Cohen Model Research Articles

A Note on Ramaswamy, Chatterjee, and Cohen's Latent Joint Segmentation Models

In this note, the authors show that the latent segmentation model developed by Ramaswamy, Chatterjee, and Cohen (1996) is nonidentifiable, and therefore, the parameters of interest are nonestimable.

A Note on Ramaswamy, Chatterjee, and Cohen's Latent Joint Segmentation Models

In this note, the authors show that the latent segmentation model developed by Ramaswamy, Chatterjee, and Cohen (1996) is nonidentifiable, and therefore, the parameters of interest are nonestimable.

An Analysis of the Relationship Between Publishing Activity and Internal Knowledge Development

Previous research has explored the value of using patent citations, versus simple patent counts, as indicators of innovative value. However, little work has delved into whether a company's patent citations are to its own patents or to external ones. This study examines the relationship between publishing and patenting using patent citation analysis that is separated into internal and external cites, with self-citations as a measure of internal knowledge development. Its results are that publishing patterns and internal knowledge development are correlated, which may provide a different view of Cohen and Levinthal's absorptive capacity model. In addition, these findings' plausibility was confirmed through an interview with a practising research manager.

On the carrier contribution to the elastic constants in ultrathin films of bismuth under quantizing magnetic field

We present a simple analysis of the carrier contribution to the elastic constants in ultrathin films of Bi under magnetic quantization in accordance with McClure-Choi, Cohen, Abrikosov, Lax and parabolic ellipsoidal band models in the presence of spin, broadening and temperature respectively. It appears that the said contribution increases with increasing electron concentration and decreasing film thickness in various manners. The McClure and Choi model shows this more significantly than other models. We have also suggested an experimental method of determining the said contribution in degenerate materials having arbitrary dispersion laws.

Ecologic Bias revisited, A rejoinder to Cohenʼs response to “Residential 222Rn exposure and Lung Cancer: Testing the Linear no-Threshold theory with Ecologic Data”

In most rigorous epidemiologic studies, such as case-control and cohort studies, the basic unit of analysis is the individual. Each individual is classified in terms of exposure and disease status. However, in ecologic epidemiologic studies, the unit of analysis is some aggregate group of individuals. Summary measures of exposure and disease frequency are obtained for each aggregate, and the analyses focus on determining whether or not the aggregates with high levels of exposure also display high disease rates. The ecologic study design has major limitations, including ecologic confounding and cross level bias. Cohen has attempted to circumvent these limitations by invoking the linear no-threshold theory of radiation carcinogenesis to derive aggregate exposures from individual-level associations. He asserts that, while an ecologic study cannot determine whether radon causes lung cancer, it can test the validity of a linear-no threshold relationship between them. Cohen compares his testing of the linear no-threshold relationship between radon exposure and lung cancer to the practice of estimating the number of deaths from the person-rem collective dose, dividing the person-rem by the number of individuals in the population to derive the individual average dose, and then determining individual average risk by dividing the number of deaths by the number of individuals in the population. We show that Cohen's erroneous assumptions concerning occupancy rates and smoking effects result in the use of the wrong model to test the linear no-threshold theory. Because of these assumptions, the ecologic confounding and cross level bias associated with Cohen's model invalidate his findings. Furthermore, when more recent Iowa county lung cancer incidence rates are regressed on Cohen's mean radon levels, the reported large negative associations between radon exposure and lung cancer are no longer obtained.

A simple theoretical analysis of the Einstein relation in ultrathin films of bismuth under quantizing magnetic field

The Einstein relation for the diffusivity-mobility ratio is studied in ultrathin films of Bi under magnetic quantization in accordance with McClure-Choi, Cohen, Arbikosov, Lax and parabolic ellipsoidal band models in the presence of spin, broadening and temperature, respectively. It appears that the same ratio increases with increasing electron concentration and decreasing film thickness in various manners. The McClure and Choi model shows this more significantly than the other models. We have also suggested an experimental method of determining the Einstein relation in degenerate materials having arbitrary dispersion laws.

Explorations of Cohen, Dunbar, and McClelland's (1990) connectionist model of Stroop performance.

Explorations of Cohen, Dunbar, and McClelland's (1990) connectionist model of Stroop performance.

Explorations of Cohen, Dunbar, and McClelland's (1990) connectionist model of Stroop performance.

