RESUMO
The formation of long-lived (tau less, similar10 mus) dipole-bound CH(3)CN(-) ions through electron transfer in K(14p)CH(3)CN collisions is investigated as a function of target temperature. The rate for their formation is observed to decrease steadily with increasing target temperature. The results are consistent with earlier suggestions that only target molecules in the ground vibrational state and low-lying rotational states can form long-lived dipole-bound anions. For CH(3)CN, the data indicate that creation of long-lived ions requires that the target molecules be in states with rotational quantum numbers j less, similar20. The measurements further demonstrate that the lifetime of the longest-lived (tau greater, similar50 mus) ions is limited by blackbody-radiation-induced photodetachment.
RESUMO
The autodetachment lifetimes of SF6-* and C6F6-* ions formed by charge transfer in K(np)/SF6, C6F6 collisions are measured as a function of target temperature over the range of approximately 300-600 K with the aid of time-of-flight techniques and a Penning ion trap. At room temperature only formation of long-lived SF6 -* ions with lifetimes tau >or similar to 1 ms is seen. As the temperature is increased the lifetime of these long-lived ions is reduced, some having lifetimes as short as approximately 0.4 ms. The appearance of a short-lived, tau
RESUMO
The lifetimes of long-lived C2Cl4(-) ions formed by Rydberg electron transfer in K(np)/C2Cl4 collisions are investigated using a Penning ion trap. Measurements at high n, n > or = 30, show that low-energy electron attachment to C2Cl4 leads to the production of C2Cl4(-) ions with a broad range of lifetimes that extends up to at least 1 ms. This is attributed to capture by molecules in different initial vibrational states. At low n, internal-to-translational energy transfer in postattachment interactions between the product K+ and C2Cl4(-) ions becomes important and leads to a substantial increase in ion lifetimes.
RESUMO
The lifetimes of SF6- ions produced by Rydberg electron transfer in K(np)SF6 collisions at high n, n greater or similar to 30, are examined using a Penning ion trap. The data point to the formation of ions with a range of lifetimes that extends from approximately 1 to greater or similar to 10 ms. Sizable numbers of ions remain in the trap even 40 ms after initial injection and at least part of this signal can be attributed to radiative stabilization. Measurements of free low-energy electron attachment to SF6 in the trap show that the product ions have lifetimes similar to those of SF6- ions formed by electron transfer in high-n collisions.
RESUMO
The nature of electron binding in C6H5NO2- ions produced by Rydberg electron transfer in K(np)C6H5NO2 collisions is investigated through measurements of the number and the lifetimes of the product ions and their dependence on Rydberg atom velocity and principal quantum number n in the range 12
RESUMO
The dynamics of free-ion production through electron transfer in K(np)/CH3CN collisions are examined through measurements using velocity-selected Rydberg atoms. The data show that Rydberg electron transfer leads to the creation of two groups of dipole-bound CH3CN- ions, one long lived (tau>85 micros), the other short lived (tau<1 micros). The velocity dependences associated with the production of both groups of ions are similar, the ion formation rate decreasing markedly with decreasing Rydberg atom velocity, principally as a consequence of postattachment electrostatic interactions between the product ions. The results are in reasonable accord with the predictions of a Monte Carlo collision model that considers the effect of crossings between the diabatic potential curves for the covalent K(np)/CH3CN system and the K+/CH3CN- ion pair. This model also accounts for the relatively small reaction rate constants, approximately 0.5-1.0 x 1.0(-8) cm(3) s(-1), associated with the formation of long-lived CH3CN- ions. No velocity dependence in the lifetime of the CH3CN- ions is observed.
RESUMO
Since the year 1992 individuals and groups of people have reported religious experiences near Marmora, Ontario, Canada. The experiences, attributed to Christ or Mary, have occurred near the top of a hill adjacent to an open pit magnetite mine that has been accumulating about 15 million gallons of water per month for more than a decade. During the period between 1992 and 1997 epicentres for local seismic events moved significantly closer to this site. Most of the messages attributed to spiritual beings by "sensitive" individuals occurred one or two days after increased global geomagnetic activity. We suggest that conditions produced by local geophysical and geological properties created the odd lights and induced physiological changes within the thousands of people who visited the area. Direct measurements indicated that weak (0.1 microTesla to 1 microTesla) complex magnetic fields, the temporal patterns of which were similar to the experimental fields we have employed to evoke the sensed presence and altered states within the laboratory, may have been generated within the area.
Assuntos
Catolicismo , Desastres , Campos Eletromagnéticos , Religião e Psicologia , Espiritualidade , Óxido Ferroso-Férrico , Humanos , Ferro , Magia , Mineração , Ontário , ÓxidosRESUMO
While non-tenured faculty receive feedback on their work in their annual evaluations for reappointment, many tenured faculty do not receive evaluations and feedback except when seeking merit award or promotion. Recent literature suggests that feedback on work at fixed time intervals, through post-tenure evaluations, can positively enhance faculty productivity. This survey study examined the attitudes of faculty teaching in baccalaureate and higher degree programs in nursing toward post-tenure performance evaluations. A random, nationwide sample of 248 nurse-faculty participated in this study. Data analysis showed that attitude toward post-tenure evaluation was not significantly related to such variables as tenure status, perceived productivity in teaching, service, scholarship, internal motivation, age, teaching experience, sex, educational preparation, or rank. Faculty clearly stated that they desire feedback on their work, an opportunity to define future objectives, and a post-tenure evaluation system in their own schools.
Assuntos
Atitude , Eficiência , Avaliação de Desempenho Profissional , Docentes de Enfermagem , Demografia , Bacharelado em Enfermagem , Educação de Pós-Graduação em Enfermagem , Humanos , Pesquisa em Educação em Enfermagem , Estudos de Amostragem , Autoavaliação (Psicologia) , Inquéritos e QuestionáriosRESUMO
The occurrence of intrusive auditory perceptions has rarely been addressed in the study of posttraumatic stress disorder. This study examined the background of 59 individuals with combat-related posttraumatic stress disorder. Subjects with and without auditory hallucinations were compared on demographic military and symptom variables. The occurrence of hallucinations among veterans with posttraumatic stress disorder appears to be more frequent among subjects of Hispanic ethnicity. This may have been related to higher combat exposure or social stresses. The occurrence of hallucinations was unrelated to drug abuse and did not appear to be associated with any particular war.