Showing papers by "Rutgers University published in 1984"

Fluids with highly directional attractive forces. I. Statistical thermodynamics

Abstract: A new formulation of statistical thermodynamics is derived for classical fluids of molecules that tend to associate into dimers and possibly highers-mers due to highly directional attraction. A breakup of the pair potential into repulsive and highly directionally attractive parts is introduced into the expansion of the logarithm of the grand partition function in fugacity graphs. The bonding by the directional attraction is used to classify the graphs and to introduce a topological reduction which results in the replacement of the fugacity by two variables: singlet densityρ and monomer densityρ 0. Results for the thermodynamic functions as functionals ofρ andρ 0 are given in the form of graph sums. Pair correlations are analyzed in terms of a new matrix analog of the direct correlation function. It is shown that the low-density limit is treated exactly, while major difficulties arise when the Mayer expansion, which employs onlyp, is used. The intricate resummations required for the Mayer expansion are illustrated for the case where dimers are the only association products.

Fluids with highly directional attractive forces. II. Thermodynamic perturbation theory and integral equations

Abstract: The formalism of statistical thermodynamics developed in the preceding paper is used as a basis for deriving tractable approximations. The system treated is one where repulsion and highly directional attraction due to a single molecular site combine to allow the formation of dimers, but no highers-mers. We derive thermodynamic perturbation theory, using the system interacting with only the repulsive potential as a reference system. Two distinct integral equations for the pair correlation are derived. The first one treats both parts of the interaction approximately; the other one employs the repulsive reference system used in perturbation theory. We show that each of these integral equations permits the calculation of an important thermodynamic function directly from the solution at a single state of density and temperature. In the first case this applies to a pressure consistent with the compressibility relation, in the second to the excess Helmholtz free energy over the reference system.

Models of hierarchically constrained dynamics for glassy relaxation

Abstract: A class of models for relaxation in strongly interacting glassy materials is suggested. Degrees of freedom are divided into a sequence of levels such that those in level $n+1$ are locked except when some of those in level $n$ find the right combination to release them, this representing the hierarchy of constraints in real systems. The Kohlrausch anomalous relaxation law, $\mathrm{exp}[\ensuremath{-}{(\frac{t}{\ensuremath{\tau}})}^{\ensuremath{\beta}}]$, emerges naturally, and a maximum time scale is found which exhibits a Vogel-Fulcher-type temperature dependence.

Dopaminergic neurotoxicity of 1-methyl-4-phenyl-1,2,5,6-tetrahydropyridine in mice

Abstract: 1-Methyl-4-phenyl-1,2,5,6- tetrahydropyri dine ( MPTP ) is known to cause an irreversible destruction of the dopaminergic nigrostriatal pathway and symptoms of parkinsonism in humans and in monkeys. However, MPTP has been reported to act only minimally or not at all in several other animal species. When MPTP (30 milligrams per kilogram of body weight) was administered parenterally to mice, a decrease in concentrations of neostriatal dopamine and its metabolites, a decrease in the capacity of neostriatal synaptosomal preparations to accumulate [3H]dopamine, and a disappearance of nerve cells in the zona compacta of the substantia nigra were observed. In contrast, MPTP administration had no effect on neostriatal concentrations of serotonin and its metabolites. MPTP administration thus results in biochemical and histological changes in mice similar to those reported in humans and monkeys and similar to those seen in Parkinson's disease in humans. The mouse should prove to be a useful small animal with which to study the mode of action of MPTP .

Why it won't happen to me: Perceptions of risk factors and susceptibility.

Abstract: Four studies were conducted with college student subjects to examine: (1) perceptions of susceptibility to health and safety risks; (2) factors that subjects see as important in determining their susceptibility; and (3) subjects' actual standing on objective risk factors. Subjects were generally unbiased about hereditary risk factors and were even somewhat pessimistic about environmental risk factors. Their views of their own actions and psychological attributes, however, were excessively optimistic. Few acknowledged actions or psychological attributes that increased their risk. This pattern of findings helps to explain why risks thought to be controllable (i.e., preventable by personal action) are likely to evoke unrealistic optimism about susceptibility. Family histories of health problems were incorporated into judgments of susceptibility, but, except for smoking, correlations between behavioral risk factors and judgments of susceptibility were surprisingly weak. Self-esteem enhancement is suggested as a motive that could explain many of the present findings. Several recommendations are offered for health campaigns that seek to produce more realistic perceptions of susceptibility to health and safety problems.

