Showing papers by "Iowa State University published in 1973"

Transformations for Estimation of Linear Models with Nested-Error Structure

Abstract: Two linear models with error structure of the nested type are considered. Transformations are presented by which uncorrelated errors with constant variances are obtained. The transformed observations are differences between the original observations and multiples of averages of subsets of the observations. The transformations permit the calculation of the generalized least-squares estimators and their covariance matrices by ordinary least-squares regression. Regression-type estimators are presented for use when the variance components are unknown. Sufficient conditions are presented under which the estimated generalized least-squares estimator is unbiased and asymptotically equivalent to the generalized least-squares estimator.

Fitting Segmented Polynomial Regression Models Whose Join Points Have to Be Estimated

Abstract: The study considers the problem of finding the least squares estimates for the unknown parameters of a regression model which consists of grafted polynomial submodels. The abscissae of the join points are a subset of the unknown parameters. Examples are given to illustrate how continuity and differentiability conditions on the model can be used to reparameterize the model so as to allow Modified Gauss-Newton fitting. A slightly generalized version of Hartley's theorem is stated to extend the Modified Gauss-Newton method to this problem.

Insect Sex Pheromones: Minor Amount of Opposite Geometrical Isomer Critical to Attraction

Abstract: (Z)-II-Tetradecenyl acetate is the reported sex pheromone of European corn borer and redbanded leafroller moths However, geometrically pure preparations of the compound are weakly attractive to these species Presence of the E geometrical isomer in the Z is necessary for maximum sex attraction and these moths are "tuned" to respond optimally to specific proportions of Z to E This discovery is important to considerations of moth pheromonal specificity, evolution, and in application of knowledge of the pheromones to insect-pest suppression

Flavor development and microbiology of swiss cheese-a review: iii. ripening and flavor production

Abstract: This paper, the third of four, dismtsses the ripening and flavor produotion processes of Swiss cheese. First, general ripening changes are reviewed; then, a discussion of eye formation and body and texture changes follows. The important flavor compounds found in Swiss cheese are examined in detail beginning with consideration of the analytical methods used to isolate and measure fatty acids. The different volatile and nonvolatile fatty acids and their importance in Swiss cheese are considered, as well as production of propionic and acetic acids from lactate, production of keto acids, and lipolysis. Then, analyses for and significance of carbonyl compounds, alcohols, esters, lactones, hydrocarbons, and diaeetyl are presented. Possibilities for production of these compounds by microorganisms are given. Subsequent sections deal with nitrogeneous componnds, degradation of caseins to peptides and amino acids and their importance to flavor, and end with a review of sulfur compounds present. After Swiss cheese has been removed from the press, brined, and prestored for 7 to 14 days, it is transferred to the hot room where the temperature is 21 to 25 C (70 to 77 F). During the period in the hot room cheese becomes sufficiently elastic and the principal ripening of the cheese, with active growth of propionibacteria, takes place, forming the typical eyes of Swiss cheese ( 430 ). When the eyes are large enough, the cheese is moved to the curing cellar or \"finished cooler\" and kept there at 2 to 5 C ( 35.6 to 41 F) for 2 to 9 mon•ths. Ripening for at least 6 months should develop the fine, full flavor characteristic of a well-ripened Swiss cheese (116); however, most commercial Swiss cheese sold in the United States today is much younger when sold (345). GENERAL ASPECTS OF S'WISS CHEESE RIPENING During the time in the press, high-temperature lactic-acid bacteria rapidly hydrolyze lactose in the young cheese to glucose and galactose (338), which, by the Embden-Meyerhof pa:thway, is oxidized to 'Journal Paper No. J-7505 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa. Project No. 1839. 'This review is appearing in four parts: I. Milk Quality and Treatments and II. Starters, Manufacturing Processes and Procedures appeared in earlier issues; IV. Defects will appear in a subsequent issue. Literature citations will follow part IV. lactic acid by the same bacteria (B). Production of lactic acid in the cheese produces a readily assimilable substrate for the propionibacteria. Propionibacteria were first found by Sherman (393) to be essential for eye formation as well as production of the characteristic sweet flavor of Swiss cheese. A large part of the lactic acid in Swiss cheese is produced by homofermentative lactic-acid fermentation, but a small portion also is produced through the heterofermentative pathway. Moderate amounts of acetic acid are found in the cheese after pressing (218). Because of this heterofermentative activity, carbon dioxide, which induces growth of propionibacteria, also has been found (150). Lactic-acid bacteria also reduce the redox potential of the Swiss cheese to -200 mv, which is favorable for growth of propionibac,\"l:eria (199 ). Another important factor for growth induction of propionibacteria is the pH-value of the cheese out of the press. The pH must be between 5.0 and 5.3 to produce good Swiss cheese. If the pH is lower than 5.0, growth of propionibacteria will not take place (431). During the hot room and curing room treatment of Swiss cheese, the number of S. therrrwphilus and L. helveticus decline (79 ), even though it has been stated that mixed cultures of S. thermophilus and L. helveticus may grow at temperatures as low as 15 C (59 F) (171). The primary reason for this numerical decline is the elimination of lactose as an energy source and the formation of some metabolic products in the cheese that may have an adverse effect on growth, especially as the cheeses are ripened near their minimum growth temperature. Lactobacillus casei, however, grows during ripening, and SGme investigators consider it an important ripening organism

