Michael T. Longnecker

Dynamic identity verification via keystroke characteristics

The implementation of safeguards for computer security is based on the ability to verify the identity of authorized computer systems users accurately. The most common form of identity verification in use today is the password, but passwords have many poor traits as an access control mechanism. To overcome the many disadvantages of simple password protection, we are proposing the use of the physiological characteristics of keyboard input as a method for verifying user identity. After an overview of the problem and summary of previous efforts, a research study is described which was conducted to determine the possibility of using keystroke characteristics as a means of dynamic identity verification. Unlike static identity verification systems in use today, a verifier based on dynamic keystroke characteristics allows continuous identity verification in real-time throughout the work session. Study results indicate significant promise in the temporal personnel identification problem.

Cryopreservation of Atlantic croaker spermatozoa

An artificial insemination method was standardized. The effects of various extenders, dilution ratios, cryoprotectants, equilibration times, freezing and thawing rates, and semen and egg quantities on fertilization capacity of post-thaw Atlantic croaker Micropogonias undulatus spermatozoa were examined to optimize cryopreservation procedures. Fertilization rates using NaCl, Glucose, and sucrose solutions were comparable to those achieved with more complex extenders. No fertilization was obtained when methanol was the cryoprotectant. The optimum ratio of semen to DMSO to extender was 10%: 15%: 75%. No significant difference (P<0.05) in fertilization rates was found among freezing rates ranging from −10°C/min to −150°C/min. The two-step freezing method gave a fertilization rate similar to that obtained with the conventional one-step freezing method.

Utilization of soy protein isolate and konjac blends in a low-fat bologna (model system)

Low-fat bologna formulations (LFBMS, <2.0% fat) were manufactured in a model system with two levels (0.5 or 1%) of two konjac blends (KB; KSS=konjac flour/starch and KNC=konjac flour/carrageenan/starch), and three levels (0, 2.2, 4.4%, DWB) of prehydrated soy protein isolate (SPI) to replace 0, 2 and 4% of the meat protein, respectively. Compared to 0.5% KB, the 1% level reduced (p<0.05) protein solubility (PS), vacuum purge (VP, %) and texture profile analysis (TPA) hardness. LFBMS containing KNC had higher (p<0.05) cooking yields, TPA fracturability and shear stress, but lower (p<0.05) expressible moisture (EM), VP values and TPA cohesiveness than KSS. Replacement of 4% meat protein with SPI increased (p<0.05) pH and yellowness (b*), but decreased (p<0.05) redness (a*), PS, EM and most textural characteristics, whereas no differences (p>0.05) were observed between 0 and 2% of meat protein replacements with SPI for most characteristics.

Survey of residual nitrite and nitrate in conventional and organic/natural/uncured/indirectly cured meats available at retail in the United States.

A survey of residual nitrite (NO(2)(-)) and nitrate (NO(3)(-)) in cured meats available at retail was conducted to verify concentrations in conventional (C) products and establish a baseline for organic/natural/uncured/indirectly cured (ONC) products. In this study, 470 cured meat products representing six major categories were taken from retail outlets in five major metropolitan cities across the United States. Random samples representing both C and ONC type products were analyzed for NO(2)(-) and NO(3)(-) content (ppm) using an ENO-20 high-performance liquid chromatography system equipped with a reverse phase column. Generally, there were no differences in NO(2)(-) concentrations between C and ONC meat categories, but a few ONC products surveyed in certain cities were lower in NO(3)(-) content. Pairwise comparisons between cities indicated that NO(2)(-) and NO(3)(-) contents of all C type products were not appreciably different, and the same was true for most ONC products. Numerical NO(2)(-) values were less variable than NO(3)(-) concentrations within each meat product category. NO(2)(-) concentrations were similar to those previously reported by Cassens ( Cassens , R. G. Residual nitrite in cured meat . Food Technol. 1997a , 51 , 53 - 55 ) in 1997. Residual NO(2)(-) and NO(3)(-) values in this study were numerically lower than those reported by NAS ( National Academy of Sciences . The Health Effects of Nitrate, Nitrite, and N-Nitroso Compounds ; National Academy Press : Washington, DC , 1981 ) in 1981. Data from this survey provide a benchmark of NO(2)(-) and NO(3)(-) concentrations for ONC products available at retail.

