P-SEMP: A platform for systems engineering modeling and planning

Systems engineering management and planning has long been a realm dominated by arcane standards, by the weight of years of practice, and by authority. However, with technological advances and the desire to solve socio-technical problems at the level of increasingly complex systems, authority alone is no longer sufficient for the justification of systems engineering practice. As new systems engineering methodologies are bought and sold in the transition towards model-based systems engineering, there is an imperative for the systems engineering practitioner to develop new techniques for estimating project performance before project completion. That is, whether debating appropriate corrective actions for a project at risk of going over budget or over schedule, or when planning a new systems engineering methodology, the systems engineer must forecast planned performance of systems engineering tasks. To this end, the International Council of Systems Engineers (INCOSE) and others have sought to bolster systems engineering measurement and the development of standardized leading indicators of systems engineering performance, which are thought to give insight into future performance in the course of program performance. Recent efforts have produced models of systems engineering performance; however, no model is yet sufficient for addressing which tasks in support of standardized processes should be planned in a systems engineering methodology. This document lays out how such a capability might be implemented by a platform for the numerical comparison of systems engineering methodologies. The idea of a platform for systems engineering modeling and planning is called P-SEMP. There are two threads in this document: a thesis and a methodology. First and foremost, the document is a thesis. The thesis, called at times the P-SEMP Thesis, is a formal argument as to how to address the problem of systems engineering task planning constructed on the basis of gaps, research questions, hypotheses, experiments, and their results. The P-SEMP Thesis aims to prove the best means for determining which systems engineering methodologies, and in particular which methods for a given systems engineering process, are better or worse. Enabling the argument of the P-SEMP Thesis is the P-SEMP Methodology, which is rooted in the fundamentals of modeling and simulation theory but made specific to the class of problems involved in systems engineering methodology comparison. The P-SEMP Methodology describes how to build a platform for P-SEMP and what a platform may entail, and the methodology is supported by a conceptual architecture description. The combined product of the P-SEMP Methodology and conceptual architecture description is a recipe: first, a recipe in terms of the proposed experiments, and then a recipe for the experimental results and conclusions of the P-SEMP Thesis and how its findings may be further applied. In order to render the P-SEMP Thesis manageable in scope, the focus will be placed on tasks surrounding the systems engineering process of validation. Validation, in different senses, can occur both early and late in the system life cycle. While validation is a controversial term, many authors agree that efforts around feasibility assessment, requirements quantification, and the early evaluation of system architectures and design against these requirements are crucial steps in early-phase validation to ensure that the system will meet stakeholder expectations before proceeding with the entirety of the system lifecycle. Concretely, as proposed sets of tasks, a portion of an Object-Oriented Systems Engineering Methodology-inspired process for Spacecraft Requirements Derivation is compared against the State Analysis Model Development method, and subsequently a third method is proposed as well regarding validation concepts. These methods for validation will be modeled and compared using the tooling developed in support of the argument for a platform for systems engineering modeling and planning, the P-SEMP Thesis, and be constructed according to the P-SEMP Methodology with results as shown in the conceptual architecture description for Platform 0.1 and Platform 1.0. The result of the experimental efforts culminates, in a concrete sense, with a domain-specific language for describing tasks in a manner suitable for simulation of the method models. However, leading indicator models are not forgotten; one in particular is replicated and added to a system modeling environment alongside the method models --- however, serious issues in parameterization are uncovered in these leading indicator models and they may not provide much insight towards task planning. Due to these issues and more, a hybrid model proved infeasible in the current situation, leading to the evolution from conceptual Platform 0.1 to the final Platform 1.0. Additionally, as the Spacecraft Requirements Derivation method is proposed specifically for a canonical system FireSat, specific modeling practice in SysML will be proposed to represent the third proposed SE methodology being compared, which requires representation of designs of experiments and probability distributions in the course of ensuring system feasibility. Another motivation for incorporating these expressions into a system model is to ensure the correctness of analytical models which underlay validation processes. This correctness is established by model verification and validation. As these analytical models represent the system from different perspectives, it is beneficial for them to be closely coupled to a unified system model depiction. However, a gap exists where while such capability is known for Multidisciplinary Design Optimization (MDO) and system models, it does not yet exist for Robust Design Simulation (RDS) or techniques for probabilistic or uncertain design processes in conjunction with a system model. Such a technology helps to support the activities above and improves confidence in the results of the early-phase system validation actions. In summation, according to the argument of the P-SEMP Thesis and the practice of the P-SEMP Methodology, a leading indicator model is replicated and found wanting. Systems engineering method model simulations are formulated, and a domain-specific language is created to capture them in the system model for exploration of task architecture. Finally, broader description of designs of experiments and probability are incorporated to improve analytical integration capabilities required for full validation activities in support of greater systems engineering methodology capability. Synthesizing the experimental results is the P-SEMP conceptual architecture Platform 1.0, which serves as a new baseline for systems engineering task planning and comparison, and which places the results into the greater context of how to build a platform and use the platform. Altogether, these pieces outline a platform for systems engineering modeling and planning on the basis of constructing a suitable platform through various models and exercising the resulting platform, thus improving systems engineering methodology analysis. Specifically, the thesis demonstrates how P-SEMP is the first known technique for SE methodology selection that supports 1) mathematical models of task performance, 2) analysis of SE methods as tasks in a concrete sense, 3) inclusion likewise of soft or subjective criteria, and 4) expandability to investigate new or different SE method proposals in a unified and effective manner.Ph.D

