Atomic dynamics in evaporative cooling of trapped alkali atoms in strong magnetic fields

We investigate how the nonlinearity of the Zeeman shift for strong magnetic fields affects the dynamics of rf field induced evaporative cooling in magnetic traps. We demonstrate for the 87-Rb and 23-Na F=2 trapping states with wave packet simulations how the cooling stops when the rf field frequency goes below a certain limit (for the 85-Rb F=2 trapping state the problem does not appear). We examine the applicability of semiclassical models for the strong field case as an extension of our previous work [Phys. Rev. A 58, 3983 (1998)]. Our results verify many of the aspects observed in a recent $^{87}$Rb experiment [Phys. Rev. A 60, R1759 (1999)].Comment: 9 pages, RevTex, eps figures embedde

Strategic Utilization of the VR and AR Technologies for the African Cultural Heritage Promotion and Management

The importance and purpose of heritage preservation have been extensively discussed in tourism research and has also been linked with regional and national development strategies. Because of time degradation, human activities, and the overcrowding effect, heritage preservation and reconstruction efforts are becoming critical to ensure the sustainability of heritage sites and disseminate the history and the potential of a region or a country. Virtual reality (VR) and augmented reality (AR) offer useful applications in heritage preservation. This study aims to explore the potential of these interactive technologies to be applied in heritage preservation in Africa, introduce strategies and applications developed Egypt and Tunis but also from Oman, and Finland, and highlight their impact in regional and national socio-economic development. As members of the Time Machine Europe this paper analyzes previous experiences in global scale and aim is to contribute in large-scale digitalization projects in Europe but also world-wide

Terveydenhuoltosektorin älypuhelinsovelluksien vaikutus arvonluontiin asiakkaan näkökulmasta

Tiivistelmä. Tässä pro gradu -tutkielmassa tutkitaan sitä, miten terveydenhuoltosektorin älypuhelinsovellukset ovat vaikuttaneet asiakkaiden kokemaan arvonmuodostumiseen. Tutkimuksen tavoitteena on selvittää, miten arvonmuodostuminen on asiakkaan näkökulmasta muuttunut, kun terveydenhuoltosektorin älypuhelinsovellukset ovat muuttaneet arvonmuodostumisen peruselementtejä digitaalisen palveluympäristön tuomien nyanssien kautta. Samalla tutkimus selvittää ovatko älypuhelinsovellukset vaikuttaneet terveydenhuoltosektorin palveluntarjoajien ja asiakkaiden väliseen transaktion määrään, sillä terveydenhuoltosektorin arvonluonnista ja transaktiosta tiedetään vielä hyvin vähän. Tutkimus on toteutettu kvalitatiivisena kyselytutkimuksena, sillä terveydenhuoltosektorin arvonmuodostumista on tutkittu toistaiseksi vielä hyvin vähän älypuhelinsovellusten kontekstissa. Laadullisella kyselytutkimuksella on siten haluttu lisätä ymmärrystä arvonmuodostumisesta ja sen muutoksesta, erityisesti älypuhelinsovellusten kautta vastaanotetun palvelun kontekstissa asiakkaan näkökulmasta. Tutkimuksessa löydettiin, että terveydenhuoltosektorin älypuhelinsovellukset ovat lisänneet asiakkaiden ja palveluntarjoajien välistä transaktion määrää, sillä asiakkaat käyttävät terveydenhuoltopalveluita entistä useammin älypuhelinsovellusten mahdollistaman helpomman ja nopeamman palveluasioinnin ansiosta. Asiakkaat kokevat siten älypuhelinsovellusten tuovan heille vaivattomamman asioinnin kautta niin paljon lisäarvoa, että he asioivat entistä pienemmistä vaivoista ja entistä useammin terveydenhuoltopalveluita tarjoavien yritysten kanssa. Tutkimuksessa tunnistettiin, että asiakkaat kokevat terveydenhuoltopalveluihin hakeutumisen nopeudella ja helppoudella olevan merkittävä vaikutus siihen hakutuvatko he ylipäätään lääkärin vastaanotolle silloin kun hoidettavat oireet eivät vaadi akuuttia hoitoa. Tutkimuksen tuloksesta voivat hyötyä julkisen sektorin prosessisuunnittelijat ja prosessivastaavat, jotka ovat vastuussa julkishallinnollisten yksiköiden digitaalisesta palveluasioinnista, sekä erityisesti ne terveydenhuoltosektorin toimijat, jotka ovat suunnittelemassa älypuhelinsovellusten integrointia osaksi julkisia terveydenhuoltopalveluita tulevaisuudessa

Virtual Reality Relaxation to Decrease Dental Anxiety:Immediate Effect Randomized Clinical Trial

