| 1. |
- Fan, W., et al.
(författare)
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Investigation of magnetization dynamics damping in Ni80Fe20/Nd-Cu bilayer at room temperature
- 2018
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Ingår i: AIP Advances. - : American Institute of Physics (AIP). - 2158-3226. ; 8:5
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Tidskriftsartikel (refereegranskat)abstract
- Focusing on the Ni80Fe20 (Py)/Nd-Cu bilayers, the magnetization dynamic damping from spin pumping effect is investigated systematically by doping itinerant Cu in rear earth metal Nd. Various Ta/Py/Nd1-xCux/Ta/Si films with x = 0%, 16%, 38%, 46% and 58% are prepared by magnetron sputtering. For every content of Cu, the thickness of Nd-Cu layer is changed from 1 nm to 32 nm. The damping coefficient increases with increasing the thickness of Nd-Cu layer, which shows the trend of the spin pumping behavior. Also, with increasing Cu concentration in the Nd-Cu layer, the damping coefficient decreases, implying that the spin-orbit coupling in Nd-Cu layer is indeed cut down by high itinerant of Cu dopants. It is interesting that the spin diffusion length (λSD) in the Nd-Cu layer for different Cu dopants is not found to increase monotonously.
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| 2. |
- Yao, S. T., et al.
(författare)
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Waves in Kinetic-Scale Magnetic Dips : MMS Observations in the Magnetosheath
- 2019
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Ingår i: Geophysical Research Letters. - : AMER GEOPHYSICAL UNION. - 0094-8276 .- 1944-8007. ; 46:2, s. 523-533
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Tidskriftsartikel (refereegranskat)abstract
- Kinetic scale magnetic dips (KSMDs), with a significant depression in magnetic field strength, and scale length close to and less than one proton gyroradius, were reported in the turbulent plasmas both in recent observation and numerical simulation studies. These KSMDs likely play important roles in energy conversion and dissipation. In this study, we present observations of the KSMDs that are labeled whistler mode waves, electrostatic solitary waves, and electron cyclotron waves in the magnetosheath. The observations suggest that electron temperature anisotropy or beams within KSMD structures provide free energy to generate these waves. In addition, the occurrence rates of the waves are higher in the center of the magnetic dips than at their edges, implying that the KSMDs might be the origin of various kinds of waves. We suggest that the KSMDs could provide favorable conditions for the generation of waves and transfer energy to the waves in turbulent magnetosheath plasmas. Plain Language Summary The Earth's magnetosheath is a turbulent plasma environment where energy conversion, particle acceleration, and mass and momentum transport take place. Many of these key processes involve kinetic-scale physics. However, in-depth studies from previous missions are limited by their lower spacecraft data resolution. The recent Magnetospheric Multiscale (MMS) mission provides us with a large amount of high-temporal cadence data for studying kinetic-scale physics in the magnetosheath. In this study, we report whistler mode waves, electrostatic solitary waves and electron cyclotron waves within kinetic-scale magnetic dips (KSMDs) that can be generated in the turbulent magnetosheath. These waves could be excited by electron temperature anisotropy or beams. As is well known, plasma waves are important processes in converting energy, accelerating and scattering electrons and ions, and modifying the distributions of charged particles. If plasma instabilities develop within the KSMDs, the resulting waves could absorb free energy from plasma particles and may propagate out of the KSMDs. Thus, our discoveries could significantly advance the understanding of energy conversion and dissipation for kinetic-scale turbulence. This study provides a new reference not only for observations in space physics but also for related basic plasma theories and numerical simulations.
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| 3. |
- Abgrall, N., et al.
(författare)
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The large enriched germanium experiment for neutrinoless double beta decay (LEGEND)
- 2017
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Ingår i: AIP Conference Proceedings. - : Author(s). - 1551-7616 .- 0094-243X. ; 1894
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Konferensbidrag (refereegranskat)abstract
- The observation of neutrinoless double-beta decay (0νββ) would show that lepton number is violated, reveal that neu-trinos are Majorana particles, and provide information on neutrino mass. A discovery-capable experiment covering the inverted ordering region, with effective Majorana neutrino masses of 15 - 50 meV, will require a tonne-scale experiment with excellent energy resolution and extremely low backgrounds, at the level of ∼0.1 count /(FWHM·t·yr) in the region of the signal. The current generation 76Ge experiments GERDA and the Majorana Demonstrator, utilizing high purity Germanium detectors with an intrinsic energy resolution of 0.12%, have achieved the lowest backgrounds by over an order of magnitude in the 0νββ signal region of all 0νββ experiments. Building on this success, the LEGEND collaboration has been formed to pursue a tonne-scale 76Ge experiment. The collaboration aims to develop a phased 0νββ experimental program with discovery potential at a half-life approaching or at 1028 years, using existing resources as appropriate to expedite physics results.
