Reversal of dormancy in switchgrass with low-light photoperiod extension.

Some switchgrass (Panicum virgatum L.) cultivars originating in the northern USA show limited late-summer and fall growth when grown in more southerly locations despite adequate temperature and moisture. Our objective was to determine the effects of low-light photoperiod extension on the dry matter yield of switchgrass cultivars originating from contrasting latitudes.

Escherichia coli O157 in feedlot cattle feces and water in four major feeder-cattle states in the USA.

The prevalence of Escherichia coli O157 was determined in 10662 fecal samples, 2130 water and 1132 water tank-sediment samples collected during the summer months in 2001 from 711 pens in 73 feedlots located in Kansas, Nebraska, Texas, or Oklahoma, USA. Overall, 10.2% of fecal samples were positive for E.

Evaluation of an auditory model for echo delay accuracy in wideband biosonar.

In a psychophysical task with echoes that jitter in delay, big brown bats can detect changes as small as 10-20 ns at an echo signal-to-noise ratio of approximately 49 dB and 40 ns at approximately 36 dB. This performance is possible to achieve with ideal coherent processing of the wideband echoes, but it is widely assumed that the bat's peripheral auditory system is incapable of encoding signal waveforms to represent delay with the requisite precision or phase at ultrasonic frequencies. This assumption was examined by modeling inner-ear transduction with a bank of parallel bandpass filters followed by low-pass smoothing.

Prevalence of Escherichia coli O157 in cattle feeds in Midwestern feedlots.

Comparisons of enrichment methods (with or without antibiotics and with or without a preenrichment step) using gram-negative (GN) broth or tryptic soy broth (TSB) were conducted with feeds inoculated with Escherichia coli O157:H7. TSB was more sensitive than GN broth, and TSB with a preenrichment step followed by TSB with antibiotics was more sensitive than plain TSB enrichment, in detecting E. coli O157 in inoculated feeds.

Application of capture-recapture methodology to estimate the prevalence of dementia in South Carolina.

Purpose: The purpose of this study was to estimate the prevalence of dementia in individuals 65 years of age and older in the state of South Carolina using capture-recapture methodology.

Methods: We linked data from the Department of Mental Health admissions, inpatient admissions, and emergency room visits. Separate log-linear models were used to obtain estimates of the underascertainment-corrected prevalence of dementia in twelve age-gender-race subgroups, which were summed to estimate the prevalence of dementia in the total population.

Occupational history and exposure and the risk of adult leukemia in Shanghai.

Purpose: Evaluation of the association of selected occupational exposures with leukemia risk.

Methods: Population-based case-control study of 486 leukemia subjects and 502 healthy controls residing in Shanghai from 1987 to 1989. Adjusted odds ratios (OR) were calculated for the association between occupational factors and leukemia risk.

The challenge of constructing large phylogenetic trees.

The amount of sequence data available to reconstruct the evolutionary history of genes and species has increased 20-fold in the past decade. Consequently the size of phylogenetic analyses has grown as well, and phylogenetic methods, algorithms and their implementations have struggled to keep pace. Computational and other challenges raised by this burgeoning database emerge at several stages of analysis, from the optimal assembly of large data matrices from sequence databases, to the efficient construction of trees from these large matrices and the piece-wise assembly of 'supertrees' from those trees in turn.

Echo delay versus spectral cues for temporal hyperacuity in the big brown bat, Eptesicus fuscus.

Big brown bats can discriminate between echoes that alternate in delay (jitter) by as little as 10-15 ns and echoes that are stationary in delay. This delay hyperacuity seems so extreme that it has been rejected in favor of an explanation in terms of artifacts in echoes, most likely spectral in nature, that presumably are correlated with delay. Using different combinations of digital, analog, and cable delays, we dissociated the overall delay of jittering echoes from the size of the analog component of delay, which alone is presumed to determine the strength of the apparatus artifact.

Using genetic programming to discover nonlinear variable interactions.