Investigation of the effect of reactor size on the nett rate of formation of hydrazine from ammonia in a glow discharge

PhD ThesisThe effect of reactor size on the nett rate of formation of hydrazine in an electrical diBcharge in ammonia gas has been studied. Three geometrically similar reactor units , the largest of which was greater in volume by a factor of 6'+:1 compared to the smallest , were used in this work. The nett rate of formation of hydrazine has been found to be inversely proportional to reactor size. Evidence has been provided which suggests that changing the reaction tube size results in a change in the concentration of atomic hydrogen in the reaction zone. i.e. the reaction tube diameter is increased the rate of diffusion of atomic hydrogen to the reaction tube surface is decreased. This results in a decrease in the rate of recombination of atomic hydrogen at the reaction tube surface , and consequently an increase in the concentration of atomic hydrogen in the reaction zone. In turn this leads to an increase in the rate of destruction of hydrazine by atomic hydrogen attack and as a result , a decrease in the nett rate of formation of hydrazine. Attempts to minimise the concentration of atomic hydrogen in a large scale reactor , by packing the reactor with a quartz surface ( wool ) , failed due to field distortion with subsequent discharge constriction, and also due to the catalytic nature of the quartz surface employed. In the early experimental work several of the major reactor design problems encountered in scale up were identified. One of these was the constriction of the discharge zone into a narrow beam thereby allowing some of the gas to by-pass this zone completely. Because of this, the early work was directed towards obtaining a set of reactor units, in which the discharge occupied the entire volume between the electrodes over a wide range of operating conditions. In this work it was found that under dc discharge conditions , electrodes of diameter greater than a critical size which is dependent upon a number of interdependent factors viz. a) the nature of the reactant gas b) reactor unit geometry c) electrode material and electrode profile d) the flow pattern of the gaseous reactant e) electrical and operating conditions - of which the most important are electric current density , operating pressure , and gas flow rate give rise to non- uniform constricted discharges. In chapter 2.3 the hypothesis that physical similarity ( similarity in the physics of the discharge ) in two geometrically similar discharges of different size, ensures chemical similarity has been examined. This was done by testing whether or not the ' similarity principle ' could be applied to electrical discharges in which chemical reactions occur. The results of this investigation show that while discharge processes depending on single electron impact activation follow the ‘ similarity principle ’ the relationship does not hold for chemical reactions where secondary processes are of primary importance. Consequently semi-theoretical methods of investigation have been used in this work and an equation of the form – [see full text for formulas] where r : nett rate of formation of hydrazine D: reaction tube diameter F: ammonia gas flow rate C: ammonia gas concentration Vp : potential difference across the reaction zone ( positive column ) of the discharge I: discharge current L: length of the reaction zone ( positive column ) p: pressure in the reaction zone ( positive column ) a , b, c: constants which was derived using the technique of dimensional analysis , has been used to correlate the experimental results satisfactorily. Finally during the course of the experimental work it was discovered that the nett rate of formation of hydrazine depended on the reactor unit ‘age’, and consequently a small amount of work was carried out to investigate this phenomenon. The results of this research indicate that the effect of reactor unit ‘age’ is primarily due to a change in either the catalytic and/or adsorption properties of the reaction tube surface , and hot due to changes in the electrode surface as was previously believed.Science Research Counci

Geography of genetic structure in barley wild relative Hordeum vulgare subsp. spontaneum in Jordan

