1,520 research outputs found

    Cold collisions of heavy 2Σ^2\Sigma molecules with alkali-metal atoms in a magnetic field: Ab initio analysis and prospects for sympathetic cooling of SrOH(2Σ)(^2\Sigma) by Li(2^2S)

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    We use accurate ab initio and quantum scattering calculations to explore the prospects for sympathetic cooling of the heavy molecular radical SrOH(2Σ^2\Sigma) by ultracold Li atoms in a magnetic trap. A two-dimensional potential energy surface (PES) for the triplet electronic state of Li-SrOH is calculated ab initio using the partially spin-restricted coupled cluster method with single, double and perturbative triple excitations and a large correlation-consistent basis set. The highly anisotropic PES has a deep global minimum in the skewed Li-HOSr geometry with De=4932D_e=4932 cm−1^{-1} and saddle points in collinear configurations. Our quantum scattering calculations predict low spin relaxation rates in fully spin-polarized Li+SrOH collisions with the ratios of elastic to inelastic collision rates well in excess of 100 over a wide range of magnetic fields (1-1000 G) and collision energies (10−5−0.1^{-5}-0.1~K) suggesting favorable prospects for sympathetic cooling of SrOH molecules with spin-polarized Li atoms in a magnetic trap. We find that spin relaxation in Li+SrOH collisions occurs via a direct mechanism mediated by the magnetic dipole-dipole interaction between the electron spins of Li and SrOH, and that the indirect (spin-rotation) mechanism is strongly suppressed. The upper limit to the Li+SrOH reaction rate coefficient calculated for the singlet PES using adiabatic capture theory is found to decrease from 4×10−104\times 10^{-10}~cm3^3/s to a limiting value of 3.5×10−103.5\times 10^{-10} cm3^3/s with decreasing temperature from 0.1 K to 1 μ\muK

    Adjuvant vs. salvage radiation therapy in men with high-risk features after radical prostatectomy: Survey of North American genitourinary expert radiation oncologists

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    INTRODUCTION: The management of patients with high-risk features after radical prostatectomy (RP) is controversial. Level 1 evidence demonstrates that adjuvant radiation therapy (RT) improves survival compared to no treatment; however, it may overtreat up to 30% of patients, as randomized clinical trials (RCTs) using salvage RT on observation arms failed to reveal a survival advantage of adjuvant RT. We, therefore, sought to determine the current view of adjuvant vs. salvage RT among North American genitourinary (GU) radiation oncology experts. METHODS: A survey was distributed to 88 practicing North American GU physicians serving on decision-making committees of cooperative group research organizations. Questions pertained to opinions regarding adjuvant vs. salvage RT for this patient population. Treatment recommendations were correlated with practice patterns using Fisher's exact test. RESULTS: Forty-two of 88 radiation oncologists completed the survey; 23 (54.8%) recommended adjuvant RT and 19 (45.2%) recommended salvage RT. Recommendation of active surveillance for Gleason 3+4 disease was a significant predictor of salvage RT recommendation (p=0.034), and monthly patient volume approached significance for recommendation of adjuvant over salvage RT; those seeing <15 patients/month trended towards recommending adjuvant over salvage RT (p=0.062). No other demographic factors approached significance. CONCLUSIONS: There is dramatic polarization among North American GU experts regarding optimal management of patients with high-risk features after RP. Ongoing RCTs will determine whether adjuvant RT improves survival over salvage RT. Until then, the almost 50/50 division seen from this analysis should encourage practicing clinicians to discuss the ambiguity with their patients

    Is moderate hypofractionation accepted as a new standard of care in north america for prostate cancer patients treated with external beam radiotherapy? Survey of genitourinary expert radiation oncologists

