Undefined Variables Research Articles

Enumerating Valid Non-Alpha-Equivalent Programs for Interpreter Testing

Skeletal program enumeration (SPE) can generate a great number of test programs for validating the correctness of compilers or interpreters. The classic SPE generates programs by exhaustively enumerating all possible variable usage patterns into a given syntactic structure. Even though it is capable of producing many test programs, the exhaustive enumeration strategy generates a large number of invalid programs, which may waste plenty of testing time and resources. To address the problem, this article proposes a tree-based SPE technique. Compared to the state-of-the-art, the key merit of the tree-based approach is that it allows us to take the dependency information into consideration when producing test programs and, thus, make it possible to (1) directly generate non-equivalent programs and (2) apply dominance relations to eliminate invalid test programs that have undefined variables. Hence, our approach significantly saves the cost of the naïve SPE approach. We have implemented our approach into an automated testing tool, IFuzzer , and applied it to test eight different implementations of Python interpreters, including CPython, PyPy, IronPython, Jython, RustPython, GPython, Pyston, and Codon. In three months of fuzzing, IFuzzer detected 142 bugs, of which 87 have been confirmed to be previously unknown bugs, of which 34 have been fixed. Compared to the state-of-the-art SPE techniques, IFuzzer takes only 61.0% of the time cost given the same number of testing seeds and improves 5.3% source code function coverage in the same time budget of testing.

A Comparison of Fuzzy Membership Numbers on the Convergence of Numerical Approaches to Solving Integro-Differential Equations

In this article examines the convergences stability of Variational Iteration Method (VIM) for solving Fuzzy Volterra Integro-Differential Equations (FVIDE) of second kind under the Seikkala derivative [13]. The advantage of the proposed method in this study compared with Adomian decomposition Method (ADM). The undefined variables are represented by membership values in trapezoids and triangles. The results of the two methods are compared to demonstrate the efficacy of fuzzy numbers in terms of increasing membership values.

Transient probability density of nonlinear oscillator under parametric harmonic and external modulated stochastic excitations

In this study, the exponential-polynomial-closure (EPC) method is applied to determine and study the non-stationary probability density function (PDF) of the nonlinear system simultaneously stimulated by parametric harmonic and modulated stochastic excitations. The non-stationary probabilistic responses are represented as a time-related exponential polynomial function with unknown variables. Integrating the weighted residual error can result in a group of first-order differential equations. Those equations can be solved by numerical techniques to obtain the undefined variables. Four examples are given to show that the non-stationary behaviors of the presented oscillators can be addressed by the presented EPC procedure effectively, especially in the probabilistic tails which are of particular importance in reliability analysis. Moreover, the outcomes show that the response means equal to zero and the response PDFs are symmetrical with respect to the zero means. In particular, the presented EPC procedure can heavily decrease the running effort with no sacrifice to the solution correctness when compared with MCS.

Out of Touch: Comparing and Contrasting Positivism and Interpretivism in Social Science

This concept paper aims to explain two paradigms positivism, and interpretivism also provides a comparison and contrast between two research philosophies. This paper introduced an in-depth explanation of positivism and interpretivism ontological and epistemological assumptions and the methodologies as well as the purpose, reality, variables, and data of both philosophies. This paper elaborated how the positivists' test theory and prove hypothesis for objective reality with defined variables by looking from the outside with data provided in numbers. Likewise, content analysis is used to analyze and comprehend the aims of philosophical frameworks. Furthermore, it explained how the interpretivists construct meaning for the social constructions reality with undefined variables by looking from inside with data provided in words. The research findings revealed some similarities between these two philosophies, such as both philosophies have general assumptions to investigate the nature of society, epistemological assumptions frequently arise from ontological assumptions, and both philosophies' research results are presented in detail, showing the research organization and implementation. There were also some significant differences between them, such as their definitions of reality, perspectives on knowledge, and data gathering methodologies. Furthermore, by evaluating books and articles on these two research philosophies, the results also indicated some implications.

