On asymptotic stability of continuous-time risk-sensitive filters with respect to initial conditions

In this paper, we consider the problem of risk-sensitive filtering for continuous-time stochastic linear Gaussian time-invariant systems. In particular, we address the problem of forgetting of initial conditions. Our results show that suboptimal risk-sensitive filters initialized with arbitrary Gaussian initial conditions asymptotically approach the optimal risk-sensitive filter for a linear Gaussian system with Gaussian but unknown initial conditions in the mean square sense at an exponential rate, provided the arbitrary initial covariance matrix results in a stabilizing solution of the (H_∞-like) Riccati equation associated with the risk-sensitive problem. More importantly, in the case of non-Gaussian initial conditions, a suboptimal risk-sensitive filter asymptotically approaches the optimal risk-sensitive filter in the mean square sense under a boundedness condition satisfied by the fourth order absolute moment of the initial non-Gaussian density and a slow growth condition satisfied by a certain Radon–Nikodym derivative.     

One-step, nanoparticle-mediated bacterial detection with magnetic relaxation

Acknowledging the need for the development of fast and sensitive bacterial detection methods, we functionalized superparamagnetic iron oxide nanoparticles to identify Mycobacterium avium spp. paratuberculosis (MAP), through magnetic relaxation. Our results indicate that the MAP nanoprobes (1) bind specifically to MAP, (2) can quantify the bacterial target quickly in milk and blood with high sensitivity, and (3) are not susceptible to interferences caused by other bacteria. The use of the described magnetic nanosensors in the identification and quantification of bacteria in clinical and environmental samples is anticipated.     

An architecture for a wavelength-interchanging cross-connectutilizing parametric wavelength converters

This paper proposes an architecture for a wavelength-interchanging cross-connect (WIXC) that can be used as a switching node of strictly transparent and scalable networks with all-optical routing and all-optical wavelength conversion capabilities. This architecture utilizes all-optical parametric wavelength converters based on difference-frequency-generation (DFG) or four-wave mixing (FWM), although this work focuses only on the implementation using difference-frequency-generation wavelength converters. The proposed WIXC architecture exploits the unique wavelength mapping properties of parametric wavelength converters: mirror image mapping and simultaneous multichannel wavelength conversion. The derivation of this architecture involves application of a space/wavelength transformation to the classical Benes switch fabric. The connection setup for the resulting architecture follows the well established looping algorithm, and the architecture is scalable in both the ports and the wavelengths. The scaling occurs in an orderly fashion, which allows modular upgrades of WIXC's for cost-effective evolution of the networks. The unique properties of the parametric wavelength converter including transparent and multichannel conversion capabilities result in a WIXC architecture that requires fewer wavelength converters while maintaining scalability and transparency     

Modular and Re-Configurable Parametric Wavelength Interchanging Cross-Connect Architectures

We report on a new technique that allows for modular expansion of strictly transparent wavelength interchangeable cross-connect utilizing parametric wavelength converters based on four-wave mixing or difference frequency generation. The proposed technique results in cost effective cross connect architectures with fewer components than other frequently proposed designs. It will be shown that employing FWM-based converters results in reconfigurable and simple to fabricate architectures.     

Uncontrolled Thyroid during Pregnancy Alters the Circulative and Exerted Metabolome

Normal levels of thyroid hormones (THs) are essential for a normal pregnancy outcome, fetal growth and the normal function of the central nervous system. Hypothyroidism, a common endocrine disorder during pregnancy, is a significant metabolic factor leading to cognitive impairments. It is essential to investigate whether patients with thyroid dysfunction may present an altered circulative and excreted metabolic profile, even after receiving treatment with thyroxine supplements. NMR metabolomics was employed to analyze 90 serum and corresponding colostrum samples. Parallel analyses of the two biological specimens provided a snapshot of the maternal metabolism through the excretive and circulating characteristics of mothers. The metabolomics data were analyzed by performing multivariate statistical, biomarker and pathway analyses. Our results highlight the impact of hypothyroidism on metabolites’ composition during pregnancy and lactation. Thyroid disorder causing metabolite fluctuations may lead to impaired lipid and glucose metabolic pathways as well as aberrant prenatal neurodevelopment, thus posing a background for the occurrence of metabolic syndrome or neurogenerative diseases later in life. This risk applies to not only untreated but also hypothyroid women under replacement therapy since our findings in both biofluids framed a different metabolic phenotype for the latter group, thus emphasizing the need to monitor women adequately after treatment initiation.     

