Nontangential and probabilistic boundary behavior of pluriharmonic functions

Let $u$ be a pluriharmonic function on the unit ball in $\mathbb{C}^n$. I consider the relationship between the set of points $L_u$ on the boundary of the ball at which $u$ converges nontangentially and the set of points $\mathcal{L}_u$ at which $u$ converges along conditioned Brownian paths. For harmonic functions $u$ of two variables, the result $L_u\stackrel{\mathrm{a.e.}}{=}\mathcal{L}_u$ has been known for some time, as has a counterexample to the same equality for three variable harmonic functions. I extend the $L_u\stackrel{\mathrm{a.e.}}{=}\mathcal{L}_u$ result to pluriharmonic functions in arbitrary dimensions.Comment: Published at http://dx.doi.org/10.1214/009117906000000188 in the Annals of Probability (http://www.imstat.org/aop/) by the Institute of Mathematical Statistics (http://www.imstat.org

Artificial intelligence techniques for modeling database user behavior

The design and development of the adaptive modeling system is described. This system models how a user accesses a relational database management system in order to improve its performance by discovering use access patterns. In the current system, these patterns are used to improve the user interface and may be used to speed data retrieval, support query optimization and support a more flexible data representation. The system models both syntactic and semantic information about the user's access and employs both procedural and rule-based logic to manipulate the model

Prototype resupply scheduler

Resupply scheduling for the Space Station presents some formidable logistics problems. One of the most basic problems is assigning supplies to a series of shuttle resupply missions. A prototype logistics expert system which constructs resupply schedules was developed. This prototype is able to reconstruct feasible resupply plans. In addition, analysts can use the system to evaluate the impact of adding, deleting or modifying launches, cargo space, experiments, etc

The use of high fidelity CAD models as the basis for training on complex systems

During the design phases of large and complex systems such as NASA's Space Station Freedom (SSF), there are few, if any physical prototypes built. This is often due to their expense and the realization that the design is likely to change. This poses a problem for training, maintainability, and operations groups who are tasked to lay the foundation of plans for using these systems. The Virtual Reality and Visualization Laboratory at the Boeing Advanced Computing Group's Huntsville facility is supporting the use of high fidelity, detailed design models that are generated during the initial design phases, for use in training, maintainability and operations exercises. This capability was used in its non-immersive form to great effect at the SSF Critical Design Review (CDR) during February, 1993. Allowing the user to move about within a CAD design supports many efforts, including training and scenario study. We will demonstrate via a video of the Maintainability SSF CDR how this type of approach can be used and why it is so effective in conveying large amounts of information quickly and concisely. We will also demonstrate why high fidelity models are so important for this type of training system and how it's immersive aspects may be exploited as well

Torsades de pointes and the classic short-long-short activation sequence in the setting of atrial fibrillation

Torsades de pointes (TdP) is an ominous form of rapid polymorphic ventricular tachycardia occurring in the setting of QT prolongation that must be addressed immediately as it often leads to ventricular fibrillation. TdP is associated with many factors that prolong the QT interval, including hypokalemia, hypomagnesemia, hypocalcemia, drugs (antiemetics, antipsychotics, SSRI's, TCA's, macrolide and fluoroquinolone antibiotics) and congenital long QT syndrome. We present a case of TdP in the setting of electrolyte abnormalities and atrial fibrillation with a classic short-long-short (SLS) activation sequence on EKG prior to deteriorating into TdP.An 88-year-old female with a history of atrial fibrillation and dementia presented to the emergency room with progressive weakness. Patient requires total care from her son at baseline. Her vitals were stable on arrival. Chemistry revealed hypokalemia, hypocalcemia, and hypomagnesemia which were contributed to poor appetite. Her troponin was elevated. Urinalysis revealed pyuria suggestive of urinary tract infection. Patient's EKG revealed atrial fibrillation and old left bundle brand block on arrival. She was given magnesium oxide and potassium chloride for electrolyte replacement.Shortly thereafter, the patient was noted to have several episodes of non-sustained ventricular tachycardia. Multiple EKGs were performed and exhibited prolonged QTc greater than 500 ms. While in the emergency room, patient was noted to have seizure-like activity and found to be pulseless. The EKG during this period showed a run of atrial fibrillation that progressed to TdP after a SLS activation sequence. The patient required chest compressions, one round of epinephrine and defibrillation before achieving ROSC with spontaneous movement and breathing. She was admitted to ICU and received aggressive electrolyte replacement and non-QT prolonging antibiotic treatment for her urinary tract infection. Her home medication list was reviewed and trazadone was discontinued due to potential QTc prolongation. Her troponin was concluded to be type 2 myocardial infract in the setting of active infection and defibrillation. She did not have any additional arrhythmia throughout her hospital stay.TdP is an uncommon but well recognized polymorphic ventricular tachycardia pattern that involves a twisting of the QRS complexes around the isoelectric line. In the setting of QTc prolongation, a SLS activation sequence has been observed to precede TdP. The sequence was theorized to promote heterogeneity of myocardial repolarization that creates potential reentry that results in TdP. Our case demonstrated another layer of arrhythmia as patient has underlying atrial fibrillation. The R-R variation in atrial fibrillation makes the widely used Bazett formula difficult to access QTc. Additionally, atrial fibrillation has been described in literature to be associated with TdP when treated with Class III antiarrhythmic for rhythm control. TdP occurring in atrial fibrillation in the absence of antiarrhythmic drugs is poorly understood. Prompt recognition of this life-threatening arrhythmia and prompt defibrillation to restore perfusion rhythm continues to be the cornerstone of treatment for an unstable patient with TdP. A careful history and medication reconciliation often guide prompt action to prevent future occurrence

