Showing papers by "Purdue University published in 1977"

Certification of programs for secure information flow

Abstract: ertification mechanism for verifying the secure flow of information through a program. Because it exploits the properties of a lattice structure among security classes, the procedure is sufficiently simple that it can easily be included in the analysis phase of most existing compilers. Appropriate semantics are presented and proved correct. An important application is the confinement problem: The mechanism can prove that a program cannot cause supposedly nonconfidential results to depend on confidential input data.

Shape Discrimination Using Fourier Descriptors

Abstract: Description or discrimination of boundary curves (shapes) is an important problem in picture processing and pattern recognition. Fourier descriptors (FD's) have interesting properties in this respect. First, a critical review is given of two kinds of FD's. Some properties of the FD's are given and a distance measure is proposed, in terms of FD's, that measures the difference between two boundary curves. It is shown how FD's can be used for obtaining skeletons of objects. Finally, experimental results are given in character recognition and machine parts recognition.

Initial and final state effects in the ESCA spectra of cadmium and silver oxides

Abstract: The factors which influence chemical shifts are examined in order to elucidate the cause of the anomalous chemical shifts for Cd and Ag oxides. The effects of extra‐atomic relaxation are accounted for using a procedure employing experimental Auger and binding energies. Atomic partial ionic charges for some simple Cd, Ag, and Zn compounds are calculated from experimental binding energies using a model which includes the effects of lattice potentials and extra‐atomic relaxation. Inclusion of extra‐atomic relaxation effects did not have a drastic effect on the relative ionicities computed for these selected compounds. However, for CdO, a large extra‐atomic relaxation energy contribution reduces the binding energy by 0.5 eV more than is predicted from nearest neighbor electronegativity arguments.

A Higher Order Closure Model for Canopy Flow

Abstract: The equations of motion were used to develop a one-dimensional, nonbuoyant mathematical model of air flow within vegetative canopies. The model consists of equations for mean horizontal momentum, Reynolds stress, and for the three components of turbulent kinetic energy with closure achieved by parameterizing the higher order terms. This eliminates the need to model the Reynolds stress directly using an eddy viscosity. The closure schemes rely upon a prescribed length scale and have been used elsewhere in modeling the atmospheric boundary layer free of vegetation. The equations were solved numerically using specified boundary conditions. Using a profile of plant area density for a crop of corn (Zea mays L.) the model predicted mean wind velocity, Reynolds stress and turbulent intensities for the region from the soil surface to twice the canopy height that compare well with experimental measurements (Shaw et al., 1974a,b). The model is believed to overestimate the intensity of turbulence generated ...

Approximating block accesses in database organizations

Abstract: When data records are grouped into blocks in secondary storage, it is frequently necessary to estimate the number of blocks XD accessed for a given query. In a recent paper [1], Cardenas gave the expression XD = m(1 - (1 - 1/m)k), (1) assuming that there are n records divided into m blocks and that the k records satisfying the query are distributed uniformly among the m blocks. The derivation of the expression was left to the reader as an exercise.

The decision tree classifier: Design and potential

Abstract: This paper presents the basic concepts of a multistage classification strategy called the decision tree classifier. Two methods for designing decision trees are discussed and experimental results are reported. The relative advantages and disadvantages of each design method are considered. A spectrum of typical applications in remote sensing is noted.

The interdigitated back contact solar cell: A silicon solar cell for use in concentrated sunlight

Abstract: The theoretical and experimental performance of an interdigitated back contact solar cell is described. This type of cell is shown to have significant advantages over a conventional solar cell design when used at high concentration levels, namely, reduced internal series resistance, nonsaturating open-circuit voltage, and an absence of shadowing by front surface contacting fingers. The results of a computer study are presented showing the effects of bulk lifetime, surface recombination velocity, device thickness, contact dimensions, and illumination intensity on the conversion efficiency and general device operation. Experimental results are presented for solar illumination intensities up to 28 W/cm2.

The use of residue number systems in the design of finite impulse response digital filters

Abstract: A technique is presented for implementing a finite impulse response (FIR) digital filter in a residue number system (RNS). For many years residue number coding has been recognized as a system which provides a capability for the implementation of high speed multiplication and addition. The advantages of residue coding for the design of high speed FIR filters result from the fact that an FIR requires only the high speed residue operations, i.e., addition and multiplication, while not requiring the slower RNS operations of division or sign detection. A new hardware implementation of the Chinese Remainder Theorem is proposed for an efficient translation of residue coded outputs into natural numbers. A numerical example illustrates the principles of residue encoding, residue arithmetic, and residue decoding for FIR filters. An RNS implementation of a 64th-order dual bandpass filter is compared with several alternative filter structures to illustrate tradeoffs between speed and hardware complexity.

