fock space and which identifies all extremal coherent states. In terms of this formalism it is then demonstrated that each pure classical coherent state is a uniformly phase locked (quantum) coherent superposition of number states. In a mixed classical coherent state the exponential of the locked phase is shown to be replaced by a rather arbitrary unitary operator in the auxiliary Hilbert space. On the other hand classes for density operators--and for their normally ordered characteristic functions--of non-classical coherent states are obtained, especially by rather weak perturbations of classical coherent states. These illustrate various forms of breaking the classical uniform phase locking and exhibit rather peculiar properties, such as asymmetric fluctuations for the quadrature phase operators. Several criteria for non-classicality are put forward and applied to the elaborated non-classical coherent states, providing counterexamples against too simple arguments for classicality. It is concluded that classicality is only a stable concept for coherent states with macroscopic intensity

Non-communicable diseases and global health governance: enhancing global processes to improve health development.

Science.gov (United States)

Magnusson, Roger S

2007-05-22

This paper assesses progress in the development of a global framework for responding to non-communicable diseases, as reflected in the policies and initiatives of the World Health Organization (WHO), World Bank and the UN: the institutions most capable of shaping a coherent global policy. Responding to the global burden of chronic disease requires a strategic assessment of the global processes that are likely to be most effective in generating commitment to policy change at country level, and in influencing industry behaviour. WHO has adopted a legal process with tobacco (the WHO Framework Convention on Tobacco Control), but a non-legal, advocacy-based approach with diet and physical activity (the Global Strategy on Diet, Physical Activity and Health). The paper assesses the merits of the Millennium Development Goals (MDGs) and the FCTC as distinct global processes for advancing health development, before considering what lessons might be learned for enhancing the implementation of the Global Strategy on Diet. While global partnerships, economic incentives, and international legal instruments could each contribute to a more effective global response to chronic diseases, the paper makes a special case for the development of international legal standards in select areas of diet and nutrition, as a strategy for ensuring that the health of future generations does not become dependent on corporate charity and voluntary commitments. A broader frame of reference for lifestyle-related chronic diseases is needed: one that draws together WHO's work in tobacco, nutrition and physical activity, and that envisages selective use of international legal obligations, non-binding recommendations, advocacy and policy advice as tools of choice for promoting different elements of the strategy.

Coherent states of the real symplectic group in a complex analytic parametrization. I. Unitary-operator coherent states

International Nuclear Information System (INIS)

Quesne, C.

1986-01-01

In the present series of papers, the coherent states of Sp(2d,R), corresponding to the positive discrete series irreducible representations 1 +n/2> encountered in physical applications, are analyzed in detail with special emphasis on those of Sp(4,R) and Sp(6,R). The present paper discusses the unitary-operator coherent states, as defined by Klauder, Perelomov, and Gilmore. These states are parametrized by the points of the coset space Sp(2d,R)/H, where H is the stability group of the Sp(2d,R) irreducible representation lowest weight state, chosen as the reference state, and depends upon the relative values of lambda 1 ,...,lambda/sub d/, subject to the conditions lambda 1 > or =lambda 2 > or = x x x > or =lambda/sub d/> or =0. A parametrization of Sp(2d,R)/H corresponding to a factorization of the latter into a product of coset spaces Sp(2d,R)/U(d) and U(d)/H is chosen. The overlap of two coherent states is calculated, the action of the Sp(2d,R) generators on the coherent states is determined, and the explicit form of the unity resolution relation satisfied by the coherent states in the representation space of the irreducible representation is obtained. The Hilbert space of analytic functions arising from the coherent state representation is studied in detail. Finally, some applications of the formalism developed in the present paper are outlined

Performance analysis of a hybrid fingerprint extracted from optical coherence tomography fingertip scans

CSIR Research Space (South Africa)

Darlow, Luke N

2016-06-01

Full Text Available The Hybrid fingerprint is a local-quality-specific blend of the surface and internal fingerprints, extracted from optical coherence tomography scans. Owing to its origin, and the manner in which it is obtained, the Hybrid fingerprint is a high...

The coherent state on SUq(2) homogeneous space

International Nuclear Information System (INIS)

Aizawa, N; Chakrabarti, R

2009-01-01

The generalized coherent states for quantum groups introduced by Jurco and StovIcek are studied for the simplest example SU q (2) in full detail. It is shown that the normalized SU q (2) coherent states enjoy the property of completeness, and allow a resolution of the unity. This feature is expected to play a key role in the application of these coherent states in physical models. The homogeneous space of SU q (2), i.e. the q-sphere of Podles, is reproduced in complex coordinates by using the coherent states. Differential calculus in the complex form on the homogeneous space is developed. The high spin limit of the SU q (2) coherent states is also discussed.

The Interplay of Reader Goals, Working Memory, and Text Structure During Reading

Science.gov (United States)

Bohn-Gettler, Catherine M.; Kendeou, Panayiota

2014-01-01

In the current study we examined the complex interactions of instructional context, text properties, and reader characteristics during comprehension. College students were tasked with the goal of reading for study versus entertainment (instructional context) while thinking-aloud about four different expository text structures (text properties). Working memory also was assessed (reader characteristics). Reading goals and working memory interacted to influence paraphrasing and non-coherence processes when thinking aloud. Reading goals, working memory, and text structure all interacted to influence text-based inferences. Text structure also influenced knowledge-based inferences. Post-reading recall was highest for those with the instructional goal of reading for study (compared to entertainment), as well as for problem-response and compare-contrast texts (compared to descriptive and chronological texts). Implications of the findings are discussed. PMID:25018581

Task-related changes in degree centrality and local coherence of the posterior cingulate cortex after major cardiac surgery in older adults.

Science.gov (United States)

Browndyke, Jeffrey N; Berger, Miles; Smith, Patrick J; Harshbarger, Todd B; Monge, Zachary A; Panchal, Viral; Bisanar, Tiffany L; Glower, Donald D; Alexander, John H; Cabeza, Roberto; Welsh-Bohmer, Kathleen; Newman, Mark F; Mathew, Joseph P

2018-02-01

Older adults often display postoperative cognitive decline (POCD) after surgery, yet it is unclear to what extent functional connectivity (FC) alterations may underlie these deficits. We examined for postoperative voxel-wise FC changes in response to increased working memory load demands in cardiac surgery patients and nonsurgical controls. Older cardiac surgery patients (n = 25) completed a verbal N-back working memory task during MRI scanning and cognitive testing before and 6 weeks after surgery; nonsurgical controls with cardiac disease (n = 26) underwent these assessments at identical time intervals. We measured postoperative changes in degree centrality, the number of edges attached to a brain node, and local coherence, the temporal homogeneity of regional functional correlations, using voxel-wise graph theory-based FC metrics. Group × time differences were evaluated in these FC metrics associated with increased N-back working memory load (2-back > 1-back), using a two-stage partitioned variance, mixed ANCOVA. Cardiac surgery patients demonstrated postoperative working memory load-related degree centrality increases in the left dorsal posterior cingulate cortex (dPCC; p < .001, cluster p-FWE < .05). The dPCC also showed a postoperative increase in working memory load-associated local coherence (p < .001, cluster p-FWE < .05). dPCC degree centrality and local coherence increases were inversely associated with global cognitive change in surgery patients (p < .01), but not in controls. Cardiac surgery patients showed postoperative increases in working memory load-associated degree centrality and local coherence of the dPCC that were inversely associated with postoperative global cognitive outcomes and independent of perioperative cerebrovascular damage. © 2017 Wiley Periodicals, Inc.

Overlapped optics induced perfect coherent effects

Science.gov (United States)

Li, Jian Jie; Zang, Xiao Fei; Mao, Jun Fa; Tang, Min; Zhu, Yi Ming; Zhuang, Song Lin

2013-12-01

For traditional coherent effects, two separated identical point sources can be interfered with each other only when the optical path difference is integer number of wavelengths, leading to alternate dark and bright fringes for different optical path difference. For hundreds of years, such a perfect coherent condition seems insurmountable. However, in this paper, based on transformation optics, two separated in-phase identical point sources can induce perfect interference with each other without satisfying the traditional coherent condition. This shifting illusion media is realized by inductor-capacitor transmission line network. Theoretical analysis, numerical simulations and experimental results are performed to confirm such a kind of perfect coherent effect and it is found that the total radiation power of multiple elements system can be greatly enhanced. Our investigation may be applicable to National Ignition Facility (NIF), Inertial Confined Fusion (ICF) of China, LED lighting technology, terahertz communication, and so on.

Higher theta and alpha1 coherence when listening to Vedic recitation compared to coherence during Transcendental Meditation practice.

Science.gov (United States)

Travis, Frederick; Parim, Niyazi; Shrivastava, Amrita

2017-03-01

This study compared subjective experiences and EEG patterns in 37 subjects when listening to live Vedic recitation and when practicing Transcendental Meditation (TM). Content analysis of experiences when listening to Vedic recitation yielded three higher-order code. Experiences during Vedic recitation were: (1) deeper than during TM practice; (2) experienced as an inner process; and (3) characterized by lively silence. EEG patterns support these higher-order codes. Theta2 and alpha1 frontal, parietal, and frontal-parietal coherence were significantly higher when listening to Vedic recitation, than during TM practice. Theta2 coherence is seen when attending to internal mental processes. Higher theta2 coherence supports subjects' descriptions that the Vedic recitations were "not external sounds but internal vibrations." Alpha1 coherence is reported during pure consciousness experiences during TM practice. Higher alpha1 coherence supports subjects' descriptions that they "experienced a depth of experience, rarely experienced even during deep TM practice." These data support the utility of listening to Vedic recitation to culture deep inner experiences. Copyright © 2017 Elsevier Inc. All rights reserved.

The Coherent X-ray Imaging (CXI) Instrument at the Linac Coherent Light Source (LCLS)

International Nuclear Information System (INIS)

Boutet, Sebastien

2011-01-01

The Linac Coherent Light Source (LCLS) has become the first ever operational hard X-ray Free Electron Laser in 2009. It will operate as a user facility capable of delivering unique research opportunities in multiple fields of science. The LCLS and the LCLS Ultrafast Science Instruments (LUSI) construction projects are developing instruments designed to make full use of the capabilities afforded by the LCLS beam. One such instrument is being designed to utilize the LCLS coherent beam to image with high resolution any sub-micron object. This instrument is called the Coherent X-ray Imaging (CXI) instrument. This instrument will provide a flexible optical system capable of tailoring key beam parameters for the users. A suite of shot-to-shot diagnostics will also be provided to characterize the beam on every pulse. The provided instrumentation will include multi-purpose sample environments, sample delivery and a custom detector capable of collecting 2D data at 120 Hz. In this article, the LCLS will be briefly introduced along with the technique of Coherent X-ray Diffractive Imaging (CXDI). A few examples of scientific opportunities using the CXI instrument will be described. Finally, the conceptual layout of the instrument will be presented along with a description of the key requirements for the overall system and specific devices required.

Performance of quantum cloning and deleting machines over coherence

Science.gov (United States)

Karmakar, Sumana; Sen, Ajoy; Sarkar, Debasis

2017-10-01

Coherence, being at the heart of interference phenomena, is found to be an useful resource in quantum information theory. Here we want to understand quantum coherence under the combination of two fundamentally dual processes, viz., cloning and deleting. We found the role of quantum cloning and deletion machines with the consumption and generation of quantum coherence. We establish cloning as a cohering process and deletion as a decohering process. Fidelity of the process will be shown to have connection with coherence generation and consumption of the processes.

Coherent dynamics of plasma mirrors

Energy Technology Data Exchange (ETDEWEB)

Thaury, C; George, H; Quere, F; Monot, P; Martin, Ph [CEA, DSM, IRAMIS, Serv Photons Atomes and Mol, F-91191 Gif Sur Yvette, (France); Loch, R [Univ Twente, Laser Phys and Nonlinear Opt Grp, Fac Sci and Technol, MESA Inst Nanotechnol, NL-7500 AE Enschede, (Netherlands); Geindre, J P [Ecole Polytech, Lab Pour Utilisat Lasers Intenses, CNRS, F-91128 Palaiseau, (France)

2008-07-01

Coherent ultrashort X-ray pulses provide new ways to probe matter and its ultrafast dynamics. One of the promising paths to generate these pulses consists of using a nonlinear interaction with a system to strongly and periodically distort the waveform of intense laser fields, and thus produce high-order harmonics. Such distortions have so far been induced by using the nonlinear polarizability of atoms, leading to the production of atto-second light bursts, short enough to study the dynamics of electrons in matter. Shorter and more intense atto-second pulses, together with higher harmonic orders, are expected by reflecting ultra intense laser pulses on a plasma mirror - a dense (approximate to 10{sup 23} electrons cm{sup -3}) plasma with a steep interface. However, short-wavelength-light sources produced by such plasmas are known to generally be incoherent. In contrast, we demonstrate that like in usual low-intensity reflection, the coherence of the light wave is preserved during harmonic generation on plasma mirrors. We then exploit this coherence for interferometric measurements and thus carry out a first study of the laser-driven coherent dynamics of the plasma electrons. (authors)

Optical coherence tomography--a new imaging method in ophthalmology.

Science.gov (United States)

Svorenova, I; Strmen, P; Olah, Z

2010-01-01

An improvement of examination methods in ophthalmology, technical digitalisation and knowledge of validity of examinations in various diseases contributes to early diagnostics, thereby leading to an opportunity for early treatment of eye disorders. Standard introduction of the so-called optical coherence tomography into the ophthamological clinical practice facilitated new options for a detailed analysis of pathological processes in the particular layers of the retina (Fig. 2, Ref. 5). Full Text (Free, PDF) www.bmj.sk.

Coherence in quantum estimation

Science.gov (United States)

Giorda, Paolo; Allegra, Michele

2018-01-01

The geometry of quantum states provides a unifying framework for estimation processes based on quantum probes, and it establishes the ultimate bounds of the achievable precision. We show a relation between the statistical distance between infinitesimally close quantum states and the second order variation of the coherence of the optimal measurement basis with respect to the state of the probe. In quantum phase estimation protocols, this leads to propose coherence as the relevant resource that one has to engineer and control to optimize the estimation precision. Furthermore, the main object of the theory i.e. the symmetric logarithmic derivative, in many cases allows one to identify a proper factorization of the whole Hilbert space in two subsystems. The factorization allows one to discuss the role of coherence versus correlations in estimation protocols; to show how certain estimation processes can be completely or effectively described within a single-qubit subsystem; and to derive lower bounds for the scaling of the estimation precision with the number of probes used. We illustrate how the framework works for both noiseless and noisy estimation procedures, in particular those based on multi-qubit GHZ-states. Finally we succinctly analyze estimation protocols based on zero-temperature critical behavior. We identify the coherence that is at the heart of their efficiency, and we show how it exhibits the non-analyticities and scaling behavior proper of a large class of quantum phase transitions.

