On-Line Symbolic Constraint Embedding for Simulation of Hybrid Dynamical Systems

In this paper we present a simulator designed to handle multibody systems with changing constraints, wherein the equations of motion for each of its constraint configurations are formulated in minimal ODE form with constraints embedded before they are passed to an ODE solver. The constraint-embedded equations are formulated symbolically according to a re-combination of terms of the unconstrained equations, and this symbolic process is undertaken on-line by the simulator. Constraint-embedding undertaken on-the-fly enables the simulation of systems with an ODE solver for which constraints are not known prior to simulation start or for which the enumeration of all constraint conditions would be unwieldy because of their complexity or number. Issues of drift associated with DAE solvers that usually require stabilization are sidestepped with the constraint-embedding approach. We apply nomenclature developed for hybrid dynamical systems to describe the system with changing constraints and to distinguish the roles of the forward dynamics solver, a collision detector, and an impact resolver. We have prototyped the simulator in MATLAB and demonstrate the design using three representative examples.     

Interpretation and topographic compensation of conifer canopy self-shadowing

The self-shadowing of conifer canopies results from the size and arrangement of trees within a stand and is a first-order term controlling radiance from forested terrain at common pixel scales of tens of meters. Although self-shadowing is a useful attribute for forest remote-sensing classification, compensation for the topographic effects of self-shadowing has proven problematic. This study used airborne canopy LiDAR measurements of 80 Pacific Northwest, USA conifer stands ranging in development stage from pre-canopy closure to old-growth in order to model canopy self-shadowing for four solar zenith angles (SZA). The shadow data were compared to physical measurements used to characterize forest stands, and were also used to test and improve terrain compensation models for remotely sensed images of forested terrain. Canopy self-shadowing on flat terrain strongly correlates with the canopy's geometric complexity as measured by the rumple index (canopy surface area/ground surface area) (R² = 0.94–0.87 depending on SZA), but is less correlated with other stand measurements: 95th percentile canopy height (R² = 0.68), mean diameter at breast height (dbh) (R² = 0.65), basal area ha^? 1 (R² = 0.18), and canopy stem count ha^? 1 (R² = 0.18). The results in this paper support interpretation of self-shadowing as a function of canopy complexity, which is an important ecological characteristic in its own right. Modeling of canopy self-shadowing was used to assess the accuracy of the Sun-Canopy-Sensor (SCS) topographic correction, and to develop a new empirical Adaptive Shade Compensation (ASC) topographic compensation model. ASC used measured shadow (as an estimate of canopy complexity) and the SCS term (to describe the illumination geometry) as independent variables in multiple regressions to determine the topographic correction. The ASC model provided more accurate radiance corrections with limited variation in results across the full range of canopy complexities and incidence angles.     

Improved land surface emissivities over agricultural areas using ASTER NDVI

Land surface emissivity retrieval over agricultural regions is important for energy balance estimations, land cover assessment and other related environmental studies. The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) produces images of sufficient spatial resolution (from 15 m to 90 m) to be of use in agricultural studies, in which fields of crops are too small to be well-resolved by low resolution sensors. The ASTER project generates land surface emissivity images as a Standard Product (AST05) using the Temperature/Emissivity Separation (TES) algorithm. However, the TES algorithm is prone to scaling errors in estimating emissivities for surfaces with low spectral contrast if the atmospheric correction is inaccurate. This paper shows a comparison between the land surface emissivity estimated with the TES algorithm and from a simple approach using the Normalized Difference Vegetation Index (NDVI) for five ASTER images (28 June 2000, 15 August 2000, 31 August 2000, 28 April 2001 and 02 August 2001) of the agricultural area of Barrax (Albacete, Spain). The results indicate that differences are < 1% for ASTER band 13 (10.7 μm) and < 1.5% for band 14 (11.3 μm), but > 2% for bands 10 (8.3 μm), 11 (8.6 μm) and 12 (9.1 μm). The emissivities for the five ASTER bands were tested against in situ measurements carried out with the CIMEL CE 312-2 field radiometer, the NDVI method giving root mean square errors (RMSE) < 0.005 over vegetated areas and RMSE < 0.015 over bare soil, and the TES algorithm giving RMSE ∼ 0.01 for vegetated areas but RMSE > 0.03 over bare soil. The errors and inconsistencies for ASTER bands 13 and 14 are within those anticipated for TES, but the greater errors for bands 10-12 suggest the presence of problems related to atmospheric compensation and model assumptions about soil spectra. The NDVI method uses visible/near-infrared data co-acquired with the thermal images to estimate vegetation cover and, hence, provides an independent constraint on emissivity. The success of this approach suggests that it may be useful for daytime images of agricultural or other heavily vegetated areas, in which the TES algorithm has occasional failures.     

