610 research outputs found

    Ultracold Metastable Calcium Ensembles, a Medium for Matter Wave Amplification ?

    Get PDF
    We propose an experimental implementation of matter wave amplification by optical pumping (MAO) with metastable calcium atoms. First experimental results indicate that pumping rates can be significantly higher than in previous experimental schemes and let it appear promising that the threshold condition for generation of degeneracy can be reached.Comment: 6 pages, 2 PS figure

    Analysis of crankshaft–crankcase interaction for the prediction of the dynamic structural response and noise radiation of IC engine structures

    Get PDF
    This thesis presents research work which is concerned with the development of analytical and numerical methods for the dynamic analysis of the crankshaft-crankcase assembly. The effects of interaction of crankshaft and crankcase on the dynamic response of an IC engine block structure are studied. These methods are especially attractive for the simulation of the steady state response of rotating systems with many degrees of freedom which are forced by multiple periodic excitations. A major novelty of the methods is the ability to model the system non-linearities successfully as frequency dependent properties. [Continues.

    Optimizing the production of metastable calcium atoms in a magneto-optical trap

    Full text link
    We investigate the production of long lived metastable (3P2, n=4) calcium atoms in a magneto-optical trap operating on the 1S0 to 1P1 transition at 423 nm. For excited 1P1-atoms a weak decay channel into the triplet states 3P2 and 3P1 exists via the singlet 1D2 (n=3) state. The undesired 3P1-atoms decay back to the ground state within 0.4 ms and can be fully recaptured if the illuminated trap volume is sufficiently large. We obtain a flux of above 10^10 atoms/s into the 3P2-state. We find that our MOT life time of 23 ms is mainly limited by this loss channel and thus the 3P2-production is not hampered by inelasic collisions. If we close the loss channel by repumping the 1D2-atoms with a 671 nm laser back into the MOT cycling transition, a non-exponential 72 ms trap decay is observed indicating the presence of inelastic two-body collisions between 1S0 and 1P1 atoms.Comment: 4 pages incl. 3 figures, submitted to Applied Physics

    Improving the retention rate for residential treatment of substance abuse by sequential intervention for social anxiety

    Get PDF
    BACKGROUND Residential drug rehabilitation is often seen as a treatment of last resort for people with severe substance abuse issues. These clients present with more severe symptoms, and frequent psychiatric comorbidities relative to outpatients. Given the complex nature of this client group, a high proportion of clients seeking treatment often do not enter treatment, and of those who do, many exit prematurely. Given the highly social nature of residential drug rehabilitation services, it has been argued that social anxieties might decrease the likelihood of an individual entering treatment, or increase the likelihood of them prematurely exiting treatment. The current paper reports on the protocol of a Randomised Control Trial which examined whether treatment of social anxiety prior to entry to treatment improves entry rates and retention in residential drug rehabilitation. METHOD/DESIGN A Randomised Control Trial comparing a social skills treatment with a treatment as usual control group was employed. The social skills training program was based on the principles of Cognitive Behaviour Therapy, and was adapted from Ron Rapee's social skills training program. A permutated block randomisation procedure was utilised. Participants are followed up at the completion of the program (or baseline plus six weeks for controls) and at three months following entry into residential rehabilitation (or six months post-baseline for participants who do not enter treatment). DISCUSSION The current study could potentially have implications for addressing social anxiety within residential drug treatment services in order to improve entry and retention in treatment. The results might suggest that the use of additional screening tools in intake assessments, a focus on coping with social anxieties in support groups for clients waiting to enter treatment, and greater awareness of social anxiety issues is warranted. AUSTRALIAN NEW ZEALAND CLINICAL TRIALS REGISTRY Australian New Zealand Clinical Trials Registry (ACTRN) registration number: ACTRN12611000579998.This research was supported under Australian Research Council's Linkage Projects funding scheme (project number: LP0990162)

    Formation and repair of psoralen-DNA adducts and pyrimidine dimers in human DNA and chromatin.

    Get PDF
    DNA damage and repair in human cells exposed to ultraviolet light (254 nm) or to psoralen derivatives plus 360 nm light were compared by means of a variety of analytic techniques. The two kinds of damage show considerable structural similarity; both involve cyclobutyl bonds to 5,6 positions of pyrimidines as major products and have various minor products. In purified DNA, pyrimidine dimers, but not psoralen adducts, cause structural distortions that are substances for digestion with single-strand-specific nucleases. Whereas pyrimidine dimers are randomly produced in chromatin, psoralen adducts, are concentrated approximately 2- to 4-fold in linker regions of chromatin at doses that are not highly lethal. Chromatin shows considerable mobility; assignment of DNA to linker or core regions is not permanent, and psoralen adducts initially concentrated in linker regions become randomized after 10 hr. Pyrimidine dimers and psoralen adducts are excised by normal cells but not by repair-deficient xeroderma pigmentosum cells. This repair process requires DNA polymerase alpha, but its rate in ultraviolet-damaged cells is twice that in psoralen-damaged cells. Conversion of monoadducts to DNA-DNA crosslinks reduces the rate of repair because of the increased complexity of the damaged site

    The use of beta-tricalcium phosphate bone graft substitute in dorsally plated, comminuted distal radius fractures

    Get PDF
    Background: Intraarticular distal radius fractures can be treated with many methods. While internal fixation with angle stable implants has become increasingly popular, the use of bone graft substitutes has also been recommended to address comminution zones and thus increase stability. Whether a combination of both methods will improve clinical outcomes was the purpose of the study Methods: The study was thus conducted as a prospective randomized clinical trial. 39 patients with unilateral, intraarticular fractures of the distal radius were included and randomized to 2 groups, one being treated with internal fixation only, while the second group received an additional bone graft substitute. Results: There was no statistical significance between both groups in functional and radiological results. The occurrence of complications did also not show statistical significance. Conclusions: No advantage of additional granular bone graft substitutes could be seen in this study. Granular bone graft substitutes do not seem to provide extra stability if dorsal angle stable implants are used. Dorsal plates have considerable complication rates such as extensor tendon ruptures and development of CRPS

    Palmar and dorsal fixed-angle plates in AO C-type fractures of the distal radius: is there an advantage of palmar plates in the long term?