Task-and phase-related changes in cortico-muscular coherence

DEFF Research Database (Denmark)

Masakado, Yoshihisa; Nielsen, Jens Bo

2008-01-01

-level tonic dorsiflexion. In all subjects coherence disappeared during the ramp phase for both isometric and quasi-isotonic contraction. Coherence at other frequencies was also not observed in any of the subjects during the ramp phase. During the hold phase at the stronger level of contraction coherence...... reappeared quickly and had the same size as at the low level of contraction. However, a significantly larger level of coherence was found during quasi-isotonic than during the isometric contraction. This demonstrates that cortico-muscular coherence in the 15-35 Hz frequency band is phase- and task......-related. The decrease in 15-35 Hz coherence during the ramp phase may be related to event-related desynchronization of EEG activity. The larger level of coherence during quasi-isotonic contraction may reflect a higher demand of precise control of the joint position. It may also reflect a greater need for binding...

Coherence matrix of plasmonic beams

DEFF Research Database (Denmark)

Novitsky, Andrey; Lavrinenko, Andrei

2013-01-01

We consider monochromatic electromagnetic beams of surface plasmon-polaritons created at interfaces between dielectric media and metals. We theoretically study non-coherent superpositions of elementary surface waves and discuss their spectral degree of polarization, Stokes parameters, and the for...... of the spectral coherence matrix. We compare the polarization properties of the surface plasmonspolaritons as three-dimensional and two-dimensional fields concluding that the latter is superior....

Coherence resonance in low-density jets

Science.gov (United States)

Zhu, Yuanhang; Gupta, Vikrant; Li, Larry K. B.

2017-11-01

Coherence resonance is a phenomenon in which the response of a stable nonlinear system to noise exhibits a peak in coherence at an intermediate noise amplitude. We report the first experimental evidence of coherence resonance in a purely hydrodynamic system, a low-density jet whose variants can be found in many natural and engineering systems. This evidence comprises four parts: (i) the jet's response amplitude increases as the Reynolds number approaches the instability boundary under a constant noise amplitude; (ii) as the noise amplitude increases, the amplitude distribution of the jet response first becomes unimodal, then bimodal, and finally unimodal again; (iii) a distinct peak emerges in the coherence factor at an intermediate noise amplitude; and (iv) for a subcritical Hopf bifurcation, the decay rate of the autocorrelation function exhibits a maximum at an intermediate noise amplitude, but for a supercritical Hopf bifurcation, the decay rate decreases monotonically with increasing noise amplitude. It is clear that coherence resonance can provide valuable information about a system's nonlinearity even in the unconditionally stable regime, opening up new possibilities for its use in system identification and flow control. This work was supported by the Research Grants Council of Hong Kong (Project No. 16235716 and 26202815).

NONINVASIVE DIAGNOSIS OF BLADDER CANCER BY CROSS-POLARIZATION OPTICAL COHERENCE TOMOGRAPHY: A BLIND STATISTICAL STUDY

Directory of Open Access Journals (Sweden)

O. S. Streltsova

2014-07-01

Full Text Available Whether cross-polarization (CP optical coherence tomography (OCT could be used to detect early bladder cancer was ascertained; it was compared with traditional OCT within the framework of blind (closed clinical statistical studies. One hundred and sixteen patients with local nonexophytic (flat pathological processes of the bladder were examined; 360 CP OCT images were obtained and analyzed. The study used an OCT 1300-U CP optical coherence tomographer. CP OCT showed a high (94% sensitivity and a high (84% specificity in the identification of suspected nonexophytic areas in the urinary bladder.

A versatile setup for ultrafast broadband optical spectroscopy of coherent collective modes in strongly correlated quantum systems

Directory of Open Access Journals (Sweden)

Edoardo Baldini

2016-11-01

Full Text Available A femtosecond pump-probe setup is described that is optimised for broadband transient reflectivity experiments on solid samples over a wide temperature range. By combining high temporal resolution and a broad detection window, this apparatus can investigate the interplay between coherent collective modes and high-energy electronic excitations, which is a distinctive characteristic of correlated electron systems. Using a single-shot readout array detector at frame rates of 10 kHz allows resolving coherent oscillations with amplitudes <10−4. We demonstrate its operation on the charge-transfer insulator La2CuO4, revealing coherent phonons with frequencies up to 13 THz and providing access into their Raman matrix elements.

Coherent γ-ray production

International Nuclear Information System (INIS)

Bertolotti, M.; Sibilia, C.

1985-01-01

In this article the authors discuss a new approach for developing a coherent source of γ-rays. They offer a completely different scheme for development of the source that should overcome most of the problems encountered in ''classical γ-ray lasers,'' and in which the use of inverse Compton scattering of laser radiation onto a relativistic electron beam is made. This kind of interaction has been used to obtain γ-ray photons with good polarization and monochromaticity properties. The authors describe a new geometry of interaction which allows one to obtain coherent emission

A coherent graph-based semantic clustering and summarization approach for biomedical literature and a new summarization evaluation method.

Science.gov (United States)

Yoo, Illhoi; Hu, Xiaohua; Song, Il-Yeol

2007-11-27

A huge amount of biomedical textual information has been produced and collected in MEDLINE for decades. In order to easily utilize biomedical information in the free text, document clustering and text summarization together are used as a solution for text information overload problem. In this paper, we introduce a coherent graph-based semantic clustering and summarization approach for biomedical literature. Our extensive experimental results show the approach shows 45% cluster quality improvement and 72% clustering reliability improvement, in terms of misclassification index, over Bisecting K-means as a leading document clustering approach. In addition, our approach provides concise but rich text summary in key concepts and sentences. Our coherent biomedical literature clustering and summarization approach that takes advantage of ontology-enriched graphical representations significantly improves the quality of document clusters and understandability of documents through summaries.

Assessment of Snow Status Changes Using L-HH Temporal-Coherence Components at Mt. Dagu, China

Directory of Open Access Journals (Sweden)

Yong Wang

2015-09-01

Full Text Available Multitemporal Phased Array type L-band Synthetic Aperture Radar (PALSAR horizontally transmitted and horizontally received (HH coherence data was decomposed into temporal-coherence, spatial-coherence, and thermal noise components. The multitemporal data spanned between February and May of 2008, and consisted of two pairs of interferometric SAR (InSAR images formed by consecutive repeat passes. With the analysis of ancillary data, a snow increase process and a snow decrease process were determined. Then, the multiple temporal-coherence components were used to study the variation of thawing and freezing statuses of snow because the components can mostly reflect the temporal change of the snow that occurred between two data acquisitions. Compared with snow mapping results derived from optical images, the outcomes from the snow increase process and the snow decrease process reached an overall accuracy of 71.3% and 79.5%, respectively. Being capable of delineating not only the areas with or without snow cover but also status changes among no-snow, wet snow, and dry snow, we have developed a critical means to assess the water resource in alpine areas.

Coherent Doppler Laser Radar: Technology Development and Applications

Science.gov (United States)

Kavaya, Michael J.; Arnold, James E. (Technical Monitor)

2000-01-01

NASA's Marshall Space Flight Center has been investigating, developing, and applying coherent Doppler laser radar technology for over 30 years. These efforts have included the first wind measurement in 1967, the first airborne flights in 1972, the first airborne wind field mapping in 1981, and the first measurement of hurricane eyewall winds in 1998. A parallel effort at MSFC since 1982 has been the study, modeling and technology development for a space-based global wind measurement system. These endeavors to date have resulted in compact, robust, eyesafe lidars at 2 micron wavelength based on solid-state laser technology; in a factor of 6 volume reduction in near diffraction limited, space-qualifiable telescopes; in sophisticated airborne scanners with full platform motion subtraction; in local oscillator lasers capable of rapid tuning of 25 GHz for removal of relative laser radar to target velocities over a 25 km/s range; in performance prediction theory and simulations that have been validated experimentally; and in extensive field campaign experience. We have also begun efforts to dramatically improve the fundamental photon efficiency of the laser radar, to demonstrate advanced lower mass laser radar telescopes and scanners; to develop laser and laser radar system alignment maintenance technologies; and to greatly improve the electrical efficiency, cooling technique, and robustness of the pulsed laser. This coherent Doppler laser radar technology is suitable for high resolution, high accuracy wind mapping; for aerosol and cloud measurement; for Differential Absorption Lidar (DIAL) measurements of atmospheric and trace gases; for hard target range and velocity measurement; and for hard target vibration spectra measurement. It is also suitable for a number of aircraft operations applications such as clear air turbulence (CAT) detection; dangerous wind shear (microburst) detection; airspeed, angle of attack, and sideslip measurement; and fuel savings through

Damage invariant and high security acquisition of the internal fingerprint using optical coherence tomography

CSIR Research Space (South Africa)

Darlow, Luke N

2016-11-01

Full Text Available representation they offer. Using an emerging fingerprint acquisition technology – optical coherence tomography – to access an internal fingerprint under the skin surface, this paper serves to address two limitations of conventional scanners: fingertip skin damage...

Coherent Forecasts of Mortality with Compositional Data Analysis

DEFF Research Database (Denmark)

Bergeron-Boucher, Marie-Pier; Canudas-Romo, Vladimir; Oeppen, Jim

2017-01-01

Data Analysis (CoDa) of the life table distribution of deaths. We adapt existing coherent and non–coherent forecasting models to CoDa and compare their results. Results We apply our coherent method to the female mortality of 15 Western European countries and show that our proposed strategy would have...

Store-operate-coherence-on-value

Science.gov (United States)

Chen, Dong; Heidelberger, Philip; Kumar, Sameer; Ohmacht, Martin; Steinmacher-Burow, Burkhard

2014-11-18

A system, method and computer program product for performing various store-operate instructions in a parallel computing environment that includes a plurality of processors and at least one cache memory device. A queue in the system receives, from a processor, a store-operate instruction that specifies under which condition a cache coherence operation is to be invoked. A hardware unit in the system runs the received store-operate instruction. The hardware unit evaluates whether a result of the running the received store-operate instruction satisfies the condition. The hardware unit invokes a cache coherence operation on a cache memory address associated with the received store-operate instruction if the result satisfies the condition. Otherwise, the hardware unit does not invoke the cache coherence operation on the cache memory device.

Martingale characterizations of coherent acceptability measures

NARCIS (Netherlands)

Roorda, Berend

2002-01-01

The coherent risk framework is linked to martingale valuation by adding hedgeinvariance as a fifth axiom, motivated by the concept of consistent hedging. The resulting subclass, called coherent pre-hedge (CoPr) measures, is characterized by a martingale condition on the test set that underlies a

Local processing enhancements associated with superior observational drawing are due to enhanced perceptual functioning, not weak central coherence.

Science.gov (United States)

Chamberlain, Rebecca; McManus, I C; Riley, Howard; Rankin, Qona; Brunswick, Nicola

2013-01-01

Individuals with drawing talent have previously been shown to exhibit enhanced local visual processing ability. The aim of the current study was to assess whether local processing biases associated with drawing ability result from a reduced ability to cohere local stimuli into global forms, or an increased ability to disregard global aspects of an image. Local and global visual processing ability was assessed in art students and controls using the Group Embedded Figures Task, Navon shape stimuli, the Block Design Task and the Autism Spectrum Quotient, whilst controlling for nonverbal IQ and artistic ability. Local processing biases associated with drawing appear to arise from an enhancement of local processing alongside successful filtering of global information, rather than a reduction in global processing. The relationship between local processing and drawing ability is independent of individual differences in nonverbal IQ and artistic ability. These findings have implications for bottom-up and attentional theories of observational drawing, as well as explanations of special skills in autism.

Quantum coherence behaviors of fermionic system in non-inertial frame

Science.gov (United States)

Huang, Zhiming; Situ, Haozhen

2018-04-01

In this paper, we analyze the quantum coherence behaviors of a single qubit in the relativistic regime beyond the single-mode approximation. Firstly, we investigate the freezing condition of quantum coherence in fermionic system. We also study the quantum coherence tradeoff between particle and antiparticle sector. It is found that there exists quantum coherence transfer between particle and antiparticle sector, but the coherence lost in particle sector is not entirely compensated by the coherence generation of antiparticle sector. Besides, we emphatically discuss the cohering power and decohering power of Unruh channel with respect to the computational basis. It is shown that cohering power is vanishing and decohering power is dependent of the choice of Unruh mode and acceleration. Finally, we compare the behaviors of quantum coherence with geometric quantum discord and entanglement in relativistic setup. Our results show that this quantifiers in two region converge at infinite acceleration limit, which implies that this measures become independent of Unruh modes beyond the single-mode approximations. It is also demonstrated that the robustness of quantum coherence and geometric quantum discord are better than entanglement under the influence of acceleration, since entanglement undergoes sudden death.

Communication: Fully coherent quantum state hopping

Energy Technology Data Exchange (ETDEWEB)

Martens, Craig C., E-mail: cmartens@uci.edu [University of California, Irvine, California 92697-2025 (United States)

2015-10-14

In this paper, we describe a new and fully coherent stochastic surface hopping method for simulating mixed quantum-classical systems. We illustrate the approach on the simple but unforgiving problem of quantum evolution of a two-state quantum system in the limit of unperturbed pure state dynamics and for dissipative evolution in the presence of both stationary and nonstationary random environments. We formulate our approach in the Liouville representation and describe the density matrix elements by ensembles of trajectories. Population dynamics are represented by stochastic surface hops for trajectories representing diagonal density matrix elements. These are combined with an unconventional coherent stochastic hopping algorithm for trajectories representing off-diagonal quantum coherences. The latter generalizes the binary (0,1) “probability” of a trajectory to be associated with a given state to allow integers that can be negative or greater than unity in magnitude. Unlike existing surface hopping methods, the dynamics of the ensembles are fully entangled, correctly capturing the coherent and nonlocal structure of quantum mechanics.

