1,028 research outputs found
Analytic results for particles with interaction in two dimensions and an external magnetic field
The -dimensional quantum problem of particles (e.g. electrons) with
interaction in a two-dimensional parabolic potential
(e.g. quantum dot) and magnetic field , reduces exactly to solving a
-dimensional problem which is independent of and . An
exact, infinite set of relative mode excitations are obtained for any . The
problem reduces to that of a ficticious particle in a two-dimensional,
non-linear potential of strength , subject to a ficticious magnetic
field , the relative angular momentum.Comment: To appear in Physical Review Letters (in press). RevTeX file. Two
figures available from [email protected] or
[email protected]
Endovascular baroreflex amplification and the effect on sympathetic nerve activity in patients with resistant hypertension: A proof-of-principle study
Background: First in human studies suggest that endovascular baroreflex amplification (EVBA) lowers blood pressure (BP). To explore potential mechanisms for BP reduction, this study examines the effects of EVBA on muscle sympathetic nerve activity (MSNA) and baroreceptor sensitivity (BRS). // Methods: In a single-center sub-study of the CALM-DIEM study (Controlling And Lowering blood pressure with the MobiusHDβDefining Efficacy Markers), 14 patients with resistant hypertension were treated with EVBA. Microneurography and non-invasive continuous BP measurements were performed at baseline and three months after MobiusHD implantation. The primary outcome was change in MSNA. Secondary outcomes were change in baroreflex sensitivity (BRS), cardiovascular responses to a sympathetic stimulus, BP, heart rate (HR) and heart rate variability (HRV). // Results: The primary endpoint was obtained in 10 of 14 patients enrolled in the sub-study. MSNA burst frequency and burst incidence decreased in 6 of 10 patients: mean change -4.1 bursts/min (95% confidence interval -12.2 to 4.0) and -3.8 bursts/100 heartbeats (-15.2 to 7.7). MSNA spike frequency and spike count decreased in 8 of 10 patients: mean change -2.8 spikes/sec (-7.3 to 1.8) and -3.0 spikes/heartbeat (-6.1 to 0.1). Change in MSNA and BP were not correlated. Office BP decreased by -14/-6 mmHg (-27 to -2/-15 to 3). We observed a trend towards decreased HR (-5 bpm, -10 to 1) and increased total power HRV (623 msec2, 78 to 1168). In contrast, BRS and cardiovascular responses remained unchanged after EVBA. // Conclusions: In this proof-of-principle study, EVBA did not significantly decrease MSNA in patients with resistant hypertension. EVBA did not impair baroreflex function
ΠΠΎΠ½ΠΈΡΠΎΡΠΈΠ½Π³ Π·Π΄Π°Π½ΠΈΠΉ ΠΌΠ΅ΡΠΎΠ΄ΠΎΠΌ Π°ΠΊΡΡΡΠΈΡΠ΅ΡΠΊΠΎΠΉ ΡΠΌΠΈΡΡΠΈΠΈ
Π ΡΠ°Π±ΠΎΡΠ΅ ΡΠ°ΡΡΠΌΠΎΡΡΠ΅Π½Ρ ΡΠΎΠ²ΡΠ΅ΠΌΠ΅Π½Π½ΡΠ΅ ΠΌΠ΅ΡΠΎΠ΄Ρ Π½Π΅ΡΠ°Π·ΡΡΡΠ°ΡΡΠ΅Π³ΠΎ ΠΊΠΎΠ½ΡΡΠΎΠ»Ρ, ΠΈΡΠΏΠΎΠ»ΡΠ·ΡΠ΅ΠΌΡΠ΅ ΠΏΡΠΈ ΠΌΠΎΠ½ΠΈΡΠΎΡΠΈΠ½Π³Π΅ Π·Π΄Π°Π½ΠΈΠΉ. ΠΡΠ΅Π΄Π»ΠΎΠΆΠ΅Π½ΠΎ ΡΡΡΡΠΎΠΉΡΡΠ²Π° ΠΌΠΎΠ½ΠΈΡΠΎΡΠΈΠ½Π³Π° Π·Π΄Π°Π½ΠΈΠΉ ΠΌΠ΅ΡΠΎΠ΄ΠΎΠΌ Π°ΠΊΡΡΡΠΈΡΠ΅ΡΠΊΠΎΠΉ ΡΠΌΠΈΡΡΠΈΠΈ. ΠΡΠ΅Π΄Π»ΠΎΠΆΠ΅Π½Ρ ΡΠ°Π·Π»ΠΈΡΠ½ΡΠ΅ Π²Π°ΡΠΈΠ°Π½ΡΡ ΠΌΠ΅ΡΠΎΠ΄ΠΎΠ² ΠΎΠ±ΡΠ°Π±ΠΎΡΠΊΠΈ ΠΏΠΎΠ»ΡΡΠ°Π΅ΠΌΠΎΠΉ ΠΈΠ½ΡΠΎΡΠΌΠ°ΡΠΈΠΈ. ΠΡΠΎΠ²Π΅Π΄Π΅Π½ΠΎ ΠΌΠΎΠ΄Π΅Π»ΠΈΡΠΎΠ²Π°Π½ΠΈΠ΅ ΡΡ
Π΅ΠΌΡ, ΠΏΠΎΡΡΠ°Π²Π»Π΅Π½ ΡΠΊΡΠΏΠ΅ΡΠΈΠΌΠ΅Π½Ρ Π΄Π»Ρ ΠΏΠΎΠ»ΡΡΠ΅Π½ΠΈΡ ΡΠΈΠ³Π½Π°Π»ΠΎΠ² Π°ΠΊΡΡΡΠΈΡΠ΅ΡΠΊΠΎΠΉ ΡΠΌΠΈΡΡΠΈΠΈ.In this work the modern methods of non-destructive testing used to monitor buildings. Proposed buildings monitoring devices of acoustic emission method. Offered various options for methods of processing of the information received. The simulation scheme, put an experiment to obtain acoustic emission signals
ΠΠ°ΡΠΊΠ΅ΡΠΈΠ½Π³ Π² ΡΠΎΡΠΈΠ°Π»ΡΠ½ΡΡ ΡΠ΅ΡΡΡ ΠΊΠ°ΠΊ ΠΈΠ½ΡΡΡΡΠΌΠ΅Π½Ρ ΠΏΡΠΎΠ΄Π²ΠΈΠΆΠ΅Π½ΠΈΡ ΡΠΎΠ²Π°ΡΠΎΠ² ΠΈ ΡΡΠ»ΡΠ³
