Non-repeatable Events Research Articles

Real-time electron density measurement technique using a microwave resonant probe for low-pressure plasmas

Abstract This paper presents a technique to perform a time-resolved electron density measurement in a plasma using a microwave resonant probe named curling probe and a Voltage Controlled Oscillator (VCO) fast-swept circuit. The technique is an interesting alternative to the Vector Network Analyzer (VNA) used in on-point mode on repetitive triggered discharges as it also works for non-repeatable events or in cases where trigger signals are unavailable. First, the temporal resolution of the presented setup is assessed to be 5 μs with an uncertainty on the electron density of 5x107 cm-3. Second, the accuracy of the diagnostic is successfully demonstrated by measuring similar electron density for different measurement rates and by measuring forced plasma oscillations at 25 kHz in a magnetic nozzle thruster. Third, the ability of the diagnostic to perform real-time measurements is demonstrated by capturing the transient dynamic of the electron density during the switch-off of the thruster, with a fast plasma density variation of the order of 6x107 cm-3/μs being measured during the first tens of microseconds after plasma extinction.

Capturing the Motion of Laser Pulse in Photoresist Mixture with Compressed Ultrafast Photography

Imaging the interaction between the laser pulse and photoresist mixture on the ultrafast time scale can track the path of the light pulse and reveal the procedure of the microstructure machining. However, most existing imaging technologies suffer from problems such as requiring multiple repeated shots or a limited time resolution. To overcome these problems, we propose to capture the motion of laser pulses in a photoresist mixture by using compressed ultrafast photography (CUP). In this method, we can recover the motion process of non-repeatable events with a single shot at the time-resolution of about 1.54×1011 fps, where the depth of the imaging sequence reaches hundreds of frames. To verify the effectiveness of the proposed method, we estimate the speed of the laser pulse in a photoresist mixture and evaluate the similarity between the image captured by a streak camera and our reconstructed ultrafast sequence; the results validate the reliability of our proposed method.

A New RCM Approach to Survival Analysis: The Conditional-Incidence-Rate Model

This article introduces a new causal analytic method for survival analysis that retains the framework of Rubin’s causal model as an alternative to the marginal structural model (MSM). The major limitation of the MSM is a systematic bias in the effects of past treatments when the method is applied to the hazard rate analysis of nonrepeatable events in the presence of unobserved heterogeneity. This systematic bias is demonstrated in the article. The method introduced here assumes a semiparametric conditional-incidence-rate model and provides consistent estimates of the effects of present and past treatments on the conditional cumulative-incidence rate in the analysis of nonrepeatable events in the presence of unobserved heterogeneity. Unlike the MSM, which requires a sequential and cumulative use of the inverse-probability-of-treatment weighting many times for data with many time points, the new method uses the inverse-probability-of-treatment weighing only twice sequentially for estimation of the present and past treatment effects at each time of entry into treatment, and not cumulatively across different treatment entry times. Analysis of the conditional-incidence rate can also provide a more efficient parameter estimate for the treatment effect than the hazard rate model in cases where a majority of sample persons experience the event and thereby cease to be members of the risk set of the hazard rate during the period of observation. An application to an analysis of sexual initiation demonstrates that leaving home promotes sexual initiation, especially premarital sexual initiation, because it greatly increases the rate of premarital sexual initiation during the year after leaving home.