Cells exploit a phase transition to mechanically remodel the fibrous extracellular matrix

Through mechanical forces, biological cells remodel the surrounding collagen network, generating striking deformation patterns. Tethers—tracts of high densification and fibre alignment—form between cells, thinner bands emanate from cell clusters. While tethers facilitate cell migration and communication, how they form is unclear. Combining modelling, simulation and experiment, we show that tether formation is a densification phase transition of the extracellular matrix, caused by buckling instability of network fibres under cell-induced compression, featuring unexpected similarities with martensitic microstructures. Multiscale averaging yields a two-phase, bistable continuum energy landscape for fibrous collagen, with a densified/aligned second phase. Simulations predict strain discontinuities between the undensified and densified phase, which localizes within tethers as experimentally observed. In our experiments, active particles induce similar localized patterns as cells. This shows how cells exploit an instability to mechanically remodel the extracellular matrix simply by contracting, thereby facilitating mechanosensing, invasion and metastasis.     

LeCORBUSIER: HIS IDEAS FOR CITIES

LeCorbusier's ideas for cities and his impact on city planning throughout the world are examined through a discussion of the factors and events that influenced his development and of the qualities and shortcomings of his principal creations: Ville Contemporaine, Ville Radieuse, Plan Voisin, Modulor, significant individual buildings, Chandigarh, and many books. The man is described as his associates saw him, and his views about American city planning are presented. Properly updated, his ideas have promising future potentialities for the work of planners.     

Hierarchical Tree Alternative Path (HTAP) algorithm for congestion control in wireless sensor networks

Recent advances in wireless sensor networks (WSNs) have lead to applications with increased traffic demands. Research is evolving from applications where performance is not considered as a crucial factor, to applications where performance is a critical factor. There are many cases in the fields of automation, health monitoring, and disaster response that demand wireless sensor networks where performance assurances are vital, especially for parameters like power, delay, and reliability. Due to the nature of these networks the higher amount of traffic is observed when the monitored event takes place. Exactly at this instance, there is a higher probability of congestion appearance in the network. Congestion in WSNs is tackled by the employment of two methods: either by reducing the load (“traffic control”), or by increasing the resources (“resource control”). In this paper we present the Hierarchical Tree Alternative Path (HTAP) algorithm, a “resource control” algorithm that attempts, through simple steps and minor computations, to mitigate congestion in wireless sensor networks by creating dynamic alternative paths to the sink. HTAP is evaluated in several scenarios in comparison with another “resource control” algorithm (TARA), as well as with a “traffic control” algorithm (SenTCP), and also the case where no congestion control exists in the network (“no CC”). Results show that HTAP is a simple and efficient algorithm capable of dealing successfully with congestion in WSNs, while preserving the performance characteristics of the network.     

Clogging of Pervious Monolayers Subjected to Radial Flow

Particle migration within porous networks often results in permeability reductions due to clogging. In many field applications, fluids and entrained particles travel radially toward producing wells. The nonhomogeneous velocity field associated with radial flow produces particle-level force variations that in turn lead to spatially dependent pore-scale mechanisms and unique clogging phenomena. The fluid-driven migration and entrapment of particles in radial flow is studied experimentally in custom-built pervious monolayers that allow for direct visualization of clogging processes. Experimental results demonstrate that in particular hydrodynamic conditions, particle clogging evolves in the form of a self-stabilizing clogging ring that localizes at a characteristic radial distance that depends on the initial producing flow rate. Gradual clogging by surface deposition of particles is observed in less severe hydrodynamic conditions. The particle migration and clogging processes observed are analyzed by considering particle-level force balance through dimensionless parameters.