Introduction: Dental anxiety is common and causes symptomatic use of oral health services. Objectives: The aim was to study if a short-term virtual reality intervention reduced preoperative dental anxiety. Methods: A randomized controlled single-center trial was conducted with 2 parallel arms in a public oral health care unit: virtual reality relaxation (VRR) and treatment as usual (TAU). The VRR group received a 1- to 3.5-min 360° immersion video of a peaceful virtual landscape with audio features and sound supporting the experience. TAU groups remained seated for 3 min. Of the powered sample of 280 participants, 255 consented and had complete data. Total and secondary sex-specific mixed effects linear regression models were completed for posttest dental anxiety (Modified Dental Anxiety Scale [MDAS] total score) and its 2 factors (anticipatory and treatment-related dental anxiety) adjusted for baseline (pretest) MDAS total and factor scores and age, taking into account the effect of blocking. Results: Total and anticipatory dental anxiety decreased more in the VRR group than the TAU group (β = −0.75, P < .001, for MDAS total score; β = −0.43, P < .001, for anticipatory anxiety score) in patients of a primary dental care clinic. In women, dental anxiety decreased more in VRR than TAU for total MDAS score (β = −1.08, P < .001) and treatment-related dental anxiety (β = −0.597, P = .011). Anticipatory dental anxiety decreased more in VRR than TAU in both men (β = −0.217, P < .026) and women (β = −0.498, P < .001). Conclusion: Short application of VRR is both feasible and effective to reduce preoperative dental anxiety in public dental care settings (ClinicalTrials.gov NCT03993080). Knowledge Transfer Statement: Dental anxiety, which is a common problem, can be reduced with short application of virtual reality relaxation applied preoperatively in the waiting room. Findings of this study indicate that it is a feasible and effective procedure to help patients with dental anxiety in normal public dental care settings.Publisher PDFPeer reviewe

Exact Soliton-like Solutions of the Radial Gross-Pitaevskii Equation

We construct exact ring soliton-like solutions of the cylindrically symmetric (i.e., radial) Gross- Pitaevskii equation with a potential, using the similarity transformation method. Depending on the choice of the allowed free functions, the solutions can take the form of stationary dark or bright rings whose time dependence is in the phase dynamics only, or oscillating and bouncing solutions, related to the second Painlev\'e transcendent. In each case the potential can be chosen to be time-independent.Comment: 8 pages, 7 figures. Version 2: stability analysis of the dark solutio

Nonlinear level crossing models

We examine the effect of nonlinearity at a level crossing on the probability for nonadiabatic transitions $P$. By using the Dykhne-Davis-Pechukas formula, we derive simple analytic estimates for $P$ for two types of nonlinear crossings. In the first type, the nonlinearity in the detuning appears as a {\it perturbative} correction to the dominant linear time dependence. Then appreciable deviations from the Landau-Zener probability $P_{LZ}$ are found to appear for large couplings only, when $P$ is very small; this explains why the Landau-Zener model is often seen to provide more accurate results than expected. In the second type of nonlinearity, called {\it essential} nonlinearity, the detuning is proportional to an odd power of time. Then the nonadiabatic probability $P$ is qualitatively and quantitatively different from $P_{LZ}$ because on the one hand, it vanishes in an oscillatory manner as the coupling increases, and on the other, it is much larger than $P_{LZ}$. We suggest an experimental situation when this deviation can be observed.Comment: 9 pages final postscript file, two-column revtex style, 5 figure

The effect of phosphonates on lanthanide separation for surface-grafted porous zirconia

The effect of phosphonate groups on selective lanthanide sorption for a series of inorganic-organic hybrid materials was investigated. Four functional ligands with an increasing number of aminomethylenephosphonate groups were attached to the porous zirconia matrix via the post-synthetic grafting method. Successful surface grafting was confirmed by FTIR and P-31 MAS-NMR spectroscopies. All the synthesized hybrids showed a lanthanide uptake of about 100 mu mol g(-1) at pH 3. The sorption studies revealed that the hybrids of ligands with a larger number of phosphonate groups possess higher selectivity, as one with the largest number showed a separation factor of over 80 for La3+ and Lu3+. Fixed-bed column experiments also demonstrated the materials' favored uptake of Lu3+ over La3+ at pH 3, in addition to the reusability and applicability to the actual separation settings. These results propose strategies for the selection of organic ligands for hybrid sorbent synthesis.Peer reviewe

Collisions of cold magnesium atoms in a weak laser field

We use quantum scattering methods to calculate the light-induced collisional loss of laser-cooled and trapped magnesium atoms for detunings up to 30 atomic linewidths to the red of the 1S_0-1P_1 cooling transition. Magnesium has no hyperfine structure to complicate the theoretical studies. We evaluate both the radiative and nonradiative mechanisms of trap loss. The radiative escape mechanism via allowed 1Sigma_u excitation is dominant for more than about one atomic linewidth detuning. Molecular vibrational structure due to photoassociative transitions to bound states begins to appear beyond about ten linewidths detuning.Comment: 4 pages with 3 embedded figure

Quantum and Semiclassical Calculations of Cold Atom Collisions in Light Fields

We derive and apply an optical Bloch equation (OBE) model for describing collisions of ground and excited laser cooled alkali atoms in the presence of near-resonant light. Typically these collisions lead to loss of atoms from traps. We compare the results obtained with a quantum mechanical complex potential treatment, semiclassical Landau-Zener models with decay, and a quantum time-dependent Monte-Carlo wave packet (MCWP) calculation. We formulate the OBE method in both adiabatic and diabatic representations. We calculate the laser intensity dependence of collision probabilities and find that the adiabatic OBE results agree quantitatively with those of the MCWP calculation, and qualitatively with the semiclassical Landau-Zener model with delayed decay, but that the complex potential method or the traditional Landau-Zener model fail in the saturation limit.Comment: 21 pages, RevTex, 7 eps figures embedded using psfig, see also http://www.physics.helsinki.fi/~kasuomin