The emission characteristics of liquid‐crystal lasers

Abstract— Liquid‐crystal lasers exhibit narrow linewidth, large coherence area, and low threshold laser emission. Moreover, the wavelength of the laser line can be readily tuned using a variety of different external stimuli, including electric fields. These combined features make them particularly attractive as compact tunable laser light sources. Recent experimental results with regards to the emission characteristics of chiral nematic photonic band‐edge lasers are discussed. This type of liquid‐crystal laser consists of a self‐organizing one‐dimensional photonic band structure and a gain medium in the form of a laser dye. Some of the generic features that are observed for these lasers are discussed, including the typical emission linewidth of the laser line, the change in emission energy of the laser for high excitation energies and high pump repetition rates, and the dependence of the excitation threshold and slope efficiency on the cell thickness. In addition, how the performance changes when either the molecular structure of the chiral nematic host or the gain medium is varied is considered. To conclude, results are presented on the laser emission for a wide‐temperature‐range blue phase I band‐edge laser which consists of a self‐organizing three‐dimensional photonic band structure.     

Development and validation of the Counseling Self-Estimate Inventory.

Describes the development of the Counseling Self-Estimate Inventory through 5 studies. A factor analysis (N?=?213) yielded 5 factors that reflect counselor trainees' confidences in using microskills, attending to process, dealing with difficult client behaviors, behaving in a culturally competent way, and being aware of one's values. Reliability estimates indicate that the items are internally consistent (α?=?.93) and stable over time. Initial validity estimates show that the instrument is (1) positively related to counselor performance, self-concept, problem-solving appraisal, performance expectations, and class satisfaction; (2) negatively related to state and trait anxiety; (3) minimally related to aptitude, achievement, personality type, and defensiveness; and (4) sensitive to change over the course of master's practicum and across different levels of counselors. Also, trait anxiety and counseling self-efficacy were significant predictors of counselor trainee performance. The development of a reliable and valid counseling self-efficacy instrument has training and research implications. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Chronic chlorpropamide therapy of noninsulin-dependent diabetes augments basal and stimulated insulin secretion by increasing islet sensitivity to glucose

To determine the effect of chronic sulfonylurea therapy on islet function in noninsulin-dependent diabetes mellitus (NIDDM), studies were performed in 18 untreated NIDDM patients before and after 12-16 weeks of chlorpropamide therapy. Fasting plasma glucose (FPG) fell with chlorpropamide therapy from 249 +/- 16 to 157 +/- 8 mg/dl (mean +/- SEM; P less than 0.001), and basal insulin increased from 17 +/- 2 to 24 +/- 3 microU/ml (P less than 0.001). The percent change in basal insulin correlated with the pretreatment FPG (r = 0.62; P less than 0.01) and inversely with the change in FPG during chlorpropamide (r = -0.57; P less than 0.025). Thus, patients with the highest pretreatment FPG showed the largest relative increase in basal insulin and the largest fall of FPG with chlorpropamide therapy. In nine patients, arginine-stimulated acute insulin responses (AIR) were studied at each of three plasma glucose (PG) levels both before and during chlorpropamide treatment. AIR at FPG was not different before and during treatment. However, when PG during treatment was matched by glucose infusion to the pretreatment FPG, the AIR was clearly increased during chlorpropamide therapy (176 +/- 65 vs. 49 +/- 11 microU/ml; P less than 0.02). When AIR is plotted against PG for each individual, the slope of the regression line generated (slope of glucose potentiation) is a measure of that patient's islet sensitivity to glucose. The logarithm of the slope of glucose potentiation correlated inversely with FPG (r = -0.92; P less than 0.001). Chlorpropamide treatment increased the slopes of potentiation from 0.26 +/- 0.11 to 1.47 +/- 0.70 (P less than 0.01). We conclude that chronic chlorpropamide therapy augments both basal and stimulated insulin secretion in NIDDM and that this may be an important mechanism of the drug's hypoglycemic effect. The data support the hypothesis that the hyperglycemia of NIDDM is related to islet insensitivity to glucose and that chlorpropamide treatment improves this impairment.     

