Flexible learning in a partnership context for beginning teachers

A preliminary inventory was carried out for a sample of male and female student teachers who had email accounts. Preliminary inventory data revealed that the mean number of times per week that males used email was significantly higher than the mean number for female students. This inventory data indicated that characteristics such as gender affect Internet educational technology utilization, and this factor was addressed within the experimental design for the main study. In the main study, student teachers were assigned to four treatment groups for learning lesson‐planning skills. The first two groups received a traditional university lecture followed by a seminar. For group I, the seminar was provided at university. For group 2, the seminar was provided as part of the student's school‐based experiences. Groups 3 and 4 received identical tuition to groups 1 and 2 respectively, except that tuition was provided on a flexible learning basis, being delivered electronically via the Internet with tutorial support from the university lecturer by way of asynchronous email. It was found that student achievement was significantly higher when tuition was provided as part of the student's school‐based experiences, and also that achievement was significantly higher when tuition was provided on a flexible learning basis involving computer‐mediated communications. A separate AN OVA was carried out for the entire sample of the four treatment groups in order to address the factor of student gender, which was controlled in the experiment. However, there were no significant differences in achievement associated with student gender. This surprising finding suggests that although male. students may make greater usage of information technology, when required to do so, female students perform on a par with their male counterparts

Horizontal Structure of the Upper Ocean Velocity and Density Fields in the Western Equatorial Pacific Warm Pool: Depth Range from 20 to 250 m

Wavenumber spectra of velocity and density fields in the western equatorial Pacific warm pool on scales 6–120 km are estimated using the shipboard survey data collected during the TOGA Coupled Ocean–Atmosphere Response Experiment (COARE). The spectra are averaged over three depth intervals: 20–60, 60–110, and 110–250 m (corresponding to the Yoshida jet, the South Equatorial Current, and the southern edge of Equatorial Undercurrent). The velocity spectra are corrected for the mean flow shear advection, which is important under conditions of low gradient Richardson number (Ri). After that, both velocity and density spectra are consistent with an internal wave spectral model including a random component (equatorial version of the Garrett and Munk spectrum) and a tidal component (the Feng et al. tidal model). Tidal peaks, previously found by other COARE investigators as being prominent on the ‘‘moored’’ spectra (i.e., on the spectra derived from mooring data), appear to be much less significant on the ‘‘towed’’ spectra (i.e., on the spectra derived from shipboard surveys). The model and observations reveal some directional anisotropy of the towed velocity spectra depending on Ri

A Near-Surface Microstructure Sensor System Used During TOGA COARE. Part II: Turbulence Measurements

New techniques developed for near-surface turbulence measurements during the Tropical Ocean Global Atmosphere (TOGA) Coupled Ocean–Atmosphere Response Experiment (COARE) employ a difference in spatial scales of turbulence and surface waves. According to this approach, high relative speed of the measurements provides separation of the turbulence and surface wave signals. During the TOGA COARE field studies, highresolution probes of pressure, temperature, conductivity, fluctuation velocity, and acceleration were mounted on the bow of the vessel at a 1.7-m depth in an undisturbed region ahead of the moving vessel. The localization in narrow frequency bands of the vibrations of the bow sensors allows accurate calculation of the dissipation rate. A coherent noise reduction algorithm effectively removes vibration contamination of the velocity dataset. Due to the presence of surface waves and the associated pitching of the vessel, the bow probes ‘‘scanned’’ the near-surface layer of the ocean. Contour plots calculated using the bow signals provide a spatial context for the analysis of near-surface turbulence. A fast-moving free-rising profiler equipped by similar probes sampled the near-surface turbulence during stations. Theory of the three-component electromagnetic velocity sensor and examples of data obtained by bow sensors and free-rising profiler are also presented in this paper

Upper ocean momentum balances in the western equatorial Pacific on the intraseasonal time scale