GexSi1−x/Si strained‐layer superlattice grown by molecular beam epitaxy

Abstract: GexSi1−x films are grown on Si by molecular beam epitaxy and analyzed by Nomarski optical interference microscopy, Rutherford ion backscattering and channeling, x‐ray diffraction, and transmission electron microscopy. The full range of alloy compositions will grow smoothly on silicon. GexSi1−x films with x≤0.5 can be grown free of dislocations by means of strained‐layer epitaxy where lattice mismatch is accommodated by tetragonal strain. Critical thickness and composition values are tabulated for strained‐layer growth. Multiple strained layers are combined to form a GexSi1−x/Si strained‐layer superlattice.

The effect of aspect ratio of inclusions on the elastic properties of unidirectionally aligned composites

Abstract: This paper examines the influence of aspect ratio α, from zero to infinity, on the effective elastic moduli of a transversely isotropic composite. The reinforcing inclusions, which could be flakes or short fibers, are assumed to be spheroidal and unidirectionally aligned. Of the five independent elastic constants, the longitudinal Young's modulus E11 and in-plane shear modulus μ12 appear to increase with increasing aspect ratio, while the transverse Young's modulus E22, out-plane shear modulus μ23, and plane-strain bulk modulus K23, generally decrease. It is further noted that E11 is more sensitive to α when α > 1 but the others are more so when α < 1. The present analysis was carried out by the combination of Eshelby's and Mori-Tanaka's theories of inclusions.

Lumbosacral Spinal Fusion A Biomechanical Study

Abstract: The effects of spinal fusion on fused segment and the adjacent, unfused segments play a significant role in the clinical effectiveness of spinal fusion for low-back pain with or without sciatica. Much of the information on this important subject is derived from clinical impressions. The purpose of this biomechanical study is to investigate the altered kinematics and biomechanics of the three different types of spinal fusion (posterior, bilateral-lateral, and anterior) on the adjacent, unfused segment as well as within the fused segment and to investigate their clinical implications. Sixteen fresh human cadaver lumbosacral spines were tested under a simulated physiologic loading condition. The test specimens included three motion segments, L3-4, L4-5, and L5-S1. To study the mechanics of the lumbar spine under combined compression and bending loads, a special apparatus was designed. These loads were applied by an MTS machine through two sets of pulley systems. The loads, as well as displacement data from both actuators, were recorded. A video camera system was utilized to record the kinematics of the spinal motion segment. The unfused specimen was tested first, and the fused specimen then was retested under the identical loading conditions. A total of 16 spine specimens were tested and evaluated--five posterior, four bilateral-lateral, and seven anterior fusions. All types of fusion resulted in increased bending and axial stiffnesses. Overall, anterior fusion provided the largest increase in stiffness, followed by bilateral-lateral fusion and posterior fusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Fluid Signs Being a Person the Tamil Way

Abstract: Fluid Signs is the product of anthropological fieldwork carried out among Tamil-speaking villagers in a Hindu village in Southern India Combining a richness of ethnographic detail with a challenging and innovative theoretical analysis, Daniel argues that symbolic anthropologists have yet to appreciate the multifaceted function of the sign and its role in the creation of culture This provocative study underscores the need for Western intellectual traditions in general and anthropology in particular to deepen its discourse with South Asian cultural and religious thought

Applied Combinatorics

Abstract: Section 13.1 . 1(a). Add edges in the order {b, e}, {d, e}, {a, e}, {c, d}; 1(b). Add edges in the order {a, b}, {b, c}, {d, e}, {e, f}, {g, h}, {h, i}, {a, d}, {d, g}; 1(c). Add edges in the order {c, g}, {a, b}, {a, d}, {f, g}, {d, f}, {e, f} where ties were broken arbitrarily; 2(a). add edges {a, e}, {b, e}, {d, e}, {c, d}; 2(b). Add edges in the order {a, b}, {b, c}, {a, d}, {d, e}, {e, f}, {d, g}, {g, h}, {h, i}; 2(c). Add edges in the order {a, b}, {a, d}, {d, f}, {f, g}, {c, g}, {e, f}; 3(a). terminate with message disconnected; T ends up with 5 edges; 3(b). terminate with message disconnected; T ends up with 7 edges; 3(c). terminate with message disconnected; T ends up with 6 edges; 5. vat pairs: {7, 8}, {6, 7}, {1, 5}, {4, 5}, {5, 8}, {2, 3}, {3, 8}; 6. component pairs: {1, 4}, {2, 6}, {3, 4}, {1, 6}, {5, 6}; 9. (a): edges {b, c}, {c, e}, {c, d}, {a, b}; (b): edges {f, i}, {e, h}, {d, g}, {c, f}, {b, e}, {a, d}, {g, h}, {h, i}; (c): edges {d, e}, {c, d}, {a, e}, {b, c}, {e, f}, {d, g}; 11. yes; 12(a). edges {a, e}, {a, b}, {c, d}, {d, e}; 12(b). edges {c, e}, {a, b}, {c, d}, {b, d}; 13. in Step 1 of Kruskal’s Algorithm, set T = { the set of edges specified as having to belong to the spanning tree }; 16(a). for network (c): G′ has edges {a, b}, {c, g}, {a, d}, {f, g}, {d, f}; in the next iteration we add {e, f} and obtain a minimum spanning tree.

