Tunable Rydberg-Rydberg transitions in helium with reduced sensitivity to dc electric fields by two-colour microwave dressing

The difference in the static electric dipole polarizabilities of the 1\mathrm{s}55\mathrm{s}\,^3\mathrm{S}_1 and 1\mathrm{s}56\mathrm{s}\,^3\mathrm{S}_1 Rydberg levels in helium has been eliminated by dressing the atom with a microwave field near resonant with the single-photon 1\mathrm{s}55\mathrm{s}\,^3\mathrm{S}_1 \rightarrow 1\mathrm{s}55\mathrm{p}\,^3\mathrm{P}_J transition. For an $2.82\,\mathrm{mV}\,\mathrm{cm}^{-1}$ amplitude dressing field, detuned by $2\pi\times10\,\mathrm{MHz}$ from the zero-field 1\mathrm{s}55\mathrm{s}\,^3\mathrm{S}_1 \rightarrow 1\mathrm{s}55\mathrm{p}\,^3\mathrm{P}_2 transition frequency, the dc Stark shift of the two-photon 1\mathrm{s}55\mathrm{s}\,^3\mathrm{S}_1 \rightarrow 1\mathrm{s}56\mathrm{s}\,^3\mathrm{S}_1 transition between these states remained within $\pm 15\,\mathrm{kHz}$ for electric fields up to ${\sim}60\,\mathrm{mV}\,\mathrm{cm}^{-1}$. This transition was probed by single-color two-photon microwave spectroscopy, and by two-color two-photon spectroscopy with one strong additional dressing field and a weak probe field. For all measurements, the transition frequencies and Stark shifts were compared, and found to be in excellent quantitative agreement with the results of Floquet calculations of the energy-level structure of the Rydberg states in the presence of the dressing fields and applied dc electric fields. The two-color microwave dressing scheme demonstrated, with one field applied to null the differential polarizability of the Rydberg–Rydberg transition, and the second exploited to allow the two-photon transition to be employed to achieve tunable absorption of single-photons from a weak probe field, will facilitate improved coherence times and tunable single-photon absorption in hybrid cavity QED experiments with Rydberg atoms and superconducting microwave circuits

Electrometry of a single resonator mode at a Rydberg-atom–superconducting-circuit interface

The electric-field distribution in a single mode of a λ/4 superconducting coplanar waveguide (CPW) microwave resonator has been probed using beams of helium Rydberg atoms. In the experiments the atoms were prepared in the 1s55s3S1 Rydberg level by laser photoexcitation. They then traveled over the CPW resonator that was fabricated on a NbN superconducting chip operated at 3.8 K. The resonator was driven at its third-harmonic frequency, near resonant with the two-photon 1s55s3S1→1s56s3S1 transition at ω55s,56s/2=2π×19.556499 GHz. The coherence times of the atom–resonator-field interaction were determined at selected locations above the resonator by time-domain measurements of Rabi oscillations and found to be up to 0.8μs for Rabi frequencies of ∼2π×3 MHz. The coherence times of the atomic superposition states, generated following the interaction of the atoms with the microwave field in the resonator, were inferred from high-resolution cavity-enhanced Ramsey spectra to be ∼2.5μs. These Ramsey spectra also allowed the measurement of residual uncanceled dc electric fields of 26.6±0.6 mV/cm at the position of the atoms ∼300μm above the surface of the superconducting chip. These results represent an essential step toward applications of hybrid systems, comprising Rydberg atoms coherently coupled to superconducting microwave circuits, in quantum optics and quantum information processing

Robust and Efficient Online Auditory Psychophysics

Most human auditory psychophysics research has historically been conducted in carefully controlled environments with calibrated audio equipment, and over potentially hours of repetitive testing with expert listeners. Here, we operationally define such conditions as having high 'auditory hygiene'. From this perspective, conducting auditory psychophysical paradigms online presents a serious challenge, in that results may hinge on absolute sound presentation level, reliably estimated perceptual thresholds, low and controlled background noise levels, and sustained motivation and attention. We introduce a set of procedures that address these challenges and facilitate auditory hygiene for online auditory psychophysics. First, we establish a simple means of setting sound presentation levels. Across a set of four level-setting conditions conducted in person, we demonstrate the stability and robustness of this level setting procedure in open air and controlled settings. Second, we test participants' tone-in-noise thresholds using widely adopted online experiment platforms and demonstrate that reliable threshold estimates can be derived online in approximately one minute of testing. Third, using these level and threshold setting procedures to establish participant-specific stimulus conditions, we show that an online implementation of the classic probe-signal paradigm can be used to demonstrate frequency-selective attention on an individual-participant basis, using a third of the trials used in recent in-lab experiments. Finally, we show how threshold and attentional measures relate to well-validated assays of online participants' in-task motivation, fatigue, and confidence. This demonstrates the promise of online auditory psychophysics for addressing new auditory perception and neuroscience questions quickly, efficiently, and with more diverse samples. Code for the tests is publicly available through Pavlovia and Gorilla