Principles of in vitro nutrition for human mesenchymal stromal cells

Background & Aim In the cultivation of stem cells in vitro, components of animal origin and/or chemically undefined extracts like human platelet lysate are still used for the formulation of culture media because the quality of the most common basal media is unsuitable for cell culture in chemically defined environments. Experimental evidence shows that the better the qualitative and quantitative composition of the basal medium, the fewer additives of animal origin or chemically undefined components are needed to achieve successful cultivation of stem cells. Methods, Results & Conclusion The contribution deals with essential aspects concerning identity and quality of culture media components for pre-clinical and clinical research. It describes the development of physico-chemically defined micro-environments for cell cultures that modulate functions of the metabolism of human stem cells from adipose tissue (hASCs). The development process consists of two parts. The first phase involves the development of fully defined cellular microenvironments capable of satisfying the essential physiological needs of the cell. For this purpose, a detailed analysis of the physical (pH, osmotic pressure) and chemical requirements (energy sources, amino acids, vitamins, precursors of fatty and nucleic acids, inorganic salts, trace elements and chemical impurities) of the cells is carried out, which are then selected for the second phase. The second phase involves the elimination of complex, chemically undefined variables such as fetal calf serum or human platelet lysate, which are to be considered as critical components in cell culture media. The selection of a suitable basal medium and relative preparation technique allows the achievement of the goal. The results show that good knowledge of the variables that influence cellular growth processes has numerous advantages. The two-step strategy described above allows the identification of the essential physiological needs of the cells, thus favouring control and modulation of the main metabolic functions. This perspective becomes even more interesting as the omission of complex and expensive medium additives in clinical culture processes leads to a reduction of contamination risk and production costs.

Limitations of Fixed-Effects Models for Panel Data

Although fixed-effects models for panel data are now widely recognized as powerful tools for longitudinal data analysis, the limitations of these models are not well known. We provide a critical discussion of 12 limitations, including a culture of omission, low statistical power, limited external validity, restricted time periods, measurement error, time invariance, undefined variables, unobserved heterogeneity, erroneous causal inferences, imprecise interpretations of coefficients, imprudent comparisons with cross-sectional models, and questionable contributions vis-à-vis previous work. Instead of discouraging the use of fixed-effects models, we encourage more critical applications of this rigorous and promising methodology. The most important deficiencies—Type II errors, biased coefficients and imprecise standard errors, misleading p values, misguided causal claims, and various theoretical concerns—should be weighed against the likely presence of unobserved heterogeneity in other regression models. Ultimately, we must do a better job of communicating the pitfalls of fixed-effects models to our colleagues and students.

Constructionist Design Methodology for Interactive Intelligences

We present a methodology for designing and implementing interactive intelligences. The constructionist design methodology (CDM) -- so called because it advocates modular building blocks and incorporation of prior work -- addresses factors that we see as key to future advances in AI, including support for interdisciplinary collaboration, coordination of teams, and large-scale systems integration. We test the methodology by building an interactive multifunctional system with a real-time perception- action loop. The system, whose construction relied entirely on the methodology, consists of an embodied virtual agent that can perceive both real and virtual objects in an augmented-reality room and interact with a user through coordinated gestures and speech. Wireless tracking technologies give the agent awareness of the environment and the user's speech and communicative acts. User and agent can communicate about things in the environment, their placement, and their function, as well as about more abstract topics, such as current news, through situated multimodal dialogue. The results demonstrate the CDM's strength in simplifying the modeling of complex, multifunctional systems that require architectural experimentation and exploration of unclear subsystem boundaries, undefined variables, and tangled data flow and control hierarchies.

