1,439 research outputs found
Diagnosability of Fuzzy Discrete Event Systems
In order to more effectively cope with the real-world problems of vagueness,
{\it fuzzy discrete event systems} (FDESs) were proposed recently, and the
supervisory control theory of FDESs was developed. In view of the importance of
failure diagnosis, in this paper, we present an approach of the failure
diagnosis in the framework of FDESs. More specifically: (1) We formalize the
definition of diagnosability for FDESs, in which the observable set and failure
set of events are {\it fuzzy}, that is, each event has certain degree to be
observable and unobservable, and, also, each event may possess different
possibility of failure occurring. (2) Through the construction of
observability-based diagnosers of FDESs, we investigate its some basic
properties. In particular, we present a necessary and sufficient condition for
diagnosability of FDESs. (3) Some examples serving to illuminate the
applications of the diagnosability of FDESs are described. To conclude, some
related issues are raised for further consideration.Comment: 14 pages; revisions have been mad
Broadband NIR-emitting Te cluster-doped glass for smart light source towards night-vision and NIR spectroscopy applications
Broadband near-infrared (NIR)-emitting materials are crucial components of the next generation of smart NIR light sources based on blue light-emitting diodes (LEDs). Here, we report a Te cluster-doped borate glass, which exhibits ultra-broadband emission around 980 nm with a full-width at half-maximum (FWHM) of 306 nm under blue light excitation. We propose adjustments of glass chemistry and processing condition as a means for topo-chemical tailoring of the NIR photoemission characteristics in such materials. Through implementing strongly reducing conditions during glass melting, Te clusters with broad NIR photoluminescence can be generated and stabilized once the melt is vitrified to the glassy state. Tunability of the NIR emission peak over the wavelength range of 904 to 1026 nm is possible in this way, allowing for fine adjustments of spectral properties relative to the stretching vibrations of common chemical bonds, for example, in water, proteins, and fats. This potentially enables high sensitivity in NIR spectroscopy. We further demonstrate potential application of glass-converted LEDs in night vision.</p
Impact of glucocorticoids on insulin resistance in the critically ill
Glucocorticoids (GCs) have been shown to reduce insulin sensitivity in healthy individuals. Widely used in critical care to treat a variety of inflammatory and allergic disorders, they may inadvertently exacerbate stress-hyperglycaemia. This research uses model-based methods to quantify the reduction of insulin sensitivity from GCs in critically ill patients, and thus their impact on glycaemic control. A clinically validated model-based measure of insulin sensitivity (SI) was used to quantify changes between two matched cohorts of 40 intensive care unit (ICU) patients who received GCs and a control cohort who did not. All patients were admitted to the Christchurch hospital ICU between 2005 and 2007 and spent at least 24 hours on the SPRINT glycaemic control protocol.
A 31% reduction in whole-cohort median insulin sensitivity was seen between the control cohort and patients receiving glucocorticoids with a median dose equivalent to 200mg/day of hydrocortisone per patient. Comparing percentile-patients as a surrogate for matched patients, reductions in median insulin sensitivity of 20, 25, and 21% were observed for the 25th, 50th and 75th-percentile patients. All these cohort and per-patient reductions are less than or equivalent to the 30-62% reductions reported in healthy subjects especially when considering the fact that the GC doses in this study are 1.3-4 times larger than those in studies of healthy subjects. This reduced suppression of insulin sensitivity in critically ill patients could be a result of saturation due to already increased levels of catecholamines and cortisol common in critically illness. Virtual trial simulation showed that reductions in insulin sensitivity of 20-30% associated with glucocorticoid treatment in the ICU have limited impact on glycaemic control levels within the context of the SPRINT protocol
Glargine as a Basal Insulin Supplement in Recovering Critically Ill Patients - An In Silico Study
Tight glycaemic control is now benefiting medical and surgical intensive care patients
by reducing complications associated with hyperglycaemia. Once patients leave this intensive
care environment, less acute wards do not continue to provide the same level of glycaemic
control. Main reason is that these less acute wards do not have the high levels of nursing
resources to provide the same level of glycaemic control. Therefore developments in protocols
that are less labour intensive are necessary. This study examines the use of insulin glargine
for basal supplement in recovering critically ill patients. These patients represent a group who
may benefit from such basal support therapy. In silico study results showed the potential in
reducing nursing effort with the use of glargine. However, a protocol using only glargine for
glucose control did not show to be effective in the simulated patients. This may be an indication
that a protocol using only glargine is more suitable after discharge from critical care
A burst with double radio spectrum observed up to 212 GHz
We study a solar flare that occurred on September 10, 2002, in active region
NOAA 10105 starting around 14:52 UT and lasting approximately 5 minutes in the
radio range. The event was classified as M2.9 in X-rays and 1N in H\alpha.