Informed collecting, conservation, monitoring and utilization of genetic diversity requires knowledge of the distribution and structure of the variation occurring in a species. Hordeum vulgare subsp. spontaneum (K. Koch) Thell., a primary wild relative of barley, is an important source of genetic diversity for barley improvement and co-occurs with the domesticate within the center of origin. We studied the current distribution of genetic diversity and population structure in H. vulgare subsp. spontaneum in Jordan and investigated whether it is correlated with either spatial or climatic variation inferred from publically available climate layers commonly used in conservation and ecogeographical studies. The genetic structure of 32 populations collected in 2012 was analyzed with 37 SSRs. Three distinct genetic clusters were identified. Populations were characterized by admixture and high allelic richness, and genetic diversity was concentrated in the northern part of the study area. Genetic structure, spatial location and climate were not correlated. This may point out a limitation in using large scale climatic data layers to predict genetic diversity, especially as it is applied to regional genetic resources collections in H. vulgare subsp. spontaneum

A study on the safety and efficacy of reveglucosidase alfa in patients with late-onset Pompe disease.

BackgroundLate-onset Pompe disease is a rare genetic neuromuscular disorder caused by lysosomal acid alpha-glucosidase (GAA) deficiency that ultimately results in mobility loss and respiratory failure. Current enzyme replacement therapy with recombinant human (rh)GAA has demonstrated efficacy in subjects with late-onset Pompe disease. However, long-term effects of rhGAA on pulmonary function have not been observed, likely related to inefficient delivery of rhGAA to skeletal muscle lysosomes and associated deficits in the central nervous system. To address this limitation, reveglucosidase alfa, a novel insulin-like growth factor 2 (IGF2)-tagged GAA analogue with improved lysosomal uptake, was developed. This study evaluated the pharmacokinetics, safety, and exploratory efficacy of reveglucosidase alfa in 22 subjects with late-onset Pompe disease who were previously untreated with rhGAA.ResultsReveglucosidase alfa plasma concentrations increased linearly with dose, and the elimination half-life was <1.2 h. Eighteen of 22 subjects completed 72 weeks of treatment. The most common adverse events were hypoglycemia (63%), dizziness, fall, headache, and nausea (55% for each). Serious adverse events included hypersensitivity (n = 1), symptomatic hypoglycemia (n = 2), presyncope (n = 1), and acute cardiac failure (n = 1). In the dose-escalation study, all treated subjects tested positive for anti-reveglucosidase alfa, anti-rhGAA, anti-IGF1, and anti-IGF2 antibodies at least once. Subjects receiving 20 mg/kg of reveglucosidase alfa demonstrated increases in predicted maximum inspiratory pressure (13.9%), predicted maximum expiratory pressure (8.0%), forced vital capacity (-0.4%), maximum voluntary ventilation (7.4 L/min), and mean absolute walking distance (22.3 m on the 6-min walk test) at 72 weeks.ConclusionsAdditional studies are needed to further assess the safety and efficacy of this approach. Improvements in respiratory muscle strength, lung function, and walking endurance in subjects with LOPD may make up for the risk of hypersensitivity reactions and hypoglycemia. Reveglucosidase alfa may provide a new treatment option for patients with late-onset Pompe disease.Trial registrationISRCTN01435772 and ISRCTN01230801 , registered 27 October 2011

A New Obesity Model Reveals the Hypophagic Properties of PACAP Involve the Regulation of Homeostatic Feeding in the Ventromedial Hypothalamic Nucleus and Hedonic Feeding in the Nucleus Accumbens

Binge eating in humans is a complex disorder that often involves discrete, compulsive feeding sessions of highly palatable foods even in the absence of a deprivation state or hunger. Binging can be effectively modeled in rodents by providing subjects with limited access to a palatable food source (Western Diet; WD) as an adjunct to ad lib access to normal chow (Standard Chow; SC). Although this design recapitulates several fundamental characteristics observed in binge eating disorder, the binge eating observed in this paradigm is likely a product of both hedonic and homeostatic drives with the need to balance energy stores still present. To isolate these feeding drives, we have developed a novel feeding regimen that modifies the classic limited access binge model to effectively delineate and separate homeostatic feeding from motivational feeding. This is achieved by entraining male Sprague-Dawley rats to a restricted feeding schedule (two hours per day) of SC followed by a short 15 minute limited access meal of either SC or WD (Restrict Fed-Limited Access; RFLA). The RFLA paradigm allows for the examination of pituitary adenylate-cyclase activating polypeptide (PACAP) on palatable food consumption in a fully satiated subject. PACAP has previously been shown to suppress feeding behavior when injected into the hypothalamus. In the current study, PACAP injected into the ventromedial hypothalamic nuclei (VMN) suppressed the two hour homeostatic SC meal, but not the subsequent 15 minute limited access meal of WD. By contrast, PACAP bilaterally administered into the nucleus accumbens (NAc) produced the opposite effect with PACAP suppressing the consumption of WD but not SC. Thus, PACAP mediated signaling in the VMN appears to be involved in homeostatic regulation of energy stores, whereas PACAP signaling in the NAc regulates feeding driven by palatability or hedonic qualities