Review of the weldability window concept and equations for explosive welding

Explosive cladding/welding is usually considered a solid state process in which the detonation of a certain amount of an explosive composition is used to accelerate one of the materials to be weld against the other in order to promote a high velocity oblique collision that will be responsible for bonding the materials. The conditions that should be met to achieve good welds define what is called as a weldability window or criteria. A weldability criteria based on the collision point velocity (Vc) and on the collision angle (β) is the most used today. In the β-Vc space the weldability window is defined by four lines or limits. Despite of its wide used in explosive welding works, neither the concepts behind those limits neither the equations used to define them in the β-Vc space are particularly clear. Contradictory concepts, and equations with undefined variables or parameters, are commonly found in the literature. This paper aims to clarify those concepts and equations through an integrated description of the weldability limits and a reviewed presentation of the associated equations with the variables and parameters, including their units, clearly defined. The reviewed concepts and equations are then used for the description of the explosive weld of stainless steel to carbon steel in cylindrical configuration.

The influence of patient and wound variables on healing of venous leg ulcers in a randomized controlled trial of growth-arrested allogeneic keratinocytes and fibroblasts

To examine patient and wound variables presumed to influence healing outcomes in the context of therapeutic trials for chronic venous leg ulcers. This double-blind, vehicle-controlled study was conducted with randomized assignment to one of four cell therapy dose groups (n = 46, 43, 44, 45) or vehicle control (n = 50). A 2-week run-in period was used to exclude rapid healers and those with infection or uncontrolled edema. This was a multicenter (ambulatory, private, hospital-based and university-based practices, and wound care centers in North America) study. Adults ≥ 18 years old with chronic venous insufficiency associated with an uninfected venous leg ulcer (2-12 cm(2) area, 6-104 weeks' duration) were included in the study. Excluded were pregnant or lactating women, wounds with exposed muscle, tendon or bone, patients unable to tolerate compression bandages, or patients who had exclusionary medical conditions or exposure to certain products. Exclusion during run-in included patients with infection, uncontrolled severe edema or with healing rates ≥ 0.349 cm/2 wk. Screen fail rate was 37% (134/362), and the withdrawal rate was~10% (23 of 228). Growth-arrested neonatal dermal fibroblasts and keratinocytes were delivered via pump spray in a fibrin sealant-based matrix, plus a foam dressing and four-layer compression bandaging. Treatment continued for 12 weeks or until healed, whichever occurred first. Patient demographic and wound-related variables were evaluated for influence on complete wound healing in all patients, as well as the subsets of treated and control patients. Wound duration (P = .004) and the presence of specific quantities of certain bacterial species (P < .001) affected healing in the vehicle group, while healing in the cell-treated groups was influenced by wound duration (P = .012), wound area (P = .026), wound location (P = .011), and specific quantities of certain bacterial species (P = .002). Age, sex, race, diabetes, HbA1C, peripheral neuropathy, and serum prealbumin did not significantly affect healing. Body mass index was positively associated with healing in cell-treated patients. Wound duration is a quantifiable surrogate for one or more undefined variables that can have a profound negative effect on venous leg ulcer healing. Although cell therapy overcame barriers to healing, the only specific barrier identified was the presence of certain bacterial species. Interventional trials of potentially effective new therapies can be most informative when patients with suspected barriers to healing are included. The specific measurement of candidate barriers such as microbial pathogens, wound inflammatory state, and fibroblast function should be considered in future randomized trials to improve our understanding of the basis for chronicity.

Comment on “Record of MIS 5 sea-level highstands based on U/Th dated coral terraces of Haiti” by Dumas et al. [Quaternary International 2006 106–118