Π Π½Π°ΡΡΠΎΡΡΠ΅Π΅ Π²ΡΠ΅ΠΌΡ Π½Π° ΡΠΌΠ΅Π½Ρ ΡΠ΅Π»Π΅Π²ΠΈΠ΄Π΅Π½ΠΈΡ, ΡΠ°Π΄ΠΈΠΎ, ΠΏΠ΅ΡΠ°ΡΠΈ ΠΈ Π΄ΡΡΠ³ΠΈΠΌ ΡΡΠ°Π΄ΠΈΡΠΈΠΎΠ½Π½ΡΠΌ ΡΡΠ΅Π΄ΡΡΠ²Π°ΠΌ ΠΌΠ°ΡΡΠΎΠ²ΠΎΠΉ ΠΈΠ½ΡΠΎΡΠΌΠ°ΡΠΈΠΈ ΠΏΡΠΈΡΠ»ΠΈ ΠΈΠ½ΡΠ΅ΡΠ½Π΅Ρ-ΠΊΠΎΠΌΠΌΡΠ½ΠΈΠΊΠ°ΡΠΈΠΈ. Π‘Π΅Π³ΠΎΠ΄Π½Ρ ΡΠΎΡΠΈΠ°Π»ΡΠ½ΡΠ΅ ΡΠ΅ΡΠΈ Π·Π°Π½ΡΠ»ΠΈ ΡΠ²ΠΎΡ Π½ΠΈΡΡ ΡΡΠ΅Π΄ΠΈ ΠΈΠ½ΡΡΡΡΠΌΠ΅Π½ΡΠΎΠ² ΠΌΠ°ΡΠΊΠ΅ΡΠΈΠ½Π³Π°. Π’Π°ΠΊ, ΠΊΠΎΠ»ΠΈΡΠ΅ΡΡΠ²ΠΎ ΠΏΠΎΠ»ΡΠ·ΠΎΠ²Π°ΡΠ΅Π»Π΅ΠΉ ΠΠ½ΡΠ΅ΡΠ½Π΅ΡΠ° Π² ΠΌΠΈΡΠ΅ ΡΠ²Π΅Π»ΠΈΡΠΈΠ²Π°Π΅ΡΡΡ Ρ ΠΊΠ°ΠΆΠ΄ΡΠΌ Π΄Π½Π΅ΠΌ, ΠΈ, ΡΠΎΠ³Π»Π°ΡΠ½ΠΎ ΠΈΠ½ΡΠΎΡΠΌΠ°ΡΠΈΠΈ "Global Digital 2018" ΠΎΡ We Are Social ΠΈ Hootsuite, ΠΏΠΎ ΡΠΎΡΡΠΎΡΠ½ΠΈΡ Π½Π° ΡΠ½Π²Π°ΡΡ 2018 Π΄ΠΎΡΡΠΈΠ³Π»ΠΎ 4,021 ΠΌΠΈΠ»Π»ΠΈΠ°ΡΠ΄Π° ΡΠ΅Π»ΠΎΠ²Π΅ΠΊ. Π’Π°ΠΊΠΈΠΌ ΠΎΠ±ΡΠ°Π·ΠΎΠΌ, ΡΠΎΡΡ Π·Π° Π³ΠΎΠ΄ ΡΠΎΡΡΠ°Π²ΠΈΠ» 7% [1]. Π, ΠΊΠΎΠ½Π΅ΡΠ½ΠΎ, ΡΠ²Π΅Π»ΠΈΡΠΈΠ²Π°Π΅ΡΡΡ ΠΈ ΠΊΠΎΠ»ΠΈΡΠ΅ΡΡΠ²ΠΎ Π»ΡΠ΄Π΅ΠΉ, ΠΊΠΎΡΠΎΡΡΠ΅ Π·Π°ΡΠ΅Π³ΠΈΡΡΡΠΈΡΠΎΠ²Π°Π½Ρ Π² ΡΠΎΡΠΈΠ°Π»ΡΠ½ΡΡ
ΡΠ΅ΡΡΡ
. Π‘ΠΎΡΠΈΠ°Π»ΡΠ½ΡΠ΅ ΠΌΠ΅Π΄ΠΈΠ° ΡΠΆΠ΅ Π΄Π°Π²Π½ΠΎ ΡΡΠ°Π»ΠΈ ΠΏΠΎΠΏΡΠ»ΡΡΠ½ΠΎΠΉ ΡΠ΅ΠΊΠ»Π°ΠΌΠ½ΠΎΠΉ ΡΡΠ΅Π΄ΠΎΠΉ Π³Π»ΠΎΠ±Π°Π»ΡΠ½ΠΎΠ³ΠΎ ΠΌΠ°ΡΡΡΠ°Π±Π°, Ρ ΠΏΠΎΠΌΠΎΡΡΡ ΠΊΠΎΡΠΎΡΠΎΠ³ΠΎ ΠΏΡΠ΅Π΄ΠΏΡΠΈΡΡΠΈΡ ΠΈ ΠΎΡΠ³Π°Π½ΠΈΠ·Π°ΡΠΈΠΈ ΠΏΡΡΠ°ΡΡΡΡ ΠΏΡΠΈΠ²Π»Π΅ΡΡ ΠΊΠ°ΠΊ ΠΌΠΎΠΆΠ½ΠΎ Π±ΠΎΠ»ΡΡΠ΅ ΠΊΠ»ΠΈΠ΅Π½ΡΠΎΠ². ΠΠΎΠΌΠΏΠ°Π½ΠΈΡ Olapic ΠΏΡΠΎΠ²Π΅Π»Π° ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΠ΅, Π² Ρ
ΠΎΠ΄Π΅ ΠΊΠΎΡΠΎΡΠΎΠ³ΠΎ ΠΈΠ·ΡΡΠ°Π»ΠΎΡΡ Π²Π»ΠΈΡΠ½ΠΈΠ΅ ΡΠΎΠ·Π΄Π°Π½Π½ΡΡ
ΠΏΠΎΠ»ΡΠ·ΠΎΠ²Π°ΡΠ΅Π»ΡΠΌΠΈ ΡΠΎΡΠΎΠ³ΡΠ°ΡΠΈΠΉ Π½Π° Π΄ΠΎΠ²Π΅ΡΠΈΠ΅ ΠΊ Π±ΡΠ΅Π½Π΄Ρ ΡΠΎ ΡΡΠΎΡΠΎΠ½Ρ ΠΏΠΎΡΡΠ΅Π±ΠΈΡΠ΅Π»Π΅ΠΉ. ΠΡΡΡΠ½ΠΈΠ»ΠΎΡΡ, ΡΡΠΎ ΠΏΠΎΠΊΡΠΏΠ°ΡΠ΅Π»ΠΈ Π² 7 ΡΠ°Π· Π±ΠΎΠ»Π΅Π΅ ΡΠΊΠ»ΠΎΠ½Π½Ρ Π΄ΠΎΠ²Π΅ΡΡΡΡ ΡΠΎΡΠΎ Π² ΡΠΎΡΠΈΠ°Π»ΡΠ½ΡΡ
ΡΠ΅ΡΡΡ
, Π½Π° ΠΊΠΎΡΠΎΡΡΡ
ΠΈΠ·ΠΎΠ±ΡΠ°ΠΆΠ΅Π½Ρ Β«ΡΠ΅Π°Π»ΡΠ½ΡΠ΅ Π»ΡΠ΄ΠΈΒ», ΡΠ΅ΠΌ ΡΡΠ°Π΄ΠΈΡΠΈΠΎΠ½Π½ΠΎΠΉ ΡΠ΅ΠΊΠ»Π°ΠΌΠ΅ [2]. ΠΡΠ°ΠΊ, Π½Π° ΡΠ΅Π³ΠΎΠ΄Π½ΡΡΠ½ΠΈΠΉ Π΄Π΅Π½Ρ ΡΠΎΡΠΈΠ°Π»ΡΠ½ΡΠ΅ ΡΠ΅ΡΠΈ Π²ΡΠ΅ ΡΠ°ΡΠ΅ ΡΠ»ΡΠΆΠ°Ρ Π½Π΅ ΠΏΡΠΎΡΡΠΎ ΡΡΠ΅Π΄ΡΡΠ²ΠΎΠΌ ΠΊΠΎΠΌΠΌΡΠ½ΠΈΠΊΠ°ΡΠΈΠΈ ΠΌΠ΅ΠΆΠ΄Ρ ΠΏΠΎΠ»ΡΠ·ΠΎΠ²Π°ΡΠ΅Π»ΡΠΌΠΈ, Π° Π΅ΡΠ΅ ΠΈ ΡΠ²Π»ΡΡΡΡΡ ΠΎΡΠ»ΠΈΡΠ½ΠΎΠΉ ΠΏΠ»ΠΎΡΠ°Π΄ΠΊΠΎΠΉ Π΄Π»Ρ ΠΏΡΠΎΠ΄Π²ΠΈΠΆΠ΅Π½ΠΈΡ ΡΠΎΠ²Π°ΡΠΎΠ² ΠΈ ΡΡΠ»ΡΠ³
Two-Photon Doppler cooling of alkaline-earth-metal and ytterbium atoms
A new possibility of laser cooling of alkaline-earth-metal and Ytterbium
atoms using a two-photon transition is analyzed. We consider a -
transition, with excitation in near resonance with the
level. This greatly increases the two-photon transition rate, allowing an