Phase-controlled coherent population trapping in superconducting quantum circuits

International Nuclear Information System (INIS)

Cheng Guang-Ling; Wang Yi-Ping; Chen Ai-Xi

2015-01-01

We investigate the influences of the-applied-field phases and amplitudes on the coherent population trapping behavior in superconducting quantum circuits. Based on the interactions of the microwave fields with a single Δ-type three-level fluxonium qubit, the coherent population trapping could be obtainable and it is very sensitive to the relative phase and amplitudes of the applied fields. When the relative phase is tuned to 0 or π, the maximal atomic coherence is present and coherent population trapping occurs. While for the choice of π/2, the atomic coherence becomes weak. Meanwhile, for the fixed relative phase π/2, the value of coherence would decrease with the increase of Rabi frequency of the external field coupled with two lower levels. The responsible physical mechanism is quantum interference induced by the control fields, which is indicated in the dressed-state representation. The microwave coherent phenomenon is present in our scheme, which will have potential applications in optical communication and nonlinear optics in solid-state devices. (paper)

European network for research in global change (ENRICH)

Energy Technology Data Exchange (ETDEWEB)

Ghazi, A [European Commission, Bruxelles (Belgium). DG XII/JRC

1996-12-31

While approaching the beginning of the twenty first century, the scientific community is faced with the formidable tasks of monitoring and detecting, understanding and predicting changes in the Earth System and its interactions with human beings. A crucial challenge is to make scientific research results accessible and usable for those involved in the decision making process related to the concept of Sustainable Development. Major international scientific programmes under the umbrella of ICSU, such as the IGBP and WCRP, are dealing with these issues. Although there exist many well developed global change research programmes in several European countries and effective collaboration networks between research institutes, there is an urgent need for overall communication with a view to promoting wider international links ensuring complementarity, synergy and coherence. Recognizing the importance of promoting coherence in research and utilising research results for various European Union (EU) policies, the European Commissioner responsible for Science, Research and Development wrote in March 1992 to all the EU Research Ministers to propose an initiative in this domain. In a rapid response, a group of Senior Experts from the EU Member States was set up in April 1992. This Group established a Task Force to develop the concept of the European Network for Research In Global CHange (ENRICH) which was approved in July 1993

European network for research in global change (ENRICH)

Energy Technology Data Exchange (ETDEWEB)

Ghazi, A. [European Commission, Bruxelles (Belgium). DG XII/JRC

1995-12-31

While approaching the beginning of the twenty first century, the scientific community is faced with the formidable tasks of monitoring and detecting, understanding and predicting changes in the Earth System and its interactions with human beings. A crucial challenge is to make scientific research results accessible and usable for those involved in the decision making process related to the concept of Sustainable Development. Major international scientific programmes under the umbrella of ICSU, such as the IGBP and WCRP, are dealing with these issues. Although there exist many well developed global change research programmes in several European countries and effective collaboration networks between research institutes, there is an urgent need for overall communication with a view to promoting wider international links ensuring complementarity, synergy and coherence. Recognizing the importance of promoting coherence in research and utilising research results for various European Union (EU) policies, the European Commissioner responsible for Science, Research and Development wrote in March 1992 to all the EU Research Ministers to propose an initiative in this domain. In a rapid response, a group of Senior Experts from the EU Member States was set up in April 1992. This Group established a Task Force to develop the concept of the European Network for Research In Global CHange (ENRICH) which was approved in July 1993

Efficient Topological Localization Using Global and Local Feature Matching

Directory of Open Access Journals (Sweden)

Junqiu Wang

2013-03-01

Full Text Available We present an efficient vision-based global topological localization approach in which different image features are used in a coarse-to-fine matching framework. Orientation Adjacency Coherence Histogram (OACH, a novel image feature, is proposed to improve the coarse localization. The coarse localization results are taken as inputs for the fine localization which is carried out by matching Harris-Laplace interest points characterized by the SIFT descriptor. The computation of OACHs and interest points is efficient due to the fact that these features are computed in an integrated process. The matching of local features is improved by using approximate nearest neighbor searching technique. We have implemented and tested the localization system in real environments. The experimental results demonstrate that our approach is efficient and reliable in both indoor and outdoor environments. This work has also been compared with previous works. The comparison results show that our approach has better performance with higher correct ratio and lower computational complexity.

arXiv Quantum coherence of cosmological perturbations

CERN Document Server

Giovannini, Massimo

2017-10-26

In this paper, the degrees of quantum coherence of cosmological perturbations of different spins are computed in the large-scale limit and compared with the standard results holding for a single mode of the electromagnetic field in an optical cavity. The degree of second-order coherence of curvature inhomogeneities (and, more generally, of the scalar modes of the geometry) reproduces faithfully the optical limit. For the vector and tensor fluctuations, the numerical values of the normalized degrees of second-order coherence in the zero time-delay limit are always larger than unity (which is the Poisson benchmark value) but differ from the corresponding expressions obtainable in the framework of the single-mode approximation. General lessons are drawn on the quantum coherence of large-scale cosmological fluctuations.

Coherence properties of the radiation from FLASH

International Nuclear Information System (INIS)

Schneidmiller, E.A.; Yurkov, M.V.

2015-02-01

FLASH is the first free electron laser user facility operating in the vacuum ultraviolet and soft x-ray wavelength range. Many user experiments require knowledge of the spatial and temporal coherence properties of the radiation. In this paper we present an analysis of the coherence properties of the radiation for the fundamental and for the higher odd frequency harmonics. We show that temporal and spatial coherence reach maximum close to the FEL saturation but may degrade significantly in the post-saturation regime. We also find that the pointing stability of short FEL pulses is limited due to the fact that non-azimuthal FEL eigenmodes are not sufficiently suppressed. We discuss possible ways for improving the degree of transverse coherence and the pointing stability.

MESI Cache Coherence Simulator for Teaching Purposes

OpenAIRE

Gómez Luna, Juan; Herruzo Gómez, Ezequiel; Benavides Benítez, José Ignacio

2009-01-01

Nowadays, the computational systems (multi and uniprocessors) need to avoid the cache coherence problem. There are some techniques to solve this problem. The MESI cache coherence protocol is one of them. This paper presents a simulator of the MESI protocol which is used for teaching the cache memory coherence on the computer systems with hierarchical memory system and for explaining the process of the cache memory location in multilevel cache memory systems. The paper shows a d...

A Poggean passport for fairness? Why Rawls’ Theory of Justice did not become global

Directory of Open Access Journals (Sweden)

Shmuel Nili

2010-11-01

Full Text Available Thomas Pogge has been challenging liberal thinking on global politics, often through critical engagement with John Rawls’ work. Pogge presents both normative and empirical arguments against Rawls: normatively, Rawls’ domestic Theory of Justice (TJ and global Law of Peoples (LP are incompatible ideal theories; empirically, LP is too removed from the actual world to guide the foreign policy of liberal societies. My main purpose here is to contest the first, ideal theory criticism in order to direct more attention to the second, non-ideal objection. I argue against Pogge that TJ and LP can be read as coherent, once one employs a Rousseauian rather than Pogge's economic Kantian reading of TJ. The first two sections present Pogge's view of TJ and contrast it with a Rousseauian alternative that is less cosmopolitan and economic and much more focused on the democratic and sovereign context of justice as fairness. The third section seeks to refute Pogge's incoherence arguments, which encompass the identity of the parties to the international original position, their motivations and their decisions. Instead of a conclusion, the last section emphasizes LP's non-ideal problems, and suggests that insofar as LP is the most robust liberal ideal theory of global politics, its empirical failure indicates the need to shift global justice theorizing even more to the non-ideal realm.

Coherent laser vision system

International Nuclear Information System (INIS)

Sebastion, R.L.

1995-01-01

The Coherent Laser Vision System (CLVS) is being developed to provide precision real-time 3D world views to support site characterization and robotic operations and during facilities Decontamination and Decommissioning. Autonomous or semiautonomous robotic operations requires an accurate, up-to-date 3D world view. Existing technologies for real-time 3D imaging, such as AM laser radar, have limited accuracy at significant ranges and have variability in range estimates caused by lighting or surface shading. Recent advances in fiber optic component technology and digital processing components have enabled the development of a new 3D vision system based upon a fiber optic FMCW coherent laser radar. The approach includes a compact scanner with no-moving parts capable of randomly addressing all pixels. The system maintains the immunity to lighting and surface shading conditions which is characteristic to coherent laser radar. The random pixel addressability allows concentration of scanning and processing on the active areas of a scene, as is done by the human eye-brain system

Coherent laser vision system

Energy Technology Data Exchange (ETDEWEB)

Sebastion, R.L. [Coleman Research Corp., Springfield, VA (United States)

1995-10-01

The Coherent Laser Vision System (CLVS) is being developed to provide precision real-time 3D world views to support site characterization and robotic operations and during facilities Decontamination and Decommissioning. Autonomous or semiautonomous robotic operations requires an accurate, up-to-date 3D world view. Existing technologies for real-time 3D imaging, such as AM laser radar, have limited accuracy at significant ranges and have variability in range estimates caused by lighting or surface shading. Recent advances in fiber optic component technology and digital processing components have enabled the development of a new 3D vision system based upon a fiber optic FMCW coherent laser radar. The approach includes a compact scanner with no-moving parts capable of randomly addressing all pixels. The system maintains the immunity to lighting and surface shading conditions which is characteristic to coherent laser radar. The random pixel addressability allows concentration of scanning and processing on the active areas of a scene, as is done by the human eye-brain system.

Coherent acceptability measures in multiperiod models

NARCIS (Netherlands)

Roorda, Berend; Schumacher, Hans; Engwerda, Jacob

2005-01-01

The framework of coherent risk measures has been introduced by Artzner et al. (1999; Math. Finance 9, 203–228) in a single-period setting. Here, we investigate a similar framework in a multiperiod context. We add an axiom of dynamic consistency to the standard coherence axioms, and obtain a

Intermuscular Coherence Between Surface EMG Signals Is Higher for Monopolar Compared to Bipolar Electrode Configurations

Directory of Open Access Journals (Sweden)

Maurice Mohr

2018-05-01

Full Text Available Introduction: The vasti muscles have to work in concert to control knee joint motion during movements like walking, running, or squatting. Coherence analysis between surface electromyography (EMG signals is a common technique to study muscle synchronization during such movements and gain insight into strategies of the central nervous system to optimize neuromuscular performance. However, different assessment methods related to EMG data acquisition, e.g., different electrode configurations or amplifier technologies, have produced inconsistent observations. Therefore, the aim of this study was to elucidate the effect of different EMG acquisition techniques (monopolar vs. bipolar electrode configuration, potential vs. current amplifier on the magnitude, reliability, and sensitivity of intermuscular coherence between two vasti muscles during stable and unstable squatting exercises.Methods: Surface EMG signals from vastus lateralis (VL and medialis (VM were obtained from eighteen adults while performing series of stable und unstable bipedal squats. The EMG signals were acquired using three different recording techniques: (1 Bipolar with a potential amplifier, (2 monopolar with a potential amplifier, and (3 monopolar electrodes with a current amplifier. VL-VM coherence between the respective raw EMG signals was determined during two trials of stable squatting and one trial of unstable squatting to compare the coherence magnitude, reliability, and sensitivity between EMG recording techniques.Results: VL-VM coherence was about twice as high for monopolar recordings compared to bipolar recordings for all squatting exercises while coherence was similar between monopolar potential and current recordings. Reliability measures were comparable between recording systems while the sensitivity to an increase in intermuscular coherence during unstable vs. stable squatting was lowest for the monopolar potential system.Discussion and Conclusion: The choice of

Wide-band coherent receiver development for enhanced surveillance

International Nuclear Information System (INIS)

Simpson, M.L.; Richards, R.K.; Hutchinson, D.P.

1998-03-01

Oak Ridge National Laboratory (ORNL) has been developing advanced coherent IR heterodyne receivers for plasma diagnostics in fusion reactors for over 20 years. Recent progress in wide band IR detectors and high speed electronics has significantly enhanced the measurement capabilities of coherent receivers. In addition, developments in new HgCdTe and quantum well IR photodetector (QWIP) focal plane arrays are providing the possibility of both active and passive coherent imaging. In this paper the authors discuss the implications of these new enabling technologies to the IR remote sensing community for enhanced surveillance. Coherent receivers, as opposed to direct or thermal detection, provide multiple dimensions of information about a scene or target in a single detector system. Combinations of range, velocity, temperature, and chemical species information are all available from a coherent heterodyne receiver. They present laboratory data showing measured noise equivalent power (NEP) of new QWIP detectors with heterodyne bandwidths greater than 7 GHz. For absorption measurements, a wide band coherent receiver provides the capability of looking between CO 2 lines at off-resonance peaks and thus the measurement of lines normally inaccessible with conventional heterodyne or direct detection systems. Also described are differential absorption lidar (DIAL) and Doppler laboratory measurements using an 8 x 8 HgCdTe focal plane array demonstrating the snapshot capability of coherent receiver detector arrays for enhanced chemical plume and moving hardbody capture. Finally they discuss a variety of coherent receiver configurations that can suppress (or enhance) sensitivity of present active remote sensing systems to speckle, glint, and other measurement anomalies

International workshop on phase retrieval and coherent scattering. Coherence 2005

International Nuclear Information System (INIS)

Nugent, K.A.; Fienup, J.R.; Van Dyck, D.; Van Aert, S.; Weitkamp, T.; Diaz, A.; Pfeiffer, F.; Cloetens, P.; Stampanoni, M.; Bunk, O.; David, C.; Bronnikov, A.V.; Shen, Q.; Xiao, X.; Gureyev, T.E.; Nesterets, Ya.I.; Paganin, D.M.; Wilkins, S.W.; Mokso, R.; Cloetens, P.; Ludwig, W.; Hignette, O.; Maire, E.; Faulkner, H.M.L.; Rodenburg, J.M.; Wu, X.; Liu, H.; Grubel, G.; Ludwig, K.F.; Livet, F.; Bley, F.; Simon, J.P.; Caudron, R.; Le Bolloc'h, D.; Moussaid, A.; Gutt, C.; Sprung, M.; Madsen, A.; Tolan, M.; Sinha, S.K.; Scheffold, F.; Schurtenberger, P.; Robert, A.; Madsen, A.; Falus, P.; Borthwick, M.A.; Mochrie, S.G.J.; Livet, F.; Sutton, M.D.; Ehrburger-Dolle, F.; Bley, F.; Geissler, E.; Sikharulidze, I.; Jeu, W.H. de; Lurio, L.B.; Hu, X.; Jiao, X.; Jiang, Z.; Lurio, L.B.; Hu, X.; Jiao, X.; Jiang, Z.; Naryanan, S.; Sinha, S.K.; Lal, J.; Naryanan, S.; Sinha, S.K.; Lal, J.; Robinson, I.K.; Chapman, H.N.; Barty, A.; Beetz, T.; Cui, C.; Hajdu, J.; Hau-Riege, S.P.; He, H.; Stadler, L.M.; Sepiol, B.; Harder, R.; Robinson, I.K.; Zontone, F.; Vogl, G.; Howells, M.; London, R.; Marchesini, S.; Shapiro, D.; Spence, J.C.H.; Weierstall, U.; Eisebitt, S.; Shapiro, D.; Lima, E.; Elser, V.; Howells, M.R.; Huang, X.; Jacobsen, C.; Kirz, J.; Miao, H.; Neiman, A.; Sayre, D.; Thibault, P.; Vartanyants, I.A.; Robinson, I.K.; Onken, J.D.; Pfeifer, M.A.; Williams, G.J.; Pfeiffer, F.; Metzger, H.; Zhong, Z.; Bauer, G.; Nishino, Y.; Miao, J.; Kohmura, Y.; Yamamoto, M.; Takahashi, Y.; Koike, K.; Ebisuzaki, T.; Ishikawa, T.; Spence, J.C.H.; Doak, B.