Electrophoresis along cell membranes

Abstract: Bioelectric fields may segregate charged components floating in the plasma membranes of cells by a process of electrophoresis along the membrane. Molecules in cell membranes may be sorted to different portions of the cell surface by such electrical gradients. We present here a theory to support this hypothesis.

Electrophoresis of concanavalin A receptors along embryonic muscle cell membrane

Abstract: Fluorescent concanavalin A (con A)-labelling showed that an electric field of 4 V cm-1 grossly redistributed con A receptors alone the plasma membranes of living muscle cells within 4 h. This field produced a voltage drop of 12 mV across these 30 micronm-wide cells. The movement of receptors was independent of cell metabolism and seemed to be electrophoretic in nature.

Information Load and Decision Quality: Some Contested Issues:

Abstract: Important conceptual-definitional and empirical issues previously have been raised with regard to information overload in the consumer context. The primary purpose of this rejoinder is to highlight...

What about Disposition

Abstract: What do consumers do with products once they have outlived their usefulness, and how does this relate to the purchase of replacement products?

Individual Recognition, Intragroup Cohesion and Intergroup Spacing: Evidence From Sound Playback To Forest Monkeys

Abstract: The contexts and functions of several loud mangabey vocalizations, particularly the "whoopgobble", were investigated observationally and experimentally. Whoopgobbles are notable for their audibility and distinctiveness over long distances, their temporal pattern of delivery, and particularly their stereotypy and individual distinctiveness. On the other hand, contexts of and responses to these vocalizations are variable and sometimes nonobvious. In order to control context and more systematically investigate response, an experimental method involving playback of recorded vocalizations was developed. Although precautions against habituation were necessary, mangabey responses to playbacks were clearcut and repeatable. Answering vocalizations, changes in group movement, and changes in the dispersion of individuals within a group occurred only in response to mangabey vocalizations. Whoopgobble playbacks provoked a pattern of response, including most notably the rapid approach of one adult male (the "RA" male) from each group, which was specific to this call. Playback of whoopgobbles between 100 and 600m from mangabey groups indicated that this call does transmit information regarding the identity of the vocalizing individual and group over these distances. Test groups moved away from neighboring- and unknown-group calls, but towards those of their own males - particularly those of RA males. RA males, on the other hand, do not approach calls of other males from their own groups. Within a group, whoopgobbles may thus increase cohesion and influence the direction of movements. Characteristics of whoopgobble form and context are discussed with regard to hypothesized functions of these and other forest monkey loud calls. Responses by free-ranging mangabeys to playback of the whoopgobble confirm its role in maintaining distance between groups. Response was found to be independent of group size, despite the fact that whoopgobble rate is closely related to this variable and thus could transmit such information. Since responses were also found to be independent of location within the home range, intergroup spacing among mangabeys appears not be be "territorial", site defense does not occur. Nevertheless, the central areas in at least some mangabey groups' home ranges were never penetrated by neighbors. Playback tests with black-and-white colobus and blue monkeys, among which territorial spacing has been reported, indicate that responses to loud calls have some degree of site-specificity among these species. But the mangabey pattern of intergroup spacing appears to result from a combination of low group density, site attachment within groups, and site-independent avoidance between groups. These results emphasize that spacing "system" and "pattern" are not necessarily equivalent; a given set of spacing behaviors can result in different spacing patterns under different ecological conditions, while a given pattern may be obtained by any of several behavioral means. Evidence for site-independent spacing in other primate species is discussed.

Organizational and Personal Correlates of Attitudes Toward Women as Managers

Abstract: This study discusses the validation of a scale designed to measure attitudes toward women as managers using a cross-section sample of 180 male and 100 female employees. The relationship of personal...

Change detection in coastal zone environments

Abstract: A study was conducted with the objective to develop and evaluate various change detection techniques based upon computer-aided analysis of Landsat multispectral scanner (MSS) data to monitor coastal zone environments. The study site selected includes a portion of the Matagorda Bay estuarine system located along the Texas Coast. The principal data sources for the study were MSS data collected on November, 27, 1972 and February 25, 1975. The MSS data were processed and a multidata eight-channel data set at a scale of 1:24,000 was obtained. A description is presented of four change detection techniques which were designed and implented for evaluation, taking into account postclassification comparison change detection, delta data change detection, spectral/temporal change classification, and layered spectral/temporal approach. The results of the investigation are discussed.