The opening sentence of the introduction [Dumas, B., Hoang, C.-T., Raffy, J., 2006. Record of MIS 5 sea-level highstands based on dated coral terraces of Haiti. Quaternary International 145–146, 106–118] “Quaternary sea-level changes are mainly deduced from the study of raised coral terraces” involves a flawed premise. As two undefined variables operate simultaneously (sea-level changes and vertical tectonic motion; both perhaps having up and down components) to produce a succession of terraces, it is impossible to solve the equation without supplying real numbers for either variable. Hence, to deduce sea-level history, either largely unprovable assumption about constant uplift and/or featureless sea-level histories are required, or a model of sea level must be imported from regions that have not experienced tectonic displacement. Furthermore, coral reefs are less than ideal monitors of sea-level change; rather, they might be preferred as monitors of sea level stability, as their response time and depositional tempo may be measured in hundreds or thousands of years. Reefs may grow and flourish during slow rise of sea level. Once accommodation space is filled, vertical growth ceases, and only erosion and diagenesis of the reef occurs, until sea level changes once more. Major intervals of sea-level change may thus be lost or never recorded in the rocks.

An econometric viability model for ongrowing sole (Solea senegalensis) in tanks using pumped well sea water

Sole (Solea senegalensis) is of great interest to marine aquaculture in the Mediterranean because of its relatively fast growth and good commercial prospects (high price). However, the wide mean annual variation in the temperature of Mediterranean sea water (14-26 deg C) is a limiting factor for the ongrowing of this species; the optimum for this process is 19-20 deg C. One of the possible mid-term solutions for ensuring a constant year-round temperature is to ongrow these fish in tanks containing pumped well water. The present work describes a mathematical model for estimating the values of economic variables associated with sole production (which to date have not been defined at the commercial level) for an onshore ongrowing plant using pumped well water at 19-20 deg C. The economic variables studied include optimum load, the sale price of the final product, the cost of juveniles and feed (these last two are influenced by mortality which is still highly variable in this species), and finally the cost of electricity and oxygen (of great importance in onshore plants). The model allows different possible situations to be analysed on the basis of still undefined variables for ongrowing (juvenile cost, feeding, survival, etc.), and establishes under which conditions sole ongrowing would be profitable.

Lock‐and‐key strategies for handling undefined variables

AbstractMost programming languages ignore the problem of undefined variables and permit compilers to allow the leftover contents of the memory cells belonging to such variables to be referenced. Although efficient, this type of semantics does not support software engineering, because defects might arise in subtle ways and might be difficult to locate. Two other types of semantics that better support software engineering are to either initialize all variables to some default, e.g. zero, or to require that all references to undefined variables be treated as errors. However, these types of semantics are obviously more expensive than simply ignoring the undefined variables entirely.In this paper, we propose a simple technique that works equally well for both of these latter two types of semantics, and whose efficiency compares favorably for certain realistic programs with more traditional implementations of these semantics. Furthermore, we provide a mechanism for using this technique through Ada implementations of two abstract data types where undefined variables respectively exhibit these two types of semantics, and whose implementations of these semantics use our technique. These abstract data types allow our technique to be selectively used in strictly those situations where the cost of the technique is justified. We provide practical examples illustrating these situations.

Variability in Response to a Low-Fat, Low-Cholesterol Diet in Children with Elevated Low-Density Lipoprotein Cholesterol Levels

The reduction of dietary cholesterol and fat lowers low-density lipoprotein cholesterol (LDL-C) and reduces risk of coronary heart disease in adults. The purpose of this study was to determine the individual variability of response of serum lipid and lipoprotein levels to a low-fat, low-cholesterol diet in children with elevated LDL-C levels. Thirty-two children (2 to 16 years of age) enrolled in a diet modification program, who had LDL-C levels of at least 110 mg/dL but normal triglyceride levels for their ages, were studied. Lipid levels and dietary nutrients were analyzed at the time of admission, and final assessments were made at least 3 months after entry. There was a significant correlation, for the group as a whole, between change in LDL-C concentration and change in grams of dietary saturated fat; however, there was marked individual variability in LDL-C response. There were no significant correlations between changes in LDL-C levels and changes in either total fat, polyunsaturated fat, or cholesterol intake. It is concluded that modest decreases in dietary saturated fat coincide with a lowering of LDL-C concentration, over a short term, in many children, but the degree of lowering varies considerably from one child to another. This variability is consistent with the concept that response of serum lipid levels to dietary changes is modified by genetic, metabolic, and other, as of yet, undefined variables.