Do metacognitive beliefs predict rumination and psychological distress independently of illness representations in adults with diabetes mellitus? A prospective mediation study

ObjectiveAdults with Diabetes Mellitus (DM) experience high levels of depression and anxiety that are not always effectively ameliorated by current therapeutic approaches. The Self-Regulatory Executive Function (S-REF) model, which underpins metacognitive therapy (MCT), posits that depression and anxiety become persistent when stored metacognitive beliefs guide an individual to respond to common thoughts and feelings in a certain way. We hypothesized that (i) metacognitive beliefs would predict depression and anxiety independently of participants' representations of their illness; and (ii) rumination would mediate independent prediction of depression and anxiety by metacognitive beliefs.DesignA prospective mediation study.MethodsFour hundred and forty-one adults with DM (Types 1 and 2) completed a two time-point survey. Metacognitive beliefs, illness representations and rumination were measured at baseline, and depression and anxiety measured at baseline and 6-months later. Data were analysed using structural equation modelling. Baseline illness representations, depression and anxiety were used as control variables.ResultsA structural equation analysis showed potential mediation, by baseline rumination, of any effects of baseline metacognitive variables on 6-month distress in Type 1 and 2 diabetes samples. Significant standardized coefficients for relationships between the metacognitive latent variable and rumination were .67 (Type 1) and .75 (Type 2) and between rumination and distress of .36 and .43, respectively. These effects were independent of direct and independent effects of illness representation variables.ConclusionsFindings are consistent with metacognitive beliefs playing a key role in depression and anxiety by increasing the likelihood of rumination in adults with DM. MCT may be an effective intervention for this population, subsequent to further longitudinal testing of the S-REF model

Seasonal change in the daily timing of behaviour of the common vole, Microtus arvalis

1. Seasonal effects on daily activity patterns in the common vole were established by periodic trapping in the field and continuous year round recording of running wheel and freeding activity in cages exposed to natural meteorological conditions. 2. Trapping revealed decreased nocturnality in winter as compared to summer. This was paralelled by a winter reduction in both nocturnal wheel running and feeding time in cages. 3. Frequent trap checks revealed a 2 h rhythm in daytime catches in winter, not in summer. Cage feeding activity in daytime was always organized in c. 2 h intervals, but day-to-day variations in phase blurred the rhythm in summer in a summation of individual daily records. Thus both seasonal and short-term temporal patterns are consistent between field trappings and cage feeding records. 4. Variables associated with the seasonal change in daily pattern were: reproductive state (sexually active voles more nocturnal), age (juveniles more nocturnal), temperature (cold days: less nocturnal), food (indicated by feeding experiments), habitat structure (more nocturnal in habitat with underground tunnels). 5. Minor discrepancies between field trappings and cage feeding activity can be explained by assuming increased trappability of voles in winter. Cage wheel running is not predictive of field trapping patterns and is thought to reflect behavioral motivations not associated with feeding but with other activities (e.g., exploratory, escape, interactive behaviour) undetected by current methods, including radiotelemetry and passage-counting. 6. Winter decrease in nocturnality appears to involve a reduction in nocturnal non-feeding and feeding behaviour and is interpreted primarily as an adaptation to reduce energy expenditure in adverse but socially stable winter conditions.

The wavelet-NARMAX representation : a hybrid model structure combining polynomial models with multiresolution wavelet decompositions

A new hybrid model structure combing polynomial models with multiresolution wavelet decompositions is introduced for nonlinear system identification. Polynomial models play an important role in approximation theory, and have been extensively used in linear and nonlinear system identification. Wavelet decompositions, in which the basis functions have the property of localization in both time and frequency, outperform many other approximation schemes and offer a flexible solution for approximating arbitrary functions. Although wavelet representations can approximate even severe nonlinearities in a given signal very well, the advantage of these representations can be lost when wavelets are used to capture linear or low-order nonlinear behaviour in a signal. In order to sufficiently utilise the global property of polynomials and the local property of wavelet representations simultaneously, in this study polynomial models and wavelet decompositions are combined together in a parallel structure to represent nonlinear input-output systems. As a special form of the NARMAX model, this hybrid model structure will be referred to as the WAvelet-NARMAX model, or simply WANARMAX. Generally, such a WANARMAX representation for an input-output system might involve a large number of basis functions and therefore a great number of model terms. Experience reveals that only a small number of these model terms are significant to the system output. A new fast orthogonal least squares algorithm, called the matching pursuit orthogonal least squares (MPOLS) algorithm, is also introduced in this study to determine which terms should be included in the final model

