| 1. |
- Güttinger, J., et al.
(författare)
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Energy-dependent path of dissipation in nanomechanical resonators
- 2017
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Ingår i: Nature Nanotechnology. - : Springer Science and Business Media LLC. - 1748-3387 .- 1748-3395. ; 12:7, s. 631-636
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Tidskriftsartikel (refereegranskat)abstract
- Energy decay plays a central role in a wide range of phenomena, such as optical emission, nuclear fission, and dissipation in quantum systems. Energy decay is usually described as a system leaking energy irreversibly into an environmental bath. Here, we report on energy decay measurements in nanomechanical systems based on multilayer graphene that cannot be explained by the paradigm of a system directly coupled to a bath. As the energy of a vibrational mode freely decays, the rate of energy decay changes abruptly to a lower value. This finding can be explained by a model where the measured mode hybridizes with other modes of the resonator at high energy. Below a threshold energy, modes are decoupled, resulting in comparatively low decay rates and giant quality factors exceeding 1 million. Our work opens up new possibilities to manipulate vibrational states, engineer hybrid states with mechanical modes at completely different frequencies, and to study the collective motion of this highly tunable system.
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| 2. |
- Kudyshev, Z. A., et al.
(författare)
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Rapid Classification of Quantum Sources Enabled by Machine Learning
- 2020
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Ingår i: Advanced Quantum Technologies. - : Wiley-VCH Verlag. - 2511-9044. ; 3:10
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Tidskriftsartikel (refereegranskat)abstract
- Deterministic nanoassembly may enable unique integrated on-chip quantum photonic devices. Such integration requires a careful large-scale selection of nanoscale building blocks such as solid-state single-photon emitters by means of optical characterization. Second-order autocorrelation is a cornerstone measurement that is particularly time-consuming to realize on a large scale. Supervised machine learning-based classification of quantum emitters as “single” or “not-single” is implemented based on their sparse autocorrelation data. The method yields a classification accuracy of 95% within an integration time of less than a second, realizing roughly a 100-fold speedup compared to the conventional Levenberg–Marquardt fitting approach. It is anticipated that machine learning-based classification will provide a unique route to enable rapid and scalable assembly of quantum nanophotonic devices.
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| 3. |
- Vatnitsky, S, et al.
(författare)
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Proton dosimetry intercomparison
- 1996
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Ingår i: Radiotherapy and Oncology. - 0167-8140 .- 1879-0887. ; 41:2, s. 169-77
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND AND PURPOSE: Methods for determining absorbed dose in clinical proton beams are based on dosimetry protocols provided by the AAPM and the ECHED. Both groups recommend the use of air-filled ionization chambers calibrated in terms of exposure or air kerma in a 60Co beam when a calorimeter or Faraday cup dosimeter is not available. The set of input data used in the AAPM and the ECHED protocols, especially proton stopping powers and w-value is different. In order to verify inter-institutional uniformity of proton beam calibration, the AAPM and the ECHED recommend periodic dosimetry intercomparisons. In this paper we report the results of an international proton dosimetry intercomparison which was held at Loma Linda University Medical Center. The goal of the intercomparison was two-fold: first, to estimate the consistency of absorbed dose delivered to patients among the participating facilities, and second, to evaluate the differences in absorbed dose determination due to differences in 60Co-based ionization chamber calibration protocols.MATERIALS AND METHODS: Thirteen institutions participated in an international proton dosimetry intercomparison. The measurements were performed in a 15-cm square field at a depth of 10 cm in both an unmodulated beam (nominal accelerator energy of 250 MeV) and a 6-cm modulated beam (nominal accelerator energy of 155 MeV), and also in a circular field of diameter 2.6 cm at a depth of 1.14 cm in a beam with 2.4 cm modulation (nominal accelerator energy of 100 MeV).RESULTS: The results of the intercomparison have shown that using ionization chambers with 60Co calibration factors traceable to standard laboratories, and institution-specific conversion factors and dose protocols, the absorbed dose specified to the patient would fall within 3% of the mean value. A single measurement using an ionization chamber with a proton chamber factor determined with a Faraday cup calibration differed from the mean by 8%.CONCLUSION: The adoption of a single ionization chamber dosimetry protocol and uniform conversion factors will establish agreement on proton absorbed dose to approximately 1.5%, consistent with that which has been observed in high-energy photon and electron dosimetry.