2005-01-01

The contributions of the participants have been organized into 3 topics: 1) phase retrieval methods, 2) X-ray photon correlation spectroscopy, and 3) coherent diffraction imaging. This document gathers the abstracts of the presentations and of the posters

International workshop on phase retrieval and coherent scattering. Coherence 2005

Energy Technology Data Exchange (ETDEWEB)

Nugent, K.A.; Fienup, J.R.; Van Dyck, D.; Van Aert, S.; Weitkamp, T.; Diaz, A.; Pfeiffer, F.; Cloetens, P.; Stampanoni, M.; Bunk, O.; David, C.; Bronnikov, A.V.; Shen, Q.; Xiao, X.; Gureyev, T.E.; Nesterets, Ya.I.; Paganin, D.M.; Wilkins, S.W.; Mokso, R.; Cloetens, P.; Ludwig, W.; Hignette, O.; Maire, E.; Faulkner, H.M.L.; Rodenburg, J.M.; Wu, X.; Liu, H.; Grubel, G.; Ludwig, K.F.; Livet, F.; Bley, F.; Simon, J.P.; Caudron, R.; Le Bolloc' h, D.; Moussaid, A.; Gutt, C.; Sprung, M.; Madsen, A.; Tolan, M.; Sinha, S.K.; Scheffold, F.; Schurtenberger, P.; Robert, A.; Madsen, A.; Falus, P.; Borthwick, M.A.; Mochrie, S.G.J.; Livet, F.; Sutton, M.D.; Ehrburger-Dolle, F.; Bley, F.; Geissler, E.; Sikharulidze, I.; Jeu, W.H. de; Lurio, L.B.; Hu, X.; Jiao, X.; Jiang, Z.; Lurio, L.B.; Hu, X.; Jiao, X.; Jiang, Z.; Naryanan, S.; Sinha, S.K.; Lal, J.; Naryanan, S.; Sinha, S.K.; Lal, J.; Robinson, I.K.; Chapman, H.N.; Barty, A.; Beetz, T.; Cui, C.; Hajdu, J.; Hau-Riege, S.P.; He, H.; Stadler, L.M.; Sepiol, B.; Harder, R.; Robinson, I.K.; Zontone, F.; Vogl, G.; Howells, M.; London, R.; Marchesini, S.; Shapiro, D.; Spence, J.C.H.; Weierstall, U.; Eisebitt, S.; Shapiro, D.; Lima, E.; Elser, V.; Howells, M.R.; Huang, X.; Jacobsen, C.; Kirz, J.; Miao, H.; Neiman, A.; Sayre, D.; Thibault, P.; Vartanyants, I.A.; Robinson, I.K.; Onken, J.D.; Pfeifer, M.A.; Williams, G.J.; Pfeiffer, F.; Metzger, H.; Zhong, Z.; Bauer, G.; Nishino, Y.; Miao, J.; Kohmura, Y.; Yamamoto, M.; Takahashi, Y.; Koike, K.; Ebisuzaki, T.; Ishikawa, T.; Spence, J.C.H.; Doak, B

2005-07-01

The contributions of the participants have been organized into 3 topics: 1) phase retrieval methods, 2) X-ray photon correlation spectroscopy, and 3) coherent diffraction imaging. This document gathers the abstracts of the presentations and of the posters.

Coherence techniques at extreme ultraviolet wavelengths

Energy Technology Data Exchange (ETDEWEB)

Chang, Chang [Univ. of California, Berkeley, CA (United States)

2002-01-01

The renaissance of Extreme Ultraviolet (EUV) and soft x-ray (SXR) optics in recent years is mainly driven by the desire of printing and observing ever smaller features, as in lithography and microscopy. This attribute is complemented by the unique opportunity for element specific identification presented by the large number of atomic resonances, essentially for all materials in this range of photon energies. Together, these have driven the need for new short-wavelength radiation sources (e.g. third generation synchrotron radiation facilities), and novel optical components, that in turn permit new research in areas that have not yet been fully explored. This dissertation is directed towards advancing this new field by contributing to the characterization of spatial coherence properties of undulator radiation and, for the first time, introducing Fourier optical elements to this short-wavelength spectral region. The first experiment in this dissertation uses the Thompson-Wolf two-pinhole method to characterize the spatial coherence properties of the undulator radiation at Beamline 12 of the Advanced Light Source. High spatial coherence EUV radiation is demonstrated with appropriate spatial filtering. The effects of small vertical source size and beamline apertures are observed. The difference in the measured horizontal and vertical coherence profile evokes further theoretical studies on coherence propagation of an EUV undulator beamline. A numerical simulation based on the Huygens-Fresnel principle is performed.

Coherence characteristics of light-emitting diodes

International Nuclear Information System (INIS)

Mehta, Dalip Singh; Saxena, Kanchan; Dubey, Satish Kumar; Shakher, Chandra

2010-01-01

We report the measurement of coherence characteristics of light-emitting diodes (LEDs). Experiments were performed using red and green color LEDs directly illuminating the Young's double slit kept in the far-zone. Fourier transform fringe analysis technique was used for the measurement of the visibility of interference fringes from which the modulus of degree of spectral coherence was determined. Low degree of spectral coherence, typically 0.4 for red and 0.2 for green LED with double-slit separation of 400 μm was observed. A variable slit was then kept in front of the LEDs and the double slit was illuminated with the light coming out of the slit. Experiments were performed with various slit sizes and the visibility of the interference fringes was observed. It was found that visibility of the interference fringes changes drastically in presence of variable slit kept in front of LEDs and a high degree of spectral coherence, typically 0.85 for red and 0.8 for green LED with double-slit separation of 400 μm and rectangular slit opening of 500 μm was observed. The experimental results are compared with the theoretical counterparts. Coherence lengths of both the LEDs were also determined and it was obtained 5.8±2 and 24±4 μm for green and red LEDs, respectively.

Coherent changes of wintertime surface air temperatures over North Asia and North America.

Science.gov (United States)

Yu, Bin; Lin, Hai

2018-03-29

The surface temperature variance and its potential change with global warming are most prominent in winter over Northern Hemisphere mid-high latitudes. Consistent wintertime surface temperature variability has been observed over large areas in Eurasia and North America on a broad range of time scales. However, it remains a challenge to quantify where and how the coherent change of temperature anomalies occur over the two continents. Here we demonstrate the coherent change of wintertime surface temperature anomalies over North Asia and the central-eastern parts of North America for the period from 1951 to 2015. This is supported by the results from the empirical orthogonal function analysis of surface temperature and temperature trend anomalies over the Northern Hemisphere extratropical lands and the timeseries analysis of the regional averaged temperature anomalies over North Asia and the Great Plains and Great Lakes. The Asian-Bering-North American (ABNA) teleconnection provides a pathway to connect the regional temperature anomalies over the two continents. The ABNA is also responsible for the decadal variation of the temperature relationship between North Asia and North America.

Occupational stress, sense of coherence, coping, burnout and work engagement of registered nurses in South Africa

Directory of Open Access Journals (Sweden)

Johanna J. van der Colff

2009-02-01

Full Text Available The aim of this study was to assess the relationship between the occupational stress, sense of coherence, coping, burnout and work engagement of registered nurses in South Africa. A cross-sectional survey design was used. The study population consisted of 818 registered nurses. The Nursing Stress Inventory, the Orientation to Life Questionnaire, the COPE, the Maslach Burnout Inventory-Human Services Survey, and the Utrecht Work Engagement Scale were administered. The results show that the experience of depletion of emotional resources and feelings of depersonalisation by registered nurses were associated with stress due to job demands and a lack of organisational support, focus on and ventilation of emotions as a coping strategy, and a weak sense of coherence. Work engagement was predicted by a strong sense of coherence and approach-coping strategies.

Celebrating the Year of Light….. from medicine to security with Optical Coherence Tomography

CSIR Research Space (South Africa)

Singh, A

2015-10-01

Full Text Available medicine to security with Optical Coherence Tomography Ann Singh1, Ameeth Sharma1, Ted Roberts1, Rethabile Khutlang2, Rocky Ramokolo1, Nico Marome1, Leandra Webb2, Natasha Botha2,Aletta Karsten3, Hencharl Strauss1 1 CSIR, National Laser Centre, P.O Box...

Modulation of EMG-EMG Coherence in a Choice Stepping Task

Directory of Open Access Journals (Sweden)

Ippei Nojima

2018-02-01

Full Text Available The voluntary step execution task is a popular measure for identifying fall risks among elderly individuals in the community setting because most falls have been reported to occur during movement. However, the neurophysiological functions during this movement are not entirely understood. Here, we used electromyography (EMG to explore the relationship between EMG-EMG coherence, which reflects common oscillatory drive to motoneurons, and motor performance associated with stepping tasks: simple reaction time (SRT and choice reaction time (CRT tasks. Ten healthy elderly adults participated in the study. Participants took a single step forward in response to a visual imperative stimulus. EMG-EMG coherence was analyzed for 1000 ms before the presentation of the stimulus (stationary standing position from proximal and distal tibialis anterior (TA and soleus (SOL muscles. The main result showed that all paired EMG-EMG coherences in the alpha and beta frequency bands were greater in the SRT than the CRT task. This finding suggests that the common oscillatory drive to the motoneurons during the SRT task occurred prior to taking a step, whereas the lower value of corticospinal activity during the CRT task prior to taking a step may indicate an involvement of inhibitory activity, which is consistent with observations from our previous study (Watanabe et al., 2016. Furthermore, the beta band coherence in intramuscular TA tended to positively correlate with the number of performance errors that are associated with fall risks in the CRT task, suggesting that a reduction in the inhibitory activity may result in a decrease of stepping performance. These findings could advance the understanding of the neurophysiological features of postural adjustments in elderly individuals.

Coherent states: a contemporary panorama Coherent states: a contemporary panorama

Science.gov (United States)

Twareque Ali, S.; Antoine, Jean-Pierre; Bagarello, Fabio; Gazeau, Jean-Pierre

2012-06-01

Coherent states (CS) of the harmonic oscillator (also called canonical CS) were introduced in 1926 by Schrödinger in answer to a remark by Lorentz on the classical interpretation of the wave function. They were rediscovered in the early 1960s, first (somewhat implicitly) by Klauder in the context of a novel representation of quantum states, then by Glauber and Sudarshan for the description of coherence in lasers. Since then, CS have grown into an extremely rich domain that pervades almost every corner of physics and have also led to the development of several flourishing topics in mathematics. Along the way, a number of review articles have appeared in the literature, devoted to CS, notably the 1985 reprint volume of Klauder and Skagerstam [1], the 1990 review paper by Zhang et al [2], the 1993 Oak Ridge Conference [3] and the 1995 review paper by Ali et al [4]. Textbooks also have been published, among which one might mention the ground breaking text of Perelomov [5] focusing on the group-theoretical aspects, that of Ali et al [6]1 analyzing systematically the mathematical structure beyond the group-theoretical approach and also the relation to wavelet analysis, that of Dodonov and Man'ko [7] mostly devoted to quantum optics, that of Gazeau [8] more oriented towards the physical, probabilistic and quantization aspects, and finally the very recent one by Combescure and Robert [9]. In retrospect, one can see that the development of CS has gone through a two-phase transition. First, the (simultaneous) discovery in 1972 by Gilmore and Perelomov that CS were rooted in group theory, then the realization that CS can be defined in a purely algebraic way, as an eigenvalue problem or by a series expansion (Malkin and Man'ko 1969, Barut and Girardello 1971, Gazeau and Klauder 1999; references to the original articles may be found in the textbooks quoted above). Both facts resulted in an explosive expansion of the CS literature. We thought, therefore, that the time was ripe

A Coherence Preservation Control Strategy in Cavity QED Based on Classical Quantum Feedback

Directory of Open Access Journals (Sweden)

Ming Li

2013-01-01

Full Text Available For eliminating the unexpected decoherence effect in cavity quantum electrodynamics (cavity QED, the transfer function of Rabi oscillation is derived theoretically using optical Bloch equations. In particular, the decoherence in cavity QED from the atomic spontaneous emission is especially considered. A feedback control strategy is proposed to preserve the coherence through Rabi oscillation stabilization. In the scheme, a classical quantum feedback channel for the quantum information acquisition is constructed via the quantum tomography technology, and a compensation system based on the root locus theory is put forward to suppress the atomic spontaneous emission and the associated decoherence. The simulation results have proved its effectiveness and superiority for the coherence preservation.

Directly Measuring the Degree of Quantum Coherence using Interference Fringes

Science.gov (United States)

Wang, Yi-Tao; Tang, Jian-Shun; Wei, Zhi-Yuan; Yu, Shang; Ke, Zhi-Jin; Xu, Xiao-Ye; Li, Chuan-Feng; Guo, Guang-Can

2017-01-01

Quantum coherence is the most distinguished feature of quantum mechanics. It lies at the heart of the quantum-information technologies as the fundamental resource and is also related to other quantum resources, including entanglement. It plays a critical role in various fields, even in biology. Nevertheless, the rigorous and systematic resource-theoretic framework of coherence has just been developed recently, and several coherence measures are proposed. Experimentally, the usual method to measure coherence is to perform state tomography and use mathematical expressions. Here, we alternatively develop a method to measure coherence directly using its most essential behavior—the interference fringes. The ancilla states are mixed into the target state with various ratios, and the minimal ratio that makes the interference fringes of the "mixed state" vanish is taken as the quantity of coherence. We also use the witness observable to witness coherence, and the optimal witness constitutes another direct method to measure coherence. For comparison, we perform tomography and calculate l1 norm of coherence, which coincides with the results of the other two methods in our situation. Our methods are explicit and robust, providing a nice alternative to the tomographic technique.

