INFLUENCE OF FAT CONTENT AND PRESERVATIVES ON THE BEHAVIOR OF LISTERIA MONOCYTOGENES IN BEAKER SAUSAGE

Behavior of Listeria monocytogenes Scott A in pork liver sausage containing 22–67% fat, and antilisterial activities of sodium lactate, sorbic acid, potassium sorbate and sodium propionate were studied during storage at 4C and 10C. Commercial pork liver sausage batter (22% fat), alone and with additions of lard (15, 30, and 45% by weight) were tested. Concentrations of 1.8% sodium lactate, 0.1% sorbate as the acid or the potassium salt, and 0.2% sodium propionate were tested in heat sterilized sausage inoculated with a 24 h culture of the organism (10⁴ CFU/g). Fat content alone caused small reductions in cell numbers by the end of the storage periods: from log CFU/g of 9.9 to 9.4 after 14 days at 10C, and from 7.3 to 6.5 after 50 days at 4C in the basic sausage formulation and with 45% added fat, respectively. The inhibitory activities of lactate and propionate increased with increase in fat content, and were more pronounced at 4C, where the effects were listericidal. Inhibition by sorbic acid was least influenced by the fat content, and the potassium salt was less antilisterial than the acid.     

Structural analysis of flagellar axonemes from inner arm dynein knockdown strains of Trypanosoma brucei

Trypanosoma brucei is a protozoan flagellate that causes African sleeping sickness. Flagellar function in this organism is critical for life cycle progression and pathogenesis, however the regulation of flagellar motility is not well understood. The flagellar axoneme produces a complex beat through the precisely coordinated firing of many proteins, including multiple dynein motors. These motors are found in the inner arm and outer arm complexes. We are studying one of the inner arm dynein motors in the T. brucei flagellum: dynein-f. RNAi knockdown of genes for two components of dynein-f: DNAH10, the α heavy chain, and IC138, an intermediate chain, cause severe motility defects including immotility. To determine if motility defects result from structural disruption of the axoneme, we used two different flagellar preparations to carefully examine axoneme structure in these strains using transmission electron microscopy (TEM). Our analysis showed that inner arm dynein size, axoneme structural integrity and fixed central pair orientation are not significantly different in either knockdown culture when compared to control cultures. These results support the idea that immotility in knockdowns affecting DNAH10 or IC138 results from loss of dynein-f function rather than from obvious structural defects in the axoneme.     

Factors Governing Lysinoalanine Formation in Soy Proteins

Exposing soy protein to alkaline conditions (pH 8-14) for various time periods (10-480 min), and temperatures (25-95°C at 10°C intervals) destroyed all of the cystine and part of arginine, lysine, serine, and threonine residues. These losses were accompanied by the appearance of lysinoalanine (LAL) and unidentified ninhydrin-positive compounds. Acylation of the proteins minimized LAL formation. Addition of cysteine, copper salts, dimethyl sulfoxide and glucose also suppressed LAL production. Oxygen, with one possible exception, did not affect LAL formation. Free and protein-bound lysinoalanine is stable to acid but not basic conditions used for protein hydrolysis. Mechanisms are described to explain the observed influence of these variables on LAL generation.     

Statistical analysis of injury severity rates

Statistical analysis of operation injury experience represent a rational method of identifying the operations for which ergonomic intervention will reap benefits. This paper presents statistical methods for the analysis of injury severity rates. Approximate expressions for upper one-sided tolerance limits on the severity rate are presented. Illustrations using injury data from a large manufacturing organization are presented.     

Stereotype Threat and Women's Performance in Engineering

Recent research has demonstrated that stereotype threat—the concern that others will judge one negatively due to a stereotype that exists about one's group—interferes with women's performance on standardized math and engineering exams. In the current research we find that when a shortened version of the Fundamental of Engineering Exam is described as a test that is diagnostic of ability (i.e., when stereotype threat is high) women perform worse than men on the test. When stereotype threat is reduced, however (by characterizing the test as non‐diagnostic or as not producing gender differences), women do just as well as men. The implication of these results for improving the engineering education environment is discussed.     

ISOLATION, ENUMERATION AND IDENTIFICATION OF AEROMONAS SP.

Methodologies for the isolation of Aeromonas sp. from various sources, utilizing a broad range of media, are presented. Recommendations are made for the identification of Aeromonas isolates to the species level. The current nomenclature of Aeromonas sp. is discussed with reference to previously used taxonomic systems.     

Physical Aging of Maltose Glasses

Physical aging is the alteration in the physical properties of a glass, as a function of time, at temperatures below its glass transition temperature (Tg). The physical aging of maltose glasses, prepared from maltose monohydrate sugar, was studied using differential scanning calorimetry (DSC). The maltose was aged at 30°C for times ranging from 5 min to ～ 10 days. The Tg and change in heat capacity of the unaged and aged maltose glasses were measured. The change in enthalpy relaxation with aging time was determined by integrating the difference between the aged and the unaged DSC thermograms. The enthalpic relaxation data were adequately described by the Williams-Watts equation.     

IS SEGREGATION-BY-PARTICLE-TYPE A GENERIC MECHANISM UNDERLYING FINGER FORMATION AT FRONTS OF FLOWING GRANULAR MEDIA?

ABSTRACT

The fronts of flowing granular media often manifest fingered patterns. For the case of a granular flow down an inclined plane, Pouliquen, Delour and Savage (1997) have proposed that such patterns are induced by the segregation of coarse irregularly shaped particles. Here, we consider a thin layer of a granular medium flowing within a cylinder that is rotated about its horizontal axis of symmetry. Our results show that—even when the medium is well-sieved and consists of nearly spherical grains—its leading edge may develop fingers. This suggests that, in general flow configurations, mechanisms other than segregation by particle type may be active in the instability of a straight front.     

MINORITIES ON THE MARGINS? THE SPATIAL ORGANIZATION OF FRINGE BANKING SERVICES

ABSTRACT: Case studies in select large cities have found that fringe services, including payday lenders, check cashers, pawn brokers, and money transmittal companies are more geographically accessible to predominantly minority neighborhoods while traditional banks are more accessible to white neighborhoods. However, many analyses are bivariate rather than multivariate and do not disentangle the influence of neighborhood socioeconomic status from that of race. Furthermore, the fringe services industry contends that market factors, such as zoning, arterials, population base, and commercial activity influence location. This study employs geographic information systems (GIS) and multiple regression to untangle the spatial relationship between minority communities and traditional and fringe banks in four small‐to‐moderate‐sized metropolitan areas. We find that, though market factors are indeed powerful determinants of fringe bank location, there are nonetheless persistent ethnic effects in two of the four cities and these effects cannot be attributed to factors correlated with a large minority presence.     

Sodium Acetate and Bifidobacteria Increase Shelf-Life of Refrigerated Catfish Fillets

Microbiological and sensory evaluations of catfish fillets treated with sodium acetate (SA) and bifidobacteria were studied at 4°C. Cultures of Bifidobacterium adolescentis, B. infantis, or B. longum (2.5% V/W) extended lag phase, but not generation time of aerobic bacteria. One-half percent (W/W) SA increased lag phase and generation time. SA and bifidobacteria reduced counts more than either alone, extending shelf-life by 3 days. Amount of culture (1.5–4.5%) or culture age (24–72 hr) had no effect on inhibition. Treated fillets odor and appearance resembled fresh fillets for up to 6 days, while untreated fillets were unacceptable aher 3 days. SA, either alone or combined with bifidobacteria, extended refrigerated shelf-life of catfish fillets.