Explaining the adoption of benefit corporation laws by the US states

PurposeOver half of the US states have jettisoned an exclusive focus on profit maximization for shareholders and created new corporate structures, called “benefit corporations”, which give equal standing to the achievement of social and environmental objectives. This paper aims to examine the factors leading to adoption of legislation for the business formation of benefit corporations by the US states.Design/methodology/approachEvent History Analysis (EHA), a time-series technique using panel data of non-repeatable events, is used to identify and understand economic, political and diffusion factors that affect the adoption of benefit corporation enabling legislation in the US states.FindingsThe results strongly indicate that politics matters – states in which the Democratic Party or liberal ideology controls governmental functions are more likely to pass these laws. There is also evidence that states that are more innovative in their approach to policy-making are more likely to adopt these laws. Otherwise, unemployment, tax burden, political culture, enacted constituency statutes and geographic diffusion have no discernible relationship with the adoption of benefit corporation laws.Practical implicationsThe paper provides warning signs to firms considering expending costly resources on the establishment of or conversion to benefit corporation status and the related investment in developing skills for the preparation, review and assurance of required annual benefit corporation reporting.Originality/valueThe findings suggest future adoption of benefit corporation enabling laws may slow considerably.

Long-Acting Injectable Antipsychotics for Schizophrenia: Sociodemographic Characteristics and Treatment Adherence.

Long-acting injectable (LAI) antipsychotic medications are employed universally for the treatment of schizophrenia. This study retrospectively assessed the variables that factor into an individual's adherence to LAIs. The data sample was obtained from the adult ambulatory services of a large general hospital mental health center located in Elizabeth, New Jersey. Reports were run in November 2015 to identify patients who had received at least 1 LAI between January 1, 2014, and October 14, 2015. In September 2016, an additional report was run to collect follow-up data. The sample included 120 women and 178 men, ranging in age from 18-81 years, who received at least 1 LAI during a 23-month period. A hazard analysis for single-decrement, nonrepeatable events was used to assess the risk of discontinuation of LAIs during the study period. Separate χ² analyses were conducted to assess differences in discontinuation rates for sociodemographic variables, program type variables, type of long-acting medication, and time effects. The cumulative continuation rate across the study period was 73%. Main effect differences were found in continuation rates for program type (χ²₂undefined= 10.252, P = .006), LAI type (χ²₅ = 23.365, P < .000), and prescribed frequency of LAI (χ²₂ = 7.622, P = .022). In addition, multiple time-dependent effect differences were found. No significant main effect results were found for LAI continuation rates and patient age (χ²₃ = 3.689, P = .297), sex (χ²₁ = 0.904, P = .342), race (χ²₃ = 5.785, P = .123), or enrollment in involuntary outpatient commitment (χ²₁ = 2.989, P = .084). The findings of the current research suggest that medication type, frequency of medication appointments, and program type may be key in increasing and maintaining LAI adherence.

A discrete-time Multiple Event Process Survival Mixture (MEPSUM) model.

Traditional survival analysis was developed to investigate the occurrence and timing of a single event, but researchers have recently begun to ask questions about the order and timing of multiple events. A multiple event process survival mixture model is developed here to analyze nonrepeatable events measured in discrete-time that may occur at the same point in time. Building on both traditional univariate survival analysis and univariate survival mixture analysis, the model approximates the underlying multivariate distribution of hazard functions via a discrete-point finite mixture in which the mixing components represent prototypical patterns of event occurrence. The model is applied in an empirical analysis concerning transitions to adulthood, where the events under study include parenthood, marriage, beginning full-time work, and obtaining a college degree. Promising opportunities, as well as possible limitations of the model and future directions for research, are discussed.

Knox meets Cox: Adapting epidemiological space-time statistics to demographic studies

Many important questions and theories in demography focus on changes over time, and on how those changes differ over geographic and social space. Space-time analysis has always been important in studying fertility transitions, for example. However demographers have seldom used formal statistical methods to describe and analyze time series of maps. One formal method, used widely in epidemiology, criminology, and public health, is Knox 's space-time interaction test. In this article, we discuss the potential of the Knox test in demographic research and note some possible pitfalls. We demonstrate how to use familiar proportional hazards models to adapt the Knox test for demographic applications. These adaptations allow for nonrepeatable events and for the incorporation of structural variables that change in space and time. We apply the modified test to data on the onset offertility decline in Brazil over 1960-2000 and show how the modified method can produce maps indicating where and when diffusion effects seem strongest, net of covariate effects.