Emergence of the Coherent Structure of Liquid Water

Directory of Open Access Journals (Sweden)

Ivan Bono

2012-07-01

Full Text Available We examine in some detail the interaction of water molecules with the radiative electromagnetic field and find the existence of phase transitions from the vapor phase to a condensed phase where all molecules oscillate in unison, in tune with a self-trapped electromagnetic field within extended mesoscopic space regions (Coherence Domains. The properties of such a condensed phase are examined and found to be compatible with the phenomenological properties of liquid water. In particular, the observed value of critical density is calculated with good accuracy.

Coherent and squeezed states in phase space

International Nuclear Information System (INIS)

Jannussis, A.; Bartzis, V.; Vlahos, E.

1990-01-01

In the present paper, the coherent and the squeezed states in phase space have been studied. From the wave functions of the coherent and the squeezed state, their corresponding Wigner distribution functions are calculated. Especially the calculation of the corresponding Wigner functions for the above states permits the determination of the mean values of position and momentum and thus the Heisenberg uncertainty relation. In fact, from the related results, it is concluded that the uncertainty relation of the coherent and associated squeezed states is the same

Self-Care, Sense Of Coherence And Depression In Patients Hospitalized For Decompensated Heart Failure

Directory of Open Access Journals (Sweden)

Viviane Martinelli Pelegrino Ferreira

2015-06-01

Full Text Available OBJECTIVE To analyze the self-care behaviors according to gender, the symptoms of depression and sense of coherence and compare the measurements of depression and sense of coherence according to gender. METHOD A correlational, cross-sectional study that investigated 132 patients with decompensated heart failure (HF. Data were collected through interviews and consultation to medical records, and analyzed using the chi-square and the Student's t tests with significance level of 0.05. Participants were 75 men and 57 women, aged 63.2 years on average (SD = 13.8. RESULTS No differences in self-care behavior by gender were found, except for rest after physical activity (p = 0.017. Patients who practiced physical activity showed fewer symptoms of depression (p<0.001. There were no differences in sense of coherence according to self-care behavior and gender. Women had more symptoms of depression than men (p = 0.002. CONCLUSION Special attention should be given to women with HF considering self-care and depressive symptoms.

A metadata initiative for global information discovery

Science.gov (United States)

Christian, E.

2001-01-01

The Global Information Locator Service (GILS) encompasses a global vision framed by the fundamental values of open societies. Societal values such as a free flow of information impose certain requirements on the society's information infrastructure. These requirements in turn shape the various laws, policies, standards, and technologies that determine the infrastructure design. A particular focus of GILS is the requirement to provide the means for people to discover sources of data and information. Information discovery in the GILS vision is designed to be decentralized yet coherent, and globally comprehensive yet useful for detailed data. This article introduces basic concepts and design issues, with emphasis on the techniques by which GILS supports interoperability. It explains the practical implications of GILS for the common roles of organizations involved in handling information, from content provider through system engineer and intermediary to searcher. The article provides examples of GILS initiatives in various types of communities: bibliographic, geographic, environmental, and government. ?? 2001 Elsevier Science Inc.

Color coherence in W + jet events

International Nuclear Information System (INIS)

Abbott, B.

1997-11-01

We report on preliminary studies of color coherence effects in p anti p collisions, based on data collected by the D0 detector during the 1994-1995 run of the Fermilab Tevatron collider, at a center of mass energy √s = 1.8 TeV. Color interference effects are studied by examining particle distribution patterns in W + Jet events. The data are compared to Monte Carlo simulations with different color coherence implementations and to a recent analytic Modified-Leading-Log perturbative calculation based on the Local Parton-Hadron Duality hypothesis. Soft particle radiation is enhanced in the event plane relative to the transverse plane, in agreement with calculations in which the effects of color coherence are fully included

Long coherence times for edge spins

Science.gov (United States)

Kemp, Jack; Yao, Norman Y.; Laumann, Christopher R.; Fendley, Paul

2017-06-01

We show that in certain one-dimensional spin chains with open boundary conditions, the edge spins retain memory of their initial state for very long times, even at infinite temperature. The long coherence times do not require disorder, only an ordered phase. In the integrable Ising and XYZ chains, the presence of a strong zero mode means the coherence time is infinite. When Ising is perturbed by interactions breaking the integrability, the coherence time remains exponentially long in the perturbing couplings. We show that this is a consequence of an edge ‘almost’ strong zero mode that almost commutes with the Hamiltonian. We compute this operator explicitly, allowing us to estimate accurately the plateau value of edge spin autocorrelator.

Coherent active polarization control without loss

Science.gov (United States)

Ye, Yuqian; Hay, Darrick; Shi, Zhimin

2017-11-01

We propose a lossless active polarization control mechanism utilizing an anisotropic dielectric medium with two coherent inputs. Using scattering matrix analysis, we derive analytically the required optical properties of the anisotropic medium that can behave as a switchable polarizing beam splitter. We also show that such a designed anisotropic medium can produce linearly polarized light at any azimuthal direction through coherent control of two inputs with a specific polarization state. Furthermore, we present a straightforward design-on-demand procedure of a subwavelength-thick metastructure that can possess the desired optical anisotropy at a flexible working wavelength. Our lossless coherent polarization control technique may lead to fast, broadband and integrated polarization control elements for applications in imaging, spectroscopy, and telecommunication.

Weak central coherence in weight-restored adolescent anorexia nervosa: Characteristics and remediation.

Science.gov (United States)

Weinbach, Noam; Perry, Amit; Sher, Helene; Lock, James D; Henik, Avishai

2017-08-01

Weak central coherence (WCC) refers to a bias towards processing details (local processing) at the expense of paying attention to the bigger picture (global processing). Multiple studies reported WCC in adults with anorexia nervosa (AN). Evidence for WCC in adolescents with AN has been inconsistent. The current study characterizes WCC in weight-restored adolescents with AN (WR-AN) using a direct measure of WCC, and examines whether WCC can be remediated by increasing alertness level-a manipulation that was found useful in enhancing global processing in healthy individuals and clinical populations. 40 adolescents (18 WR-AN and 22 healthy adolescents) performed a global/local processing task (Navon task). Auditory alerting cues that elevate alertness level were integrated into the task. Both groups processed global information faster than local information. However, compared with controls, adolescents with WR-AN were better at ignoring an irrelevant bigger picture while attending to details (smaller global interference) and had greater difficulty ignoring irrelevant details while attending to the bigger picture (larger local interference). These differences were attenuated when adolescents with WR-AN were under a state of high alertness. Additionally, the local interference effect was positively correlated with three independent self-report questionnaires assessing eating disorders symptomatology. This study suggests that abnormal interference by irrelevant global and local information is a central characteristic of WCC in adolescents with WR-AN that cannot be accounted for by enduring illness or malnourishment. Additionally, this study demonstrates that WCC can be temporarily remediated by encouraging a state of high alertness. © 2017 Wiley Periodicals, Inc.

Symmetric configurations highlighted by collective quantum coherence

Energy Technology Data Exchange (ETDEWEB)

Obster, Dennis [Radboud University, Institute for Mathematics, Astrophysics and Particle Physics, Nijmegen (Netherlands); Kyoto University, Yukawa Institute for Theoretical Physics, Kyoto (Japan); Sasakura, Naoki [Kyoto University, Yukawa Institute for Theoretical Physics, Kyoto (Japan)

2017-11-15

Recent developments in quantum gravity have shown the Lorentzian treatment to be a fruitful approach towards the emergence of macroscopic space-times. In this paper, we discuss another related aspect of the Lorentzian treatment: we argue that collective quantum coherence may provide a simple mechanism for highlighting symmetric configurations over generic non-symmetric ones. After presenting the general framework of the mechanism, we show the phenomenon in some concrete simple examples in the randomly connected tensor network, which is tightly related to a certain model of quantum gravity, i.e., the canonical tensor model. We find large peaks at configurations invariant under Lie-group symmetries as well as a preference for charge quantization, even in the Abelian case. In future study, this simple mechanism may provide a way to analyze the emergence of macroscopic space-times with global symmetries as well as various other symmetries existing in nature, which are usually postulated. (orig.)

Hilbert-Schmidt quantum coherence in multi-qudit systems

Science.gov (United States)

Maziero, Jonas

2017-11-01

Using Bloch's parametrization for qudits ( d-level quantum systems), we write the Hilbert-Schmidt distance (HSD) between two generic n-qudit states as an Euclidean distance between two vectors of observables mean values in R^{Π_{s=1}nds2-1}, where ds is the dimension for qudit s. Then, applying the generalized Gell-Mann's matrices to generate SU(ds), we use that result to obtain the Hilbert-Schmidt quantum coherence (HSC) of n-qudit systems. As examples, we consider in detail one-qubit, one-qutrit, two-qubit, and two copies of one-qubit states. In this last case, the possibility for controlling local and non-local coherences by tuning local populations is studied, and the contrasting behaviors of HSC, l1-norm coherence, and relative entropy of coherence in this regard are noticed. We also investigate the decoherent dynamics of these coherence functions under the action of qutrit dephasing and dissipation channels. At last, we analyze the non-monotonicity of HSD under tensor products and report the first instance of a consequence (for coherence quantification) of this kind of property of a quantum distance measure.

Extreme sub-wavelength atom localization via coherent population trapping

OpenAIRE

Agarwal, Girish S.; Kapale, Kishore T.

2005-01-01

We demonstrate an atom localization scheme based on monitoring of the atomic coherences. We consider atomic transitions in a Lambda configuration where the control field is a standing wave field. The probe field and the control field produce coherence between the two ground states. We show that this coherence has the same fringe pattern as produced by a Fabry-Perot interferometer and thus measurement of the atomic coherence would localize the atom. Interestingly enough the role of the cavity ...

MORPHOLOGICAL STRATEGIES IN TEXT MESSAGING AMONG ...

African Journals Online (AJOL)

Text messaging is the application of abridged morphological forms in order ... the emergence of the Global System for Mobile Communication (GSM) in the world. ... Our thesis statement is that these morphological patterns as used in SMS are ...

Manipulating Quantum Coherence in Solid State Systems

CERN Document Server

Flatté, Michael E; The NATO Advanced Study Institute "Manipulating Quantum Coherence in Solid State Systems"

2007-01-01

The NATO Advanced Study Institute "Manipulating Quantum Coherence in Solid State Systems", in Cluj-Napoca, Romania, August 29-September 9, 2005, presented a fundamental introduction to solid-state approaches to achieving quantum computation. This proceedings volume describes the properties of quantum coherence in semiconductor spin-based systems and the behavior of quantum coherence in superconducting systems. Semiconductor spin-based approaches to quantum computation have made tremendous advances in the past several years. Coherent populations of spins can be oriented, manipulated and detected experimentally. Rapid progress has been made towards performing the same tasks on individual spins (nuclear, ionic, or electronic) with all-electrical means. Superconducting approaches to quantum computation have demonstrated single qubits based on charge eigenstates as well as flux eigenstates. These topics have been presented in a pedagogical fashion by leading researchers in the fields of semiconductor-spin-based qu...

Is Social Categorization the Missing Link between Weak Central Coherence and Mental State Inference Abilities in Autism? Preliminary Evidence from a General Population Sample

Science.gov (United States)

Skorich, Daniel P.; May, Adrienne R.; Talipski, Louisa A.; Hall, Marnie H.; Dolstra, Anita J.; Gash, Tahlia B.; Gunningham, Beth H.

2016-01-01

We explore the relationship between the "theory of mind" (ToM) and "central coherence" difficulties of autism. We introduce covariation between hierarchically-embedded categories and social information--at the local level, the global level, or at both levels simultaneously--within a category confusion task. We then ask…

Significance tests for the wavelet cross spectrum and wavelet linear coherence

Directory of Open Access Journals (Sweden)

Z. Ge

2008-12-01

Full Text Available This work attempts to develop significance tests for the wavelet cross spectrum and the wavelet linear coherence as a follow-up study on Ge (2007. Conventional approaches that are used by Torrence and Compo (1998 based on stationary background noise time series were used here in estimating the sampling distributions of the wavelet cross spectrum and the wavelet linear coherence. The sampling distributions are then used for establishing significance levels for these two wavelet-based quantities. In addition to these two wavelet quantities, properties of the phase angle of the wavelet cross spectrum of, or the phase difference between, two Gaussian white noise series are discussed. It is found that the tangent of the principal part of the phase angle approximately has a standard Cauchy distribution and the phase angle is uniformly distributed, which makes it impossible to establish significance levels for the phase angle. The simulated signals clearly show that, when there is no linear relation between the two analysed signals, the phase angle disperses into the entire range of [−π,π] with fairly high probabilities for values close to ±π to occur. Conversely, when linear relations are present, the phase angle of the wavelet cross spectrum settles around an associated value with considerably reduced fluctuations. When two signals are linearly coupled, their wavelet linear coherence will attain values close to one. The significance test of the wavelet linear coherence can therefore be used to complement the inspection of the phase angle of the wavelet cross spectrum. The developed significance tests are also applied to actual data sets, simultaneously recorded wind speed and wave elevation series measured from a NOAA buoy on Lake Michigan. Significance levels of the wavelet cross spectrum and the wavelet linear coherence between the winds and the waves reasonably separated meaningful peaks from those generated by randomness in the data set. As

Globalisation and global health governance: implications for public health.

Science.gov (United States)

Kruk, Margaret E

2012-01-01

Globalisation is a defining economic and social trend of the past several decades. Globalisation affects health directly and indirectly and creates economic and health disparities within and across countries. The political response to address these disparities, exemplified by the Millennium Development Goals, has put pressure on the global community to redress massive inequities in health and other determinants of human capability across countries. This, in turn, has accelerated a transformation in the architecture of global health governance. The entrance of new actors, such as private foundations and multi-stakeholder initiatives, contributed to a doubling of funds for global health between 2000 and 2010. Today the governance of public health is in flux, with diminished leadership from multilateral institutions, such as the WHO, and poor coherence in policy and programming that undermines the potential for sustainable health gains. These trends pose new challenges and opportunities for global public health, which is centrally concerned with identifying and addressing threats to the health of vulnerable populations worldwide.

In Search of Moral Coherence: Reconciling Uneasy Histories and Identities

Directory of Open Access Journals (Sweden)

Katy Campbell PhD

2008-12-01

Full Text Available Through an autoethnographic account the authors explore the various entanglements, ambiguities, and conflicts inherent in the research relationships of institutionally marginalized communities. Agency and moral coherence are constructs with which personal, political, and sociocultural dimensions of negotiating a research identity are framed. They use a feminist lens to examine relations, autoethnography to reflexively examine these relations, and poststructuralist notions to illuminate cultural influences on the shifting identity of one actor.