Actinomycosis of the posterior triangle: a case report and review of the literature

Actinomycosis presents acutely as an abscess, or as a chronic lesion mimicking malignancy, tuberculosis, or aspergillosis. Most disease involves the mouth and its immediate site of lymphatic drainage, the anterior triangle of the neck. We present a case of actinomycosis at the apex of the posterior triangle, suspected of being a malignancy, and discuss the importance of being aware of this as a cause of neck lumps. The diagnosis is usually made late because of the difficulties in culturing the organism, or in identifying characteristic 'sulphur granules' in pus or biopsy specimens. For these reasons, the disease is underdiagnosed. When acute or chronic neck lesions prove difficult to diagnose, microscopy and prolonged anaerobic culture of pus and biopsy specimens should be performed in addition in Ziehl-Neelsen staining, tuberculosis and fungal cultures. The tests should be repeated if negative. Specific treatment requires prolonged courses of antibiotics, despite adequate surgical excision, to prevent relapse.     

Defective gas mixers, a cause of retro-pollution of medical gas distribution pipelines]

PURPOSE: To study the distribution and mechanism of traumatic injuries to the nerves supplying the eye and muscles protecting the visual apparatus. METHODS: Brain autopsy was carried out in 12 consecutive patients who died within three days after closed head injury. A segment of the brainstem with the entire intracranial portion of nerves II-VII was dissected out in each case and fixed in formalin. The specimens were stripped of the leptomeninges and inspected thoroughly under magnification. RESULTS: Injuries to the nerves were seen in nine subjects. The oculomotor nerve was completely torn off from the midbrain unilaterally in three and bilaterally in two cases. In one patient only a portion of the superficial fibres on the medial aspect of the nerve was ripped out from the brainstem. In two patients the fourth nerve was ruptured. The root of the fifth cranial nerve was contused and the fibres between the brainstem and Gasserian ganglion crushed and separated in one case. Bilateral avulsion of the root of the sixth nerve from the brainstem was found in two cases. The initial segment of the facial nerve was crushed in two subjects. No visible injury to the optic nerves was found. CONCLUSIONS: Cranial nerves related to the visual system are subject to serious injury in a large proportion of cases of severe head trauma resulting from automobile accidents. In the majority of cases damage results from ripping the roots of these nerves out of the brainstem.     

Assessing the patient at risk for oral squamous cell carcinoma

Patients and health care workers require continuing education to promote knowledge of the signs, symptoms, and risk factors for oral cancer. This paper reviews the literature assessing diagnostic tools that are currently available or being developed, in order to assist in the biopsy site selection and subsequent diagnosis of patients at risk for oral cancer. There is a general consensus that oral examination of patients at risk for oral squamous cell carcinoma (SCC) should be conducted on a routine basis. However, there can be false-positive and false-negative findings. Toluidine blue has been shown to be useful as an adjunct to the clinical examination when used by experienced clinicians. Exfoliative cytology is not currently used as a routine measure for the evaluation of lesions of the oral mucosa, but further development and the application of biologic markers to cytologic specimens may increase its value. Fluorescent imaging of malignant lesions of the oral mucosa has been shown to be sensitive and specific in animal models but thus far has been reported in only one human trial. The sensitivity and specificity of these techniques when used by general practitioners need to be assessed. Further, none of the above procedures has yet been shown to be a cost-effective public health measure in screening for oral cancer.