Alcohol drinking: abnormal intake caused by tetrahydropapaveroline in brain

Abstract: Tetrahydropapaveroline (THP), a dopamine-dopaldehyde condensation product, was delivered directly into the cerebral ventricle of rats automatically every 15 minutes for 12 days. The animals were given access to both water and ethylalcohol, the latter being presented in 12 concentrations from 3 to 30 percent. Within 3 to 6 days of the start of the infusion of THP, the rats, which normally rejected alcohol, drank alcohol solutions in increasingly excessive amounts; this was accompanied by symptoms that were similar to those of withdrawal and intoxication. These results provide evidence that an abnormal metabolite in the brain may produce the addictive state caused by alcoholic beverages.

Some aspects of the structure and conformational properties of serum albumin

Abstract: Publisher Summary This chapter presents the structure and conformational properties of serum albumin. The functional properties of serum albumin, other than from its possibly coincidental importance in the maintenance of proper osmotic balance, relate to its unusual and versatile liganding ability. Well-known are its ability to bind such diversified substances as fatty acids, bilirubin, tryptophan, various metal ions, most anions, some hormones, and numerous drugs. Undoubtedly serum albumin serves a role in transporting such substances, but also it may serve an equally vital role in buffering or regulating the concentrations of various low molecular weight substances. Two general aspects of serum albumin structure and function are considered: (1) the heterogeneity and microheterogeneity of the protein and (2) the conformational transformations that the protein undergoes in solution.

Cellobiase from Trichoderma viride: Purification, properties, kinetics, and mechanism

Abstract: Three distinct cellobiase components were isolated from a commercial Trichoderma viride cellulase preparation by repeated chromatography on DEAE cellulose eluting by a salt gradient. The purified cellobiase preparations were evaluated for physical properties, kinetics, and mechanism. Results from this work include: (1) development of a one step enzyme purification procedure using DEAE-cellulose; (2) isolation of three chromatographically distinct, yet kinetically similar, cellobiase fractions of molecular weight of ∼76,000; (3) determination of kinetics which shows that cellobiase hydrolyzes cellobiose by a noncompetitive mechanism and that the product, glucose, inhibits the enzyme, and (4) development of an equation, based on the mechanism of cellobiase action, which accurately predicts the time course of cellobiose hydrolysis over an eightfold range of substrate concentration and conversions of up to 90%. Based on the data presented in the paper, it is shown that product inhibition of cellobiase significantly retards the rate of cellobiose hydrolysis.

Secondary Wind Speed Maxima Inside Plant Canopies

Abstract: It is noted that wind profiles measured in forest and crop canopies normally contain a secondary maximum or a region of very small shear beneath the level of greatest foliage density. One-dimensional models utilizing a turbulent transport coefficient cannot predict a reversed velocity gradient and, as a result, profile analyses normally imply coefficients that are unrealistic or nonsensical. Examination of the equation for the local rate of change of Reynolds stress u′w′ shows that the velocity gradient can reverse in sign if the divergence of the turbulent transport of stress is of opposite sign and exceeds in magnitude the pressure-velocity gradient correlation. Direct measurements of the turbulent transport of u′w′ in corn (Zea mays L.) indicate that its value is considerably larger than in the air layers above and show that stress is transported downward from the upper parts of the vegetation. A one-dimensional model of canopy flow which solves the equations for momentum, Reynolds stress and ...

Sexual aggression: a second look at the offended female.

Abstract: A replication of earlier studies of male sex aggression conducted during the mid-1950s basically finds little modification in incidence and frequency. Approximately 50% of a sample of university women report being victims of sexual aggression during the academic year. Major changes from the earlier research appear to be focused around the nature of the pair relationships and the characteristics of the offended females.

Generalized Inverses, Wald's Method, and the Construction of Chi-Squared Tests of Fit

Abstract: Wald's method constructs test statistics having chi-squared limiting distributions from estimators having nonsingular multivariate normal limiting distributions, using the inverse of the covariance matrix of the limiting distribution. This method is here extended to singular multivariate normal limiting distributions by use of generalized inverses. The generalized Wald's method is then applied to give a quite general solution to the problem of constructing chi-squared type statistics for testing fit to a parametric family when unknown parameters are estimated in various ways.