Multilevel use of coherence for complex radiosity environments

OpenAIRE

Vilaplana Pasto, Josep; Pueyo Sánchez, Xavier

1993-01-01

The performance of radiosity algorithm has been improved in the last years by means of using coherence when evaluating the visibility function for form factor computation. We present here a characterization of the uses of coherence for this goal. The characterization includes both, previously proposed techniques and unexplored ones. Afterwards we propose new uses of coherence for visibility computation in form factor determination and we discuss the results of its implementation.

Petroleum Pumps’ Current and Vibration Signatures Analysis Using Wavelet Coherence Technique

Directory of Open Access Journals (Sweden)

Rmdan Shnibha

2013-01-01

Full Text Available Vibration analysis is widely used for rotating machinery diagnostics; however measuring vibration of operational oil well pumps is not possible. The pump’s driver’s current signatures may provide condition-related information without the need for an access to the pump itself. This paper investigates the degree of relationship between the pump’s driver’s current signatures and its induced vibration. This relationship between the driver’s current signatures (DCS and its vibration signatures (DVS is studied by calculating magnitude-squared coherence and phase coherence parameters at a certain frequency band using continuous wavelet transform (CWT. The CWT coherence-based technique allows better analysis of temporal evolution of the frequency content of dynamic signals and areas in the time-frequency plane where the two signals exhibit common power or consistent phase behaviour indicating a relationship between the signals. This novel approach is validated by experimental data acquired from 3 kW petroleum pump’s driver. Both vibration and current signatures were acquired under different speed and load conditions. The outcomes of this research suggest the use of DCS analysis as reliable and inexpensive condition monitoring tool, which could be implemented for oil pumps, real-time monitoring associated with condition-based maintenance (CBM program.

A Cache System Design for CMPs with Built-In Coherence Verification

Directory of Open Access Journals (Sweden)

Mamata Dalui

2016-01-01

Full Text Available This work reports an effective design of cache system for Chip Multiprocessors (CMPs. It introduces built-in logic for verification of cache coherence in CMPs realizing directory based protocol. It is developed around the cellular automata (CA machine, invented by John von Neumann in the 1950s. A special class of CA referred to as single length cycle 2-attractor cellular automata (TACA has been planted to detect the inconsistencies in cache line states of processors’ private caches. The TACA module captures coherence status of the CMPs’ cache system and memorizes any inconsistent recording of the cache line states during the processors’ reference to a memory block. Theory has been developed to empower a TACA to analyse the cache state updates and then to settle to an attractor state indicating quick decision on a faulty recording of cache line status. The introduction of segmentation of the CMPs’ processor pool ensures a better efficiency, in determining the inconsistencies, by reducing the number of computation steps in the verification logic. The hardware requirement for the verification logic points to the fact that the overhead of proposed coherence verification module is much lesser than that of the conventional verification units and is insignificant with respect to the cost involved in CMPs’ cache system.

Elastic energies of coherent germanium islands on silicon

International Nuclear Information System (INIS)

Vanderbilt, D.; Wickham, L.K.

1991-01-01

Motivated by recent observations of coherent Ge island formation during growth of Ge on Si (100), the authors of this paper have carried out a theoretical study of the elastic energies associated with the evolution of a uniform strained overlayer as it segregates into coherent islands. In the context of a two-dimensional model, the authors have explored the conditions under which coherent islands may be energetically favored over both uniform epitaxial films and dislocated islands. The authors find that if the interface energy (for dislocated islands) is more than about 15% of the surface energy, then there is a range of island sizes for which the coherent island structure is preferred

Coherent lattice vibrations in superconductors

International Nuclear Information System (INIS)

Kadin, Alan M.

2008-01-01

A recent analysis has shown that the pair wavefunction within the BCS theory may be represented in real-space as a spherical electronic orbital (on the scale of the coherence length ξ 0 ) coupled to a standing-wave lattice vibration with wavevector 2k F and a near-resonant phonon frequency. The present paper extends this picture to a coherent pattern of phonon standing-waves on the macroscopic scale, with electrons forming Bloch waves and an energy gap much like those in the classic band theory of crystals. These parallel planes form a diffractive waveguide permitting electron waves to traveling parallel to the planes, corresponding to lossless supercurrent. A similar picture may be extended to unconventional superconductors such as the cuprates, with an array of standing spin waves rather than phonons. Such coherent lattice vibrations should be universal indicators of the superconducting state, and should be observable below T c using X-ray and neutron diffraction techniques. Further implications of this picture are discussed

Propagation of partially coherent Lorentz-Gauss vortex beam through oceanic turbulence.

Science.gov (United States)

Liu, Dajun; Yin, Hongming; Wang, Guiqiu; Wang, Yaochuan

2017-11-01

The partially coherent Lorentz-Gauss vortex beam generated by a Schell-model source has been introduced. Based on the extended Huygens-Fresnel principle, the cross-spectral density function of a partially coherent Lorentz-Gauss vortex beam propagating in oceanic turbulence is derived. The influences of coherence length, topological charge M, and oceanic turbulence on the spreading properties and position of the coherence vortex for a partially coherent Lorentz-Gauss vortex beam are analyzed in detail. The results show that a partially coherent Lorentz-Gauss vortex beam propagating in stronger oceanic turbulence will evolve into a Gaussian-like beam more rapidly as the propagation distance increases, and the number of coherent vortices will change.

Emotion regulation and emotion coherence: evidence for strategy-specific effects.

Science.gov (United States)

Dan-Glauser, Elise S; Gross, James J

2013-10-01

One of the central tenets of emotion theory is that emotions involve coordinated changes across experiential, behavioral, and physiological response domains. Surprisingly little is known, however, about how the strength of this emotion coherence is altered when people try to regulate their emotions. To address this issue, we recorded experiential, behavioral, and physiological responses while participants watched negative and positive pictures. Cross-correlations were used to quantify emotion coherence. Study 1 tested how two types of suppression (expressive and physiological) influence coherence. Results showed that both strategies decreased the response coherence measured in negative and positive contexts. Study 2 tested how multichannel suppression (simultaneously targeting expressive and physiological responses) and acceptance influence emotion coherence. Results again showed that suppression decreased coherence. By contrast, acceptance was not significantly different from the unregulated condition. These findings help to clarify the nature of emotion response coherence by showing how different forms of emotion regulation may differentially affect it.

Emotion Regulation and Emotion Coherence: Evidence for Strategy-Specific Effects

Science.gov (United States)

Dan-Glauser, Elise S.; Gross, James J.

2014-01-01

One of the central tenets of emotion theory is that emotions involve coordinated changes across experiential, behavioral, and physiological response domains. Surprisingly little is known, however, on how the strength of this emotion coherence is altered when people try to regulate their emotions. To address this issue, we recorded experiential, behavioral, and physiological responses while participants watched negative and positive pictures. Cross-correlations were used to quantify emotion coherence. Study 1 tested how two types of suppression (expressive and physiological) influence coherence. Results showed that both strategies decreased the response coherence measured in negative and positive contexts. Study 2 tested how multi-channel suppression (simultaneously targeting expressive and physiological responses) and acceptance influence emotion coherence. Results again showed that suppression decreased coherence. By contrast, acceptance was not significantly different from the unregulated condition. These findings help to clarify the nature of emotion response coherence by showing how different forms of emotion regulation may differentially affect it. PMID:23731438

Coherent imaging with incoherent light in digital holographic microscopy

Science.gov (United States)

Chmelik, Radim

2012-01-01

Digital holographic microscope (DHM) allows for imaging with a quantitative phase contrast. In this way it becomes an important instrument, a completely non-invasive tool for a contrast intravital observation of living cells and a cell drymass density distribution measurement. A serious drawback of current DHMs is highly coherent illumination which makes the lateral resolution worse and impairs the image quality by a coherence noise and a parasitic interference. An uncompromising solution to this problem can be found in the Leith concept of incoherent holography. An off-axis hologram can be formed with arbitrary degree of light coherence in systems equipped with an achromatic interferometer and thus the resolution and the image quality typical for an incoherent-light wide-field microscopy can be achieved. In addition, advanced imaging modes based on limited coherence can be utilized. The typical example is a coherence-gating effect which provides a finite axial resolution and makes DHM image similar to that of a confocal microscope. These possibilities were described theoretically using the formalism of three-dimensional coherent transfer functions and proved experimentally by the coherence-controlled holographic microscope which is DHM based on the Leith achromatic interferometer. Quantitative-phase-contrast imaging is demonstrated with incoherent light by the living cancer cells observation and their motility evaluation. The coherence-gating effect was proved by imaging of model samples through a scattering layer and living cells inside an opalescent medium.

Modes of storage ring coherent instabilities

Energy Technology Data Exchange (ETDEWEB)

Wang, J.M.

1986-12-01

Longitudinal impedance in a beam and various modes of longitudinal coherent instabilities are discussed. The coasting beam coherent instability, microwave instability, and single-bunch longitudinal coherent instabilities are considered. The Vlasov equation is formulated, and a method of solving it is developed. The synchrotron modes are treated, which take the possible bunch shape distortion fully into consideration. A method of treating the synchrotron mode coupling in the case of a small bunch is discussed which takes advantage of the fact that only a few of the synchrotron modes can contribute in such a case. The effect of many bunches on the coherent motion of the beam and the longitudinal symmetric coupled bunch modes are discussed. The transverse impedance is then introduced, and the transverse coasting beam instability is discussed. Various bunched beam instabilities are discussed, including both single bunch instabilities and coupled bunch instabilities. The Vlasov equation for transverse as well as longitudinal motion of particles is introduced as well as a method of solving it within a linear approximation. Head-tail modes and short bunch instabilities and strong coupling instabilities in the long bunch case are covered. (LEW)

Modes of storage ring coherent instabilities

International Nuclear Information System (INIS)

Wang, J.M.

1986-12-01

Longitudinal impedance in a beam and various modes of longitudinal coherent instabilities are discussed. The coasting beam coherent instability, microwave instability, and single-bunch longitudinal coherent instabilities are considered. The Vlasov equation is formulated, and a method of solving it is developed. The synchrotron modes are treated, which take the possible bunch shape distortion fully into consideration. A method of treating the synchrotron mode coupling in the case of a small bunch is discussed which takes advantage of the fact that only a few of the synchrotron modes can contribute in such a case. The effect of many bunches on the coherent motion of the beam and the longitudinal symmetric coupled bunch modes are discussed. The transverse impedance is then introduced, and the transverse coasting beam instability is discussed. Various bunched beam instabilities are discussed, including both single bunch instabilities and coupled bunch instabilities. The Vlasov equation for transverse as well as longitudinal motion of particles is introduced as well as a method of solving it within a linear approximation. Head-tail modes and short bunch instabilities and strong coupling instabilities in the long bunch case are covered

Interpreting quantum coherence through a quantum measurement process

Science.gov (United States)

Yao, Yao; Dong, G. H.; Xiao, Xing; Li, Mo; Sun, C. P.

2017-11-01

Recently, there has been a renewed interest in the quantification of coherence or other coherencelike concepts within the framework of quantum resource theory. However, rigorously defined or not, the notion of coherence or decoherence has already been used by the community for decades since the advent of quantum theory. Intuitively, the definitions of coherence and decoherence should be two sides of the same coin. Therefore, a natural question is raised: How can the conventional decoherence processes, such as the von Neumann-Lüders (projective) measurement postulation or partially dephasing channels, fit into the bigger picture of the recently established theoretical framework? Here we show that the state collapse rules of the von Neumann or Lüders-type measurements, as special cases of genuinely incoherent operations (GIOs), are consistent with the resource theories of quantum coherence. New hierarchical measures of coherence are proposed for the Lüders-type measurement and their relationship with measurement-dependent discord is addressed. Moreover, utilizing the fixed-point theory for C* algebra, we prove that GIOs indeed represent a particular type of partially dephasing (phase-damping) channels which have a matrix representation based on the Schur product. By virtue of the Stinespring dilation theorem, the physical realizations of incoherent operations are investigated in detail and we find that GIOs in fact constitute the core of strictly incoherent operations and generally incoherent operations and the unspeakable notion of coherence induced by GIOs can be transferred to the theories of speakable coherence by the corresponding permutation or relabeling operators.

Coherent hard x-ray focusing optics and applications

Energy Technology Data Exchange (ETDEWEB)

Yun, W.B.; Viccaro, P.J.; Chrzas, J.; Lai, B.

1991-01-01

Coherent hard x-ray beams with a flux exceeding 10{sup 9} photons/second with a bandwidth of 0.1% will be provided by the undulator at the third generation synchrotron radiation sources such as APS, ESRF, and Spring-8. The availability of such high flux coherent x-ray beams offers excellent opportunities for extending the coherence-based techniques developed in the visible and soft x-ray part of the electromagnetic spectrum to the hard x-rays. These x-ray techniques (e.g., diffraction limited microfocusing, holography, interferometry, phase contrast imaging and signal enhancement), may offer substantial advantages over non-coherence-based x-ray techniques currently used. For example, the signal enhancement technique may be used to enhance an anomalous x-ray or magnetic x-ray scattering signal by several orders of magnitude. Coherent x-rays can be focused to a very small (diffraction-limited) spot size, thus allowing high spatial resolution microprobes to be constructed. The paper will discuss the feasibility of the extension of some coherence-based techniques to the hard x-ray range and the significant progress that has been made in the development of diffraction-limited focusing optics. Specific experimental results for a transmission Fresnel phase zone plate that can focus 8.2 keV x-rays to a spot size of about 2 microns will be briefly discussed. The comparison of measured focusing efficiency of the zone plate with that calculated will be made. Some specific applications of zone plates as coherent x-ray optics will be discussed. 17 refs., 4 figs.

Order in the turbulent phase of globally coupled maps

International Nuclear Information System (INIS)

Perez, G.; Sinha, S.; Cerdeira, H.A.

1991-04-01

The very surprising broad peaks seen in the power spectra of the mean field in a globally coupled map system, indicating subtle coherences between the elements even in the ''turbulent'' phase, are investigated in detail with respect to number of elements coupled, nonlinearity and global coupling strength. We find that the peaks are determined by two distinct components: effective renormalization of the nonlinearity parameter in the local mapping and the strength of the mean field iteration term. We also demonstrate the influence of background noise on the peaks - which is quite counterintuitive, as the peaks become sharper with increase in strength of noise, up to a certain critical noise strength. (author). 11 refs, 10 figs

Transient Aspects of Wave Propagation Connected with Spatial Coherence

Directory of Open Access Journals (Sweden)

Ezzat G. Bakhoum

2013-01-01

Full Text Available This study presents transient aspects of light wave propagation connected with spatial coherence. It is shown that reflection and refraction phenomena involve spatial patterns which are created within a certain transient time interval. After this transient time interval, these patterns act like a memory, determining the wave vector for subsequent sets of reflected/refracted waves. The validity of this model is based on intuitive aspects regarding phase conservation of energy for waves reflected/refracted by multiple centers in a certain material medium.