effective transfer of momentum. The experimental implementation of this
technique is discussed and we show that for Calcium, for example, two-photon
cooling can be used to achieve a Doppler limit of 123 microKelvin. The
efficiency of this cooling scheme and the main loss mechanisms are analyzed.Comment: 7 pages, 5 figure
Experimental demonstration of ground state laser cooling with electromagnetically induced transparency
Ground state laser cooling of a single trapped ion is achieved using a
technique which tailors the absorption profile for the cooling laser by
exploiting electromagnetically induced transparency in the Zeeman structure of
a dipole transition. This new method is robust, easy to implement and proves
particularly useful for cooling several motional degrees of freedom
simultaneously, which is of great practical importance for the implementation
of quantum logic schemes with trapped ions.Comment: 4 pages, 4 figure
Laser Cooling of two trapped ions: Sideband cooling beyond the Lamb-Dicke limit
We study laser cooling of two ions that are trapped in a harmonic potential
and interact by Coulomb repulsion. Sideband cooling in the Lamb-Dicke regime is
shown to work analogously to sideband cooling of a single ion. Outside the
Lamb-Dicke regime, the incommensurable frequencies of the two vibrational modes
result in a quasi-continuous energy spectrum that significantly alters the
cooling dynamics. The cooling time decreases nonlinearly with the linewidth of
the cooling transition, and the effect of trapping states which may slow down
the cooling is considerably reduced. We show that cooling to the ground state
is possible also outside the Lamb-Dicke regime. We develop the model and use
Quantum Monte Carlo calculations for specific examples. We show that a rate
equation treatment is a good approximation in all cases.Comment: 13 pages, 10 figure
Motional sidebands and direct measurement of the cooling rate in the resonance fluorescence of a single trapped ion
