384 research outputs found
Growth and survival of nearshore fishes in Lake Michigan
Illinois Department of Natural resources Grant/Contract No: F-138INHS Technical Report Prepared for Illinois Department of Natural resource
Identifying Patterns of Relationships between Professional Development and Professional Culture with Texas High School Science Teachers and Students
Professional development (PD) is used as the primary means for ensuring the continued learning of teachers. PD opportunities and support vary in type and quality. Little is known about the participation in and support of PD for high school science teachers. The establishment of supportive professional cultures provides a means to support teachers' PD in addition to providing meaningful interactions between teachers to improve practices related to teaching, learning, and assessment. Even less is known about patterns of relationships between professional culture with high school science teachers and students. PD and professional culture have been reported to increase teacher retention and student achievement. The studies presented in this dissertation use mixed methods approaches to explore data collected by the Policy Research Initiative in Science Education Research Group during the 2007-2008 academic year.
The first study assessed PD of high school science teachers from two perspectives: (1) teachers' participation in PD, and (2) schools' practices to support teachers' participation. Teachers' participation was determined using self-reported survey data. Schools' PD support was operationalized using data collected from administrative interviews. Descriptive statistics revealed little relationship between teachers' participation in PD, schools' PD support, and teacher retention. Descriptive statistics of schools' PD support indicated associations with student achievement.
The second study operationalized school science professional culture with a rubric developed for the study. Elements within the rubric addressed many components mentioned in the literature as indicative of positive professional culture. School science professional culture had little relationship with either teacher retention or student achievement. Strong associations were found among the elements associated with school science professional culture. These results provide support for the inclusion of these elements in future studies of school science professional culture.
The final chapter provides a summary of both studies. Recommendations are made for improving policies in place to support PD and professional cultures experienced by high school science teachers. Specific attention should be directed at the development of cohesive PD programs that address both schools' and teachers' needs. Additionally, more opportunities for in-depth communication regarding school practices for teaching, learning, and assessment need to be provided
Overexpression and Divalent Metal Binding Properties of the Methionyl Aminopeptidase from \u3cem\u3ePyrococcus furiosus\u3c/em\u3e
The gene encoding for the methionyl aminopeptidase from the hyperthermophilic archaeon Pyrococcus furiosus (PfMetAP-II; EC 3.4.11.18) has been inserted into a pET 27b(+) vector and overexpressed in Escherichia coli. The new expression system resulted in a 5-fold increase in purified enzyme obtained from a 5 L fermentor growth. The as-purified PfMetAP-II enzyme, to which no exogenous metal ions or EDTA was added, was found to have 1.2 equiv of zinc and 0.1 equiv of iron present by ICP-AES analysis. This enzyme had a specific activity of 5 units/mg, a 60-fold decrease from the fully loaded Fe(II) enzymes. When an additional 2 equiv of Zn(II) was added to the as-purified PfMetAP-II, no activity could be detected. The combination of these data with previously reported whole cell studies on EcMetAP-I further supports the suggestion that the in vivo metal ion for all MetAP\u27s is Fe(II). Both Co(II)- and Fe(II)-loaded PfMetAP-II showed similar substrate specificities to EcMetAP-I. Substrate binding was largely affected by the amino acid in the P1 position and the length of the polypeptide. The substrates MSSHRWDW and MP-p-NA showed the smallest Km values while the substrates MGMM and MP-p-NA provided the highest turnover. The catalytic efficiency (kcat/Km) of PfMetAP-II for MP-p-NA at 30 °C was 799 500 and 340 930 M-1 s-1 for Co(II)- and Fe(II)-loaded PfMetAP-II, respectively. Maximum catalytic activity was obtained with 1 equiv of Co(II) or Fe(II), and the dissociation constants (Kd) for the first metal binding site were found to be 50 ± 15 and 20 ± 15 nM for Co(II)- and Fe(II)-substituted PfMetAP-II, respectively. Electronic absorption spectral titration of a 1 mM sample of apo-PfMetAP-II with Co(II) provided a dissociation constant of 0.35 ± 0.02 mM for the second metal binding site, a 17500-fold increase compared to the first metal binding site. The electronic absorption data also indicated that both Co(II) ions reside in a pentacoordinate geometry. PfMetAP-II shows unique thermostability and the optimal temperature for substrate turnover was found to be ∼85 °C at pH 7.5 in 25 mM Hepes and 150 mM KCl buffer. The hydrolysis of MGMM was measured in triplicate between 25 and 85 °C at eight substrate concentrations ranging from 2 to 20 mM. Both specific activity and Km values increased with increasing temperature. An Arrhenius plot was constructed from the kcat values and was found to be linear over the temperature range 25−85 °C, indicating that the rate-limiting step in PfMetAP-II peptide hydrolysis does not change as a function of temperature. Co(II)- and Fe(II)-loaded PfMetAP-II have similar activation energies (13.3 and 19.4 kJ/mol, respectively). The thermodynamic parameters calculated at 25 °C are as follows:  ΔG⧧ = 46.23 kJ/mol, ΔH⧧ = 10.79 kJ/mol, and ΔS⧧ = −119.72 J·mol-1·K-1 for Co(II)-loaded PfMetAP; ΔG⧧ = 46.44 kJ/mol, ΔH⧧ = 16.94 kJ/mol, and ΔS⧧ = −99.67 J·mol-1·K-1 for Fe(II)-loaded PfMetAP. Interestingly, at higher temperatures (\u3e50 °C), Fe(II)-loaded PfMetAP-II is more active (1.4-fold at 85 °C) than Co(II)-loaded PfMetAP-II
Determining the structure of Ru(0001) from low-energy electron diffraction of a single terrace
While a perfect hcp (0001) surface has three-fold symmetry, the diffraction
patterns commonly obtained are six-fold symmetric. This apparent change in
symmetry occurs because on a stepped surface, the atomic layers on adjacent
terraces are rotated by 180 degrees. Here we use a Low-Energy Electron
Microscope to acquire the three-fold diffraction pattern from a single hcp Ru
terrace and measure the intensity-vs-energy curves for several diffracted
beams. By means of multiple scattering calculations fitted to the experimental
data with a Pendry R-factor of 0.077, we find that the surface is contracted by
3.5(+-0.9) at 456 K.Comment: 10 pages, 4 figures. Corrected some typos, added more details.