On formation of a partially coherent beam in a stable-resonator laser

International Nuclear Information System (INIS)

Suvorov, A A

2010-01-01

A new method involving the expansion of the field coherence function in partially coherent modes - the eigensolutions of the problem for the second-order coherence function in a stable resonator - is proposed for the theoretical description of the process of multimode laser beam formation. The method for solving the problem for arbitrary partially coherent modes is formulated and the expressions for these modes are derived in the general form. The characteristics of the fundamental partially coherent mode, which coincides with the coherence function of a Gaussian partially coherent beam, are analysed in detail. The partially coherent modes are shown to possess two spatial scales - the effective radius and the coherence radius, which makes them a convenient tool for solving the problem of generation of a partially coherent beam. It is found that the unambiguous relation between the characteristics of partially coherent modes and the stable-resonator parameters is achieved by involving into consideration not only the process of the beam formation by the resonator mirrors but also the process of interaction of radiation with the active laser medium. (laser beams and resonators)

Cohesion, Coherence, and the Construction of Discourse Objects: a Glimpse of a Sociocognitive and Interacional Perspective on Teaching of Writing

Directory of Open Access Journals (Sweden)

Silvia Augusta Albert Bachur

2016-07-01

Full Text Available This article aims at presenting how current theoretical advances on Text Linguistics in its sociocognitive and interactional perspective, by approaching the concepts of cohesion, coherence, and referentiation, may contribute to the pedagogical practice regarding the teaching and learning of writing vis-à-vis the development of writing proficiency. Hence, cohesion and coherence are considered the criteria for textualization, and both their reciprocity and their mutual determination in the referentiation process are here acknowledged. From this point view, the construction of cohesion and coherence is a dynamic process that occurs via inferences and cognitive devices to which the linguistic marks, the speakers’ interaction, and the context contribute. Accordingly, a selection of nominal forms in the building of representations of discourse objects is to be highlighted and related to the project of saying enounced by the herald of college entrance essays. The hypothesis is thus that, by constructing representations of discourse objects, referentiation establishes a groundwork for text structuring and provides hints to produce meaning in writing. The main studies this article is grounded on are Koch (2006, Marcuschi (2006; 2007; 2008, Cavalcante et al. (2010, and Bentes (2012.

Analytic coherent states for generalized potentials

International Nuclear Information System (INIS)

Nieto, M.M.; Simmons, L.M. Jr.

1978-01-01

A prescription is given for finding coherent states in generalized potentials. By coherent states is meant states which in time follow the motion that a classical particle would. This prescription is based upon finding those natural classical variables which vary as the sine and the cosine of the classical ω/sub c/t. As an example, the symmetric Rosen--Morse potential is discussed in detail

Completeness for coherent states in a magnetic–solenoid field

International Nuclear Information System (INIS)

Bagrov, V G; Gavrilov, S P; Gitman, D M; Górska, K

2012-01-01

This paper completes our study of coherent states in the so-called magnetic–solenoid field (a collinear combination of a constant uniform magnetic field and Aharonov–Bohm solenoid field) presented in Bagrov et al (2010 J. Phys. A: Math. Theor. 43 354016, 2011 J. Phys. A: Math. Theor. 44 055301). Here, we succeeded in proving nontrivial completeness relations for non-relativistic and relativistic coherent states in such a field. In addition, we solve here the relevant Stieltjes moment problem and present a comparative analysis of our coherent states and the well-known, in the case of pure uniform magnetic field, Malkin–Man’ko coherent states. This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical devoted to ‘Coherent states: mathematical and physical aspects’. (paper)

Propagation of partially coherent vector anomalous vortex beam in turbulent atmosphere

Science.gov (United States)

Zhang, Xu; Wang, Haiyan; Tang, Lei

2018-01-01

A theoretical model is proposed to describe a partially coherent vector anomalous vortex(AV) beam. Based on the extended Huygens-Fresnel principle, analytical propagation formula for the proposed beams in turbulent atmosphere is derived. The spectral properties of the partially coherent vector AV beam are explored by using the unified theory of coherence and polarization in detail. It is interesting to find that the turbulence of atmosphere and the source parameter of the partially coherent vector AV beam( order, topological charge, coherence length, beam waist size etc) have significantly impacted the propagation properties of the partially coherent vector AV beam in turbulent atmosphere.

Texte, intertexte et iconotexte dans le message publicitaire

Directory of Open Access Journals (Sweden)

I. C. CORJAN

2007-12-01

Full Text Available The paper states the fact that although the roles of the text and of the image in an advertisement are dynamic and appear in variable proportions depending on numerous criteria, they are also beautifully balanced, especially if compared from a functional point of view, determining and depending upon each other in a coherent discursive unity. Between text and image there are usually the following relations of reciprocity: support (argumentation, redundancy, paraphrase; complementarity (in-formation that is autonomous in form, but convergent in content; rhetorical amplification (meaning transfer, metaphorisation, hyperbolisation etc.; opposition (antithesis, exaggeration, non-antagonistic contradiction etc.. In general, both the verbal and the iconic develop, much to their mutual advantage, an extra meaning which the former establishes linguistically, and the latter exaggerates visually. In this case, however, the image always goes beyond the verbal information, thanks to its deep-rooted polysemy. Thus, in the special case of printed advertising, there are a few prevalent icono-textual structures, with obvious intertextual and paratextual functions: intertextuality of the writ-ten text; figurative iconic intertextuality; icono-textual intertextuality; double intertextuality: verbal-written and icono-textual. The end of the study puts forward a new formulation of the icono-text and of the typology of printed advertising included in written media and indoor/ outdoor posting.

Coherent Synchrotron Radiation: Theory and Simulations

International Nuclear Information System (INIS)

Novokhatski, Alexander

2012-01-01

The physics of coherent synchrotron radiation (CSR) emitted by ultra-relativistic electron bunches, known since the last century, has become increasingly important with the development of high peak current free electron lasers and shorter bunch lengths in storage rings. Coherent radiation can be described as a low frequency part of the familiar synchrotron radiation in bending magnets. As this part is independent of the electron energy, the fields of different electrons of a short bunch can be in phase and the total power of the radiation will be quadratic with the number of electrons. Naturally the frequency spectrum of the longitudinal electron distribution in a bunch is of the same importance as the overall electron bunch length. The interest in the utilization of high power radiation from the terahertz and far infrared region in the field of chemical, physical and biological processes has led synchrotron radiation facilities to pay more attention to the production of coherent radiation. Several laboratories have proposed the construction of a facility wholly dedicated to terahertz production using the coherent radiation in bending magnets initiated by the longitudinal instabilities in the ring. Existing synchrotron radiation facilities also consider such a possibility among their future plans. There is a beautiful introduction to CSR in the 'ICFA Beam Dynamics Newsletter' N 35 (Editor C. Biscari). In this paper we recall the basic properties of CSR from the theory and what new effects, we can get from the precise simulations of the coherent radiation using numerical solutions of Maxwell's equations. In particular, transverse variation of the particle energy loss in a bunch, discovered in these simulations, explains the slice emittance growth in bending magnets of the bunch compressors and transverse de-coherence in undulators. CSR may play same the role as the effect of quantum fluctuations of synchrotron radiation in damping rings. It can limit the minimum

GLOBAL CHANGES IN THE SEA ICE COVER AND ASSOCIATED SURFACE TEMPERATURE CHANGES

Directory of Open Access Journals (Sweden)

J. C. Comiso

2016-06-01

Full Text Available The trends in the sea ice cover in the two hemispheres have been observed to be asymmetric with the rate of change in the Arctic being negative at −3.8 % per decade while that of the Antarctic is positive at 1.7 % per decade. These observations are confirmed in this study through analyses of a more robust data set that has been enhanced for better consistency and updated for improved statistics. With reports of anthropogenic global warming such phenomenon appears physically counter intuitive but trend studies of surface temperature over the same time period show the occurrence of a similar asymmetry. Satellite surface temperature data show that while global warming is strong and dominant in the Arctic, it is relatively minor in the Antarctic with the trends in sea ice covered areas and surrounding ice free regions observed to be even negative. A strong correlation of ice extent with surface temperature is observed, especially during the growth season, and the observed trends in the sea ice cover are coherent with the trends in surface temperature. The trend of global averages of the ice cover is negative but modest and is consistent and compatible with the positive but modest trend in global surface temperature. A continuation of the trend would mean the disappearance of summer ice by the end of the century but modelling projections indicate that the summer ice could be salvaged if anthropogenic greenhouse gases in the atmosphere are kept constant at the current level.

Passive Double-Sensory Evoked Coherence Correlates with Long-Term Memory Capacity

Directory of Open Access Journals (Sweden)

Anna Horwitz

2017-12-01

Full Text Available HIGHLIGHTSMemory correlates with the difference between single and double-sensory evoked steady-state coherence in the gamma range (ΔC.The correlation is most pronounced for the anterior brain region (ΔCA.The correlation is not driven by birth size, education, speed of processing, or intelligence.The sensitivity of ΔCA for detecting low memory capacity is 90%.Cerebral rhythmic activity and oscillations are important pathways of communication between cortical cell assemblies and may be key factors in memory. We asked whether memory performance is related to gamma coherence in a non-task sensory steady-state stimulation. We investigated 40 healthy males born in 1953 who were part of a Danish birth cohort study. Coherence was measured in the gamma range in response to a single-sensory visual stimulation (36 Hz and a double-sensory combined audiovisual stimulation (auditive: 40 Hz; visual: 36 Hz. The individual difference in coherence (ΔC between the bimodal and monomodal stimulation was calculated for each subject and used as the main explanatory variable. ΔC in total brain were significantly negatively correlated with long-term verbal recall. This correlation was pronounced for the anterior region. In addition, the correlation between ΔC and long-term memory was robust when controlling for working memory, as well as a wide range of potentially confounding factors, including intelligence, length of education, speed of processing, visual attention and executive function. Moreover, we found that the difference in anterior coherence (ΔCA is a better predictor of memory than power in multivariate models. The sensitivity of ΔCA for detecting low memory capacity is 92%. Finally, ΔCA was also associated with other types of memory: verbal learning, visual recognition, and spatial memory, and these additional correlations were also robust enough to control for a range of potentially confounding factors. Thus, the ΔC is a predictor of memory

Quantifying quantum coherence with quantum Fisher information.

Science.gov (United States)

Feng, X N; Wei, L F

2017-11-14

Quantum coherence is one of the old but always important concepts in quantum mechanics, and now it has been regarded as a necessary resource for quantum information processing and quantum metrology. However, the question of how to quantify the quantum coherence has just been paid the attention recently (see, e.g., Baumgratz et al. PRL, 113. 140401 (2014)). In this paper we verify that the well-known quantum Fisher information (QFI) can be utilized to quantify the quantum coherence, as it satisfies the monotonicity under the typical incoherent operations and the convexity under the mixing of the quantum states. Differing from most of the pure axiomatic methods, quantifying quantum coherence by QFI could be experimentally testable, as the bound of the QFI is practically measurable. The validity of our proposal is specifically demonstrated with the typical phase-damping and depolarizing evolution processes of a generic single-qubit state, and also by comparing it with the other quantifying methods proposed previously.

Enhanced coherent undulator radiation from bunched electron beams

International Nuclear Information System (INIS)

Berryman, K.W.; Crosson, E.R.; Ricci, K.N.; Smith, T.I.

1996-01-01

When energetic bunches of electrons traverse an undulator field, they can spontaneously emit radiation both coherently and incoherently. Although it has generally been assumed that undulator radiation is incoherent at wavelengths short compared to the longitudinal size of the electron bunch, several recent observations have proved this assumption false. Furthermore, the appearance of coherent radiation is often accompanied by a significant increase in radiated power. Here we report observations of strongly enhanced coherent spontaneous radiation together with direct measurements, using transition radiation techniques, of the electron distributions responsible for the coherent emission. We also report demonstrated enhancements in the predicted spontaneous radiated power by as much as 6x10 4 using electron bunch compression. copyright 1996 American Institute of Physics

Coherent methods in X-ray scattering

International Nuclear Information System (INIS)

Gorobtsov, Oleg

2017-05-01

X-ray radiation has been used to study structural properties of materials for more than a hundred years. Construction of extremely coherent and bright X-ray radiation sources such as free electron lasers (FELs) and latest generationstorage rings led to rapid development of experimental methods relying on high radiation coherence. These methods allow to perform revolutionary studies in a wide range of fields from solid state physics to biology. In this thesis I focus on several important problems connected with the coherent methods. The first part considers applications of dynamical diffraction theory on crystals to studies with coherent X-ray radiation. It presents the design of a high-resolution spectrometer for free electron lasers that should allow to resolve spectral structure of individual FEL pulses. The spectrometer is based on the principle of dynamical diffraction focusing. The knowledge of individual FEL pulse spectra is necessary for understanding FEL longitudinal coherence. In the same part I present quasi-kinematical approximation to dynamical theory which allows to treat analytically phase effects observed in X-ray coherent imaging on nanocrystals. These effects may play a big role when methods such as ptychography are used to study crystalline samples. The second part deals with measurements of FEL coherence properties using intensity - intensity interferometry. Results of several experiments performed at FELs FLASH and LCLS are revealed in this section. I have developed models and theories to explain the behavior observed in experiments on FLASH. These models allowed to extract information about external positional jitter of FEL pulses and secondary beams present in FEL radiation. In the LCLS experiment the Hanbury Brown and Twiss type interferometry was performed on Bragg peaks from colloidal crystal. This did not require additional measurements without the sample and information was extracted directly from diffraction patterns. Therefore intensity

Coherent methods in X-ray scattering

Energy Technology Data Exchange (ETDEWEB)