Rotation and Translation of Regular and Irregular Solid Spherical Harmonics

Abstract: Publisher Summary Quantum-mechanical calculations of molecular properties and reactions require the introduction of atomic orbitals (AO's) that are centered on the nuclei of the different atoms of the investigated molecule or molecular complex. Each atomic orbital is a certain mathematical function of the coordinates of one electron with respect to a coordinate system that has its origin in the nucleus of the considered atom. The main difficulties of quantum-mechanical theories are because of operators that may be considered as special cases of irregular solid spherical harmonics. The formulas derived to describe the transformation properties of solid spherical harmonics under rotations and translations have been found useful for the calculation of molecular integrals. The chapter describes the solid spherical harmonics and presents certain relations that are to be used in the sequel. The behavior of spherical harmonics under rotations is discussed to obtain a set of uniform formulas useful for subsequent considerations. The derivation of the transformation of solid spherical harmonics under translations is facilitated by the translation of general functions and by deriving some auxiliary identities needed in the sequel.

Gibbs free-energy barrier against irreversible magnetic flux entry into a superconductor

Abstract: We have calculated the Gibbs free-energy barrier against irreversible magnetic flux entry into a superconductor for a long cylinder with elliptical cross section which approximates a long, flat strip. Our model is simplified to the two-dimensional case by assuming magnetic flux to enter in the form of a long, narrow, normal domain parallel to the axis of the cylinder. The following four contributions to the Gibbs free energy have been taken into account: (1) loss of condensation energy and gain of magnetic field energy inside the superconductor, (2) magnetic field energy outside the superconductor, (3) energy of interaction of the domain with an applied magnetic field, and (4) energy of interaction with an applied electrical transport current. Because of the Gibbs free-energy barrier, the critical magnetic field for entry of magnetic flux can be enhanced considerably above that calculated using Silsbee's rule. This enhancement is found to be proportional to the square root of the width of the superconducting cylinder. Important consequences of this are the enhancement of the critical current in a superconducting strip in zero magnetic field at which electrical resistance starts to appear and a corresponding modification of Silsbee's rule. We have demonstrated these effects experimentally through measurements of the onset of the current-induced resistive state in a series of superconducting indium strips of different widths and thicknesses. The experimental results confirm the theoretical predictions. The Gibbs free-energy-barrier effect described here can be interpreted as a novel flux-pinning mechanism, which might be called edge pinning.

Flavor development and microbiology of swiss cheese-a review

Abstract: This review, appearing in four parts, deals with relationships between flavor development and the microbiology of Swiss cheese. Body and texture characteristics of Swiss cheese also will be discussed, however, to a lesser degree and, wherever possible, in association with the flavor of Swiss cheese. The first section, presented here, discusses use of raw milk and how the bacterial content of raw milk influences Swiss cheese quality. Thereafter, other milk treatments used in the cheese industry are discussed. They include clarification, heat-treatment, homogenization, and H2O2-catalase treatment of cheese milk. Changes in microbial flora and subsequent effects on Swiss cheese quality are included. Production of Swiss cheese with desirable body, flavor, and texture characteristics depends on use of low bacterial count, properly clarified milk. Mild [68 C (154.4 F) to 72 C (161.6 F) for 15 to 18 sec] heat treatment is recommended. Homogenization of cheese milk is not used and the H2O2-catalase treatment is n...

Stratigraphical Relationships of the Plio-Pleistocene Deposits, East Rudolf, Kenya

Abstract: This report summarizes the stratigraphical relationships of the Plio-Pleistocene sediments at East Rudolf and formalizes the Stratigraphical nomenclature.

Lengthening kinetics of ferrite and bainite sideplates

Abstract: The rate of lengthening of ferrite and bainite sideplates and the radius of curvature of the plate edges were measured as a function of reaction temperature in three Fe-C alloys. These data were analyzed on the basis of an equation due to Trivedi. The analysis proved that the mobility of the sideplate edges is limited. The interfacial energy of these edges is of the order of 200 erg/cm2. Most of the supersaturation is used to drive the diffusion of carbon in austenite; comparatively little is accounted for by capillarity and by the finite mobility of the interface. On the basis of both the present results and of published micro-structural observations, it was concluded that ferrite and bainite sideplates lengthen by a ledge mechanism.

