| 1. |
- Güttinger, J., et al.
(författare)
-
Energy-dependent path of dissipation in nanomechanical resonators
- 2017
-
Ingår i: Nature Nanotechnology. - : Springer Science and Business Media LLC. - 1748-3387 .- 1748-3395. ; 12:7, s. 631-636
-
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.
|
|
| 2. |
|
|
| 3. |
- Hakkinen, P., et al.
(författare)
-
Charge Sensitivity Enhancement via Mechanical Oscillation in Suspended Carbon Nanotube Devices
- 2015
-
Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 15:3, s. 1667-1672
-
Tidskriftsartikel (refereegranskat)abstract
- Single electron transistors (SETs) fabricated from single-walled carbon nanotubes (SWNTs) can be operated as highly sensitive charge detectors reaching sensitivity levels comparable to metallic radio frequency SETs (rf-SETs). Here, we demonstrate how the charge sensitivity of the device can be improved by using the mechanical oscillations of a single-walled carbon nanotube quantum dot. To optimize the charge sensitivity dQ, we drive the mechanical resonator far into the nonlinear regime and bias it to an operating point where the mechanical third order nonlinearity is canceled out. This way we enhance dQ, from 6 mu e/(Hz)(1/2) for the static case to 0.97 mu e/(Hz)(1/2) at a probe frequency of similar to 1.3 kHz.
|
|
| 4. |
- Isacsson, G., et al.
(författare)
-
Bibloc and Monobloc Oral appliances in the Treatment of Obstructive Sleep apnoea : a Multicenter, Randomized, Blinded, Parallel-Group Trial
- 2017
-
Ingår i: Sleep Medicine. - : Elsevier. - 1389-9457 .- 1878-5506. ; 40:Suppl 1, s. E142-E143
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Introduction: The clinical benefit of bibloc over monobloc appliances has not been established in randomized trials treating obstructive sleep apnoea (OSA). We hypothesized that the two types of appliances are equally effective in treating moderate to severe OSA. Materials and methods: We performed a blinded, multicenter, randomized, controlled, prospective, parallel-group trial including patients aged 18 years or older who had moderate-to-severe OSA. Patients were randomly assigned to receive either a bibloc or a monobloc appliance with the intention to protrude the mandible 75% of the individual maximal protrusion capacity. At baseline a one-night respiratory polygraphy was done without any respiratory support. The polygraphy was iterated with the appliance in place at a 6-week follow-up. The primary outcome was the absolute change in the apnoea-hypopnea-index (AHI) from baseline to the 6-week follow-up, analysed in the per-protocol population. All patients who received an appliance were included in the safety analysis. This trial is registered with ClinicalTrials.gov, number NCT02148510, and approved by Uppsala Regional Ethical Review Board, Sweden (#2014/021). Results: We recruited patients from three dental specialist clinics in Sweden; enrolment of 302 patients was done between March 2014 and April 2016; 146 randomized to bibloc and 156 to monobloc appliance. Twenty-three patients in the bibloc group and 17 in the monobloc group were withdrawn due to reasons like appliance could not be fitted, lack of compliance, adverse events or non-valid follow-up polygraphy i.e. a per-protocol group of 123 bibloc and 139 monobloc treated patients. The mean change of AHI from baseline to 6 weeks of treatment was -13.8 (95% CI -16.1 to -11.5; p < 0.001) in the bibloc group and -12.5 (95% CI -14.8 to -10.3; p < 0.001) in the monobloc group. The mean difference was not significant between the groups (-1.3 (95% CI -4.5 to 1.9). The most common adverse event in the orofacial region was upper airway infection followed by complains from various parts of the mouth, jaws and teeth. Conclusions: Bibloc and monobloc appliance treatment was equal in their effects in treating OSA as measured by at home polygraphic respiratory measures and the appliances were associated with a similar degree of adverse events. Acknowledgements: Funding from Uppsala-Örebro Regional Research Council and Vastmanland County Council, Sweden.
|
|
| 5. |
- Morell, Nicolas, et al.