An investigation into how business excellence can contribute to sustained organizational performance in both private and public sector organizations

Business Excellence, or Total Quality Management as it is also known, is a philosophy that may be traced back to the 1950's when Deming and Juran showed the way to the Japanese at the end of the second world war (Oakland (2003a)). Some of the principles may even be traced back to the Egyptians (Tanner and Walker (2002)). Despite this, Business Excellence theory is it an early stage of development (Dale, Wu et al. (2001)). For over a decade, organizations have pursued the benefits of adopting a Business Excellence approach and have sought external recognition through the achievement of regional, national and even continent Quality Awards (Porter and Tanner (2003)). One day soon, there could even be a 'World Quality Award'. The research set out with two clear aims. Firstly, there was an objective to add to the growing body of knowledge supporting the benefits of the adoption of Business Excellence. Secondly, there was a desire to provide an insight into why Business Excellence delivers such benefits. The thesis makes a contribution in both these areas. The research was also novel in that both private and public organizations were included in the study, and it represents one of the few studies to examine public sector organizations at a time when the UK government is investing heavily in Business Excellence as a way to improve public services (PriceWaterhouseCoopers (2000)). The work also partially replicated the research of two other authors, Hall (Hall (1991); Hall (1992); Hall (1994)) and Lindgren (2001), and not only provides support for their findings, but also support for the current work. The research examined how Business Excellence could lead to a source of competitive advantage (or source of organizational advantage, as it was termed, as the sample included both public and private organizations). Use was made of the resource-based view of the firm as a basis for the theory underpinning the research ((Tena, Llusar et al. (2001)) taking a scientific Structure - Conduct – Performance perspective (Barney (1991a)). The literature review identified an initial research model that had the constructs of Organizational Context, Environmental Dynamics, Leadership Excellence and Strategic Capability as independent variables, and Performance across a number of Stakeholder groups as the dependent variable. A positivist approach was taken to collect data using a self-reporting postal questionnaire from 193 organizations. Use was made of existing instruments following Churchill‟s 9-step process (Churchill and Iacobucci (2002)), with some instruments being converted for use in the public sector. Although primarily a positivist approach, the research also made use of social construction techniques in the design of the questionnaire and to validate the findings (Jick (1979); Easterby-Smith, Thorpe et al. (2002)). The first area examined was the benefits of Business Excellence. A comprehensive review of the literature concluded there was a strong case for its use, although the majority of work had been conducted on the American Malcolm Baldrige National Quality Award (MBNQA) framework and not on the more local EFQM Excellence Model® framework. A number of hypotheses were developed, covering areas such as the difference in benefit reported between small and large organizations, and whether whole organizations demonstrated more benefit than business units. There was also an interest in whether there was a difference in the benefits achieved between public sector and private sector organizations. The two most frequently used methodologies for studying Business Excellence benefits was found to be share price event studies and surveys, with the latter being used in the current work. A Leadership Excellence instrument was used to operationalize Business Excellence following a review of the critical success factors of Business Excellence. The results indicated that Business Excellence had a positive relationship with overall performance, as well as with individual performance indicators representing different stakeholder groups. Business Excellence had a positive relationship with key performance outcomes representing the organization, employee satisfaction representing the employees, and customer satisfaction representing the customers. These relationships were found for both private and public sector organizations. Societal satisfaction, the fourth results area representing society as a stakeholder, did not appear to be correlated with the Business Excellence approach. Despite an acceptance that leadership is a driver of organisational performance, there is very little empirical evidence to support this generalization (Bolden (2004); Burgoyne, Hirsh et al. (2004)). Although not part of the original scope of the research, as a leadership instrument has been used to operationalize Business Excellence, the research contributes to the leadership body of knowledge, providing such empirical evidence of a positive relationship. The second area considered was the sources of competitive advantage, or sources of organizational advantage, as the sample included both public and private organizations. Partially replicating the work of Hall, employee-know how was found to be a main source of advantage in public sector organizations, with employee know-how and reputation being important in private sector organizations. The time to develop the advantage was measured in terms of „Replacement periods‟, and this was found to be in the order of 2 to 3 years in most cases, with reputation having a slightly higher replacement period. The third area examined the relationship between the ease with which organizations respond to change, termed „Strategic Capability‟ in this study, and the performance achieved. The result provided support for the concept of dynamic capabilities (Teece, Pisano et al. (1997); Eisenhardt and Martin (2000); Zott (2003)). It was concluded that Business Excellence and the ability of an organization to react to change exhibited a relationship supporting the „mental buffer‟ theory of Savolainen (2000a). The dynamics of the external environment was also considered to see if this affected the relationships based on the theory of Eisenhardt and Martin (2000), but no such relationship could be found. This lack of a relationship was attributed to either measurement and/ or sampling issues. The fourth area and final examined sought to establish a relationship between Business Excellence, strategic capability and performance. Prahalad (2000) argued the most important challenge facing managers in the 21st century was the challenge to manage change in fast-moving environments. The current work developed a framework to aid the understanding of dynamic capabilities and this framework represents a contribution to theory. It is hoped the framework will be of value to both practitioners and researchers as this exciting area of strategy is taken forward