Gonadotropin Levels in Lactating Rats: Effect of Ovariectomy

Abstract: The effect of suckling on synthesis and release of FSH and LH was investigated in intact and ovariectomized, lactating rats. Litter size was adjusted on Day 2 postpartum to 0, 3, 6 or 12 pups, and ovariectomies were performed at this time. Pituitary concentrations of FSH and LH were low on Day 2 and increased by Day 6. Pituitary FSH levels were greater in ovariectomized rats than in intact dams by Day 6 in rats with 0 and 3 pups and by Day 18 in dams nursing 6 pups. Pituitary LH concentrations were similar in all groups on Day 6, and the levels increased in ovariectomized rats with 0 and 3 pups by Day 12 and in dams nursing 6 pups by Day 18. Pituitary FSH and LH levels of intact and ovariectomized rats nursing 12 pups did not differ significantly during the first 18 days of lactation. Serum FSH and LH levels were elevated after ovariectomy; the rate and magnitude of these increases were diminished as litter size increased. Serum FSH and LH were elevated to detectable levels in all dams 12 hr after their p...

Fresh meat color

Abstract: This review presents a critical evaluation of the recent developments in the study of fresh meat color. Importance of color as a primary quality attribute deciding the consumer acceptance of fresh meats, is pointed out. The stability of myoglobin pigment, essential for the maintenance of fresh meat color, is examined in the light of 3‐dimensional structure of the molecule. The dynamic and reversible nature of color cycle involving constant oxygenation, oxidation, and reduction is emphasized. Oxygenation and oxidation are discussed on the basis of thermodynamic principles. The factors affecting fresh meat color are examined. The enzymic and nonenzymic metmyoglobin reducing systems are discussed in relation to fresh meat color. A full discussion on the inter‐relationship between lipid and pigment oxidation is presented. Recent developments on the methodology of color measurement are traced, pointing out the advantages and limitations of various methods.

Falcon Herpesvirus, the Etiologic Agent of Inclusion Body Disease of Falcons

Abstract: A viral agent has been isolated from five fatal cases of naturally occurring inclusion body disease in three different falcon species, namely, the prairie falcon (Falco mexicanus), the red-headed falcon (F. chiquera), and the peregrine falcon (F. peregrinus). The virus has been shown to possess the physical, chemical, and biological properties of a herpesvirus and has been used to reproduce inclusion body disease in the prairie falcon, merlin (F. columbarius), and American kestrel (F. sparverius). A similar disease was also produced with this virus in the great horned owl (Bubo virginianus), screech owl (Otus asio), and ring-necked turtle dove (Streptopelia risoria). Serological comparison of the falcon herpesvirus with other known avian herpesviruses revealed that the virus is antigenically closely related to a pigeon herpesvirus and an owl herpesvirus while differing from the former in host range. No antigenic relationship to infectious laryngotracheitis virus, duck virus enteritis, or Marek9s disease virus could be demonstrated. Images

The Effect of Wilting on Proline Metabolism in Excised Bean Leaves in the Dark

Abstract: The effects of wilting on the fate of proline and on the rates of nonprotein proline formation and utilization have been determined in excised bean leaves. Wilting did not alter the fate of exogenously added (14)C-l-proline (2 mm) in either non-starved leaves (from plants previously in the light) or starved leaves (from plants previously in the dark). The fate of proline in nonstarved leaves was protein synthesis and in starved leaves was protein synthesis and oxidation to other compounds.Wilting caused an increase in non-protein proline formation, possibly including release by proteolysis and synthesis from precursors in both starved and nonstarved leaves. Wilting caused a decrease in proline utilization in nonstarved leaves by decreasing protein synthesis. In starved leaves, wilting caused an increase in the rate of proline utilization but this is due to the higher content of proline in wilted leaves compared to the turgid leaves which causes more proline utilization by oxidation. Thus, the primary effects of wilting which lead to the accumulation of proline were to decrease protein synthesis and to increase proline formation. The source of the proline is not known but the increased formation due to wilting is not affected by the carbohydrate content of the leaf. The role of carbohydrates is to prevent the loss of accumulating proline by oxidation.

Transformations to Improve Reliability and/or Validity for Affective Scales

Abstract: THE psychological literature is rich with studies demonstrating that collecting responses to affective stimuli using a large number of ordered categories is not effective when compared with using some smaller number (e.g., Matell and Jacoby, 1971; Komorita and Graham, 1965). Thus, a 20-point scale is no better, and perhaps worse, in terms of reliability and validity than, say, a 5-point scale. However, these studies uniformly rank the categories and analyze these ranks. There is a small, circumscribed body of literature (Liu, 1971 ; Warren, Klonglan, and Sabri, 1969) which indicates that the use of normalized ranks or, in the case of large numbers of categories, normal deviates results in an increasing, monotonic relationship between reliability and number of categories. Such transformations weight highly response differences in the ends of the scale

Immobilized glucoamylase on porous glass

Abstract: A study was made to determine the controlling mass transfer resistance in the overall reaction rate for conversion of maltose to glucose, catalyzed by glucoamylase immobilized onto porous glass. For normal operation of a packed column and air-stirred batch reactor, the rate controlling step was found to be the internal resistance of simultaneous pore diffusion and chemical reaction. Experimental effectiveness factors were determined and are compared with those derived from a theoretical diffusion model based on Michaelis-Menten kinetics. Also given are temperature and pH relationships for the free and immobilized glucoamylase.