Effects of red imported fire ants on newly-hatched northern bobwhite.

We examined the response of pen-raised northern bobwhite (Colinus virginianus) to the presence of red imported fire ants (Solenopsis invicta) during the first 6 days post-hatching in a 9-week field experiment during spring and summer 1993 in southeastern Texas. We recorded behavior of a focal animal continuously for 15 minutes in a 30-m 2 area from which fire ants had been removed and in a similar, adjacent area with natural densities of fire ants. We categorized activities of a focal animal as: response to fire ants, moving, inactivity, sleeping, and pecking at food. Red imported fire ants altered daily activity budgets of pen-raised northern bobwhite chicks. Time spent responding directly to fire ants affected the allotment of time to other behaviors such as moving, sleeping, and pecking at food. The effects on chick behavior varied seasonally, in relation to ant activity, and age of the chick. Ant activity and age of the chick also influenced allotment of time to all activities, including response to fire ants.

Effects of temperature and tissue type on Chrysomya rufifacies (Diptera: Calliphoridae) (Macquart) development

The hairy maggot blow fly, Chrysomya rufifacies (Diptera: Calliphoridae), is a forensically important fly often encountered on human and other vertebrate remains in temperate and tropic regions throughout the world including Australia, Asia, Central America and North America. C. rufifacies was reared under controlled laboratory conditions on three muscle types (i.e., porcine, equine and canine) at three temperatures (i.e., 20.8, 24.8 and 28.3°C). Rate of larval weight gain across time was statistically significant between muscle types (P≤0.0001) and approaching significance across time between temperatures (P=0.0511). This research represents the first development study for C. rufifacies from central Texas, USA and the first study to examine the impact of tissue type on its development. Furthermore, these data, when compared to those available in the literature, indicate developmental differences that could be due to genetic differences in populations or possibly methods employed during the studies. Caution should be emphasized when applying development data for this species from one region to forensic investigations in other ecoregions as such differences in development based on tissue fed upon by larvae, population genetics, and methodologies used in the studies could represent error in estimating the time of colonization.

An Evaluation of an Electronic Logbook as a More Accurate Method of Estimating Spatial Patterns of Trawling Effort and Bycatch in the Gulf of Mexico Shrimp Fishery

Abstract Penaeid shrimp trawling effort in the Gulf of Mexico is not measured directly but is estimated from landings and interview data gathered by port agents of the National Marine Fisheries Service (NMFS). The total pounds landed from each trip are assigned to one or more of the 219 statistical area-depth zone cells for which a catch rate (pounds per nominal day fished or catch per unit effort (CPUE)) is also obtained. Each month, the total landings in pounds for each cell are divided by the CPUE of the cell to determine effort or days fished. These values are summed across all cells and months to provide an estimate of total effort. The accuracy of total effort estimates is directly proportional to the accuracy of the landings allocations and estimated CPUE values. It has been assumed that allocation errors are random and that directional bias is negligible. In a previous paper, we described an electronic logbook (ELB) that enables accurate measurement of the spatial patterns of fishing effort. Herei...

Role in Diuresis of a Calcitonin Receptor (GPRCAL1) Expressed in a Distal-Proximal Gradient in Renal Organs of the Mosquito Aedes aegypti (L.)