The J. D. Cohen, K. Dunbar, and J. L. McClelland (1990) model of Stroop task performance is used to model data from a study by D. H. Spielder, D. A. Balota, and M. E. Faust (1996). The results indicate that the model fails to capture overall differences between word reading and color naming latencies when set size is increased beyond 2 response alternatives. Further empirical evidence is presented that suggests that the influence of increasing response set size in Stroop task performance is to increase the difference between overall color naming and word reading, which is in direct opposition to the decrease produced by the Cohen et al. architecture. Although the Cohen et al. model provides a useful description of meaning-level interference effects, the qualitative differences between word reading and color naming preclude a model that uses identical architectures for each process, such as that of Cohen et al., to fully capture performance in the Stroop task.

Moral Panic or Moral Action? The Appropriation of Moral Panics in the Exercise of Social Control

Cohen's early work on moral panics has been influential, not necessarily through direct knowledge of his work, but through correspondence of the concept with a widely-held view of media effect and through the concept's usefulness in explaining particular forms of social action. The public reaction to the first widespread publicity given to the issue of sexual abuse by clergy in 1992 fits Cohen's description of a moral panic. But a study of that case, the social situation that surrounded it, and subsequent events, raise questions about aspects of Cohen's model and highlight particular political uses which can be made of the model in situations of social resistance or political suppression.

On Ciesielski's Problems

We discuss some problems posed by Ciesielski. For example we show that, consistently, d_c is a singular cardinal and e_c R there are functions g_n,h_n:R ---> R, n< omega, such that f(x,y)= sum_{n=0}^{infty} g_n(x)h_n(y). Finally, we deal with countably continuous functions and we show that in the Cohen model they are exactly the functions f with the property that (for all U in [R]^{aleph_1})(exists U^* in [U]^{aleph_1}) (f restriction U^* is continuous).

Hippocampus, delay neurons, and sensory heterogeneity

AbstractWe raise three issues concerning the Eichenbaum, Otto &amp; Cohen (1994) model. (1) We argue against the strict division of labor that Eichenbaum et al. attribute to neocortical and limbic regions. (2) We raise the possibility that the anterior and posterior portions of the hippocampus may be important for different types of information processing. (3) We argue that, rather than reflecting relational processing, different neural responses to “match” and “nonmatch” trials may relate to different required spatial responses.

Constitutive modeling of trip steel and its application to the improvement of mechanical properties

The transformation-induced plasticity (TRIP) steel possesses such favorable mechanical properties as high work-hardening characteristics, tenacity and strength. The strain-induced martensitic transformation, however, strongly depends on the temperature and strain rate imposed, and an appropriate improvement of mechanical properties is realized under quite restricted circumstances. To obtain the required mechanical properties, a constitutive model which can suitably predict the deformation behavior including transformation under a wide range of deformation rate and temperature has been developed by employing Olson and Cohen's model for strain-induced martensitic transformation kinetics. Then, the deformation behavior of a SUS304 (18-8) cylinder has been simulated under different environmental temperature with different strain rates by the thermocoupled finite-element method accounting for the latent heat induced by martensitic transformation. The possibility of the improvement of such mechanical properties of the material as strength, ductility and toughness has been individually discussed.

Generic trees

AbstractWe continue the investigation of the Laver ideal ℓ0 and Miller ideal m0 started in [GJSp] and [GRShSp]; these are the ideals on the Baire space associated with Laver forcing and Miller forcing. We solve several open problems from these papers. The main result is the construction of models for t &lt; add(ℓ0), &lt; add(m0), where add denotes the additivity coefficient of an ideal. For this we construct amoeba forcings for these forcings which do not add Cohen reals. We show that = ω2 implies add(m0) ≤ . We show that , implies cov(ℓ0) ≤ +, cov(m0) ≤ + respectively. Here cov denotes the covering coefficient. We also show that in the Cohen model cov(m0) &lt; holds. Finally we prove that Cohen forcing does not add a superperfect tree of Cohen reals.

On the heterogeneous nucleation of martensite

Martensitic nucleation near inhomogeneities is modeled using linear elasticity. The coherent strain energy due to the formation of a martensite embryo decreases when the inhomogeneity is elastically stiffer than the matrix and vice versa. A maximum reduction of 20% in strain energy is calculated for the case when the embryo is formed near a free surface. The results are consistent with the experimental observations of preferential nucleation of martensite at a free surface. A possible explanation for the nature of the “preexisting martensite embryo” in the Kaufman and Cohen model of a nucleation site is also proposed: the dislocation loop in the parent phase is itself the site for the embryo such that it will transform into martensite during transformation. The calculated critical characteristics of this embryo are in good agreement with the model of Chen and Chiao and their experimental results.

