On-line learning of dynamical systems in the presence of model mismatch and disturbances

This paper is concerned with the on-line learning of unknown dynamical systems using a recurrent neural network. The unknown dynamic systems to be learned are subject to disturbances and possibly unstable. The neural-network model used has a simple architecture with one layer of adaptive connection weights. Four learning rules are proposed for the cases where the system state is measurable in continuous or discrete time. Some of these learning rules extend the sigma-modification of the standard gradient learning rule. Convergence properties are given to show that the weight parameters of the recurrent neural network are bounded and the state estimation error converges exponentially to a bounded set, which depends on the modeling error and the disturbance bound. The effectiveness of the proposed learning rules for the recurrent neural network is demonstrated using an illustrative example of tracking a Brownian motion.

Adsorption of Pseudomonas putida on clay minerals and iron oxide

Adsorption of Pseudomonas putida on minerals including montmorillonite, kaolinite and goethite was studied. The adsorption isotherms of P. putida on the examined minerals conformed to the Langmuir equation. The amount of P. putida adsorbed followed the order: goethite > kaolinite > montmorillonite. A greater extent of P. putida adsorption on minerals was observed in the range of temperature from 15 to 35 degrees C. The adsorption of P. putida on minerals decreased with the increase of pH from 3.0 to 10.0. Magnesium ion was more efficient than sodium ion in promoting P. putida adsorption on minerals. The results suggest that electrostatic interactions play a vital role in P. putida adsorption by soil colloidal factions. The information obtained in this study is of fundamental significance for the understanding of the survival and transport of bacteria in soil systems.

Zinc tetraaminophthalocyanine-Fe3O4 nanoparticle composite for laccase immobilization

Zinc tetraaminophthalocyanine-Fe3O4 nanoparticle composites were prepared by organic-inorganic complex technology and characterized. It has been proved that the ZnTAPc dispersed randomly onto the surface of Fe3O4 nanoparticles to form molecular dispersion layer and there was a relatively strong bond between central zinc cation and oxygen. The nanoparticle composite took the shape of roundish spheres with the mean diameter of about 15 nm. Active amino groups of magnetic carriers could be used to bind laccase via glutaraldehyde. The optimal pH for the activity of the immobilized laccases and free laccase were the same at pH 3.0 and the optimal temperature for laccase immobilization on ZnTAPc-Fe3O4 nanoparticle composite was 45 degrees. The immobilization yields and K(m) value of the laccase immobilized on ZnTAPc-Fe3O4 nanoparticle composite were 25% and 20.1 microM, respectively. This kind of immobilized laccase has good thermal, storage and operation stability, and could be used as the sensing biocomponent for the fiber optic biosensor based on enzyme catalysis.

Raman spectrum of graphene and graphene layers

Graphene is the two-dimensional building block for carbon allotropes of every other dimensionality. We show that its electronic structure is captured in its Raman spectrum that clearly evolves with the number of layers. The D peak second order changes in shape, width, and position for an increasing number of layers, reflecting the change in the electron bands via a double resonant Raman process. The G peak slightly down-shifts. This allows unambiguous, high-throughput, nondestructive identification of graphene layers, which is critically lacking in this emerging research area.

The role of hyaluronan degradation products as innate alloimmune agonists

Dendritic cells (DCs) play a key role in initiating alloimmunity yet the substances that activate them during the host response to transplantation remain elusive. In this study we examined the potential roles of endogenous innate immune agonists in activating dendritic cell-dependent alloimmunity. Using a murine in vitro culture system, we show that 135 KDa fragments of the extracellular matrix glycosaminoglycan hyaluronan induce dendritic cell maturation and initiate alloimmunity. Priming of alloimmunity by hyaluronan-activated DCs was dependent on signaling via TIR-associated protein, a Toll-like receptor (TLR) adaptor downstream of TLRs 2 and 4. However, this effect was independent of alternate TLR adaptors, MyD88 or Trif. Using an in vivo murine transplant model, we show that hyaluronan accumulated during skin transplant rejection. Examination of human lung transplant recipients demonstrated that increased levels of intragraft hyaluronan were associated with bronchiolitis obliterans syndrome. In conclusion, our study suggests that fragments of hyaluronan can act as innate immune agonists that activate alloimmunity.

Hematopoietic stem cell mobilization after rat partial orthotopic liver transplantation

BACKGROUND

On the basis of the recently recognized potential of hematopoietic stem cells (HSC) to give rise to hepatocytes, we investigated the possibility that HSC could be mobilized and home to the injured liver promoting tissue repair after 50% partial orthotopic liver transplantation (PLTx) in the rat.