Beewild' bundleflower, a new summer-growing perennial legume for central and south Texas and Mexico

Last updated: 10/19/201

The genetic basis for panicle trait variation in switchgrass (Panicum virgatum)

Key message: We investigate the genetic basis of panicle architecture in switchgrass in two mapping populations across a latitudinal gradient, and find many stable, repeatable genetic effects and limited genetic interactions with the environment. Abstract: Grass species exhibit large diversity in panicle architecture influenced by genes, the environment, and their interaction. The genetic study of panicle architecture in perennial grasses is limited. In this study, we evaluate the genetic basis of panicle architecture including panicle length, primary branching number, and secondary branching number in an outcrossed switchgrass QTL population grown across ten field sites in the central USA through multi-environment mixed QTL analysis. We also evaluate genetic effects in a diversity panel of switchgrass grown at three of the ten field sites using genome-wide association (GWAS) and multivariate adaptive shrinkage. Furthermore, we search for candidate genes underlying panicle traits in both of these independent mapping populations. Overall, 18 QTL were detected in the QTL mapping population for the three panicle traits, and 146 unlinked genomic regions in the diversity panel affected one or more panicle trait. Twelve of the QTL exhibited consistent effects (i.e., no QTL by environment interactions or no QTL × E), and most (four of six) of the effects with QTL × E exhibited site-specific effects. Most (59.3%) significant partially linked diversity panel SNPs had significant effects in all panicle traits and all field sites and showed pervasive pleiotropy and limited environment interactions. Panicle QTL co-localized with significant SNPs found using GWAS, providing additional power to distinguish between true and false associations in the diversity panel

Attitudes and Performance: An Analysis of Russian Workers

This paper investigates the relationship between locus of control and performance among Russian employees, using survey data collected at 28 workplaces in 2002 in Taganrog and at 47 workplaces in 2003 in Ekaterinburg. We develop a measure that allows us to categorize the Russian employees participating in our survey as exhibiting an internal or external locus of control. We then assess the extent to which there are significant differences between “internals” and “externals” in work-related attitudes that may affect performance. In particular, we focus on (1) attitudes about outcomes associated with hard work, (2) level of job satisfaction, (3) expectation of receiving a desired reward, and (4) loyalty to and involvement with one’s organization. In each case we identify where gender and generational differences emerge. Our main objective is to determine whether Russian employees who exhibit an internal locus of control perform better than employees with an external locus of control. Our performance measures include earnings, expected promotions, and assessments of the quantity and quality of work in comparison to others at the same organization doing a similar job. Controlling for a variety of worker characteristics, we find that (1) individuals who exhibit an internal locus of control perform better, but this result is not always statistically significant; (2) even among “internals,” women earn significantly less than men and have a much lower expectation of promotion; (3) even among “internals,” experience with unemployment has a negative influence on performance.http://deepblue.lib.umich.edu/bitstream/2027.42/40144/3/wp758.pd

Lay beliefs of TB and TB/HIV co-infection in Addis Ababa, Ethiopia: a qualitative study

<p>Abstract</p> <p>Background</p> <p>Knowledge about lay beliefs of etiology, transmission and treatment of TB, and lay perceptions of the relationship between TB and HIV is important for understanding patients' health seeking behavior and adherence to treatment. We conducted a study to explore lay beliefs about TB and TB/HIV co-infection in Addis Ababa, Ethiopia.</p> <p>Findings</p> <p>We conducted a qualitative study using in-depth interviews with 15 TB/HIV co-infected patients and 9 health professionals and focus group discussions with 14 co-infected patients in Addis-Ababa, Ethiopia. We found that a predominant lay belief was that TB was caused by exposure to cold. Excessive sun exposure, exposure to mud, smoking, alcohol, khat and inadequate food intake were also reported as causes for TB. Such beliefs initially led to self-treatment. The majority of patients were aware of an association between TB and HIV. Some reported that TB could transform into HIV, while others said that the body could be weakened by HIV and become more susceptible to illnesses such as TB. Some patients classified TB as either HIV-related or non-HIV-related, and weight loss was a hallmark for HIV-related TB. The majority of patients believed that people in the community knew that there was an association between TB and HIV, and some feared that this would predispose them to HIV-related stigma.</p> <p>Conclusion</p> <p>There is a need for culturally sensitive information and educational efforts to address misperceptions about TB and HIV. Health professionals should provide information about causes and treatment of TB and HIV to co-infected patients.</p