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Universal Framework for Edge Controllability of Complex Network

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Dynamical processes occurring on the edges in complex networks are relevant to a variety of real-world situations. Despite recent advances, a framework for edge controllability is still required for complex networks of arbitrary structure and interaction strength. Generalizing a previously

Dynamical processes occurring on the edges in complex networks are relevant to a variety of real-world situations. Despite recent advances, a framework for edge controllability is still required for complex networks of arbitrary structure and interaction strength. Generalizing a previously introduced class of processes for edge dynamics, the switchboard dynamics, and exploit- ing the exact controllability theory, we develop a universal framework in which the controllability of any node is exclusively determined by its local weighted structure. This framework enables us to identify a unique set of critical nodes for control, to derive analytic formulas and articulate efficient algorithms to determine the exact upper and lower controllability bounds, and to evaluate strongly structural controllability of any given network. Applying our framework to a large number of model and real-world networks, we find that the interaction strength plays a more significant role in edge controllability than the network structure does, due to a vast range between the bounds determined mainly by the interaction strength. Moreover, transcriptional regulatory networks and electronic circuits are much more strongly structurally controllable (SSC) than other types of real-world networks, directed networks are more SSC than undirected networks, and sparse networks are typically more SSC than dense networks.

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2017-06-26

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Universal Formalism of Fano Resonance

Description

The phenomenon of Fano resonance is ubiquitous in a large variety of wave scattering systems, where the resonance profile is typically asymmetric. Whether the parameter characterizing the asymmetry should be complex or real is an issue of great experimental interest.

The phenomenon of Fano resonance is ubiquitous in a large variety of wave scattering systems, where the resonance profile is typically asymmetric. Whether the parameter characterizing the asymmetry should be complex or real is an issue of great experimental interest. Using coherent quantum transport as a paradigm and taking into account of the collective contribution from all available scattering channels, we derive a universal formula for the Fano-resonance profile. We show that our formula bridges naturally the traditional Fano formulas with complex and real asymmetry parameters, indicating that the two types of formulas are fundamentally equivalent (except for an offset). The connection also reveals a clear footprint for the conductance resonance during a dephasing process. Therefore, the emergence of complex asymmetric parameter when fitting with experimental data needs to be properly interpreted. Furthermore, we have provided a theory for the width of the resonance, which relates explicitly the width to the degree of localization of the close-by eigenstates and the corresponding coupling matrices or the self-energies caused by the leads. Our work not only resolves the issue about the nature of the asymmetry parameter, but also provides deeper physical insights into the origin of Fano resonance. Since the only assumption in our treatment is that the transport can be described by the Green’s function formalism, our results are also valid for broad disciplines including scattering problems of electromagnetic waves, acoustics, and seismology.

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2015-01-01

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Universal Flux-Fluctuation Law in Small Systems

Description

The relation between flux and fluctuation is fundamental to complex physical systems that support and transport flows. A recently obtained law predicts monotonous enhancement of fluctuation as the average flux is increased, which in principle is valid but only for

The relation between flux and fluctuation is fundamental to complex physical systems that support and transport flows. A recently obtained law predicts monotonous enhancement of fluctuation as the average flux is increased, which in principle is valid but only for large systems. For realistic complex systems of small sizes, this law breaks down when both the average flux and fluctuation become large. Here we demonstrate the failure of this law in small systems using real data and model complex networked systems, derive analytically a modified flux-fluctuation law, and validate it through computations of a large number of complex networked systems. Our law is more general in that its predictions agree with numerics and it reduces naturally to the previous law in the limit of large system size, leading to new insights into the flow dynamics in small-size complex systems with significant implications for the statistical and scaling behaviors of small systems, a topic of great recent interest.

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2014-10-27

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Water Footprint of Cities: A Review and Suggestions for Future Research

Description

Cities are hotspots of commodity consumption, with implications for both local and systemic water resources. Water flows “virtually” into and out of cities through the extensive cross-boundary exchange of goods and services. Both virtual and real water flows are affected

Cities are hotspots of commodity consumption, with implications for both local and systemic water resources. Water flows “virtually” into and out of cities through the extensive cross-boundary exchange of goods and services. Both virtual and real water flows are affected by water supply investments and urban planning decisions, which influence residential, commercial, and industrial development. This form of water “teleconnection” is being increasingly recognized as an important aspect of water decision-making. The role of trade and virtual water flows as an alternative to expanding a city’s “real” water supply is rarely acknowledged, with an emphasis placed instead on monotonic expansion of engineering potable water supplies. We perform a literature review of water footprint studies to evaluate the potential and importance of taking virtual flows into account in urban planning and policy. We compare and contrast current methods to assess virtual water flows. We also identify and discuss priorities for future research in urban water footprint analysis.