Gorobtsov, Oleg

2017-05-15

X-ray radiation has been used to study structural properties of materials for more than a hundred years. Construction of extremely coherent and bright X-ray radiation sources such as free electron lasers (FELs) and latest generationstorage rings led to rapid development of experimental methods relying on high radiation coherence. These methods allow to perform revolutionary studies in a wide range of fields from solid state physics to biology. In this thesis I focus on several important problems connected with the coherent methods. The first part considers applications of dynamical diffraction theory on crystals to studies with coherent X-ray radiation. It presents the design of a high-resolution spectrometer for free electron lasers that should allow to resolve spectral structure of individual FEL pulses. The spectrometer is based on the principle of dynamical diffraction focusing. The knowledge of individual FEL pulse spectra is necessary for understanding FEL longitudinal coherence. In the same part I present quasi-kinematical approximation to dynamical theory which allows to treat analytically phase effects observed in X-ray coherent imaging on nanocrystals. These effects may play a big role when methods such as ptychography are used to study crystalline samples. The second part deals with measurements of FEL coherence properties using intensity - intensity interferometry. Results of several experiments performed at FELs FLASH and LCLS are revealed in this section. I have developed models and theories to explain the behavior observed in experiments on FLASH. These models allowed to extract information about external positional jitter of FEL pulses and secondary beams present in FEL radiation. In the LCLS experiment the Hanbury Brown and Twiss type interferometry was performed on Bragg peaks from colloidal crystal. This did not require additional measurements without the sample and information was extracted directly from diffraction patterns. Therefore intensity

Coherence and Coupling Functions Reveal Microvascular Impairment in Treated Hypertension

Directory of Open Access Journals (Sweden)

Valentina Ticcinelli

2017-10-01

Full Text Available The complex interactions that give rise to heart rate variability (HRV involve coupled physiological oscillators operating over a wide range of different frequencies and length-scales. Based on the premise that interactions are key to the functioning of complex systems, the time-dependent deterministic coupling parameters underlying cardiac, respiratory and vascular regulation have been investigated at both the central and microvascular levels. Hypertension was considered as an example of a globally altered state of the complex dynamics of the cardiovascular system. Its effects were established through analysis of simultaneous recordings of the electrocardiogram (ECG, respiratory effort, and microvascular blood flow [by laser Doppler flowmetry (LDF]. The signals were analyzed by methods developed to capture time-dependent dynamics, including the wavelet transform, wavelet-based phase coherence, non-linear mode decomposition, and dynamical Bayesian inference, all of which can encompass the inherent frequency and coupling variability of living systems. Phases of oscillatory modes corresponding to the cardiac (around 1.0 Hz, respiratory (around 0.25 Hz, and vascular myogenic activities (around 0.1 Hz were extracted and combined into two coupled networks describing the central and peripheral systems, respectively. The corresponding spectral powers and coupling functions were computed. The same measurements and analyses were performed for three groups of subjects: healthy young (Y group, 24.4 ± 3.4 y, healthy aged (A group, 71.1 ± 6.6 y, and aged treated hypertensive patients (ATH group, 70.3 ± 6.7 y. It was established that the degree of coherence between low-frequency oscillations near 0.1 Hz in blood flow and in HRV time series differs markedly between the groups, declining with age and nearly disappearing in treated hypertension. Comparing the two healthy groups it was found that the couplings to the cardiac rhythm from both respiration and

von Neumann's hypothesis concerning coherent states

International Nuclear Information System (INIS)

Zak, J

2003-01-01

An orthonormal basis of modified coherent states is constructed. Each member of the basis is an infinite sum of coherent states on a von Neumann lattice. A single state is assigned to each unit cell of area h (Planck constant) in the phase plane. The uncertainties of the coordinate x and the square of the momentum p 2 for these states are shown to be similar to those for the usual coherent states. Expansions in the newly established set are discussed and it is shown that any function in the kq-representation can be written as a sum of two fixed kq-functions. Approximate commuting operators for x and p 2 are defined on a lattice in phase plane according to von Neumann's prescription. (leeter to the editor)

Coherence in the Danish Healthcare System

DEFF Research Database (Denmark)

Frederiksen, Jesper; Olivares Bøgeskov, Benjamin Miguel

2017-01-01

In this article, we investigate ‘coherence in healthcare’ as a strategy of welfare policy. We conduct our investigation within the theoretical and methodological framework of Scandinavian praxeology, and we construct our empirical data from Danish administrative documents. The tools and terms...... of this tradition are used to generate data from discourse as representations of institutional logics. The aim is to uncover how coherence in healthcare emerges as different strategies in healthcare governance in relation to different institutions seen as positions. Hence, our findings suggest that, although...... the stated aim in policy is to improve coherence in healthcare for the benefit of the patients, various ambiguities within the institutions producing policy tend to maintain a certain order rather than introducing changes. Furthermore, we discuss how this section of the welfare state, examined in relation...

Globalization challenges in a globalized world

Directory of Open Access Journals (Sweden)

Dr.Sc. Gjon Boriçi

2016-01-01

Full Text Available Globalization is an ongoing phenomenon trying to redefine the economic, social, cultural and political dynamics of contemporary societies. The communication among countries and not only them, has been increased expanding political ties, making possible greater economic integration and wider cultural relations combined with augmented global wealth across the world. But, the process of globalization is in wider terms considered a beneficial one, but also viewed by some countries as a menace to national sovereignty and national culture. This paper tries to explain the obstacles to the process of globalization and its attendant benefits. Although globalization has arisen as a result of a more stable world, the factors that had contributed to its rise also help the factions interested to bring destabilization. In an academic approach in this article, between the research and comparative methods, I have been trying to get the maxims between economy, politics and diplomacy in their efforts of affecting the global era.

Optical coherence tomography imaging of chorioretinal folds associated with hypotony maculopathy following pars plana vitrectomy

Directory of Open Access Journals (Sweden)

Williams Jr BK

2015-09-01

Full Text Available Basil K Williams Jr, Jonathan S Chang, Harry W Flynn Jr Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, USA Abstract: Chorioretinal folds may occur as a consequence of hypotony and can be a cause of vision loss when associated with macular involvement. In this report, the spectral domain ocular coherence tomography imaging of three patients with chorioretinal folds before and after management are presented. The cases had unique presentations and each underwent different management approaches, but the results included improved visual acuities and lessened chorioretinal folds. Keywords: hypotony, chorioretinal folds, ocular coherence tomography

Music increases frontal EEG coherence during verbal learning.

Science.gov (United States)

Peterson, David A; Thaut, Michael H

2007-02-02

Anecdotal and some empirical evidence suggests that music can enhance learning and memory. However, the mechanisms by which music modulates the neural activity associated with learning and memory remain largely unexplored. We evaluated coherent frontal oscillations in the electroencephalogram (EEG) while subjects were engaged in a modified version of Rey's Auditory Verbal Learning Test (AVLT). Subjects heard either a spoken version of the AVLT or the conventional AVLT word list sung. Learning-related changes in coherence (LRCC) were measured by comparing the EEG during word encoding on correctly recalled trials to the immediately preceding trial on which the same word was not recalled. There were no significant changes in coherence associated with conventional verbal learning. However, musical verbal learning was associated with increased coherence within and between left and right frontal areas in theta, alpha, and gamma frequency bands. It is unlikely that the different patterns of LRCC reflect general performance differences; the groups exhibited similar learning performance. The results suggest that verbal learning with a musical template strengthens coherent oscillations in frontal cortical networks involved in verbal encoding.

Quantum Coherent Dynamics Enhanced by Synchronization with Nonequilibrium Environments

Science.gov (United States)

Ishikawa, Akira; Okada, Ryo; Uchiyama, Kazuharu; Hori, Hirokazu; Kobayashi, Kiyoshi

2018-05-01

We report the discovery of the anomalous enhancement of quantum coherent dynamics (CD) due to a non-Markovian mechanism originating from not thermal-equilibrium phonon baths but nonequilibrium coherent phonons. CD is an elementary process for quantum phenomena in nanosystems, such as excitation transfer (ET) in semiconductor nanostructures and light-harvesting systems. CD occurs in homogeneous nanosystems because system inhomogeneity typically destroys coherence. In real systems, however, nanosystems behave as open systems surrounded by environments such as phonon systems. Typically, CD in inhomogeneous nanosystems is enhanced by the absorption and emission of thermal-equilibrium phonons, and the enhancement is described by the conventional master equation. On the other hand, CD is also enhanced by synchronization between population dynamics in nanosystems and coherent phonons; namely, coherent phonons, which are self-consistently induced by phase matching with Rabi oscillation, are fed back to enhance CD. This anomalous enhancement of CD essentially originates from the nonequilibrium and dynamical non-Markovian nature of coherent phonon environments, and the enhancement is firstly predicted by applying time-dependent projection operators to nonequilibrium and dynamical environments. Moreover, CD is discussed by considering ET from a donor to an acceptor. It is found that the enhancement of ET by synchronization with coherent phonons depends on the competition between the output time from a system to an acceptor and the formation time of coherent phonons. These findings in this study will stimulate the design and manipulation of CD via structured environments from the viewpoint of application to nano-photoelectronic devices.

Coherent states for quadratic Hamiltonians

International Nuclear Information System (INIS)

Contreras-Astorga, Alonso; Fernandez C, David J; Velazquez, Mercedes

2011-01-01

The coherent states for a set of quadratic Hamiltonians in the trap regime are constructed. A matrix technique which allows us to directly identify the creation and annihilation operators will be presented. Then, the coherent states as simultaneous eigenstates of the annihilation operators will be derived, and will be compared with those attained through the displacement operator method. The corresponding wavefunction will be found, and a general procedure for obtaining several mean values involving the canonical operators in these states will be described. The results will be illustrated through the asymmetric Penning trap.

Complete destructive interference of partially coherent fields

NARCIS (Netherlands)

Gbur, G.J.; Visser, T.D.; Wolf, E.

2004-01-01

A three-point source model is used to study the interference of wavefields which are mutually partially coherent. It is shown that complete destructive interference of the fields is possible in such a "three-pinhole interferometer" even if the sources are not fully coherent with respect to each

Konservasi Global, Taman Nasional dan Praktek Lokal di Pulau Siberut, Sumatera Barat

Directory of Open Access Journals (Sweden)

Darmanto

2011-01-01

Full Text Available Siberut Island (West Sumatra has high profile for conservation. This island of 403,500 ha has endemic species, ecological uniqueness and indigenous peoples assumed to have traditional ecological knowledge. Using ecological politics, this article will describe history of biodiversity conservation in Siberut. Discourse of Siberut conservation influenced by biological crisis narrative in the global context, scientific research and government policy. Conservation discourse was institutionalized during national parkestablishment in 1993 together with PKAT project and foreign debt from Asian Development Bank Nevertheless, conservation issue is not easy to implement in the local context and coherent with local practice. Indigenous people of Siberut interpret, articulate and produce meaning for conservation differently with other actors. The relationship between indigenous peoples and conservation issue has been characterized with negotiable features, ambiguity and instability. Meaning negotiation on how resources should be managed by actors with different interests resulted in dilemma of conservation.

Understanding photon sideband statistics and correlation for determining phonon coherence

Science.gov (United States)

Ding, Ding; Yin, Xiaobo; Li, Baowen

2018-01-01

Generating and detecting coherent high-frequency heat-carrying phonons have been topics of great interest in recent years. Although there have been successful attempts in generating and observing coherent phonons, rigorous techniques to characterize and detect phonon coherence in a crystalline material have been lagging compared to what has been achieved for photons. One main challenge is a lack of detailed understanding of how detection signals for phonons can be related to coherence. The quantum theory of photoelectric detection has greatly advanced the ability to characterize photon coherence in the past century, and a similar theory for phonon detection is necessary. Here, we reexamine the optical sideband fluorescence technique that has been used to detect high-frequency phonons in materials with optically active defects. We propose a quantum theory of phonon detection using the sideband technique and found that there are distinct differences in sideband counting statistics between thermal and coherent phonons. We further propose a second-order correlation function unique to sideband signals that allows for a rigorous distinction between thermal and coherent phonons. Our theory is relevant to a correlation measurement with nontrivial response functions at the quantum level and can potentially bridge the gap of experimentally determining phonon coherence to be on par with that of photons.

Coherent states approach to Penning trap

International Nuclear Information System (INIS)

Fernandez, David J; Velazquez, Mercedes

2009-01-01

By using a matrix technique, which allows us to identify directly the ladder operators, the Penning trap coherent states are derived as eigenstates of the appropriate annihilation operators. These states are compared with those obtained through the displacement operator. The associated wavefunctions and mean values for some relevant operators in these states are also evaluated. It turns out that the Penning trap coherent states minimize the Heisenberg uncertainty relation

Coherent states in quantum mechanics; Estados coerentes em mecanica quantica

Energy Technology Data Exchange (ETDEWEB)

Rodrigues, R. de Lima [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil)]. E-mail: rafaelr@cbpf.br; Fernandes Junior, Damasio; Batista, Sheyla Marques [Paraiba Univ., Campina Grande, PB (Brazil). Dept. de Engenharia Eletrica

2001-12-01

We present a review work on the coherent states is non-relativistic quantum mechanics analysing the quantum oscillators in the coherent states. The coherent states obtained via a displacement operator that act on the wave function of ground state of the oscillator and the connection with Quantum Optics which were implemented by Glauber have also been considered. A possible generalization to the construction of new coherent states it is point out. (author)

Quantum correlations between each two-level system in a pair of atoms and general coherent fields

Directory of Open Access Journals (Sweden)

S. Abdel-Khalek

Full Text Available The quantitative description of the quantum correlations between each two-level system in a two-atom system and the coherent fields initially defined in a coherent state in the framework of power-law potentials (PLPCSs is considered. Specifically, we consider two atoms locally interacting with PLPCSs and take into account the different terms of interactions, the entanglement and quantum discord are studied including the time-dependent coupling and photon transition effects. Using the monogamic relation between the entanglement of formation and quantum discord in tripartite systems, we show that the control and preservation of the different kinds of quantum correlations greatly benefit from the combination of the choice of the physical quantities. Finally, we explore the link between the dynamical behavior of quantum correlations and nonclassicality of the fields with and without atomic motion effect. Keywords: Quantum correlations, Monogamic relation, Coherent states, Power-law potentials, Wehrl entropy

Coherent states on horospheric three-dimensional Lobachevsky space

Energy Technology Data Exchange (ETDEWEB)

Kurochkin, Yu., E-mail: y.kurochkin@ifanbel.bas-net.by; Shoukavy, Dz., E-mail: shoukavy@ifanbel.bas-net.by [Institute of Physics, National Academy of Sciences of Belarus, 68 Nezalezhnasci Ave., Minsk 220072 (Belarus); Rybak, I., E-mail: Ivan.Rybak@astro.up.pt [Institute of Physics, National Academy of Sciences of Belarus, 68 Nezalezhnasci Ave., Minsk 220072 (Belarus); Instituto de Astrofísica e Ciências do Espaço, CAUP, Rua das Estrelas, 4150-762 Porto (Portugal); Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre 687, 4169-007 Porto (Portugal)