Resonance fluorescence of a single trapped ion is spectrally analyzed using a
heterodyne technique. Motional sidebands due to the oscillation of the ion in
the harmonic trap potential are observed in the fluorescence spectrum. From the
width of the sidebands the cooling rate is obtained and found to be in
agreement with the theoretical prediction.Comment: 4 pages, 4 figures. Final version after minor changes, 1 figure
replaced; to be published in PRL, July 10, 200
Thoracic Impedance as a Potential Indicator of Gz-induced Presyncope
We investigated fluid shifts and regulatory responses to variations of posture, exercise, Gz level and radius of rotation in subjects riding NASA Ames 20G centrifuge. Results are from 4 protocols that address radius and exercise effects only. Protocol A: After 10 min supine control, 12 healthy men (35 9 yr, 82.8 7.9 kg) were exposed to rotational 1 Gz (2.5 m radius) for 2 min followed by 20 min alternating between 1 and 1.25 Gz. Blood samples were taken pre and post spin. Protocol B: Same as A, but lower limb exercise (70% V02max) preceded ramps to 1.25 Gz. Protocol C: Same as A but radius of rotation 8.3 m. Protocol D: Same as B but at 8.3 m. The 8 subjects who completed all protocols, increased heart rate (HR) from control by: A: 5, B: 39, C: 11, D: 44 bpm; and the 4 who did not: A: 6, B: 35, C: 20, D: 50 bpm. For thoracic fluid volume, (bioimpedance), the 8 subjects changed from control: A: -394, B: -548, C: -537, D: -708 mL; and the 4: A: -516, B: -652, C: -583, D: -1263 mL. The 4 subjects lost more thoracic fluid volume than the 8, especially in protocol D. A slightly greater increase in HR for the 4 compared to the 8 was not adequate to maintain cardiac output during D. Our data support the concept that thoracic impedance can detect inability to return adequate fluid to the heart, thereby predicting presyncope
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