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| 4. |
- Baigi, A, et al.
(författare)
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Causes of death between 1911-1950 in a Swedish province with a population characterized by longevity: Effects on life expectancy
- 2003
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Ingår i: Scandinavian Journal of Public Health. - : SAGE Publications. - 1651-1905 .- 1403-4948. ; 31:6, s. 418-427
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Tidskriftsartikel (refereegranskat)abstract
- Aims: Life expectancy in Sweden is among the highest in the world, and the province of Halland has the highest life expectancy in Sweden today. In an earlier paper the authors reported that life expectancy in the province of Halland in the south-west of the country was approx. 3.5 years above the national average between 1911 and 1950. The aim of this study was to explore the influence of different causes of death on life expectancy in Sweden and the distribution of these causes of death in Halland compared with Sweden as a whole during the same period of time. Method: Causes of death between 1911 and 1950 in the whole of Sweden and in Halland were obtained from the archives of Statistics Sweden. A trend analysis was performed on the impact of the various causes of death on life expectancy in Sweden. Calendar year, age, and sex were controlled for in a Poisson model. The distribution and incidence of the most frequent causes of death were compared between Halland and Sweden as a whole. Results: The decreasing mortality risk due to infectious diseases and the simultaneous increase in the risk of mortality from tumours and circulatory diseases contributed most to the change in life expectancy in Sweden. In Halland there was a lower mortality risk in the seven most important causes of death, which accounted for approx 80% of all deaths during the study period. Conclusions: The lower mortality risk from infectious diseases mostly favoured the improvement in life expectancy in Halland up to the mid-1930s. Thereafter, a low mortality risk from tumours and particularly circulatory diseases gained increasing importance although there was always a difference in favour of Halland from the beginning of the study period. Thus, the positive trend in life expectancy that favours Halland today seems to have existed for a long period of time.
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| 5. |
- Fountoulakis, KN, et al.
(författare)
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Relationship of suicide rates to economic variables in Europe: 2000-2011
- 2014
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Ingår i: The British journal of psychiatry : the journal of mental science. - : Royal College of Psychiatrists. - 1472-1465. ; 205:6, s. 486-496
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Tidskriftsartikel (refereegranskat)abstract
- It is unclear whether there is a direct link between economic crises and changes in suicide rates.AimsThe Lopez-Ibor Foundation launched an initiative to study the possible impact of the economic crisis on European suicide rates.MethodData was gathered and analysed from 29 European countries and included the number of deaths by suicide in men and women, the unemployment rate, the gross domestic product (GDP) per capita, the annual economic growth rate and inflation.ResultsThere was a strong correlation between suicide rates and all economic indices except GPD per capita in men but only a correlation with unemployment in women. However, the increase in suicide rates occurred several months before the economic crisis emerged.ConclusionsOverall, this study confirms a general relationship between the economic environment and suicide rates; however, it does not support there being a clear causal relationship between the current economic crisis and an increase in the suicide rate.
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| 9. |
- Isacsson, A, et al.
(författare)
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Social network, social support and the prevalence of neck and low back pain after retirement. A population study of men born in 1914 in Malmo, Sweden
- 1995
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Ingår i: Scandinavian Journal of Social Medicine. - 0300-8037. ; 23:1, s. 17-22
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Tidskriftsartikel (refereegranskat)abstract
- In this study we investigated the importance of social network and social support systems outside the workplace and workload and psychological job strain in former work for the prevalence of daily neck and low back pain. The study population (n = 621) comprised a random half of all male residents in Malmo, Sweden, born in 1914, of whom 500 (80.5%) participated. Two of the social network and social support indices (social anchorage and availability of material and informational support) were independent of life-style factors (leisure time physical activity, smoking and alcohol consumption) related to daily neck and back pain after retirement (OR = 2.0, 95% CI 1.2-3.4 and OR = 1.7, 95% CI 1.0-2.7, respectively), while the psycho-social and physical factors in former work were not. As no conclusion about the direction of the association can be drawn, prospective studies are needed to further explore these findings.
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