Accepted for publication in Surface Science (Letters
Recommended from our members
Diamond switches for high temperature electronics
This paper presents the results of switching voltages of 500 V and currents of 10 A using chemical vapor deposited (CVD) diamond as a switching material. The switching is performed by using an electron beam that penetrates the diamond, creates electron hole pairs, and lowers its resistivity to about 20 {Omega}-cm and its resistance to about 4 {Omega}. Tests were performed at room temperature but in a configuration that allows for 250 C
Using a family systems approach to treat tobacco use among cancer patients
Tobacco use treatment is an essential component of cancer care. Family members play a significant role in smoking behavior, but more research is needed regarding the development, implementation, and impact of family-based interventions in cancer care. The UNC Tobacco Treatment Program conducted an 18-month pilot study to examine the feasibility of implementing a family systems approach to treat tobacco use among patients at the North Carolina Cancer Hospital and to measure the impact of such an approach on patient abstinence. Implementation included four phases: (1) modifying the electronic health record and monthly report generated from the electronic health record; (2) training Tobacco Treatment Specialists to provide family counseling; (3) integrating family members into patients’ treatment; and (4) conducting six-month follow-up calls. During the course of the study, 42% (N = 221/532) of patients had family members integrated into their tobacco use treatment. Only 21 patients (4%) had family members present but not integrated into the treatment plan. At the six-month follow up time point, the seven-day point-prevalence quit rate for patients with family integration was 28% (N = 56/200), compared to 23% (N = 67/291) (p = 0.105) for patients without family integration. Integration of family members is clearly possible in an academic medical center’s oncology tobacco treatment program. Although pilot results were not statistically significant at 6 months, a potentially higher quit rate suggests a need for expanded research on methods to integrate family members in oncology settings for patients with tobacco-related cancers
Kinetic and Structural Characterization of Manganese(II)-Loaded Methionyl Aminopeptidases
Manganese(II) activation of the methionyl aminopeptidases from Escherichia coli (EcMetAP-I) and the hyperthermophilic archaeon Pyrococcus furiosus (PfMetAP-II) was investigated. Maximum catalytic activity for both enzymes was obtained with 1 equiv of Mn(II), and the dissociation constants (Kd) for the first metal binding site were found to be 6 ± 0.5 and 1 ± 0.5 μM for EcMetAP-I and PfMetAP-II, respectively. These Kd values were verified by isothermal titration calorimetry (ITC) and found to be 3.0 ± 0.2 and 1.4 ± 0.2 μM for EcMetAP-I and PfMetAP-II, respectively. The hydrolysis of MGMM was measured in triplicate between 25 and 85 °C at eight substrate concentrations ranging from 2 to 20 mM for PfMetAP-II. Both specific activity and Km values increased with increasing temperature. An Arrhenius plot was constructed from the kcat values and was found to be linear over the temperature range 25−85 °C. The activation energy for the Mn(II)-loaded PfMetAP-II hydrolysis of MGMM was found to be 25.7 kJ/mol while the remaining thermodynamic parameters calculated at 25 °C are ΔG⧧ = 50.1 kJ/mol, ΔH⧧ = 23.2 kJ/mol, and ΔS⧧ = −90.2 J·mol-1·K-1
Regional Dissemination of a Trimethoprim-Resistance Gene Cassette via a Successful Transposable Element
Antimicrobial resistance is a growing international problem. We observed a 50% increase in the prevalence of trimethoprim resistance among fecal Escherichia coli from healthy Nigerian students between 1998 and 2005, a trend to increase that continued in 2009.A PCR-based screen revealed that 131 (43.1%) of isolates obtained in Nigeria in 2005 and 2009 carried integron-borne dfrA cassettes. In the case of 67 (51.1%) of these isolates, the cassette was a class 1-integron-borne dfrA7 gene, which has been reported at high prevalence from E. coli isolates from other parts of Africa. Complete sequencing of a 27 Kb dfrA7-bearing plasmid from one isolate located the dfrA7 gene within a Tn21-type transposon. The transposon also contained an IS26-derived bla/sul/str element, encoding resistance to β-lactams, sulphonamides and streptomycin, and mercury resistance genes. Although the plasmid backbone was only found in 12 (5.8%) of trimethoprim-resistant isolates, dfrA7 and other transposon-borne genes were detected in 14 (16.3%) and 32 (26.3%) of trimethoprim resistant isolates collected in Nigeria in 2005 and 2009, respectively. Additionally, 37 (19.3%) of trimethoprim-resistant E. coli isolates collected between 2006 and 2008 from Ghana were positive for the dfrA7 and a transposon marker, but only 4 (2.1%) harbored the plasmid backbone.Our data point to transposition as a principal mechanism for disseminating dfrA7 among E. coli from Nigeria and Ghana. On-going intensive use of the affordable broad-spectrum antibacterials is likely to promote selective success of a highly prevalent transposable element in West Africa
- …