METHODS

Using sex-mismatched (female to male) syngeneic SD rats, we performed 50% PLTx or whole orthotopic liver transplantation (WLTx) versus 50% partial hepatectomy (PHx) and sham operation (O). Elements with stem cell markers were detected in peripheral blood (PB) and in the liver. Liver injury and regeneration were estimated. The sex-determining region for Y chromosome gene (SRY) was used to define cell origin by in situ hybridization in liver sections.

RESULTS

Comparison of WLTx and PHx groups showed a lower survival rate (50%), in the PLTx group were (P<.05). Further, the liver injury was more serious and the levels of serum biochemical parameters were higher. Compared with PHx groups, on days 3 and 5 postoperatively, the mitosis index and the expression of PCNA were lower among the PLTx groups. Compared with WLTx and sham operation groups, beta2m-/Thy-1.1+, CD34+ cells in PB in PLTx groups and PHx were increased on day 1 postoperatively and decreased on the following days. Compared with PHx groups, beta2m-/Thy-1.1+, CD34+ cells were higher in PLTx. The CD34-, c-kit-, and Thy-1.1-positive cells detected in portal tract areas peaked during 3 to 5 days postoperatively in PLTx. Few SRY+ cells were detected in PLTx liver grafts.

CONCLUSIONS

beta2m-/Thy-1.1+ and CD34+ stem cells mobilized after PLTx and PHx may be related to the reduced-size liver. Few HSC are involved in liver regeneration in PLTx.

Strong suppression of weak localization in graphene

Low-field magnetoresistance is ubiquitous in low-dimensional metallic systems with high resistivity and well understood as arising due to quantum interference on self-intersecting diffusive trajectories. We have found that in graphene this weak-localization magnetoresistance is strongly suppressed and, in some cases, completely absent. The unexpected observation is attributed to mesoscopic corrugations of graphene sheets which can cause a dephasing effect similar to that of a random magnetic field.

Immobilization of Pycnoporus sanguineus laccase on copper tetra-aminophthalocyanine–Fe3O4 nanoparticle composite

A magnetic nanoparticle composite of CuTAPc (copper tetra-aminophthalocyanine)-Fe(3)O(4) was prepared by in situ complexation and was characterized by FTIR (Fourier-transform IR) spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, FESEM (field emission scanning electron microscopy) micrograph and hysteresis loop. The results showed that CuTAPc formed the covering layer on the surface of the composite. Using glutaraldehyde, laccase was covalently attached to the surface of the composite. When white-rot-fungus (Pycnoporus sanguineus) laccase was immobilized on the CuTAPc-Fe(3)O(4) nanoparticle composite in PBS, the optimal reaction pH was 5.0 and the optimal temperature was 0 degrees C. When 2.0 mg/ml laccase solution was used, the immobilization yield was 20%. The activity, K(m), k(cat)/K(m) and V(max) values of the immobilized laccase were 1.43 units/mg, 2.38 x 10(-5) mol/l, 2.1 x 10(3) mol(-1) x s(-1) x l and 1.19 x 10(-6) mol x l(-1) /x min(-1) respectively. The system exhibited maximum enzyme activity at pH 3.0 and at 45 degrees C. After storage at 4 degrees C for 1 month, the residual activity of the immobilized laccase was 85% of its initial activity, while that of free laccase was only 30%. During 240 min incubation at 55 degrees C, the activity of immobilized laccase quickly increased to a maximum after 150 min and then decreased to 95% in the next 90 min, while the activity of the free enzyme decreased monotonically to 28%. After five consecutive operations, the immobilized laccase still retained 80% of its initial activity.

Acute presentation of a fibroepithelial pharyngeal polyp

We report the case of a 60-year-old Caucasian man who presented with choking and airway compromise due to a large pharyngeal polyp. It was resected as an emergency procedure and subjected to macroscopic and microscopic examination. The fibroepithelial polyp arose from the right pharyngeal wall and consisted of adipose tissue covered by squamous epithelium without evidence of malignancy. This is a particularly rare lesion in adults and there are few references in the medical literature. To our knowledge this is the first English case report of an acute presentation of adult fibroepithelial pharyngeal polyp. This case report also discusses the issues raised in the management of a potentially fatal lesion that may have resulted in complete airway obstruction.