Theoretical weaknesses: Fundamental flaws in cognitive-behavioral theories are more than a problem of probability

Corrigan (this issue) has responded to my recent article (Lee, 1989) with a defence of the status quo, which raises some apparently strong arguments but, in my opinion, misses the fundamental point that I am endeavoring to make. The basic argument raised by Lee (1989) is that many modern theories of psychology suffer from an insurmountable flaw: they rely on undefined and unobservable variables in order to explain behavior. These variables are hypothesized to interact in a complex manner to produce everyday human behavior. The undefined nature of the variables, the lack of consensus concerning subtle differences between differently named variables, and the unspecified and unobservable nature of their interactions, however, in combination with the difficulties of reliance on self-report, produce fundamental problems. These problems mean that the models are useless in understanding or predicting behavior, although they may be seductive ways of talking about that behavior afterwards. Corrigan (this issue) appears to be arguing that this problem is surmountable. It is a problem, he says, of research design. rather than a fundamental weakness in the models themselves. The use of appropriate statistics, he argues, should allow us to make guesses about the relationships of these variables. Armed with these preliminary hypotheses, we could then collect further information and test specific models. In this way the models would be strengthened and we would eventually develop better theories. They would need to be probabilistic in nature, rather than completely deterministic, because (I think this is the argument) they are. after all, dealing with selfreports. which are imperfect indicators of what is really going on. Research attempting to refine the nature of the relationships between cognitive variables has, of course, been going on for some time. Much of this research is extremely rigorously conducted and makes use of large samples and complex statistical techniques such as the ones Corrigan mentions (e.g., Feltz & Mugno, 1983; Godding & Glasgow, 1985). I have even conducted some of it myself (e.g., Lee, 1984). But a relatively large proportion of the variance in behavior is left unexplained by cognitive variables (e.g., Baer, Holt, & Lichtenstein, 1986). while observable variables such as behavior are frequently found to be more accurate predictors of outcomes than are sophisticated assessments of self-report (e.g., Feltz & Mugno, 1983; Lee, 1983). Models with a basis in behavior theory and empirical evidence are already providing alternatives to their more baroque cognitive competitors (e.g., Biglan, 1987; Rachlin, Logue, Gibbon, & Frankel, 1986; Tryon, 1982), although they do not have the same popularity. Baer, Wolf, and Risley (1987) argue that psychologists generally find non-cognitive explanations of

Run‐time detection of undefined variables considered essential

AbstractAccess to an undefined variable—one which has never been assigned a value—can be detected by automatic means. However, today's compilers do not detect undefined variables comprehensively, and the environment dependence of these errors often allows them to evade normal testing procedures. Language standards for Pascal, Modula‐2 and Ada specify the circumstances in which the undefined variable access should cause an error trap. The logic of undefined in these standards is compared, revealing problems in security, implementation effort and consistency with accepted programming practice. An alternative logic, ‘undefined if totally‐undefined’ is proposed.

Anthropometric design criteria: correction variables for military aircraft.

Significant errors in the application of dimensional anthropometric design criteria for tactical military aircraft cockpits have been identified. These errors result from insufficient consideration of previously undefined variables relative to posture, restraint system items, and aviators' personal protection equipment as discussed by McConville and Laubach in 1978.