Author Posting. © The Authors, 2004. This is the author's version of the work. It is posted here by permission of Elsevier B. V. for personal use, not for redistribution. The definitive version was published in Deep Sea Research Part I: Oceanographic Research Papers 52 (2005): 749-765, doi:10.1016/j.dsr.2004.12.004.Surface Meteorology, upper ocean current, and hydrographic measurements, collected along a repeated survey pattern and from a central mooring in the western equatorial Pacific during late 1992 to early 1993, were used to analyse upper ocean momentum balances on the intraseasonal time scale. Wind stresses derived from meteorological measurements were compared with numerical weather prediction products. Advection terms in the momentum equations were estimated by planar fits to the current and hydrographic data. Pressure gradient terms were derived from planar fits to the dynamic heights calculated from the hydrographic data, referenced by balancing the momentum equation in a selected layer below the mixed layer. Under prevailing westerly winds, westward pressure gradient forcings of 2x10-7 m s-2 were set up in the western equatorial Pacific, countering the surface wind, while the total advection tended to accelerate the eastward momentum in the surface layer. During both calm wind and westerly wind burst periods, zonal turbulent momentum fluxes estimated from the ocean budgets were comparable with those estimated from microstructure dissipation rate measurements and with zonal wind stresses, so that the zonal momentum could be balanced within error bars. The meridional momentum balances were noisier, which might be due to the fact that the short meridional length scale of the equatorial inertial-gravity waves could contaminate the dynamic signals in the mixed temporal/spatial sampling data, so that the meridional gradient estimates from the planar fits could be biased.MF acknowledges the support of Strategic Research Fund for Marine Environment. RL and PH were supported by NSF grant OCE-9525986. RW and AP were supported by NSF Grants OCE- 9110559 and OCE-9110554, respectively

Performance of Two-Stage Cervical Cancer Screening With Primary High-Risk Human Papillomavirus Testing in Women Living With Human Immunodeficiency Virus

OBJECTIVE: To evaluate the performance of cervical cancer screening algorithms for women living with human immunodeficiency virus (HIV), using primary high-risk human papillomavirus (HPV) testing followed by cytology, visual inspection with acetic acid, or colposcopy. METHODS: We conducted a prospective cohort study of women living with HIV in Botswana. All participants underwent high-risk HPV testing. Participants with positive high-risk HPV test results underwent cytology, visual inspection with acetic acid, colposcopy, and biopsy. Participants with negative high-risk HPV test results also underwent cytology. Histopathology was the reference standard for determination of preinvasive cervical disease and cervical cancer. Sensitivity, specificity, positive predictive value (PPV), negative predictive value, and likelihood ratios (LR) of high-risk HPV-based two-stage screening algorithms were calculated. RESULTS: Among 300 women screened, 88 (29%) had a positive high-risk HPV test result, and 29 of the 88 (35%) women who tested positive for high-risk HPV had CIN 2 or higher on histopathology. High-risk HPV followed by colposcopy resulted in a sensitivity of 83%, specificity of 49%, PPV of 47%, LR+ of +1.6, and LR− of −0.4. High-risk HPV followed by visual inspection with acetic acid resulted in a reduced sensitivity of 59%, specificity of 49%, PPV of 39%, LR+ of +1.2, and LR− of −0.8. High-risk HPV testing followed by cytology also resulted in a reduced sensitivity of 62%, specificity of 77%, PPV of 60%, LR+ of +2.7, and LR− of −0.5. Stratification by HPV 16/18/45 did not improve performance of the algorithms. CONCLUSION: In a high-risk population with HIV, high-risk HPV testing followed by colposcopy demonstrated the highest sensitivity and PPV in detecting high-grade cervical dysplasia. Allocating resources to colposcopy in resource-limited settings may be more effective than other screening strategies

Thermochronology of mineral grains in the Red and Mekong Rivers, Vietnam: Provenance and exhumation implications for Southeast Asia

Sand samples from the mouths of the Red and Mekong Rivers were analyzed to determine the provenance and exhumation history of their source regions. U-Pb dating of detrital zircon grains shows that the main sources comprise crust formed within the Yangtze Craton and during the Triassic Indosinian Orogeny. Indosinian grains in the Mekong are younger (210-240 Ma) than those in the Red River (230-290 Ma), suggesting preferential erosion of the Qiangtang Block of Tibet into the Mekong. The Red River has a higher proportion of 700-800 Ma grains originally derived from the Yangtze Craton. 40Ar/ 39Ar dating of muscovite grains demonstrates that rocks cooled during the Indosinian Orogeny are dominant in both rivers, although the Mekong also shows a grain population cooling at 150-200 Ma that is not seen in the Red River and which is probably of original Qiangtang Block origin. Conversely, the Red River contains a significant mica population (350-500 Ma) eroded from the Yangtze Craton. High-grade metamorphic rocks exposed in the Cenozoic shear zones of southeast Tibet-Yunnan are minority sources to the rivers. However, apatite and zircon fission track ages show evidence for the dominant sources, especially in the Red River, only being exhumed through the shallowest 5-3 km of the crust since ̃25 Ma. The thermochronology data are consistent with erosion of recycled sediment from the inverted Simao and Chuxiong Basins, from gorges that incise the eastern flank of the plateau. Average Neogene exhumation rates are 104-191 m/Myr in the Red River basin, which is within error of the 178 ± 35 m/Myr estimated from Pleistocene sediment volumes. Sparse fission track data from the Mekong River support the Ar-Ar and U-Pb ages in favoring tectonically driven rock uplift and gorge incision as the dominant control on erosion, with precipitation being an important secondary influence. © 2006 by the American Geophysical Union