Development and Validation of the Behavioral Tendencies Questionnaire

At a fundamental level, taxonomy of behavior and behavioral tendencies can be described in terms of approach, avoid, or equivocate (i.e., neither approach nor avoid). While there are numerous theories of personality, temperament, and character, few seem to take advantage of parsimonious taxonomy. The present study sought to implement this taxonomy by creating a questionnaire based on a categorization of behavioral temperaments/tendencies first identified in Buddhist accounts over fifteen hundred years ago. Items were developed using historical and contemporary texts of the behavioral temperaments, described as “Greedy/Faithful”, “Aversive/Discerning”, and “Deluded/Speculative”. To both maintain this categorical typology and benefit from the advantageous properties of forced-choice response format (e.g., reduction of response biases), binary pairwise preferences for items were modeled using Latent Class Analysis (LCA). One sample (n1 = 394) was used to estimate the item parameters, and the second sample (n2 = 504) was used to classify the participants using the established parameters and cross-validate the classification against multiple other measures. The cross-validated measure exhibited good nomothetic span (construct-consistent relationships with related measures) that seemed to corroborate the ideas present in the original Buddhist source documents. The final 13-block questionnaire created from the best performing items (the Behavioral Tendencies Questionnaire or BTQ) is a psychometrically valid questionnaire that is historically consistent, based in behavioral tendencies, and promises practical and clinical utility particularly in settings that teach and study meditation practices such as Mindfulness Based Stress Reduction (MBSR)

Clades and clans: a comparison study of two evolutionary models

The Yule-Harding-Kingman (YHK) model and the proportional to distinguishable arrangements (PDA) model are two binary tree generating models that are widely used in evolutionary biology. Understanding the distributions of clade sizes under these two models provides valuable insights into macro-evolutionary processes, and is important in hypothesis testing and Bayesian analyses in phylogenetics. Here we show that these distributions are log-convex, which implies that very large clades or very small clades are more likely to occur under these two models. Moreover, we prove that there exists a critical value $\kappa(n)$ for each $n\geqslant 4$ such that for a given clade with size $k$, the probability that this clade is contained in a random tree with $n$ leaves generated under the YHK model is higher than that under the PDA model if $1<k<\kappa(n)$, and lower if $\kappa(n)<k<n$. Finally, we extend our results to binary unrooted trees, and obtain similar results for the distributions of clan sizes.Comment: 21page

Territorialising brand experience and consumption: negotiating a role for pop-up retailing

The evolving consumption landscape creates challenges for retailers in accommodating their modus operandi to negotiate changing consumer needs, arguably requiring a ‘new’ type of retailing to hopefully facilitate future success. We suggest that an important aspect of such negotiation will be the use of ‘pop-up’ activity, and we critically evaluate the potential of these ephemeral consumption spaces to constitute and shape consumers’ brand-oriented relations and experiences into the future. Informed by the work of Deleuze and Guattari, we take a territorological perspective. Drawing on data from eight UK-based pop-up cases, we analyse: (1) how these temporary ‘territories’ of brand experience are developed and implemented; (2) what differentiates them from other, traditionally conceived, territories of brand experience; and (3) critically evaluate pop-up’s neglected characterisation in terms of a more ‘fluid’ spatial-temporal retail territory, to better understand its role in contemporary consumer culture. We posit that the development of pop-up activities occurs through the coordination of actions of a variety of stakeholders, constituting a spatial-temporal confluence of both material and processual elements to create a ‘refrain’, through the compression and compaction of interior, intermediary, exterior and annexed milieus. In doing so, we offer a new lens through which to view the creation of retail consumption spaces

Normalization factors for magnetic relaxation of small particle systems in non-zero magnetic field

We critically discuss relaxation experiments in magnetic systems that can be characterized in terms of an energy barrier distribution, showing that proper normalization of the relaxation data is needed whenever curves corresponding to different temperatures are to be compared. We show how these normalization factors can be obtained from experimental data by using the $T \ln(t/\tau_0)$ scaling method without making any assumptions about the nature of the energy barrier distribution. The validity of the procedure is tested using a ferrofluid of Fe_3O_4 particles.Comment: 5 pages, 6 eps figures added in April 22, to be published in Phys. Rev. B 55 (1 April 1997