(författare)
-
Optomechanical Measurement of Thermal Transport in Two-Dimensional MoSe2 Lattices
- 2019
-
Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 19:5, s. 3143-3150
-
Tidskriftsartikel (refereegranskat)abstract
- Nanomechanical resonators have emerged as sensors with exceptional sensitivities. These sensing capabilities open new possibilities in the studies of the thermodynamic properties in condensed matter. Here, we use mechanical sensing as a novel approach to measure the thermal properties of low-dimensional materials. We measure the temperature dependence of both the thermal conductivity and the specific heat capacity of a transition metal dichalcogenide monolayer down to cryogenic temperature, something that has not been achieved thus far with a single nanoscale object. These measurements show how heat is transported by phonons in two-dimensional systems. Both the thermal conductivity and the specific heat capacity measurements are consistent with predictions based on first-principles.
|
|
| 6. |
- Olsson, O., et al.
(författare)
-
Epidemiology of intra- and peri-articular structural injuries in traumatic knee joint hemarthrosis – data from 1145 consecutive knees with subacute MRI
- 2016
-
Ingår i: Osteoarthritis and Cartilage. - : Elsevier BV. - 1063-4584. ; 24:11, s. 1890-1897
-
Tidskriftsartikel (refereegranskat)abstract
- Objective In patients with traumatic knee distorsion and hemarthrosis, to investigate the panorama of structural injury, as visualized on magnetic resonance imaging (MRI). Design Cohort study of 1145 consecutive patients with traumatic knee distorsion who underwent MRI within median 8 days after injury. We present structural injury as visualized on MRI in relation to age, sex and activity at injury. Population based gender specific annual incidences of common structural injuries were calculated. Results The majority of injuries (72%) occurred during sports. Overall, anterior cruciate ligament (ACL) rupture was the most common structural injury (52%), followed by meniscal tear (41%) and lateral patella dislocation (LPD, 17%). Only 12% of ACL tears were isolated with meniscal tear being the most common associated injury (55%). The annual incidence of ACL injury was 77 (70–85, 95% CI) per 100,000 inhabitants with significant differences between men (91, 80–103) and women (63, 53–73). In those aged 16 years and younger, LPD was the most frequent structural injury, both in boys (39%) and girls (43%). In this age group, the annual incidence of LPD was 88 (68–113) and higher in boys (113, 81–154) than in girls (62, 39–95). Conclusions ACL injury occurs in one out of two knees with traumatic hemarthrosis but only 12% are without concomitant structural injury. The overall rate of traumatic knee hemarthrosis and ACL injury is higher in men. In those aged 10–19 years, ACL rupture is more common among girls than boys whereas in those 16 years and younger, LPD is more common among boys than girls.
|
|
| 7. |
- Tegelberg, Åke, et al.
(författare)
-
Respiratory outcome after one-year treatment of obstructive sleep apnea with bibloc versus monobloc oral appliances : a multicenter, randomized equivalence trial
- 2019
-
Ingår i: Sleep Medicine. - : Elsevier. - 1389-9457 .- 1878-5506. ; 64:Suppl. 1, s. S378-S378
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Background: The benefit of bibloc over monobloc appliances in one-year obstructive sleep apnea (OSA) has not been evaluated in randomized trials. We hypothesized that these types of appliances are equally effective.Methods: In this multicenter, randomized equivalence trial patients with OSA were assigned to either bibloc or monobloc appliance treatment. At baseline a one-night home respiratory polygraphy was done without respiratory support, and at one-year follow-up examination iterated with the appliance in place. The outcome was the change in the apnea-hypopnea-index (AHI) and the equivalence limits were set at ±5.Results: Out of 302 patients 146 were randomly assigned to bibloc and 156 to monobloc. In 88 and 104 patients, respectively, were analysed per-protocol with a significant reduction of AHI with a mean change -16.7 (95% CI -19.4 to -14.1) in the bibloc and -11.8 (-14.9 to -8.7) in the monobloc and not significantly equivalent. The proportion of responders defined as AHI < 10 at the follow-up was 68% and 65% for bibloc and monobloc, respectively. Treatment related adverse events were generally mild and transient and occurred similar in frequencies between groups.Conclusions: Bibloc and monobloc appliance treatment gave a significant positive effect in treating OSA. The treatment modalities were not statistically equivalent, with a numerically greater reduction with bibloc, and, were associated with a similar degree of adverse events.
|
|
| 8. |
|
|