Psychology has to deal with many interacting variables. The analyses usually used to uncover such relationships have many constraints that limit their utility. We briefly discuss these and describe recent work that uses genetic programming to evolve equations to combine variables in nonlinear ways in a number of different domains.

The role of cGMP in the regulation of rabbit airway ciliary beat frequency.

The involvement of cyclic guanosine 3',5'-monophosphate (cGMP) and cGMP-dependent protein kinase (PKG) and their interaction with the Ca2+-dependent mechanisms in the regulation of ciliary activity are not well understood. To investigate how cGMP regulates ciliary activity, changes in ciliary beat frequency (CBF) and intracellular calcium concentration ([Ca2+]i) of rabbit tracheal ciliated cells in response to 8-bromo-cGMP (Br-cGMP) were simultaneously quantified using digital, high-speed phase-contrast and fluorescence imaging. Br-cGMP induced a response in ciliary activity that could be separated into two parts.

Detecting fetal macrosomia with abdominal circumference alone.

Objective: To determine if abdominal circumference (AC) can identify macrosomia (> or = 4,000 g) at or beyond 37 weeks.

Study Design: Prospectively, parturients at term admitted for delivery underwent sonographic mensuration of AC. A receiver-operating characteristic (ROC) curve was constructed to determine if AC can differentiate between normal (birth weight < 3,999 g) and macrosomia.

The small-world dynamics of tree networks and data mining in phyloinformatics.

Motivation: A noble and ultimate objective of phyloinformatic research is to assemble, synthesize, and explore the evolutionary history of life on earth. Data mining methods for performing these tasks are not yet well developed, but one avenue of research suggests that network connectivity dynamics will play an important role in future methods. Analysis of disordered networks, such as small-world networks, has applications as diverse as disease propagation, collaborative networks, and power grids.

Obtaining maximal concatenated phylogenetic data sets from large sequence databases.

To improve the accuracy of tree reconstruction, phylogeneticists are extracting increasingly large multigene data sets from sequence databases. Determining whether a database contains at least k genes sampled from at least m species is an NP-complete problem. However, the skewed distribution of sequences in these databases permits all such data sets to be obtained in reasonable computing times even for large numbers of sequences.

Airway contractility and smooth muscle Ca(2+) signaling in lung slices from different mouse strains.

To investigate the hypothesis that altered Ca2+ signaling in airway smooth muscle cells (SMCs) is responsible for airway hyperreactivity, we compared, with the use of confocal and phase-contrast microscopy, the airway contractility and Ca2+ changes in SMCs induced by acetylcholine (ACh) in lung slices from different mouse strains (A/J, Balb/C, and C3H/ HeJ). The airways from each mouse strain displayed a concentration-dependent contraction to ACh. The contractile response of the airways of the C3H/HeJ mice was found, in contrast to earlier studies, to be much greater and faster than that of A/J and Balb/C mice.

Molecular data from 27 proteins do not support a Precambrian origin of land plants.

Heckman et al. (Science 293: 1129-1133) used sequences obtained from GenBank to infer divergence times in fungi and green plants. They estimated that the crown group of land plants originated in the Precambrian, at 703 ± 45 mya, a date much older than dates implied by the fossils, which are no older than about 450 mya.

Time-frequency model for echo-delay resolution in wideband biosonar.

A time/frequency model of the bat's auditory system was developed to examine the basis for the fine (approximately 2 micros) echo-delay resolution of big brown bats (Eptesicus fuscus), and its performance at resolving closely spaced FM sonar echoes in the bat's 20-100-kHz band at different signal-to-noise ratios was computed. The model uses parallel bandpass filters spaced over this band to generate envelopes that individually can have much lower bandwidth than the bat's ultrasonic sonar sounds and still achieve fine delay resolution. Because fine delay separations are inside the integration time of the model's filters (approximately 250-300 micros), resolving them means using interference patterns along the frequency dimension (spectral peaks and notches).

Evidence of a novel transduction pathway mediating detection of polyamines by the zebrafish olfactory system.