Nonequilibrium steady states of stochastic lattice gas models of fast ionic conductors

Abstract: We investigate theoretically and via computer simulation the stationary nonequilibrium states of a stochastic lattice gas under the influence of a uniform external fieldE. The effect of the field is to bias jumps in the field direction and thus produce a current carrying steady state. Simulations on a periodic 30 × 30 square lattice with attractive nearest-neighbor interactions suggest a nonequilibrium phase transition from a disordered phase to an ordered one, similar to the para-to-ferromagnetic transition in equilibriumE=0. At low temperatures and largeE the system segregates into two phases with an interface oriented parallel to the field. The critical temperature is larger than the equilibrium Onsager value atE=0 and increases with the field. For repulsive interactions the usual equilibrium phase transition (ordering on sublattices) is suppressed. We report on conductivity, bulk diffusivity, structure function, etc. in the steady state over a wide range of temperature and electric field. We also present rigorous proofs of the Kubo formula for bulk diffusivity and electrical conductivity and show the positivity of the entropy production for a general class of stochastic lattice gases in a uniform electric field.

Cancer therapy with chemically modified enzymes. I. Antitumor properties of polyethylene glycol-asparaginase conjugates.

Abstract: The covalent attachment of monomethoxypolyethylene glycol (PEG) to asparaginases from Escherichia coli and Vibrio succinogenes by new coupling methodology produced conjugates that are active, stable, without significant immune response, and with greatly extended plasma half-lives in mice. Therapeutic efficacies were greater for the PEG-asparaginases than for the unmodified asparaginases in mice infected with the L5178Y lymphosarcoma or the 6C3HED tumor. Large single doses of native or modified enzymes were more effective against tumors than the same amount of enzyme given in smaller doses over several days.

Hedgerows and hedgerow networks in landscape ecology

Abstract: Hedgerows originated and coexist with agriculture. Their internal structure and species diversity vary widely with origin (planted, spontaneous, or remnant), farming practices in adjacent fields, and the refined art of hedgerow management. Most hedgerow species are forest-edge species, and apparently none is limited to hedgerows. Wide hedgerows composed of trees and shrubs appear to function as corridors for movement of many plants and animals across a landscape. The reduction of crop loss, by dampening pest population fluctuations with hedgerow predators, remains a hypothesis for study.

Roof duality, complementation and persistency in quadratic 0–1 optimization

Abstract: The paper is concerned with the ‘primal’ problem of maximizing a given quadratic pseudo-boolean function. Four equivalent problems are discussed—the primal, the ‘complementation’, the ‘discrete Rhys LP’ and the ‘weighted stability problem of a SAM graph’. Each of them has a relaxation—the ‘roof dual’, the ‘quadratic complementation,’ the ‘continuous Rhys LP’ and the ‘fractional weighted stability problem of a SAM graph’. The main result is that the four gaps associated with the four relaxations are equal. Furthermore, a solution to any of these problems leads at once to solutions of the other three equivalent ones. The four relaxations can be solved in polynomial time by transforming them to a bipartite maximum flow problem. The optimal solutions of the ‘roof-dual’ define ‘best’ linear majorantsp(x) off, having the following persistency property: if theith coefficient inp is positive (negative) thenx i=1 (0) in every optimum of the primal problem. Several characterizations are given for the case where these persistency results cannot be used to fix any variable of the primal. On the other hand, a class of gap-free functions (properly including the supermodular ones) is exhibited.

Agency Theory, Managerial Welfare, and Takeover Bid Resistance

Abstract: Tender offers provide an ideal setting for the analysis of agency relationships since the best interests of the principal (target firm shareholders) and agent (target firm managers) are often in conflict. Moreover, the actions and stated rationale of target managers in resisting or not resisting tender offers are readily observable, and the size of the possible agency costs is great. This research provides direct empirical evidence on the relationship between managerial welfare and takeover bid resistance. Tests on a sample of cash tender offers provide support for the managerial welfare hypothesis. The existence or absence of bid resistance is found to be directly related to the personal wealth changes of the target firm's managers. The relationships between managerial actions and bid premium size, bidder nationality, conglomerate offers, and "ex post settling up" are also examined.