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    INTRODUCTION: Several recent randomized clinical trials have evaluated hypofractionated regimens against conventionally fractionated EBRT and shown similar effectiveness with conflicting toxicity results. The current view regarding hypofractionation compared to conventional EBRT among North American genitourinary experts for management of prostate cancer has not been investigated. MATERIALS AND METHODS: A survey was distributed to 88 practicing North American GU physicians serving on decision - making committees of cooperative group research organizations. Questions pertained to opinions regarding the default EBRT dose and fractionation for a hypothetical example of a favorable intermediate - risk prostate cancer (Gleason 3 + 4). Treatment recommendations were correlated with practice patterns using Fisher's exact test. RESULTS: Forty - two respondents (48%) completed the survey. We excluded from analysis two respondents who selected radical hypofractionation with 5 - 12 fractions as a preferred treatment modality. Among the 40 analyzed respondents, 23 (57.5%) recommend conventional fractionation and 17 (42.5%) recommended moderate hypofractionation. No demographic factors were found to be associated with preference for a fractionation regimen. Support for brachytherapy as a first choice treatment modality for low - risk prostate cancer was borderline significantly associated with support for moderate hypofractionated EBRT treatment modality (p = 0.089). CONCLUSIONS: There is an almost equal split among North American GU expert radiation oncologists regarding the appropriateness to consider moderately hypofractionated EBRT as a new standard of care in management of patients with prostate cancer. Physicians who embrace brachytherapy may be more inclined to support moderate hypofractionated regimen for EBRT. It is unclear whether reports with longer followups will impact this balance, or whether national care and reimbursement policies will drive the clinical decisions. In the day and age of patient - centered care delivery, patients should receive an objective recommendation based on available clinical evidence. The stark division among GU experts may influence the design of future clinical trials utilizing EBRT for patients with prostate cancer

    Cloud computing: global trends and challenges for Russia in the time of sanctions

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    Relevance. Cloud computing brings significant benefits to economy; the speed of its adoption is crucial for emerging as well as for established businesses. In 2022, since the sanctions against Russia were introduced, the dynamically developing Russian cloud market has been dealing with new challenges, which require scholarly attention.Research Objective. The purpose of this study is to summarize the key factors that determine cloud adoption globally, identify the peculiarities of the Russian cloud market and outline the prospects for the development of cloud computing in Russia, taking into account the sanctions imposed in 2022.Data and methods. The study relies on the statistical data from global databases and market surveys. The methodological framework of the study comprises comparative analysis and scenario methods.Results. The main drivers of cloud adoption are infrastructural, economic, social and legal factors. Even though in some of these parameters Russia has achieved good results, the overall level of adoption of cloud services in the country is quite low. The Russian cloud market has a large share of local players, but the negative factor is SMEs’ reluctance to move to the cloud. Further growth in this sphere is possible, however, even if the size of the cloud market shrinks.Conclusions. The 2022 sanctions have posed a major threat to the Russian cloud market as they affected the segments of the critical IT infrastructure. However, there is likelihood that local cloud service providers might be able to substitute global providers. In many ways, it depends on the success of import substitution programs in the field of IT equipment, the policy of local providers, legislative support, and businesses’ willingness to move to the cloud

    Commodity flow model for an exclave region: Rent-seeking in the "transitional period" of the special economic zone

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    This article focuses on a commodity flow model for an exclave region (CFMER). The CFMER development is aimed at identifying aggregate proportions of the exclave's economy in the transitional period of the special economic zone (SEZ) functioning. The key method of analysis is the comparison of data on the generation of gross regional product and regional foreign economic activities (including export and import of goods and moving goods from/into the Kaliningrad region to other Russian regions). It results in a conceptual CFMER, which is assessed as of 2011. The availability of additional -as compared to a regular region- data on commodity flows in the framework of the SEZ transitional period makes it possible to identify structural disproportions in the economy. It is shown that the introduction of the SEZ transitional period did not result in a change in the conceptual model of the regional economy's functioning merely increasing the opportunities for rent extraction. The authors predict structural imbalances in the exclave economy at the microlevel, in particular, the article analyses the conceptual model of rent extraction in the SEZ transitional period. The CFMER can be used for forecasting the development of exclave's economy under different scenarios of the evolution of SEZ in the Kaliningrad region

    Generation and Direct Detection of Broadband Mesoscopic Polarization-Squeezed Vacuum

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    Using a traveling-wave OPA with two orthogonally oriented type-I BBO crystals pumped by picosecond pulses, we generate vertically and horizontally polarized squeezed vacuum states within a broad range of wavelengths and angles. Depending on the phase between these states, fluctuations in one or another Stokes parameters are suppressed below the shot-noise limit. Due to the large number of photon pairs produced, no local oscillator is required, and 3dB squeezing is observed by means of direct detection.Comment: 4 pages, 4 figures, submitted to PR
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