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2015-06-30

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Ventricular Shape and Relative Position Abnormalities in Preterm Neonates

Description

Recent neuroimaging findings have highlighted the impact of premature birth on subcortical development and morphological changes in the deep grey nuclei and ventricular system. To help characterize subcortical microstructural changes in preterm neonates, we recently implemented a multivariate tensor-based method

Recent neuroimaging findings have highlighted the impact of premature birth on subcortical development and morphological changes in the deep grey nuclei and ventricular system. To help characterize subcortical microstructural changes in preterm neonates, we recently implemented a multivariate tensor-based method (mTBM). This method allows to precisely measure local surface deformation of brain structures in infants. Here, we investigated ventricular abnormalities and their spatial relationships with surrounding subcortical structures in preterm neonates. We performed regional group comparisons on the surface morphometry and relative position of the lateral ventricles between 19 full-term and 17 preterm born neonates at term-equivalent age. Furthermore, a relative pose analysis was used to detect individual differences in translation, rotation, and scale of a given brain structure with respect to an average. Our mTBM results revealed broad areas of alterations on the frontal horn and body of the left ventricle, and narrower areas of differences on the temporal horn of the right ventricle. A significant shift in the rotation of the left ventricle was also found in preterm neonates. Furthermore, we located significant correlations between morphology and pose parameters of the lateral ventricles and that of the putamen and thalamus. These results show that regional abnormalities on the surface and pose of the ventricles are also associated with alterations on the putamen and thalamus. The complementarity of the information provided by the surface and pose analysis may help to identify abnormal white and grey matter growth, hinting toward a pattern of neural and cellular dysmaturation.

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Date Created
2017-05-28

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Overlapping Narrative of Muslim Refugees and (Undocumented) Immigrants

Description

Muslim refugees and Muslim immigrants, and undocumented immigrants have been a prominent part of American culture and have been woven into the history of the United States. Both group's presence in the United States has elicited rhetoric from U.S citizens

Muslim refugees and Muslim immigrants, and undocumented immigrants have been a prominent part of American culture and have been woven into the history of the United States. Both group's presence in the United States has elicited rhetoric from U.S citizens and U.S public officials. One may infer that the narrative of Muslim refugees and Muslim immigrants overlaps the narrative of undocumented immigrants living in the United States. Both Muslim refugees and immigrants as well as unauthorized immigrants, are criminalized in the United States, or are associated to crime by default of their faith and or their legal status. The association that Muslim refugees and Muslim immigrants, and undocumented immigrants have with crime, based on their rhetoric, has elicited a policy from the United States government as well. The United States government has responded to a presumed threat that both groups pose to U.S. citizens and the nation by means of aggressive legislation, both local and federal. In this research paper, past and present discourse on Muslim refugees and Muslim immigrants and undocumented immigrants was analyzed to determine each of the group's narrative; the mainstream media, newspapers and photographic images, was also considered to determine the narrative of both groups. Based on the discourse on Muslim refugees and Muslim immigrants and on undocumented immigrants, the media portrayal of both groups, and on the change of public policy one may assert that the narratives of both groups overlaps; as both Muslim refugees and immigrants and unauthorized immigrants are seen as a possible threat to the American people.

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Date Created
2017-05

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Utilizing a Logic Model Framework to Develop a Conceptual Model for Community Garden Implementation in the U.S.

Description

Community gardens have wide-reaching potential for addressing public health issues. However, of the thousands of gardens located in the United States, many lack rigorous planning and encounter crippling obstacles, like disinterest from community members, soon after implementation. This study created

Community gardens have wide-reaching potential for addressing public health issues. However, of the thousands of gardens located in the United States, many lack rigorous planning and encounter crippling obstacles, like disinterest from community members, soon after implementation. This study created a processual typology to summarize steps in the implementation process for existing gardens described within peer-reviewed, academic journals and offers recommendations for more sustainably planning future garden projects up to ten years in advance. A systematic review was conducted to identify descriptions of community gardens in peer-reviewed, academic literature. A general logic model was used as a basic structure and themes for each step (inputs, activities, outputs, short/long term outcomes, impacts, and methods of evaluation) were summarized from the included studies to construct a processual typology for evaluating community garden implementation in the United States. This typology was then used to assess a case study of a garden in Des Moines, Iowa, which generated the author's interest in conducting this research after assisting with that space through an AmeriCorps community health program. Results showed that existing gardens shared common attributes and could be categorized according to one of two speeds of implementation ("regular" or "accelerated") and according to one of three types of organizational structure ("grassroots," "externally-organized," or "externally-managed"). The typology was assessed for limitations from having been based on a systematic review of only peer-reviewed, academic articles and, referring to its themes, was used to construct a logic model for a hypothetical community garden project. The processual typology developed in this study is limited in its power to summarize all existing community gardens but offers a first step toward informing the creation of logic models for future projects in order to improve sustainability and attain more funding.