A speckle-based CMOS sensor for arbitrary surface movement detection with correlated double sampling and gain error correction

We present a CMOS sensor for accurate tracking of speckle movements on arbitrary surfaces. The sensor is made of a pair of comb filters with a pitch of 5.6 mu m and decayed by 90 degrees to produce quadrature signals. The readout circuit is a 60 dB amplification chain with offset and KTC noise compensation. Integrated into a 180nm CMOS process, the sensor and readout circuit occupy an area of about 0.1 mm(2) and consume 24 mu W at full speed of 64 ksample/s. The direction and frequency of the quadrature signals are resolved externally by zero- crossing detection, giving an accuracy of about 5 mu m. Thanks to a careful layout for gain error minimization, and the use of KTC noise cancellation, a negligible residual drift was observed, and a minimal displacement of 5 mu m was measured

Uptake of HIV testing and outcomes within a Community-based Therapeutic Care (CTC) programme to treat Severe Acute Malnutrition in Malawi: a descriptive study

<p>Abstract</p> <p>Background</p> <p>In Malawi and other high HIV prevalence countries, studies suggest that more than 30% of all severely malnourished children admitted to inpatient nutrition rehabilitation units are HIV-infected. However, clinical algorithms designed to diagnose paediatric HIV are neither sensitive nor specific in severely malnourished children. The present study was conducted to assess : i) whether HIV testing can be integrated into Community-based Therapeutic Care (CTC); ii) to determine if CTC can improve the identification of HIV infected children; and iii) to assess the impact of CTC programmes on the rehabilitation of HIV-infected children with Severe Acute Malnutrition (SAM).</p> <p>Methods</p> <p>This community-based cohort study was conducted in Dowa District, Central Malawi, a rural area 50 km from the capital, Lilongwe. Caregivers and children admitted in the Dowa CTC programme were prospectively (Prospective Cohort = PC) and retrospectively (Retrospective Cohort = RC) admitted into the study and offered HIV testing and counseling. Basic medical care and community nutrition rehabilitation was provided for children with SAM. The outcomes of interest were uptake of HIV testing, and recovery, relapse, and growth rates of HIV-positive and uninfected children in the CTC programme. Student's t-test and analysis of variance were used to compare means and Kruskall Wallis tests were used to compare medians. Dichotomous variables were compared using Chi²analyses and Fisher's exact test. Stepwise logistic regression with backward elimination was used to identify predictors of HIV infection (α = 0.05).</p> <p>Results</p> <p>1273 and 735 children were enrolled in the RC and PC. For the RC, the average age (SD) at CTC admission was 30.0 (17.2) months. For the PC, the average age at admission was 26.5 (13.7) months. Overall uptake of HIV testing was 60.7% for parents and 94% for children. HIV prevalence in severely malnourished children was 3%, much lower than anticipated. 59% of HIV-positive and 83% of HIV-negative children achieved discharge Weight-For-Height (WFH) ≥ 80% of the NCHS reference median (p = 0.003). Clinical algorithms for diagnosing HIV in SAM children had poor sensitivity and specificity.</p> <p>Conclusion</p> <p>CTC is a potentially valuable entry point for providing HIV testing and care in the community to HIV infected children with SAM.</p