Identification of the Pangenome and Its Components in 14 Distinct Aggregatibacter actinomycetemcomitans Strains by Comparative Genomic Analysis

Aggregatibacter actinomycetemcomitans is genetically heterogeneous and comprises distinct clonal lineages that may have different virulence potentials. However, limited information of the strain-to-strain genomic variations is available.The genome sequences of 11 A. actinomycetemcomitans strains (serotypes a-f) were generated de novo, annotated and combined with three previously sequenced genomes (serotypes a-c) for comparative genomic analysis. Two major groups were identified; serotypes a, d, e, and f, and serotypes b and c. A serotype e strain was found to be distinct from both groups. The size of the pangenome was 3,301 genes, which included 2,034 core genes and 1,267 flexible genes. The number of core genes is estimated to stabilize at 2,060, while the size of the pangenome is estimated to increase by 16 genes with every additional strain sequenced in the future. Within each strain 16.7-29.4% of the genome belonged to the flexible gene pool. Between any two strains 0.4-19.5% of the genomes were different. The genomic differences were occasionally greater for strains of the same serotypes than strains of different serotypes. Furthermore, 171 genomic islands were identified. Cumulatively, 777 strain-specific genes were found on these islands and represented 61% of the flexible gene pool.Substantial genomic differences were detected among A. actinomycetemcomitans strains. Genomic islands account for more than half of the flexible genes. The phenotype and virulence of A. actinomycetemcomitans may not be defined by any single strain. Moreover, the genomic variation within each clonal lineage of A. actinomycetemcomitans (as defined by serotype grouping) may be greater than between clonal lineages. The large genomic data set in this study will be useful to further examine the molecular basis of variable virulence among A. actinomycetemcomitans strains

An Approach to Parameterization of the Oceanic Turbulent Boundary Layer in the Western Pacific Warm Pool

Vertical profiles of zonal velocity and the dissipation rate ε of the turbulent kinetic energy obtained during the Tropical Ocean-Global Atmosphere Coupled Ocean-Atmosphere Response Experiment (COARE) are analyzed in the context of planetary boundary layer relationships previously derived from atmospheric measurements. The presence of a barrier layer and the striking effect of increased dimensionless shear and ε at the bottom of the surface mixed layer of the ocean, features often observed in the western Pacific warm pool area, are consistent with the boundary layer laws. The gradient Richardson number Ri is found to be a convenient parameter for scaling the nonstationary and horizontally heterogeneous mixed layer in the warm pool area. The approach to parameterization of the turbulent eddy coefficient within the mixed layer as a function of Ri is tested as part of a one-dimensional model. A comparison between the observed and modeled upper ocean temperatures for two COARE examples shows a reasonable agreement over a wide range of wind speed conditions

A three-way comparative genomic analysis of Mannheimia haemolytica isolates

<p>Abstract</p> <p>Background</p> <p><it>Mannhemia haemolytica </it>is a Gram-negative bacterium and the principal etiological agent associated with bovine respiratory disease complex. They transform from a benign commensal to a deadly pathogen, during stress such as viral infection and transportation to feedlots and cause acute pleuropneumonia commonly known as shipping fever. The U.S beef industry alone loses more than one billion dollars annually due to shipping fever. Despite its enormous economic importance there are no specific and accurate genetic markers, which will aid in understanding the pathogenesis and epidemiology of <it>M. haemolytica </it>at molecular level and assist in devising an effective control strategy.</p> <p>Description</p> <p>During our comparative genomic sequence analysis of three <it>Mannheimia haemolytica </it>isolates, we identified a number of genes that are unique to each strain. These genes are "high value targets" for future studies that attempt to correlate the variable gene pool with phenotype. We also identified a number of high confidence single nucleotide polymorphisms (hcSNPs) spread throughout the genome and focused on non-synonymous SNPs in known virulence genes. These SNPs will be used to design new hcSNP arrays to study variation across strains, and will potentially aid in understanding gene regulation and the mode of action of various virulence factors.</p> <p>Conclusions</p> <p>During our analysis we identified previously unknown possible type III secretion effector proteins, clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated sequences (Cas). The presence of CRISPR regions is indicative of likely co-evolution with an associated phage. If proven functional, the presence of a type III secretion system in <it>M. haemolytica </it>will help us re-evaluate our approach to study host-pathogen interactions. We also identified various adhesins containing immuno-dominant domains, which may interfere with host-innate immunity and which could potentially serve as effective vaccine candidates.</p