3,924 research outputs found

    Der ethische Konflikt des Tierversuchs

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    Public and Private Enforcement of Title VII of the Civil Rights Act of 1964—A Ten-Year Perspective

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    The purpose of this Article is to describe the enforcement provisions of the Act and to outline the litigative activities by government agencies and private parties in the three types of cases that have characterized court action under Title VII during the ten-year period since the Act\u27s adoption. The record of enforcement compels the conclusion that effective enforcement of the Act has barely commenced. A much larger volume of litigation probably will be filed before the country approaches widespread compliance with the law against discrimination in employment

    Observation of Interactions between Trapped Ions and Ultracold Rydberg Atoms

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    We report on the observation of interactions between ultracold Rydberg atoms and ions in a Paul trap. The rate of observed inelastic collisions, which manifest themselves as charge transfer between the Rydberg atoms and ions, exceeds that of Langevin collisions for ground state atoms by about three orders of magnitude. This indicates a huge increase in interaction strength. We study the effect of the vacant Paul trap's electric fields on the Rydberg excitation spectra. To quantitatively describe the exhibited shape of the ion loss spectra, we need to include the ion-induced Stark shift on the Rydberg atoms. Furthermore, we demonstrate Rydberg excitation on a dipole-forbidden transition with the aid of the electric field of a single trapped ion. Our results confirm that interactions between ultracold atoms and trapped ions can be controlled by laser coupling to Rydberg states. Adding dynamic Rydberg dressing may allow for the creation of spin-spin interactions between atoms and ions, and the elimination of collisional heating due to ionic micromotion in atom-ion mixtures.Comment: 7 pages, 5 figures, including appendices. Note that the title has been changed in version

    S-4B orbital workshop attitude control system study

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    Saturn S-4B orbital workshop attitude control system analysi

    Observation of collisions between cold Li atoms and Yb+^+ ions

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    We report on the observation of cold collisions between 6^6Li atoms and Yb+^+ ions. This combination of species has recently been proposed as the most suitable for reaching the quantum limit in hybrid atom-ion systems, due to its large mass ratio. For atoms and ions prepared in the 2S1/2^2S_{1/2} ground state, the charge transfer and association rate is found to be at least~103^{3} times smaller than the Langevin collision rate. These results confirm the excellent prospects of 6^6Li--Yb+^+ for sympathetic cooling and quantum information applications. For ions prepared in the excited electronic states 2P1/2^2P_{1/2}, 2D3/2^2D_{3/2} and 2F7/2^2F_{7/2}, we find that the reaction rate is dominated by charge transfer and does not depend on the ionic isotope nor the collision energy in the range \sim~1--120~mK. The low charge transfer rate for ground state collisions is corroborated by theory, but the 4f4f shell in the Yb+^+ ion prevents an accurate prediction for the charge transfer rate of the 2P1/2^2P_{1/2}, 2D3/2^2D_{3/2} and 2F7/2^2F_{7/2} states. Using \textit{ab initio} methods of quantum chemistry we calculate the atom-ion interaction potentials up to energies of 30×103\times 10^3~cm1^{-1}, and use these to give qualitative explanations of the observed rates.Comment: 8 pages, 7 figures (including appendices

    Trapped ions in Rydberg-dressed atomic gases

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    We theoretically study trapped ions that are immersed in an ultracold gas of Rydberg-dressed atoms. By off-resonant coupling on a dipole-forbidden transition, the adiabatic atom-ion potential can be made repulsive. We study the energy exchange between the atoms and a single trapped ion and find that Langevin collisions are inhibited in the ultracold regime for these repulsive interactions. Therefore, the proposed system avoids recently observed ion heating in hybrid atom-ion systems caused by coupling to the ion's radio frequency trapping field and retains ultracold temperatures even in the presence of excess micromotion.Comment: 9 pages, 5 figures including appendice