Microstrain detection using simultaneous endoscopic pulsed digital holography

A simultaneous 2-D pulsed digital holographic setup that incorporates a rigid endoscope is used to inspect hidden object areas in order to measure microstrains. The system was tested on the internal surface of a harmonically vibrating rectangular metal box with a fracture on its surface. The simultaneous setup allows the acquisition of displacement data from two different object illumination positions at the same time, so that the system is capable of studying nonrepeatable dynamic events. Further analysis using displacement data generates a gradient strain map where the fracture is successfully detected with the corresponding strain magnitude and direction quantified.

Effects of Age Shift on the Tempo and Quantum of Non-Repeatable Events

Effects of age shift on the tempo and quantum of non-repeatable demographic events are examined. The purpose is to develop a period index theory based on the survival model and to provide a mathematically consistent interpretation of Bongaarts and Feeney's tempo adjustment arguments. The survival model for non-repeatable events is introduced. In the time-inhomogeneous case, three types of period survival models are considered. McKendrick equation is used to formulate the risk population dynamics. The tempo and quantum indices for three period survival models are computed when the period age shift occurs for the hazard, the incidence, and the survival rates. Bongaarts and Feeney's tempo adjustment arguments are consistently based on the scenario of the period age shift on the survival rate, and they give translation formulae between period indices without referring to cohort. Traditional demographic translation formulae between cohort and period indices are reviewed to clarify differences between cohort- and period-oriented translation procedures.

Cross-layer adaptive control for wireless mesh networks

This paper investigates optimal routing and adaptive scheduling in a wireless mesh network composed of mesh clients and mesh routers. The mesh clients are power constrained mobile nodes with relatively little knowledge of the overall network topology. The mesh routers are stationary wireless nodes with higher transmission rates and more capabilities. We develop a notion of instantaneous capacity regions, and construct algorithms for multi-hop routing and transmission scheduling that achieve network stability and fairness with respect to these regions. The algorithms are shown to operate under arbitrary client mobility models (including non-ergodic models with non-repeatable events), and provide analytical delay guarantees that are independent of the timescales of the mobility process. Our control strategies apply techniques of backpressure, shortest path routing, and Lyapunov optimization.

Planar Array Infrared Emission Spectroscopy

Planar array infrared spectroscopy (PA-IR) is shown to be a powerful new approach to infrared emission spectroscopy (IRES). A proof-of-concept study of selected polymers indicates that PA-IRES allows acquisition of emission spectra with a high signal-to-noise ratio at temperatures as low as 80 degrees C. It is shown that a time resolution below 20 ms is readily achievable for time-resolved characterization of single non-repeatable events. The possibility of recording spatially resolved emission spectra is also demonstrated, and potential applications of this novel technique are finally described.

Discrete-Time Survival Mixture Analysis

This article proposes a general latent variable approach to discrete-time survival analysis of nonrepeatable events such as onset of drug use. It is shown how the survival analysis can be formulated as a generalized latent class analysis of event history indicators. The latent class analysis can use covariates and can be combined with the joint modeling of other outcomes such as repeated measures for a related process. It is shown that conventional discrete-time survival analysis corresponds to a single-class latent class analysis. Multiple-class extensions are proposed, including the special cases of a class of long-term survivors and classes defined by outcomes related to survival. The estimation uses a general latent variable framework, including both categorical and continuous latent variables and incorporated in the Mplus program. Estimation is carried out using maximum likelihood via the EM algorithm. Two examples serve as illustrations. The first example concerns recidivism after incarceration in a randomized field experiment. The second example concerns school removal related to the development of aggressive behavior in the classroom.

Acquisition of mid-infrared spectra from nonrepeatable events with sub-100-micros temporal resolution using planar array infrared spectroscopy.