Interpretation of deformation fabrics of infrastructure zone rocks in the context of channel flow and other tectonic models

Infrastructure zones are essentially horizontal to shallowly dipping crustal-scale zones of non-coaxial flow, with two possible interpretations: (a) a crustal-scale shear zone, transporting upper crust over lower crust and/or mantle (transport flow); or (b) a zone of channel flow in which there is a flux of weak crust between relatively strong upper and lower crust and/or mantle, away from the centre of the orogen. Transport flow has a constant shear sense across the zone, whereas in channel flow the sense of shear reverses across the zone. Channel flow may be driven by extrusion (extrusive channel flow), due to the two channel walls approaching one another, or by a pressure gradient along the channel (normal channel flow), with no convergence of the walls necessary. Arguments based on strain compatibility and mechanics suggest that extrusive channel flow is unlikely. Kinematic vorticity numbers have been used to show that infrastructure and other shear zones have undergone flattening strains, but we show that the numbers are incompatible with extrusion. We also show that in addition to the problems inherent in determining kinematic vorticity numbers from fabric, the numbers cannot be related to bulk flow in mechanically heterogeneous zones, because of flow partitioning. Drag folds are a better indication, albeit qualitative, of whether a zone is thinning or not. They also give a conservative estimate of the minimum accumulated shear strains, and may inhibit strain localization. Like snowball garnets, they indicate shear strains that are so large that the pure-shear-thinning component for a steady-shear zone has to be small.

Two-dimensional gas of massless Dirac fermions in graphene

Quantum electrodynamics (resulting from the merger of quantum mechanics and relativity theory) has provided a clear understanding of phenomena ranging from particle physics to cosmology and from astrophysics to quantum chemistry. The ideas underlying quantum electrodynamics also influence the theory of condensed matter, but quantum relativistic effects are usually minute in the known experimental systems that can be described accurately by the non-relativistic Schrödinger equation. Here we report an experimental study of a condensed-matter system (graphene, a single atomic layer of carbon) in which electron transport is essentially governed by Dirac's (relativistic) equation. The charge carriers in graphene mimic relativistic particles with zero rest mass and have an effective 'speed of light' c* approximately 10(6) m s(-1). Our study reveals a variety of unusual phenomena that are characteristic of two-dimensional Dirac fermions. In particular we have observed the following: first, graphene's conductivity never falls below a minimum value corresponding to the quantum unit of conductance, even when concentrations of charge carriers tend to zero; second, the integer quantum Hall effect in graphene is anomalous in that it occurs at half-integer filling factors; and third, the cyclotron mass m(c) of massless carriers in graphene is described by E = m(c)c*2. This two-dimensional system is not only interesting in itself but also allows access to the subtle and rich physics of quantum electrodynamics in a bench-top experiment.

Two-dimensional atomic crystals

We report free-standing atomic crystals that are strictly 2D and can be viewed as individual atomic planes pulled out of bulk crystals or as unrolled single-wall nanotubes. By using micromechanical cleavage, we have prepared and studied a variety of 2D crystals including single layers of boron nitride, graphite, several dichalcogenides, and complex oxides. These atomically thin sheets (essentially gigantic 2D molecules unprotected from the immediate environment) are stable under ambient conditions, exhibit high crystal quality, and are continuous on a macroscopic scale.

Identification of a novel HLA-DRB1 allele (HLA-DRB1*111902*)

In this paper, we report a new HLA-DRB1 allele identified in a male acute myeloid leukaemia Chinese patient. This sample was initially typed as DRB1*11XX using commercial polymerase chain reaction-sequence-specific primers kit. When it was typed using a chip-based sequence-specific oligonucleotide technique, a novel hybridization pattern that does not match any known alleles was observed. Through sequencing, we have identified this allele as a new HLA-DRB1 allele, which was later named HLA-DRB1*111902 by the WHO Nomenclature Committee. The sequence of this new allele differs from DRB1*111901 by one nucleotide (from G to C) at 203nt of exon 2 but does not cause any amino acid substitution.

The Effects of Mass Loading the Ossicles with a Floating Mass Transducer on Middle Ear Transfer Function

HYPOTHESIS

The aim of this study was to measure the mass loading effect of an active middle-ear implant (the Vibrant Soundbridge) in cadaver temporal bones.

BACKGROUND

Implantable middle ear hearing devices such as Vibrant Soundbridge have been used as an alternative to conventional hearing aids for the rehabilitation of sensorineural hearing loss. Other than the obvious disadvantage of requiring implantation middle ear surgery, it also applies a direct weight on the ossicular chain which, in turn, may have an impact on residual hearing. Previous studies have shown that applying a mass directly on the ossicular chain has a damping effect on its response to sound. However, little has been done to investigate the magnitude and the frequency characteristics of the mass loading effect in devices such as the Vibrant Soundbridge.

METHODS

Five fresh cadaver temporal bones were used. The stapes displacement was measured using laser Doppler vibrometry before and after the placement of a Vibrant Soundbridge floating mass transducer. The effects of mass and attachment site were compared with the unloaded response. Measurements were obtained at frequencies between 0.1 and 10 kHz and at acoustic input levels of 100 dB sound pressure level. Each temporal bone acted as its own control.