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2017-05

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Wavelength-Tunable Infrared Metamaterial by Tailoring Magnetic Resonance Condition With VO2 Phase Transition

Description

In this work, we report the design of a wavelength-tunable infrared metamaterial by tailoring magnetic resonance condition with the phase transition of vanadium dioxide (VO2). Numerical simulation based on the finite-difference time-domain method shows a broad absorption peak at the

In this work, we report the design of a wavelength-tunable infrared metamaterial by tailoring magnetic resonance condition with the phase transition of vanadium dioxide (VO2). Numerical simulation based on the finite-difference time-domain method shows a broad absorption peak at the wavelength of 10.9 μm when VO2 is a metal, but it shifts to 15.1 μm when VO2 changes to dielectric phase below its phase transition temperature of 68 °C. The large tunability of 38.5% in the resonance wavelength stems from the different excitation conditions of magnetic resonance mediated by plasmon in metallic VO2 but optical phonons in dielectric VO2. The physical mechanism is elucidated with the aid of electromagnetic field distribution at the resonance wavelengths. A hybrid magnetic resonance mode due to the plasmon-phonon coupling is also discussed. The results here would be beneficial for active control of thermal radiation in novel electronic, optical, and thermal devices.

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2014-09-28

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Vorinostat Differentially Alters 3D Nuclear Structure of Cancer and Non-Cancerous Esophageal Cells

Description

The histone deacetylase (HDAC) inhibitor vorinostat has received significant attention in recent years as an ‘epigenetic’ drug used to treat solid tumors. However, its mechanisms of action are not entirely understood, particularly with regard to its interaction with the aberrations

The histone deacetylase (HDAC) inhibitor vorinostat has received significant attention in recent years as an ‘epigenetic’ drug used to treat solid tumors. However, its mechanisms of action are not entirely understood, particularly with regard to its interaction with the aberrations in 3D nuclear structure that accompany neoplastic progression. We investigated the impact of vorinostat on human esophageal epithelial cell lines derived from normal, metaplastic (pre-cancerous), and malignant tissue. Using a combination of novel optical computed tomography (CT)-based quantitative 3D absorption microscopy and conventional confocal fluorescence microscopy, we show that subjecting malignant cells to vorinostat preferentially alters their 3D nuclear architecture relative to non-cancerous cells. Optical CT (cell CT) imaging of fixed single cells showed that drug-treated cancer cells exhibit significant alterations in nuclear morphometry. Confocal microscopy revealed that vorinostat caused changes in the distribution of H3K9ac-marked euchromatin and H3K9me3-marked constitutive heterochromatin. Additionally, 3D immuno-FISH showed that drug-induced expression of the DNA repair gene MGMT was accompanied by spatial relocation toward the center of the nucleus in the nuclei of metaplastic but not in non-neoplastic cells. Our data suggest that vorinostat’s differential modulation of 3D nuclear architecture in normal and abnormal cells could play a functional role in its anti-cancer action.

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Date Created
2016-08-09

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Video Traffic Characteristics of Modern Encoding Standards: H.264/AVC With SVC and MVC Extensions and H.265/HEVC

Description

Video encoding for multimedia services over communication networks has significantly advanced in recent years with the development of the highly efficient and flexible H.264/AVC video coding standard and its SVC extension. The emerging H.265/HEVC video coding standard as well as

Video encoding for multimedia services over communication networks has significantly advanced in recent years with the development of the highly efficient and flexible H.264/AVC video coding standard and its SVC extension. The emerging H.265/HEVC video coding standard as well as 3D video coding further advance video coding for multimedia communications. This paper first gives an overview of these new video coding standards and then examines their implications for multimedia communications by studying the traffic characteristics of long videos encoded with the new coding standards. We review video coding advances from MPEG-2 and MPEG-4 Part 2 to H.264/AVC and its SVC and MVC extensions as well as H.265/HEVC. For single-layer (nonscalable) video, we compare H.265/HEVC and H.264/AVC in terms of video traffic and statistical multiplexing characteristics. Our study is the first to examine the H.265/HEVC traffic variability for long videos. We also illustrate the video traffic characteristics and statistical multiplexing of scalable video encoded with the SVC extension of H.264/AVC as well as 3D video encoded with the MVC extension of H.264/AVC.

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Date Created
2014-02-20