A novel method is presented that is capable of collecting time-resolved vibrational spectroscopic information with sub-100-micros temporal resolution. Unlike previous step scan FT-IR approaches, the phenomena under study do not necessarily need to be repeatable. The methodology described herein is based on the planar array infrared (PA-IR) technique, which utilizes a spectrograph for wavelength dispersion and a mid-infrared focal plane array (FPA) detector for simultaneous detection of multiple wavelengths. Unlike previous PA-IR approaches, a rolling mode FPA is employed. This unique data readout mode, where data are read out of the array two rows at a time, is exploited to generate increased temporal resolution. The capabilities of this technique are demonstrated using the example of the electric field-induced Freedericksz transition of a nematic liquid crystal. It is shown that the orientational dynamics of a single transition can be tracked over a spectral range of 154 cm(-)(1) with a temporal resolution of 99.17 micros while requiring a total experimental time of less than 1 s.

Bacon, Boole, the EPA, and scientific standards.

The scientific standards of the Environmental Protection Agency (EPA) include the use of retrospective meta-analysis. This analysis entails a use of the theory of probability that is only a simulation and cannot accurately measure the confidence that should be placed in the results. The uncertainty necessary for probability is, in a retrospective study, simulated rather than real. There are three logical forms for establishing a proposition. In the logic of the syllogism, a proposition is established by deduction from assumed propositions. In the logic of the physical sciences, a proposition is established by its ability to predict the outcomes of future experiments. In the logic of the courtroom, a proposition is established by its ability to explain past events. The logic of the courtroom operates under the handicap of working with nonrepeatable events. It is more subject to the preferences of the judge than the logic of the physical sciences or that of the syllogism. Because the logic of the courtroom is less reliable than either the logic of the physical sciences or that of the syllogism, it is the logic of last resort, i.e., it is used only when the other two are not applicable. Under the EPA scientific standards, the logic of the courtroom is accepted for establishing propositions about the physical world. As the logic of the courtroom is less reliable than that of the physical sciences, this practice increases the likelihood of errors.

Cohort Quantum as a Function of Time-dependent Period Quantum for Non-repeatable Events

The paper discusses translation formulae for time-dependent cohort and period quantum for non-repeatable events. Cohort quantum expressions are investigated for two cases: one in which period quantum, and another in which the sum of the period rates decreases linearly with time. In both cases the assumption is that period tempo does not change. Sufficient conditions are given for the situation in which the cohort quantum simply equals the period quantum measured at the time when the cohort reaches the mean age of the period schedule of age-specific rates, given that the period rate sum is a polynomial function of time. The paper takes up an issue which was unresolved in the article ‘Translation formulae for non-repeatable events’, which appeared in the July 1994 issue of Population Studies.

Unfolding event histories: Scaling of non-repeating events

The present paper discusses the use of Coombs' (1950, 1964) unfolding procedure applied to event history data. This procedure is appropriate when several stimuli are rated according to the individuals' preference, and yields scale values for stimuli and individuals, as well as a ‘best’ order of stimuli. We propose to consider the order of occurrence in time of non-repeatable events (such as first marriage, leaving home, and first job) as an indication of the subjects' preference for these stimuli. In that case unfolding may be applied to the analysis of event history-data. The statistical principles of unfolding analysis in general are briefly discussed. Subsequently an illustration is given, using data concerning the life course of 216 Dutch women of birth cohort 1961, concerning five events: first steady relationship, leaving home, first child, first job, and first occurrence of living together. It is shown that these events can be ordered at an underlying one-dimensional continuum on which individuals can be scaled. Furthermore, using regression analysis it is shown that the location of the subjects at this continuum correlates significantly with various explanatory variables, showing how unfolding may be used in practical applications.

Translation Formulae for Non-repeatable Events

Ryder's translation expressions for repeatable events are extended to the case of non-repeatable events. It is found that cohort quantum is a constant function of time when period quantum is constant, and period tempo, as measured by the moments of the age pattern of the occurrence-exposure rates, change linearly with time. The degree of distributional distortion (that is, the upward or downward shift in cohort caused by changes in the period age pattern), given a set of occurrence-exposure rates, is generally less for non-repeatable than for repeatable events in this case, in particular at high quantum levels. Furthermore, it is found that when period tempo is constant over time, and period quantum falls linearly, period quantum underestimates cohort quantum for high period quantum levels, and overestimates it for low period quantum levels.

