275 research outputs found
Structural Analysis and Control of a Model of Two-site Electricity and Heat Supply
This paper introduces a control problem of regulation of energy flows in a
two-site electricity and heat supply system, where two Combined Heat and Power
(CHP) plants are interconnected via electricity and heat flows. The control
problem is motivated by recent development of fast operation of CHP plants to
provide ancillary services of power system on the order of tens of seconds to
minutes. Due to the physical constraint that the responses of the heat
subsystem are not necessary as fast as those of the electric subsystem, the
target controlled state is not represented by any isolated equilibrium point,
implying that stability of the system is lost in the long-term sense on the
order of hours. In this paper, we first prove in the context of nonlinear
control theory that the state-space model of the two-site system is non-minimum
phase due to nonexistence of isolated equilibrium points of the associated zero
dynamics.Instead, we locate a one-dimensional invariant manifold that
represents the target controlled flows completely. Then, by utilizing a virtual
output under which the state-space model becomes minimum phase, we synthesize a
controller that achieves not only the regulation of energy flows in the
short-term regime but also stabilization of an equilibrium point in the
long-term regime. Effectiveness of the synthesized controller is established
with numerical simulations with a practical set of model parameters
Motion-tracking skill assist and power assist for sinusoidal motions with a semi-active assist mechanism using energy control
The nanoscale phase separation in hole-doped manganites
A macroscopic phase separation, in which ferromagnetic clusters are observed
in an insulating matrix, is sometimes observed, and believed to be essential to
the colossal magnetoresistive (CMR) properties of manganese oxides. The
application of a magnetic field may indeed trigger large magnetoresistance
effects due to the percolation between clusters allowing the movement of the
charge carriers. However, this macroscopic phase separation is mainly related
to extrinsic defects or impurities, which hinder the long-ranged charge-orbital
order of the system. We show in the present article that rather than the
macroscopic phase separation, an homogeneous short-ranged charge-orbital order
accompanied by a spin glass state occurs, as an intrinsic result of the
uniformity of the random potential perturbation induced by the solid solution
of the cations on the -sites of the structure of these materials. Hence the
phase separation does occur, but in a more subtle and interesting nanoscopic
form, here referred as ``homogeneous''. Remarkably, this ``nanoscale phase
separation'' alone is able to bring forth the colossal magnetoresistance in the
perovskite manganites, and is potentially relevant to a wide variety of other
magnetic and/or electrical properties of manganites, as well as many other
transition metal oxides, in bulk or thin film form as we exemplify throughout
the article.Comment: jpsj2 TeX style (J. Phys. Soc. Jpn); 18 pages, 7 figure
Guillain-Barré syndrome: a century of progress
In 1916, Guillain, Barré and Strohl reported on two cases of acute flaccid paralysis with high cerebrospinal fluid protein levels and normal cell counts — novel findings that identified the disease we now know as Guillain–Barré syndrome (GBS). 100 years on, we have made great progress with the clinical and pathological characterization of GBS. Early clinicopathological and animal studies indicated that GBS was an immune-mediated demyelinating disorder, and that severe GBS could result in secondary axonal injury; the current treatments of plasma exchange and intravenous immunoglobulin, which were developed in the 1980s, are based on this premise. Subsequent work has, however, shown that primary axonal injury can be the underlying disease. The association of Campylobacter jejuni strains has led to confirmation that anti-ganglioside antibodies are pathogenic and that axonal GBS involves an antibody and complement-mediated disruption of nodes of Ranvier, neuromuscular junctions and other neuronal and glial membranes. Now, ongoing clinical trials of the complement inhibitor eculizumab are the first targeted immunotherapy in GBS
Enteritis caused by Campylobacter jejuni followed by acute motor axonal neuropathy: a case report
Glial ankyrins facilitate paranodal axoglial junction assembly
Neuron-glia interactions establish functional membrane domains along myelinated axons. These include nodes of Ranvier, paranodal axoglial junctions, and juxtaparanodes. Paranodal junctions are the largest vertebrate junctional adhesion complex, are essential for rapid saltatory conduction, and contribute to assembly and maintenance of nodes. However, the molecular mechanisms underlying paranodal junction assembly are poorly understood. Ankyrins are cytoskeletal scaffolds traditionally associated with Na+ channel clustering in neurons and important for membrane domain establishment and maintenance in many cell types. Here, we show that ankyrinB, expressed by Schwann cells, and ankyrinG, expressed by oligodendrocytes, are highly enriched at the glial side of paranodal junctions where they interact with the essential glial junctional component neurofascin 155. Conditional knockout of ankyrins in oligodendrocytes disrupts paranodal junction assembly and delays nerve conduction during early development in mice. Thus, glial ankyrins function as major scaffolds that facilitate early and efficient paranodal junction assembly in the developing central nervous system
Guillain-Barré Syndrome and Preceding Infection with Campylobacter, Influenza and Epstein-Barr Virus in the General Practice Research Database
BACKGROUND: A number of infectious agents have previously been suggested as risk factors for the development of Guillain-Barré syndrome (GBS), but robust epidemiologic evidence for these associations is lacking. METHODS AND FINDINGS: We conducted a nested case-control study using data from the United Kingdom General Practice Research Database between 1991 and 2001. Controls were matched to cases on general practice clinic, sex, year of birth and date of outcome diagnosis in their matched case. We found positive associations between GBS and infection with Campylobacter, Epstein-Barr virus and influenza-like illness in the previous two months, as well as evidence of a protective effect of influenza vaccination. After correction for under-ascertainment of Campylobacter infection, the excess risk of GBS following Campylobacter enteritis was 60-fold and 20% of GBS cases were attributable to this pathogen. CONCLUSIONS: Our findings indicate a far greater excess risk of GBS among Campylobacter enteritis patients than previously reported by retrospective serological studies. In addition, they confirm previously suggested associations between infection due to Epstein-Barr virus infection and influenza-like illness and GBS. Finally, we report evidence of a protective effect of influenza vaccination on GBS risk, which may be mediated through protection against influenza disease, or result from a lower likelihood of vaccination among those with recent infection. Cohort studies of GBS incidence in this population would help to clarify the burden of GBS due to influenza, and any potential protective effect of influenza vaccination
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