High-precision determination of transition amplitudes of principal transitions in Cs from van der Waals coefficient C_6

A method for determination of atomic dipole matrix elements of principal transitions from the value of dispersion coefficient C_6 of molecular potentials correlating to two ground-state atoms is proposed. The method is illustrated on atomic Cs using C_6 deduced from high-resolution Feshbach spectroscopy. The following reduced matrix elements are determined < 6S_{1/2} || D || 6P_{1/2} > =4.5028(60) |e| a0 and =6.3373(84) |e| a0 (a0= 0.529177 \times 10^{-8} cm.) These matrix elements are consistent with the results of the most accurate direct lifetime measurements and have a similar uncertainty. It is argued that the uncertainty can be considerably reduced as the coefficient C_6 is constrained further.Comment: 4 pages; 3 fig

Precise calculation of parity nonconservation in cesium and test of the standard model

We have calculated the 6s-7s parity nonconserving (PNC) E1 transition amplitude, E_{PNC}, in cesium. We have used an improved all-order technique in the calculation of the correlations and have included all significant contributions to E_{PNC}. Our final value E_{PNC} = 0.904 (1 +/- 0.5 %) \times 10^{-11}iea_{B}(-Q_{W}/N) has half the uncertainty claimed in old calculations used for the interpretation of Cs PNC experiments. The resulting nuclear weak charge Q_{W} for Cs deviates by about 2 standard deviations from the value predicted by the standard model.Comment: 24 pages, 8 figure

Theoretical overview of atomic parity violation. Recent developments and challenges

Recent advances in interpreting the most accurate to-date measurement of atomic parity violation in Cs are reviewed. The inferred nuclear weak charge, Q_W = - 72.65(28)_expt (36)_theor, agrees with the prediction of the standard model at 1 sigma level. Further improved interpretation is limited by an accuracy of solving basic correlation problem of atomic structure. We report on our progress in solving this problem within the relativistic coupled-cluster formalism. We include single-, double- and triple- electronic excitations in the coupled-cluster expansion. Numerical results for energies, electric-dipole matrix elements, and hyperfine-structure constants of Cs are presented.Comment: PAVI'06 proceedings + EJPA; refs + SM Qw fixe

Optical decay from a Fabry-Perot cavity faster than the decay time

The dynamical response of an optical Fabry-Perot cavity is investigated experimentally. We observe oscillations in the transmitted and reflected light intensity if the frequency of the incoupled light field is rapidly changed. In addition, the decay of a cavity-stored light field is accelerated if the phase and intensity of the incoupled light are switched in an appropriate way. The theoretical model by M. J. Lawrence em et al, JOSA B 16, 523 (1999) agrees with our observations.Comment: submitted to Josa

Laser nanotraps and nanotweezers for cold atoms: 3D gradient dipole force trap in the vicinity of Scanning Near-field Optical Microscope tip

Using a two-dipole model of an optical near-field of Scanning Near-field Optical Microscope tip, i. e. taking into account contributions of magnetic and electric dipoles, we propose and analyze a new type of 3D optical nanotrap found for certain relations between electric and magnetic dipoles. Electric field attains a minimum value in vacuum in the vicinity of the tip and hence such a trap is quite suitable for manipulations with cold atoms.Comment: 9 pages, 6 figure

Measurement of the 6s - 7p transition probabilities in atomic cesium and a revised value for the weak charge Q_W

We have measured the 6s - 7p_{1/2,3/2} transition probabilities in atomic cesium using a direct absorption technique. We use our result plus other previously measured transition rates to derive an accurate value of the vector transition polarizability \beta and, consequently, re-evaluate the weak charge Q_W. Our derived value Q_W=-72.65(49) agrees with the prediction of the standard model to within one standard deviation.Comment: 4 pages, 2 figure

Sex differences in stress reactivity and responses to novelty in the gray short-tailed opossum (Monodelphis domestica)