Reply to R. A. Sayer

Sayer concedes several points in his second reply, but he still finds Conceptions of Space in Social Thought: A Geographic Perspective to contain errors, specifically five. The first (his point four) refers to my analysis of generalizations. The second (his point five) concerns explanation. The third (his point six) concerns closed and open systems. The fourth (his point seven) concerns science. The fifth (his point eight) concerns hermeneutics. Then there follows a discussion about meaning which seems to be part of the hermeneutics argument. As I see it, the first four (his points four through seven) can be addressed as one issue--that of science. The fifth point, hermeneutics (which is his eighth point) can be considered an application of science. I will consider first the issue of science and then the problem of hermeneutics. My remarks about science which are most pertinent to Sayer's criticisms are found on pages 35 and 41-2 of my book. I do not say empirical regularities are all there is to science. Yet this is what Sayer seems to believe I said. He sets up two types of explanations (which are not clearly differentiated) and claims my conception of science is about only one of them--the wrong one, i.e., the one linked to something like empirical regularities. Supposing he has read my statements about science, how can his remarks be interpreted? One possibility is that his own conception of science and explanation differs so radically from the one I outlined above that he would believe any provision for statistical testing and verification irrevocably dilutes the search for, and proof of, true explanations. In other words, he cannot entertain a science incorporating something like both of the explanatory types he outlines. Take his example of the nation state. He states 'to exist as a nation state certain social relations must be established on the basis of some degree of understanding (not necessarily a clear or very correct one) of the meaning of its concept'. Though I do not pretend to know precisely what is meant by this, his subsequent discussion suggests that trying to test it, or trying to see somehow if it corresponds to evidence, is taking the wrong approach. In my book I have discussed how testing is frought with philosophical and empirical problems, and how it alone does not establish cause and effect or give us true explanations. But I maintained that something along these lines must be done and is done in the practice of science. If Sayer is arguing that correspondence to evidence is not necessary at all, then he is indeed presenting a radically different picture of science and explanation than I have presented. It is also one that may be worth developing, although I cannot imagine how it could avoid being completely idealistic and solipsistic. But Sayer may not be saying that testing is unnecessary. Rather he may be saying that it is impossible because among other things: human behaviour is composed of non-repeatable or unique events; the causes of behaviour are so varied; the systems are so open; and there is an interdependent relationship between the language of observation and the theory to be tested. Here I would agree that human behaviour appears to present such conditions in abundance, (whether more than non-human action is questionable) and that it does create problems of testing, validating, explaining, and so on. But I would hasten to remind Sayer and the reader that after a long history of wrestling with these problems (often within the contexts

Subjective qualitative information structures based on orderings

This paper is motivated by the following question: Can one axiomatize information first and then probability in terms of information rather than vice versa as suggested by information theory? The emphasis here is on a new methodological approach toward a conceptualization of behavioral information which might be better suited for inferences involving nonrepeatable events or an insufficient number of repeatable events, based on the assumption that information is prior to probability statements. The main idea is to generate (via a Boolean homorphism) a Boolean algebra of events by an appropriate information structure and to utilize the notion of a topogeneous order similar to that of a Boolean order.

Subjective Qualitative Information Structures Based on Orderings

This paper is motivated by the following question: Can one axiomatize information first and then probability in terms of information rather than vice versa as suggested by information theory? The emphasis here is on a new methodological approach toward a conceptualization of behavioral information which might be better suited for inferences involving nonrepeatable events or an insufficient number of repeatable events, based on the assumption that information is prior to probability statements. The main idea is to generate (via a Boolean homorphism) a Boolean algebra of events by an appropriate information structure and to utilize the notion of a topogeneous order similar to that of a Boolean order.