    Get PDF
    <p>Abstract</p> <p>Background</p> <p>Current surgical approaches to the distal radius include dorsal and palmar plate fixation. While palmar plates have gained widespread popularity, few reports have provided data on long term clinical outcomes in comparison. This paper reports the result of a randomised clinical study comparing dorsal Pi plates and palmar, angle-stable plates for treatment of comminuted, intraarticular fractures of the distal radius over the course of twelve months.</p> <p>Methods</p> <p>42 patients with unilateral, intraarticular fractures of the distal radius were included and randomised to 2 groups, 22 were treated with a palmar plate, 20 received a dorsal Pi-plate. Results were evaluated after 6 weeks, 3, 6 and 12 months postoperatively focussing on functional recovery as well as radiological results.</p> <p>Results</p> <p>The palmar plate group demonstrated significantly better results regarding range of motion and grip strength over the course of 12 months. While a comparable increase in function was observed in both groups, the better results from the early postoperative period in the palmar plate group prevailed over the whole course. Radiological results showed a significantly increased palmar tilt and carpal sag in dorsal plates, with other radiological parameters being comparable. Pain levels were decreased in dorsal plates after hardware removal and failed to show significant differences after 12 months. However, complications such as tendon ruptures were more frequent in the dorsal plate group.</p> <p>Conclusions</p> <p>Functional advantage of palmar plates gained within the first 6 weeks prevails over the course of a year. Both groups demonstrate further gradual increase of function after 6 months, although dorsal plates did not catch up completely. Improved early postoperative function seems to be the cornerstone for the best possible results. Patients with dorsal plates benefit from hardware removal more than palmar plates in terms of reduction of pain levels. The advantage of palmar plates is a faster functional recovery with lower complication rates. This is especially important in the elderly population. Radiological results did not show a superiority of palmar plates over dorsal plates.</p

    Rule-based spatial modeling with diffusing, geometrically constrained molecules

    Get PDF
    <p>Abstract</p> <p>Background</p> <p>We suggest a new type of modeling approach for the coarse grained, particle-based spatial simulation of combinatorially complex chemical reaction systems. In our approach molecules possess a location in the reactor as well as an orientation and geometry, while the reactions are carried out according to a list of implicitly specified reaction rules. Because the reaction rules can contain patterns for molecules, a combinatorially complex or even infinitely sized reaction network can be defined.</p> <p>For our implementation (based on LAMMPS), we have chosen an already existing formalism (BioNetGen) for the implicit specification of the reaction network. This compatibility allows to import existing models easily, i.e., only additional geometry data files have to be provided.</p> <p>Results</p> <p>Our simulations show that the obtained dynamics can be fundamentally different from those simulations that use classical reaction-diffusion approaches like Partial Differential Equations or Gillespie-type spatial stochastic simulation. We show, for example, that the combination of combinatorial complexity and geometric effects leads to the emergence of complex self-assemblies and transportation phenomena happening faster than diffusion (using a model of molecular walkers on microtubules). When the mentioned classical simulation approaches are applied, these aspects of modeled systems cannot be observed without very special treatment. Further more, we show that the geometric information can even change the organizational structure of the reaction system. That is, a set of chemical species that can in principle form a stationary state in a Differential Equation formalism, is potentially unstable when geometry is considered, and vice versa.</p> <p>Conclusions</p> <p>We conclude that our approach provides a new general framework filling a gap in between approaches with no or rigid spatial representation like Partial Differential Equations and specialized coarse-grained spatial simulation systems like those for DNA or virus capsid self-assembly.</p

    Improving the retention rate for residential treatment of substance abuse by sequential intervention for social anxiety

    Get PDF
    Background: Residential drug rehabilitation is often seen as a treatment of last resort for people with severe substance abuse issues. These clients present with more severe symptoms, and frequent psychiatric comorbidities relative to outpatients. Given the complex nature of this client group, a high proportion of clients seeking treatment often do not enter treatment, and of those who do, many exit prematurely. Given the highly social nature of residential drug rehabilitation services, it has been argued that social anxieties might decrease the likelihood of an individual entering treatment, or increase the likelihood of them prematurely exiting treatment. The current paper reports on the protocol of a Randomised Control Trial which examined whether treatment of social anxiety prior to entry to treatment improves entry rates and retention in residential drug rehabilitation. Method/design: A Randomised Control Trial comparing a social skills treatment with a treatment as usual control group was employed. The social skills training program was based on the principles of Cognitive Behaviour Therapy, and was adapted from Ron Rapee's social skills training program. A permutated block randomisation procedure was utilised. Participants are followed up at the completion of the program (or baseline plus six weeks for controls) and at three months following entry into residential rehabilitation (or six months post-baseline for participants who do not enter treatment). Discussion: The current study could potentially have implications for addressing social anxiety within residential drug treatment services in order to improve entry and retention in treatment. The results might suggest that the use of additional screening tools in intake assessments, a focus on coping with social anxieties in support groups for clients waiting to enter treatment, and greater awareness of social anxiety issues is warranted
    corecore