Introduction: Investigating how exposures to stress and novel environments influence behavior is important for translational research that aims to improve mental health. Previous studies have focused on reactions to novelty and revealed changes in defense reactions and exploratory behavior. (Pisula et al., 2012). Objective: The focus of the present study is to investigate sex differences in behavioral responses to novel environments and restraint stress in the gray short-tailed opossums (Monodelphis domestica). Using the Monodelphis is innovative because it is a non-traditional animal model that is ideal for developmental research. Methods: Using AnyMaze video tracking software, animals’ behaviors (6 males, 6 females) in the restraint stress task (3 min) and open field task (10 min) were recorded. AnyMaze and JWatcher were used to quantify movements, both locomotor and non-locomotor, and finally the data collected analyzed using SPSS. Restraint was used to inflict stress in the subjects, and the reactions were movements in paw, tail, and head. Reactions to a novel environment were assessed via exploratory and locomotor behaviors in an open field. Results: The results of a t-test revealed that the movement of the head was significantly different between sexes when considering p\u3c0.05 cutoff, with the female showing higher reactivity than their male counterparts (t(10)= 2.278, p\u3c 0.05). There were no sex differences in the other behaviors. To further compare the results, an open field paradigm was used, where subjects were introduced to a new environment and their reactions were reviewed. Our preliminary observations indicate that males were more prone to vast exploration of the new environment and at a faster pace, while females exhibit slower movements and limited exploration, mainly focusing in the areas closer to the walls. Discussion: We are currently conducting additional experiments with more subjects to determine if the behavior exhibited by females are a consequence of them feeling stressed by the novelty of the environment. If the results favor our hypothesis, then we could conclude that females are more susceptible to experiencing stress. To further analyze the data collected from both experiments, we are taking into consideration the age of the subjects, as considering this variable can help understand their behavior and stress reactivity at different stages of life. Conclusions: Clinical and epidemiological research have identified major gender/sex differences in neuropsychiatric disorders, and stress is a major contributor to mental health problems. Our results support the hypothesis that sex differences in stress reactivity and responses to novelty are present in Monodelphis, suggesting that sex differences have a biological component and that animal models can be used to study mechanisms that underlie sex differences in stress responses

Laser gas-discharge absorption measurements of the ratio of two transition rates in argon

The ratio of two line strengths at 922.7 nm and 978.7 nm of argon is measured in an argon pulsed discharge with the use of a single-mode Ti:Sapphire laser. The result 3.29(0.13) is in agreement with our theoretical prediction 3.23 and with a less accurate ratio 2.89(0.43) from the NIST database.Comment: 5 pages, 2 figures, 1 tabl

Controlling dipole-dipole frequency shifts in a lattice-based optical atomic clock

Motivated by the ideas of using cold alkaline earth atoms trapped in an optical lattice for realization of optical atomic clocks, we investigate theoretically the perturbative effects of atom-atom interactions on a clock transition frequency. These interactions are mediated by the dipole fields associated with the optically excited atoms. We predict resonance-like features in the frequency shifts when constructive interference among atomic dipoles occur. We theoretically demonstrate that by fine-tuning the coherent dipole-dipole couplings in appropriately designed lattice geometries, the undesirable frequency shifts can be greatly suppressed.Comment: 14 pages, 4 figure

Sex differences in stress reactivity, brain morphology, and oxytocin in the hypothalamus of the gray short-tailed opossum (Monodelphis domestica)

Understanding the effects of stress on behavior and cognition is important due to its impact on mental health and wellbeing (Schneiderman et al. 2005). Translational animal research can contribute to the development of new treatments that can improve therapeutic outcomes and our understanding of the neurobiology of stress. In the present study, we complement behavioral stress reactivity with immunohistochemical localization of oxytocin in the hypothalamus, a neuropeptide that regulates stress (Neumann & Slattery, 2016). Oxytocin has potential therapeutic use for mental health disorders (Neumann & Slattery, 2016), and the effects of oxytocin seem to be sexually dimorphic (Love, 2018). Using the Monodelphis Domestica, we examined biological sex differences in brain and behavior and hypothesized that there would be sexually dimorphic expression of oxytocin in the hypothalamus of the Monodelphis brain. Open field tests were used to investigate stress in the Monodelphis (4 females, 4 males), their exploratory behavior was recorded and quantified using AnyMaze software, and data were analyzed with SPSS software. Immunohistochemistry was used to study oxytocin expression in the paraventricular nucleus (PVN) of the hypothalamus and the supraoptic nucleus (SON) (Love, 2018). Preliminary results indicate that there is a sex difference in stress reactivity in the Monodelphis Domestica; females exhibit higher mobility duration than males. The preliminary results from our pilot immunohistochemistry study demonstrated that oxytocin expression is present in both the PVN and SON areas. Future studies will explore sexual dimorphisms in this species, including sex differences in the expression of oxytocin in the Monodelphis brain. In conclusion, the present study contributes to our understanding of stress in the Monodelphis, and we observed that oxytocin expression in the Monodelphis model is not as extensive as it is in rodents. Findings will contribute to treatment research, which can improve therapeutic outcomes for individuals with stress-related mental disorders