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| 4. |
- Chen, Q. M., et al.
(författare)
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A new route toward light emission from Ge: tensile-strained quantum dots
- 2015
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Ingår i: Nanoscale. - : Royal Society of Chemistry (RSC). - 2040-3372 .- 2040-3364. ; 7:19, s. 8725-8730
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Tidskriftsartikel (refereegranskat)abstract
- The tensile-strained Ge quantum dot (QD) is proposed as a new route for the realization of direct band gap conversion in Ge. Ge QDs were successfully grown on an InP substrate by molecular beam epitaxy. The strain field in the QDs were analyzed by high resolution transmission electron microscopy and simulated by the finite element method based on the measured geometries. The strain field in the QDs is found to be non-uniform and the shear component plays a significant role in the energy band structure, leading to larger required hydrostatic strain than that in the Ge thin films under biaxial strain to become a direct band gap.
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| 5. |
- Yue, L., et al.
(författare)
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Novel InGaPBi single crystal grown by molecular beam epitaxy
- 2015
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Ingår i: Applied Physics Express. - : IOP Publishing. - 1882-0786 .- 1882-0778. ; 8:4, s. Art. no. 041201-
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Tidskriftsartikel (refereegranskat)abstract
- InGaPBi crystalline thin films with up to 2.1% bismuth concentration have been grown on GaAs substrates by molecular beam epitaxy. Rutherford backscattering spectrometry confirms that the majority of Bi atoms are located at substitutional lattice sites. The films exhibit good surface, structural, and interface quality, and their strains can be tuned from tensile to compressive by increasing the Bi content. InBi LO and GaBi LO vibrational modes in Raman spectroscopy were observed, and their intensities increased with Bi concentration. A weak photoluminescence signal was observed at 1.78 eV at room temperature for the sample with a Bi content of 0.5%.
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| 6. |
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| 7. |
- Dagenais, G. R., et al.
(författare)
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Variations in Diabetes Prevalence in Low-, Middle-, and High-Income Countries: Results From the Prospective Urban and Rural Epidemiological Study
- 2016
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Ingår i: Diabetes Care. - : American Diabetes Association. - 0149-5992 .- 1935-5548. ; 39:5, s. 780-787
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE The goal of this study was to assess whether diabetes prevalence varies by countries at different economic levels and whether this can be explained by known risk factors. The prevalence of diabetes, defined as self-reported or fasting glycemia >= 7 mmol/L, was documented in 119,666 adults from three high-income (HIC), seven upper-middle-income (UMIC), four lower-middle-income (LMIC), and four low-income (LIC) countries. Relationships between diabetes and its risk factors within these country groupings were assessed using multivariable analyses. Age- and sex-adjusted diabetes prevalences were highest in the poorer countries and lowest in the wealthiest countries (LIC 12.3%, UMIC 11.1%, LMIC 8.7%, and HIC 6.6%; P < 0.0001). In the overall population, diabetes risk was higher with a 5-year increase in age (odds ratio 1.29 [95% CI 1.28-1.31]), male sex (1.19 [1.13-1.25]), urban residency (1.24 [1.11-1.38]), low versus high education level (1.10 [1.02-1.19]), low versus high physical activity (1.28 [1.20-1.38]), family history of diabetes (3.15 [3.00-3.31]), higherwaist-to-hip ratio (highest vs. lowest quartile; 3.63 [3.33-3.96]), and BMI (>= 35 vs. < 25 kg/m(2); 2.76 [2.52-3.03]). The relationship between diabetes prevalence and both BMI and family history of diabetes differed in higher-versus lower-income country groups (P for interaction < 0.0001). After adjustment for all risk factors and ethnicity, diabetes prevalences continued to show a gradient (LIC 14.0%, LMIC 10.1%, UMIC 10.9%, and HIC 5.6%). Conventional risk factors do not fully account for the higher prevalence of diabetes in LIC countries. These findings suggest that other factors are responsible for the higher prevalence of diabetes in LIC countries.
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| 8. |
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| 9. |
- Ge, Q., et al.
(författare)
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Active contour evolved by joint probability classification on Riemannian manifold
- 2016
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Ingår i: Signal, Image and Video Processing. - : Springer London. - 1863-1703 .- 1863-1711. ; 10:7, s. 1257-1264
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we present an active contour model for image segmentation based on a nonparametric distribution metric without any intensity a priori of the image. A novel nonparametric distance metric, which is called joint probability classification, is established to drive the active contour avoiding the instability induced by multimodal intensity distribution. Considering an image as a Riemannian manifold with spatial and intensity information, the contour evolution is performed on the image manifold by embedding geometric image feature into the active contour model. The experimental results on medical and texture images demonstrate the advantages of the proposed method.
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| 10. |
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