Self-assembly of basement membrane collagen

Abstract: The in vitro self-assembly of murine type IV collagen was examined by using biochemical and morphological techniques. Dimeric collagen undergoes a rapid and reversible thermal gelation at neutral pH without an appreciable lag period. The process is seen to be concentration dependent and inhibited by 2 M urea. The formed complex can be visualized by electron microscopy rotary shadowing as an irregular polygonal lattice network with extensive side by side associations within the collagenous triple-helical part of the molecules, two and three strands thick. Measurements on the matrix suggest a median stagger dimension of 170 nm, one-fifth the length of a dimer. The conversion of pepsin-generated monomers into N-terminally bound tetramers can also be demonstrated in vitro. This process is also concentration dependent and inhibited and reversed by 2 M urea but is thermally irreversible and occurs at a slow rate relative to the lateral associations. These tetramers can be seen by rotary shadowing as four-armed "spider" structures. It is proposed that lateral associations, by virtue of their faster rate of formation, precede 7S bond formation, and several models for the assembly of basement membrane collagen are discussed.

Tree graph inequalities and critical behavior in percolation models

Abstract: Various inequalities are derived and used for the study of the critical behavior in independent percolation models. In particular, we consider the critical exponent γ associated with the expected cluster sizex and the structure of then-site connection probabilities τ=τn(x1,..., xn). It is shown that quite generally γ⩾ 1. The upper critical dimension, above which γ attains the Bethe lattice value 1, is characterized both in terms of the geometry of incipient clusters and a diagramatic convergence condition. For homogeneousd-dimensional lattices with τ(x, y)=O(¦x -y¦−(d−2+η), atp=p c, our criterion shows that γ=1 if η> (6-d)/3. The connectivity functions τn are generally bounded by tree diagrams which involve the two-point function. We conjecture that above the critical dimension the asymptotic behavior of τn, in the critical regime, is actually given by such tree diagrams modified by a nonsingular vertex factor. Other results deal with the exponential decay of the cluster-size distribution and the function τ2 (x, y).

A natural representation of the Fischer-Griess Monster with the modular function J as character

Abstract: We announce the construction of an irreducible graded module V for an “affine” commutative nonassociative algebra [unk]. This algebra is an “affinization” of a slight variant [unk] of the commutative nonassociative algebra B defined by Griess in his construction of the Monster sporadic group F1. The character of V is given by the modular function J(q) = q-1 + 0 + 196884q +.... We obtain a natural action of the Monster on V compatible with the action of [unk], thus conceptually explaining a major part of the numerical observations known as Monstrous Moonshine. Our construction starts from ideas in the theory of the basic representations of affine Lie algebras and develops further the calculus of vertex operators. In particular, the homogeneous and principal representations of the simplest affine Lie algebra A1(l) and the relation between them play an important role in our construction. As a corollary we deduce Griess's results, obtained previously by direct calculation, about the algebra structure of B and the action of F1 on it. In this work, the Monster, a finite group, is defined and studied by means of a canonical infinite-dimensional representation.

A Practical Guide to Designing Expert Systems

Abstract: This book offers a practical introduction to expert systems and is designed not only for computer programmers but for all those who want to know how expert systems are structured and what they can do.

Brown & Hanlon revisited: mothers' sensitivity to ungrammatical forms*

Abstract: Brown & Hanlon (1970) reported that parents' explicit approval or disapproval of their child's utterances was not contingent on the well-formedness of that utterance. Rather, parents seemed attuned to the semantic value of their child's speech. Using 40 mother–child dyads, 10 from each of four age groups, 2–5 years, we replicated these results. We expanded upon this earlier work, however, to suggest that parents are not totally indifferent to the grammatical form of their child's utterances. Focusing on repetitions, we found that mothers are more inclined to repeat ungrammatical than grammatical sentences generated by 2- year-old subjects. This indicates that the language learning environment does present subtle cues that distinguish between well-formed and ill-formed sentences. Whether the child is capable of capitalizing on these cues remains unanswered.

Solution of the multichannel Kondo problem

Abstract: The multichannel Kondo model is exactly diagonalized for any impurity spin and for an arbitrary number of orbital channels. The impurity free energy is found and its properties deduced for high and low temperatures. When the number of channels is sufficiently large a nontrivial fixed point appears. Its critical exponents are calculated.

An algebraic approach to bounded controllability of linear systems

Abstract: In this paper we present an algebraic approach to the proof that a linear system with matrices (A, B) is null–controllable using bounded inputs if and only if it is null–controllable (with unbounde...