Identification of FIR Wiener systems with unknown,non-invertible,polynomial non-linearities

Wiener systems consist of a linear dynamic system whose output is measured through a static non-linearity. In this paper we study the identification of single-input single-output Wiener systems with finite impulse response dynamics and polynomial output non-linearities. Using multi-index notation, we solve a least squares problem to estimate products of the coefficients of the non-linearity and the impulse response of the linear system. We then consider four methods for extracting the coefficients of the non-linearity and impulse response: direct algebraic solution, singular value decomposition, multi-dimensional singular value decomposition and prediction error optimization.     

‘Zoning’ before zoning: the regulation of apartment housing in early twentieth century Winnipeg and Toronto

‘Residential restrictions’ were widely used in North American cities prior to the development of more comprehensive zoning schemes. This paper examines the use of restrictive by-laws to control the spread of apartment housing in two Canadian cities, Toronto and Winnipeg, prior to World War II. In both cities apartment-house booms in the early 1910s and late 1920s were perceived as threatening the growth of suburban homeownership. Drawing on newspaper reports, council records and correspondence, as well as more quantitative local government records, it is argued that the apparently ‘populist’ anti-apartment regulations in Toronto were actually more flexible and more favourable to developers than less extensive, but more rigid by-laws in Winnipeg. In both cities, the application of regulations both reflected and created distinctive social geographies. The paper indicates the need to focus on how residential restrictions were implemented on the ground as much as on debates surrounding the formulation of policy or the passage of legislation.     

A context noise model of episodic word recognition.

Item noise models of recognition assert that interference at retrieval is generated by the words from the study list. Context noise models of recognition assert that interference at retrieval is generated by the contexts in which the test word has appeared. The authors introduce the bind cue decide model of episodic memory, a Bayesian context noise model, and demonstrate how it can account for data from the item noise and dual-processing approaches to recognition memory. From the item noise perspective, list strength and list length effects, the mirror effect for word frequency and concreteness, and the effects of the similarity of other words in a list are considered. From the dual-processing perspective, process dissociation data on the effects of length. temporal separation of lists, strength, and diagnosticity of context are examined. The authors conclude that the context noise approach to recognition is a viable alternative to existing approaches. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Microstructural Characterization of Lamellar Features in TiAl by FIB Imaging

A novel experimental procedure is introduced to determine phase fractions and the distribution of individual phases of TiAl‐based two‐phase alloys using the focused ion beam (FIB) technique. Two γ‐titanium aluminide alloys with a fine‐grained duplex and a nearly lamellar microstructure are examined. The special FIB‐based preparation procedure results in high contrast ion beam‐induced images for all investigated alloys and allows to quantify the phase contents easily by automated microstructural analysis. Fine two‐phase structures, e.g. lamellar colonies in γ‐TiAl, can be imaged in high resolution with respect to different phases. To validate the FIB‐derived data, we compare them to results obtained with another method to determine phase fractions, electron back‐scatter diffraction (EBSD). This direct comparison shows that the FIB‐based technique generally provides slightly higher α₂‐fractions, and thus helps to overcome the limited lateral resolution near grain boundaries and interfaces associated with the conventional EBSD approach. Our study demonstrates that the FIB‐based technique is a simple, fast, and more exact way to determine high resolution microstructural characteristics with respect to different phase constitutions in two‐phase TiAl alloys and other such materials with fine, lamellar microstructures.     

Antibiotic lock: In vitro stability of gentamicin and sodium citrate stored in dialysis catheters at 37 °C

Catheter‐related bacteremia (CRB) is a major cause of morbidity and mortality especially among patients receiving hemodialysis. Antibiotic lock therapy represents a promising technique in the treatment of CRB. Several studies have evaluated antibiotics in combination with heparin as an interdialytic locking solution for prophylaxis of CRB. The objective of this study was to evaluate the stability of gentamicin and sodium citrate in hemodialysis catheters as an interdialytic lock. Solutions containing gentamicin 2.5 mg/mL and sodium citrate 40 mg/mL (4%) were prepared individually and in combination. The solutions were instilled into dialysis catheters and stored at 37 °C for 96 h. Samples were withdrawn randomly from catheter lumens at 24‐hour intervals for 4 days and stored at ?20 °C until analysis. The samples were analyzed with validated, stability‐indicating HPLC assays. The luminal concentration of gentamicin 2.5 mg/mL, sodium citrate 40 mg/mL (4%), and the combination was determined on study days 0, 1, 2, 3, and 4. When gentamicin was combined with sodium citrate and stored at 37 °C in dialysis catheters, the solution showed no decrease in either the gentamicin or the sodium citrate concentrations over the 96‐hour study period. The percent of the original concentration at 96 h was 102.4±1.03 for gentamicin and 102.9±1.25 for citrate (P=0.5556). The combination of gentamicin 2.5 mg/mL and sodium citrate 40 mg/mL (4%) can be retained in hemodialysis catheters for at least 96 h at 37 °C with no evidence of degradation.     

Extracting Behavioral Data from Physical Descriptions of MEMS for Simulation

The work described here deals with the problems of modeling and simulation for MEMS devices. The eventual goal is to produce a top-down MEMS design system similar to today’s powerful VLSI design systems. In this work a fixed fabrication process (MUMPS) and a fixed layout tool (L-Edit) are chosen. Thus our efforts are concentrated on reliable simulation of designs and eventual comparison with actual fabricated parts. The cantilever beam is chosen as an example of how extraction from a physical layout may be modeled and interfaced with various simulators.     

Minimizing expected waiting in a medical appointment system

An appointment policy is established for a specific outpatient system, with the goal of reducing a combination of patients' expected waiting times and doctor's expected overtime. Service times are stochastic, and patients are assumed to be punctual if they show for their appointments. Substantial reductions in waiting times can be obtained over traditional scheduling practices, and the procedure is easily implemented by a naive scheduler once the optimal policy is established.     

Team cognition in group interventions: The relation between coleaders' shared mental models and group climate.

The relation between the convergence in group coleaders' mental models of their groups and group members' perceptions of group climate was examined. Coleaders of 8 intergroup dialogue groups provided paired-comparison ratings of the similarity of their group members, and group members provided group climate ratings, following each of 7 sessions. The paired-comparison ratings were analyzed using pathfinder network analysis (Schvaneveldt, 1990) to examine the structure of each coleader's mental model of her or his group, and to compare these mental models within coleader pairs to determine degree of similarity in coleaders' mental models for each coleader pair for each week (i.e., how similarly coleaders of a group view their group). Growth curve analyses of the degree of similarity and group climate data showed an increase in similarity of coleaders' mental models within groups across sessions, and that similarity in coleader mental models was related to increases in the engaged and decreases in the avoiding aspects of the group climate. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The Determination of Fatty Acid Primary Amides by Capillary Gas Chromatography

A method has been developed for the determination of 12 primary amides of long-chain fatty acids by capillary column gas chromatography. The method uses no derivatization or sample preparation other than extraction of the sample. A variety of commercial amidecontaining materials have been analyzed successfully. The amides, along with other soluble materials, are first separated from the host using refluxing 2-propanol containing an internal standard. The fatty acid amides are then identified and measured by gas chromatography over a programmed temperature range of 200 to 260 C. The chromatograms obtained show sharp peaks, unique retention times and acceptable reproducibility for quantitation.Cis- trans isomers of several of the fatty acid amides were tested and found to be resolved under the conditions employed.