Solar Submillimeter Telescope observations, in addition to microwave data give
us a good spectral coverage between 1.415 and 212 GHz. We combine these data
with ultraviolet images, hard and soft X-rays observations and full-disk
magnetograms. Images obtained from Ramaty High Energy Solar Spectroscopic
Imaging data are used to identify the locations of X-ray sources at different
energies and to determine the X-ray spectrum, while ultra violet images allow
us to characterize the coronal flaring region. The magnetic field evolution of
the active region is analyzed using Michelson Doppler Imager magnetograms. The
burst is detected at all available radio-frequencies. X-ray images (between 12
keV and 300 keV) reveal two compact sources and 212 GHz data, used to estimate
the radio source position, show a single compact source displaced by 25" from
one of the hard X-ray footpoints. We model the radio spectra using two
homogeneous sources, and combine this analysis with that of hard X-rays to
understand the dynamics of the particles. Relativistic particles, observed at
radio wavelengths above 50 GHz, have an electron index evolving with the
typical soft-hard-soft behaviour.Comment: Submitted to Solar Physics, 20 pages, 8 fugure
Modeled Insulin Sensitivity and Interstitial Insulin Action from a Pilot Study of Dynamic Insulin Sensitivity Tests
An accurate test for insulin resistance can delay or prevent the development of Type 2 diabetes and its complications. The current gold standard test, CLAMP, is too labor intensive to be used in general practice. A recently developed dynamic insulin sensitivity test,
DIST, uses a glucose-insulin-C-peptide model to calculate model-based insulin sensitivity, SI.
Preliminary results show good correlation to CLAMP. However both CLAMP and DIST ignore
saturation in insulin-mediated glucose removal. This study uses the data from 17 patients who
underwent multiple DISTs to investigate interstitial insulin action and its influence on modeled
insulin sensitivity. The critical parameters influencing interstitial insulin action are saturation
in insulin receptor binding, αG, and plasma-interstitial difiusion rate, nI . Very low values of αG
and very low values of nI produced the most intra-patient variability in SI. Repeatability in SI
is enhanced with modeled insulin receptor saturation. Future parameter study on subjects with
varying degree of insulin resistance may provide a better understanding of different contributing
factors of insulin resistance
Non-Supersymmetric Deformations of Non-Critical Superstrings
We study certain supersymmetry breaking deformations of linear dilaton
backgrounds in different dimensions. In some cases, the deformed theory has
bulk closed strings tachyons. In other cases there are no bulk tachyons, but
there are localized tachyons. The real time condensation of these localized
tachyons is described by an exactly solvable worldsheet CFT. We also find some
stable, non-supersymmetric backgrounds.Comment: 33 pages, references adde
Endogenous insulin secretion in critically ill patients
1-pageGlucose-insulin system models can be used for improved glycemic control of critically ill patients. A key component of glucose-insulin models is pancreatic insulin secretion. There is limited data in the literature quantifying insulin secretion in critically ill patients at physiologic levels. This study presents a model pancreatic insulin secretion in critically ill patients based on data from a critically ill population
Strings in Homogeneous Background Spacetimes
The string equations of motion for some homogeneous (Kantowski-Sachs, Bianchi
I and Bianchi IX) background spacetimes are given, and solved explicitly in
some simple cases. This is motivated by the recent developments in string
cosmology, where it has been shown that, under certain circumstances, such
spacetimes appear as string-vacua.
Both tensile and null strings are considered. Generally, it is much simpler
to solve for the null strings since then we deal with the null geodesic
equations of General Relativity plus some additional constraints.
We consider in detail an ansatz corresponding to circular strings, and we
discuss the possibility of using an elliptic-shape string ansatz in the case of
homogeneous (but anisotropic) backgrounds.Comment: 25 pages, REVTE
- …