Linear viscous fingering: New experimental results, direct simulation and the evaluation of averaged models

In this paper, miscible viscous fingering results have been presented for almost homogeneous “two-dimensional linear” (relatively long and narrow) displacement experiments at mobility ratios of approximately M = 4, 11 and 30. Both effluent profiles (recoveries) and pressure drops along the fingers have been measured and the reproducibility of these in each of the experimental cycles in repacked beds is very good. These viscous unstable experiments have been modelled by direct simulation using a high-accuracy numerical model. A comparison is made between experiment and direct numerical simulation for the effluent concentration and oil production profile as well as pressure behaviour and the viscous fingering patterns. A number of averaged models of viscous fingering have been evaluated using the experimental pressure data including the Koval, Todd and Longstaff, Fayers and the Odeh and Cohen models. It has been found that direct numerical simulation reproduces both the experimental effluent concentration profiles and the observed pressure drop behaviour very well. Numerically simulated viscous fingering patterns match the main features of the experimental observation. The numerical model used only measured laboratory data together with a random mechanism for initiating fingers in the simulation. However, of the averaged model approaches, the Todd and Longstaff and an equivalent mixing model give the most satisfactory agreement with the observed effective in situ mobilities (pressure drops) in the fingering zone. Both the original Koval model and the modification proposed by Odeh and Cohen do not give good agreement with experimental pressure drop measurements. The approach of Fayers also has some shortcomings in that it predicts a viscosity in the finger zone that is too low (i.e. effective mobility is too high) due to the presence of an unphysical shock front behaviour which this model exhibits.

RESISTANCE AND MOTIVATION - MORAL, POLITICAL OR PERSONAL? ISRAELI SOLDIERS AS SELECTIVE CONSCIENTIOUS OBJECTORS DURING THE INTIFADA

A person's belief in the moral character of his own act is surely not the only court before which that act may be judged. While a reflective conscience is a necessary court, and a very important one, it is not a sufficient one. The audience would want to know whether the individual was acting conscientiously, and whether this way of acting might have moral and/or political motivation. The following paper utilizes Cohen's model for identification of the motivatio n for conscientious disobedience and develops a model of a personally motivated refusal as well.

Numerical Simulation of Deformation Behavior of TRIP Steels.

The transformation-induced plasticity (TRIP) steel possesses such favorable mechanical properties as high work-hardening characteristics, tenacity and strength. The strain-induced martensitic transformation, however, strongly depends on the temperature and strain rate imposed, and an appropriate improvement of mechanical properties is realized under quite restricted circumstances. To obtain the required mechanical properties, a constitutive model which can suitably predict the deformation behavior including transformation under a wide range of deformation conditions has been developed by employing Olson and Cohen's model for strain induced martensitic transformation kinetics. Then, deformation behavior of SUS304 (18-8) cylinder has been simulated under different environmental temperature with different strain rates by thermocoupled finite element method accounting for the latent heat induced by martensitic transformation. The possibility of the improvement of such mechanical properties of the material as strength, ductility and toughness has been individually discussed.

All meager filters may be null

We show that in the Cohen model the sum of two nonmeasurable sets is always nonmeager. As a consequence we show that it is consistent with ZFC that all filters which have the Baire property are Lebesgue measurable. We also show that the existence of a Sierpinski set implies that there exists a nonmeasurable filter which has the Baire property.

Topological invariants in the Cohen model

It is shown that in any model obtained by adding ℵ 2 Cohen reals to a model of the continuum hypothesis any two P-points in β N ⧹ N have the same topological type. At the same time it is possible to construct P-points with contrasting combinatorial properties.

Aluminum agglomeration in ammonium perchlorate/cyclotrimethylene trinitramine/aluminum/hydroxy-terminated polybutadiene propellant combustion

Aluminum combustion efficiency and agglomeration in 13 equal-composition AP/RDX/A1/HTPB propellants were experimentally investigated using a quenched particle collection bomb (QPCB) under pressures up to 6895 kN/m. Formulation parameters studied included RDX size, Al size, fine AP size, and AP coarse/fine weight ratio. The results indicate that formulation variables can affect the combustion efficiency through either propellant microstructure changes, or extended condensed phase reactions associated with significant fine AP fraction. Effects of formulation variables on combustion efficiency are in qualitative agreement with the trends predicted by Cohen's pocket model. The addition of RDX has an adverse effect on agglomerate size, possibly through formation of a molten layer that facilitates the retention and coalescence of AI particles on the burning surface. Agglomerate sizes are adequately characterized by two microstructure parameters from a simplified pocket model. A correlation for estimation of agglomerate size of AP/Nitramine/Al/HTPB propellent is tentatively proposed based on the data from various sources. Moreover, the combustion efficiency was found to be inversely proportional to the agglomerate size.