RESULTS

Placement of the floating mass transducer caused a reduction of the stapes displacement. There were variations between the bones. The change of the stapes displacement varied from 0 dB to 28 dB. The effect was more prominent at frequencies above 1,000 Hz. Placing the floating mass transducer close to the incudostapedial joint reduced the mass loading effect.

CONCLUSION

The floating mass transducer produces a measurable reduction of the stapes displacement in the temporal bone model. The effect is more prominent at high frequencies.

Minimally invasive approach and fixation of cochlear and middle ear implants

One of the conventional surgical approaches for cochlear implantation is a retro-auricular incision with a posterior-inferiorly based skin and subcutaneous tissue flap and a superiorly based periosteal flap. The obvious advantage is an open operating field but the disadvantages are a large wound and a lengthy operating time. It may also result in more wound-related complications. To overcome these disadvantages, we have developed a minimally invasive technique that includes a small retro-auricular single layer incision. We have used a metal bridge beneath the posterior flap to increase accessibility when creating a recess for the implant. A novel technique is used to place the securing suture deep to the flap. This technique has been used in 49 paediatric and adult patients, and there have been no wound-related complications. Although this technique was initially designed for the CLARION CII implant, it has been used to place and secure the new CLARION HiRes 90 K, the Nucleus device, the MEDEL device and the Vibrant Soundbridge.

Electric Field Effect in Atomically Thin Carbon Films

We describe monocrystalline graphitic films, which are a few atoms thick but are nonetheless stable under ambient conditions, metallic, and of remarkably high quality. The films are found to be a two-dimensional semimetal with a tiny overlap between valence and conductance bands, and they exhibit a strong ambipolar electric field effect such that electrons and holes in concentrations up to 10 13 per square centimeter and with room-temperature mobilities of ∼10,000 square centimeters per volt-second can be induced by applying gate voltage.

Diffusion of single cardiac ryanodine receptors in lipid bilayers is decreased by annexin 12

Diffusion of cardiac ryanodine receptors (RyR2) in lipid bilayers was characterized. RyR2 location was monitored by imaging fluo-3 fluorescence due to Ca2+ flux through RyR2 channels or fluorescence from RyR2 conjugated with Alexa 488 or containing green fluorescent protein. Single channel currents were recorded to ensure that functional channels were studied. RyR2 exhibited an apparent diffusion coefficient (DRyR) of 1.2 x 10(-8) cm2 s(-1) and a mean path length of 5.0 microm. Optimal use of optical methods for analysis of RyR2 channel function requires that RyR2 diffusion be limited. Therefore, we tested the effect of annexin 12, which interacts with anionic phospholipids in a Ca2+-dependent manner. Addition of annexin 12 (0.25-4.0 microM) to the trans side of bilayers containing an 80:20 ratio of phosphatidylethanolamine/phosphatidylserine decreased RyR2 diffusion in a concentration-dependent manner. Annexin 12 (2 microM) decreased the apparent DRyR 683-fold from 1.2-10(-8) to 1.8 x 10(-11) cm2 s(-1) and the mean path length 10-fold from 5.0 to 0.5 micro m without obvious changes in the conductance of the native bilayer or in activation of RyR2 channels by Ca2+ or suramin. Thus, annexin 12 may provide a useful tool for optimizing optical analysis of RyR2 channels in lipid bilayers.

The influence of long-term tracheostomy on speech and language development in children

BACKGROUND

Individuals diagnosed as having primary neurological disorders have a high incidence of abnormal speech and language development. However, results in cohorts where this group are excluded are controversial. With no coexisting neurological impairment, some suggested that tracheostomy has little influence on speech development, whilst others showed a clear pattern of language disability. The aim of this study is to evaluate the influence of tracheostomy on speech and language development.

METHOD

Retrospective study using standardised outcome measures.

RESULTS

A series of 39 paediatric tracheostomies was studied. In the group where children had neurological disorders, 94% showed no language or delayed language development. In contrast, of the group of children without a neurological impairment, 60.9% had normal speech and language development. The median age at the decannulation in those children with delayed speech was 23 months, whilst in those children with normal speech it was 14.5 months.

CONCLUSION

Tracheostomy affects speech and language development in those with and without neurological disorders. Crucial factors affecting speech and language development within the neurologically normal group are age at the tracheostomy, and the duration of the tracheostomy until decannulation. Achieving earliest decannulation improves the chance of a normal speech and language development.

Carbon monoxide concentrations in paediatric sepsis syndrome

Plasma carbon monoxide (CO) concentrations were measured in 12 patients with sepsis syndrome. CO concentrations were found to be significantly increased in patients compared with those in 30 normal controls. Patients with septic shock had significantly higher plasma CO concentrations than those without shock. Results suggest that CO might play an important role in paediatric sepsis syndrome.