Root Morphology and Vigor Effects on Winter Heaving of Established Alfalfa1

AbstractThere has been considerable speculation regarding the influence of root system morphology on the susceptibility of alfalfa (Medicago sativa L.) to frost heaving injury. This field study represents a first attempt at quantification of that relationship. A tagging technique was developed for monitoring heave of established alfalfa plants during winter. Measurements were made on a Collamer silt loam (Glossoboric Hapludalf) intergrading to a Niagara silt loam (Aeric Ochraqualf) near Ithaca, NY. Final (net) crown displacement above the soil surface was positively correlated with plant upheaval in midwinter, although maximal uplift was partially reversed as the soil thawed. Plants were retrieved after the winter and evaluated for differences in vigor and taproot architecture. Under comparable soil heaving conditions, 2‐yr‐old plants with the creeping root trait experienced a mean net uplift of 5.5±1.1 mm compared to 8.5±1.2 mm for plants with a pronounced taproot; this difference was significant at P &lt; 0.06. In contrast, spatial variation in maximum soil heave was more important than root morphological parameters in determining uplift of 3‐yr‐old plants from a single taprooted cultivar. Only 45% of the total variance in maximal crown displacement could be explained by multiple regression analysis, suggesting that undefined variables, such as root anchorage and tissue elasticity, may be involved. Approximately 60% of the taproots appeared to have heave related lesions. The vigor of these mature plants was generally unrelated to frost heaving; net upheaval was correlated with the degree of crown rot, but not with root rot, number of crown buds, or curculio (Sitona hispidula F.) scarring.

A survey of 112,000 anaesthetics at one teaching hospital (1975-83).

This paper describes the outcome of a nine-year post-anaesthetic followup program in a large teaching hospital (N = 112,721 anaesthetics). Between time periods 1975-78 and 1979-83, more seriously ill patients (higher ASA physical status) were being treated. Anaesthetic practice also changed, with an increased use of balanced (multiple drug) anaesthetic procedures, a decrease in the use of halothane and an increase in the use of monitoring. Nonfatal anaesthetic complications--intraoperative, recovery room and postoperative--were rare but there was an increase in the reported complication rate over time. From 1975-78, 7.6 per cent of all cases had at least one intraoperative complication and from 1979-83, this rose to 10.6 per cent of all cases. For recovery room complications, there was an increase to 5.9 per cent in 1979-83 from 3.1 per cent in 1975-78. In time period 2 there was a 9.4 per cent chance of having a postoperative anaesthetic-related complication, and a 0.45 per cent chance of a significant morbidity as a result. This represents an increase over time period 1 (8.9 and 0.40 per cent respectively). It is concluded that the anaesthetic experience, while associated with low mortality rates in recent years, is still associated with significant morbidity. It is conjectural at present whether this is reflective of preoperative patient status, anaesthetic practice, or other undefined variables associated with an operative experience.

Spread-Wing Postures and the Water Repellency of Feathers: A Test of Rijke's Hypothesis

Spread-Wing Postures and the Water Repellency of Feathers: A Test of Rijke's Hypothesis

A survey of run-time and logic errors in a classroom environment

This paper presents the results of a survey of programming errors in an introductory programming class conducted at Kansas State University. The objective of the study was to gain a better understanding of some of the errors made by beginning student programmers, particularly those effors normally detected by run-time packages (e.g., undefined variables, division by zero, arithmethic overflow) as well as the many effors that pass undetected by compilers and run-time tools (e.g., logic and conceptual effors). The survey involved the analysis of 1088 program runs collected from approximately 50 students in a FORTRAN programming course.The effors were tallied and analyzed, and were then recorded under eight general categories: Input/Output (e. g., missing I/O statements, missing or incorrect I/O variables or data); Assignment (e. g., incorrect operators, missing assignments); Loops (e. g., incorrect loop parameters, missing or extra loops); Decision and Branching (e. g., jump to wrong places, incorrect decisions; Arrays (e. g., incorrect subscripts, missing array); Subprograms (e. g., incorrect or missing parameters, incorrect number of calls); Declarations (e. g., issing or wrong declaration statements, wrong names in declaration statements); and Miscellaneous (e. g., unused variables, redundant decisions, wrong logic). The study found that two classes of errors accounted for over half of all noncompiletime errors: those errors related to input/output and assignment statements. Further analysis showed that less than half of the run-time error messages generated by the compiler actually pinpointed the cause of error or provided a meaningful hint.