Evolution of anthropophilic hematophagy in insects resulted in the coordination of various physiological processes for survival. In female mosquitoes, a large blood meal provides proteins for egg production and as a trade-off, rapid elimination of the excess water and solutes (Na+, Cl−) is critical for maintaining homeostasis and removing excess weight to resume flight and avoid predation. This post-prandial excretion is achieved by the concerted action of multiple hormones. Diuresis and natriuresis elicited by the calcitonin-like diuretic hormone 31 (DH31) are believed to be mediated by a yet uncharacterized calcitonin receptor (GPRCAL) in the mosquito Malpighian tubules (MTs), the renal organs. To contribute knowledge on endocrinology of mosquito diuresis we cloned GPRCAL1 from MT cDNA. This receptor is the ortholog of the DH31 receptor from Drosophila melanogaster that is expressed in principal cells of the fruit fly MT. Immunofluorescence similarly showed AaegGPRCAL1 is present in MT principal cells in A. aegypti, however, exhibiting an overall gradient-like pattern along the tubule novel for a GPCR in insects. Variegated, cell-specific receptor expression revealed a subpopulation of otherwise phenotypically similar principal cells. To investigate the receptor contribution to fluid elimination, RNAi was followed by urine measurement assays. In vitro, MTs from females that underwent AaegGPRcal1 knock-down exhibited up to 57% decrease in the rate of fluid secretion in response to DH31. Live females treated with AaegGPRcal1 dsRNA exhibited 30% reduction in fluid excreted after a blood meal. The RNAi-induced phenotype demonstrates the critical contribution of this single secretin-like family B GPCR to fluid excretion in invertebrates and highlights its relevance for the blood feeding adaptation. Our results with the mosquito AaegGPRCAL1 imply that the regulatory function of calcitonin-like receptors for ion and fluid transport in renal organs arose early in evolution.

Probability Distribution Functions for Generation Reliability Indices - Analytical Approach

The primary objective of this research is to analytically develop probability density functions (p.d.f.) for the widely used power generation reliability indices, Loss of Load and Unserved Energy. The equations to calculate the parameters of the distributions of these indices upon a prescribed load plan are derived. In order to develop the theoretical structure for the problem stated, classical and decision theoretic (Bayesian) statistical inference are used as major tools along with the univariate and multivariate asymptotic theory. Consequently, an approximate numerical multiple integration scheme is employed to compute the parameters of the asymptotic normal densities of the reliability indices for the sample power networks. The authors believe that this statistical approach offers a more realistic alternative to the conventional reliability evaluation in generation systems; that is, to the calculation of an averaged valtie for the Loss of Load and Unserved Energy where outage data is traditionally assumed to be deterministic with certainty.

A survey of nitrate and nitrite concentrations in conventional and organic-labeled raw vegetables at retail.

A national survey of the nitrate ( NO3(-)) and nitrite ( NO2(-)) concentrations in raw and highly consumed vegetables available at retail in the United States was conducted. A total of 194 samples of fresh broccoli, cabbage, celery, lettuce, and spinach categorized as conventional or organic by label were collected from 5 major cities in different geographic regions of the United States and analyzed to determine NO3(-) and NO2(-) concentrations. There were no differences in the mean NO2(-) values of conventional compared with organic vegetables taken from the 5 metropolitan areas. However, significant differences in mean pairwise comparisons between some conventional and organic vegetables for NO3(-) content were observed. The mean NO2(-) concentration of both conventional and organic vegetables ranged between 0.1 and 1.2 mg/kg of fresh weight (FW) with the exception of conventional spinach that contained 8.0 mg/kg FW. Mean NO3(-) contents of conventional broccoli, cabbage, celery, lettuce, and spinach were 394, 418, 1496, 851, and 2797 mg/kg FW, respectively, while their organic-labeled counterparts averaged 204, 552, 912, 844, and 1318 mg/kg FW. In most cases, organic vegetables were numerically lower in NO3(-) content than their conventional counterparts. Based on survey results, the finding that low NO3(-) levels were observed in some organic vegetables in different cities may warrant further study to determine if true differences exist, due to production practices, seasonal differences, and the magnitudes of those differences. Furthermore, the geographic differences in NO3(-) content of vegetables may flaw estimates of daily NO2(-) and NO3(-) exposure.