To better understand the full extent of the odorant detection capabilities of fish, we investigated the olfactory sensitivity of zebrafish to a monoamine and several polyamines using electrophysiological and activity-dependent labeling techniques. Electro-olfactogram (EOG) recording methods established the relative stimulatory effectiveness of these odorants as: spermine >> spermidine approximately agmatine > glutamine > putrescine >or= cadaverine >or= histamine > artificial freshwater. The detection threshold for the potent polyamines was approximately 1 micromol l(-1).

Video-rate confocal microscopy.

The CLSM described here can be built with relatively little electronic or optical experience and with a budget of approximately $20,000-$30,000 (excluding microscope and table). This cost is substantially less than that of commercial counterparts. However, this CLSM has excellent spatial and temporal resolution and the convenience of digital recording and playback.

Oscillations in ciliary beat frequency and intracellular calcium concentration in rabbit tracheal epithelial cells induced by ATP.

To investigate how Ca(2+) regulates airway ciliary activity, changes in ciliary beat frequency (CBF) and intracellular calcium concentration ([Ca(2+)](i)) of rabbit tracheal ciliated cells, in response to ATP, were simultaneously quantified with high-speed phase-contrast and fast fluorescence imaging. [ATP] 1 but < 16 microM induced a similar increase in [Ca(2+)](i) and CBF but this was followed by oscillations in CBF and [Ca(2+)](i).

r8s: inferring absolute rates of molecular evolution and divergence times in the absence of a molecular clock.

Summary: Estimating divergence times and rates of substitution from sequence data is plagued by the problem of rate variation between lineages. R8s version 1.5 is a program which uses parametric, nonparametric and semiparametric methods to relax the assumption of constant rates of evolution to obtain better estimates of rates and times.

Production and feeding strategies for phosphorus management on dairy farms.

Long-term accumulation of soil phosphorus (P) is becoming a concern on some watersheds heavily populated with animal feeding facilities, including dairy farms. Management changes in crop production and feeding may help reduce the accumulation of excess P, but farm profitability must be maintained or improved to assure adoption of such changes. Whole-farm simulation was used to evaluate the long-term effects of changes in feeding, cropping, and other production strategies on P loading and the economics of 100-cow and 800-cow dairy farms in southeastern New York.

Relationships among seed plants inferred from highly conserved genes: sorting conflicting phylogenetic signals among ancient lineages.

Phylogenetic studies based on different types and treatment of data provide substantially conflicting hypotheses of relationships among seed plants. We conducted phylogenetic analyses of sequences of two highly conserved chloroplast genes, psaA and psbB, for a comprehensive taxonomic sample of seed plants and land plants. Parsimony analyses of two different codon position partitions resulted in well-supported, but significantly conflicting, phylogenetic trees.

Database searching for thymidine and thymidylate kinase inhibitors using three-dimensional structure-based methods.

Structure-based drug design methods were used to search for novel inhibitors of herpes simplex virus type 1 (HSV-1) thymidine kinase and Mycobacterium tuberculosis thymidylate kinase. The method involved the use of crystal structure complexes to guide database searching for potential inhibitors. A number of weak inhibitors of HSV-2 were identified, one of which was found to inhibit HSV-1 TK and HSV-1 TK-deficient viral strains.

Comparison of growth and performance in upland and lowland switchgrass types to water and nitrogen stress.

The objective of the study was to examine lowland (Alamo and Kanlow) and upland (Blackwell and Caddo) cultivars of switchgrass (Panicum virgatum L.) for differences in response to water deficit and nitrogen fertilizer. Cultivars were grown in pots with fritted clay at two water levels: well watered and deficit conditions (-0.

Physical and mental health effects of intimate partner violence for men and women.

Background: Few population-based studies have assessed the physical and mental health consequences of both psychological and physical intimate partner violence (IPV) among women or men victims. This study estimated IPV prevalence by type (physical, sexual, and psychological) and associated physical and mental health consequences among women and men.

Methods: The study analyzed data from the National Violence Against Women Survey (NVAWS) of women and men aged 18 to 65.