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Certain racial and ethnic groups, individuals with disabilities, and those from low socioeconomic backgrounds remain underrepresented (UR) in the biomedical sciences. This underrepresentation becomes more extreme at each higher education stage. To support UR scholars during the critical transition from baccalaureate to PhD, we established an intensive, 1-yr postbaccalaureate training program. We hypothesized that this intervention would strengthen each participant's competitiveness for leading PhD programs and build a foundation of skills and self-efficacy important for success during and after graduate school. Scholar critical analysis skills, lab technique knowledge, and Graduate Record Examination scores all improved significantly during the program. Scholars reported significant confidence growth in 21 of 24 categories related to success in research careers. In 5 yr, 91% (41/45) of scholars transitioned directly into PhD programs. Importantly, 40% (18/45) of participating postbaccalaureate scholars had previously been declined acceptance into graduate school; however, 17/18 of these scholars directly entered competitive PhD programs following our training program. Alumni reported they were "extremely well" prepared for graduate school, and 95% (39/41) are currently making progress to graduation with a PhD. In conclusion, we report a model for postbaccalaureate training that could be replicated to increase participation and success among UR scholars in the biomedical sciences.

Petri Nets have been successfully used to model and evaluate the performance of distributed systems. Several researchers have extended the basic Petri Net model to include time, and have demonstrated that restricted classes of Petri Nets can be analyzed efficiently. Unfortunately, the restrictions prohibit the techniques from being applied to many interesting systems, e.g. communication protocols. This paper proposes a version of timed Petri Nets which accurately models communication protocols, and which can be analyzed using Timed Reachability Graphs. Procedures for constructing and analyzing these graphs are presented. The analysis is shown to be applicable to a larger class of Timed Petri Nets than previously thought. The model and the analysis technique are demonstrated using a simple communication protocol.

Collisional destruction rate coefficients for c 3Π-u metastable states by thermal energy hydrogen molecules have been measured for various vibrational and rotational levels (N=1, v=0,1,2,3 and v=1, N=1,2,3). The rate coefficients were found to be independent of vibrational and rotational quantum number and had a mean value of (1.88±0.10)×10-15 m3 s-1 at 300 K. Destruction rate coefficients and radiative lifetimes of the a 3Σ+g state have also been measured. Collisional quenching rate coefficients at 300 K of (11.5±1.0) and (6.3±0.8)×10-16 m3 s-1 were obtained for the v=0 and 1 levels, respectively. Radiative lifetimes of 11.1±0.3 ns for v=0 and 10.4±0.3 ns for a a 3Σ+g (v=1) are in good agreement with recent experiment and theory. Collisional excitation transfer between the N=1 levels of the a 3Σ+g and c 3Π-u states was observed for v=0 and 1. No collisional excitation transfer between other a 3Σ+g and c 3Π-u levels or between two c 3Π-u levels was detected. Measured fractional absorption signals and detailed balancing arguments were used to determine the excitation transfer rate coefficient for the v=1, N=1 level of the a 3Σ+g state to the v=1, N=1 level of the c 3Π-u state as (3±2)×10-16 m3 s-1 and that for the reverse process as (1.8±1)×10-16 m3 s-1 for a calculated gas temperature of 410 K. Excitation transfer to the c 3Πu state and subsequent rapid quenching accounts for a large fraction, if not all, of the collisional quenching of the a 3Σ+g (v=1, N=1) state. [ABSTRACT FROM AUTHOR]

Presents a study which suggested consistent sets of argon (Ar)[sup+]+Ar and Ar[sup++]+Ar differential and integral cross sections for modeling ion scattering. Role of ion collisions with gas atoms or molecules in understanding and prediction of etching rates and side-wall characteristics; Procedure for treating the ion-atom collision in ion flux models; Recommendation on cross sections for Ar.

Examines the use of an improved set of electron-collision cross sections to calculate transport, ionization, attachment and dissociation coefficients for pure SF[sub6] and its mixtures. Information on the cross section and electron transport in pure SF[sub6]; Calculation of the reaction and transport coefficients for the mixtures; Information on the critical field and dissociation coefficient.

Excitation coefficients for the production of vibrationally exicted D2 by low energy electrons have been determined from measurements of the intensity of infrared emission from mixtures of D2 and small concentrations of CO2 or CO. The measurements were made using the electron drift tube technique and covered electric field to gas density ratios (E/n) from (5 to 80)×10-21 V m2, corresponding to mean electron energies between 0.45 and 4.5 eV. The CO2 and CO concentrations were chosen to allow efficient excitation transfer from the D2 to the carbon containing molecule, but to minimize direct excitation of the CO2 or CO. The measured infrared intensities were normalized to predicted values for N2–CO2 and N2–CO mixtures at E/n where the efficiency of vibrational excitation is known to be very close to 100%. The experimental excitation coefficients are in satisfactory agreement with predictions based on electron–D2 cross sections at mean electron energies below 1 eV, but are about 50% too high at mean energies above about 2 eV. Application of the technique to H2 did not yield useful vibrational excitation coefficients. The effective coefficients in H2–CO2 mixtures were a factor of about 3 times the predicted values. For our H2–CO mixtures the excitation of CO via excitation transfer from H2 is small compared to direct electron excitation of CO molecules. Published experiments and theories on electron–H2 and electron–D2 collisions are reviewed to obtain the cross sections used in the predictions. [ABSTRACT FROM AUTHOR]

Quenching and rotational coupling rate coefficients have been measured for the J=4–10, v=0 levels of the a‘ 1Σg+ metastable state of N2 in collisions with ground state N2. Laser absorption is used to monitor the population of rotational levels of the a‘ 1Σg+ state following depletion of the population of one or more levels by optical pumping to other states. The observed time dependence of the recovery of population of the perturbed level and the collision induced growth and decay of the populations of adjacent levels are interpreted in terms of quenching to other electronic levels and excitation exchange among adjacent rotational levels. For the J=6, v=0 level of the a‘ 1Σg+ state the rate coefficients extrapolated to zero discharge current at 300 K are 2.3±0.1×10-16 m3/s for electronic quenching and 1.1±0.6×10-16 m3/s for excitation transfer to the J=4 and J=8 levels in collisions with N2. Very similar rate coefficients were obtained for the J=4, 7, and 8 levels. [ABSTRACT FROM AUTHOR]

Focuses on a study which measured and analyzed the ionization and current growth in molecular nitrogen. Measurements of the transported charge on the time scales of electron transit, ion transit and metastable decay; Findings on the growth of steady-state discharge currents as a function of discharge voltage; Discussion on the contributions of avalanches resulting from ion and metastable induced secondary electrons.

Presents a study which examined the longitudinal electron diffusion coefficients in noble gases. Method; Results; Discussion.

We show that Phillips et al. [J. Appl. Phys. 96, 3095 (2004)] have not made convincing calorimetric tests of the model of energy generation by Mills et al. [Int. J. Hydrogen Energy 25, 1171 (2000)]. In addition, we contend that the other experiments discussed by Phillips et al. are misinterpreted as providing support for the energy generation model. [ABSTRACT FROM AUTHOR]