    An Examination of Non-Exercise Activity Thermogenesis in Rural Youth

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    Weight gain among United States\u27 children, adolescents and adults has become a pandemic problem, and is of great public health concern, given the increased risk for myriad chronic health problems and associated medical expenditures. It is well established that increased energy expenditure through physical activity may reduce weight and improve health. However, the predominant focus of this research has been with moderate to vigorous levels of activity (MVPA). A growing body of evidence suggests that activity levels below this (i.e., light levels), may also be beneficial. Specific to light activity, a recent area of focus has been on non-exercise activity thermogenesis (NEAT), which includes non-volitional activities and activities of daily living, as well as fidgeting. Correlations exist between higher levels of NEAT and lower body weight across a variety of individuals. The main objective of this project was to increase the understanding of NEAT, utilizing objectively measured light physical activity as a proxy, among a group of rural children and adolescents during the school day. The light activity portion of the accelerometry data was used as a proxy or surrogate for NEAT because it provides an indication of the amount of NEAT in which these youth engage during the school day. In the first study, the relationship between age and NEAT during one physical education (PE) class was examined using linear regression. Accelerometry data from elementary and high school students were utilized. Results indicated that there is an inverse relationship between age and NEAT levels, such that the elementary aged children engaged in higher levels of NEAT during their PE class than did the high school students. Studies 2 and 3 utilized accelerometry data from the high school students only, across a 1-week time period, during the beginning of their semester. Study 2 examined the relative stability of NEAT both during PE class, and during the non-PE class school day. Utilizing two mixed models, performed for males and females, and including gender as a fixed effect, study 2 examined both between-person variation estimates and within-person estimates. Results from this study revealed that the between-person variation during PE class was higher among males than females, yet similar during non-PE classes. Regarding males only, more between-person variation was present during PE class than non-PE classes. Similar results occurred for the females, where more between-person variation was present during PE class than non-PE classes. Finally, within-person effects during PE class were more variable than during the non-PE class school day. Lastly, study 3 examined activity compensation. Specifically, this study sought to determine whether adolescents differentially engage in NEAT activities during the non-PE class school day, as a result of their MVPA and NEAT activity during PE class. Two generalized linear mixed models were performed. The first model was a logistic model of the odds of an individual engaging in ≥10% of NEAT during non-PE classes versus \u3c10% NEAT during non-PE classes. The second model was a traditional linear mixed model to examine whether activity compensation occurred among individuals who engaged in any NEAT. Results from both models found that there was a positive relationship between percent of time spent in NEAT during PE class and the amount of time spent in NEAT during non-PE classes. This result indicates that, among this sample, activity compensation does not occur. In fact, it appears that individuals who engage in higher levels of NEAT, do so across a variety of environments, and the amount of imposed physical activity does not appear to have an effect on this. One of the major strengths of these studies is that objectively measured physical activity via accelerometers was utilized. In addition, these studies were among the first to examine NEAT in a relatively large sample of rural children and adolescents. Although the utilization of light physical activity as a proxy for NEAT may have underestimated NEAT, as triaxial accelerometers and posture position measurements capture \u3e80% of NEAT activities, these studies provided a necessary first step for the characterization of NEAT in rural youth. Future work is needed to examine NEAT in rural youth outside of the school day, as well as whether sport or activity type during PE has an influence on NEAT

    Street Graphics and the Law

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    The evolution of barriers to exploitation: Sometimes the Red Queen can take a break.

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    We propose a general barrier theory as an evolutionary framework for understanding coevolutionary effects of conflicts of interest in natural and human systems. It is generalized from the barrier theory of cancer, which describes how cancer develops through the evasion of mechanisms, that block unregulated cellular reproduction and survival. Barriers are naturally evolved or artificially implemented mechanisms for blocking exploitation; restraints are mechanisms that impede but do not block exploitation. When conflicts of interest arise, selection will favor exploiters that are capable of overcoming barriers and restraints. When barriers are in place, they halt, at least temporarily, coevolutionary arms races (the Red Queen can stop running). Barriers occur in a broad spectrum of interactions characterized by conflicts of interest: barriers to cellular survival (apoptosis) and reproduction (cell cycle arrest) may block a virus from replicating its genome through reproduction of its host cell. Vaccines may completely protect against targeted pathogens. A plant may escape herbivory by evolving defensive chemicals that block herbivory. Obligate mutualisms may evolve when barriers to horizontal transmission favor symbionts that increasingly lose mechanisms that contribute to horizontal transmission. Here, we show how the barrier theory applies across a spectrum of natural and social systems
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