415 research outputs found
Low back pain and psychosocial factors are not predictive of future pain impact in hip and knee osteoarthritis
Testing the gravitational field generated by a quantum superposition
What gravitational field is generated by a massive quantum system in a spatial superposition? Despite decades of intensive theoretical and experimental research, we still do not know the answer. On the experimental side, the difficulty lies in the fact that gravity is weak and requires large masses to be detectable. However, it becomes increasingly difficult to generate spatial quantum superpositions for increasingly large masses, in light of the stronger environmental effects on such systems. Clearly, a delicate balance between the need for strong gravitational effects and weak decoherence should be found. We show that such a trade off could be achieved in an optomechanics scenario that allows to witness whether the gravitational field generated by a quantum system in a spatial superposition is in a coherent superposition or not. We estimate the magnitude of the effect and show that it offers perspectives for observability
Non-interferometric test of the Continuous Spontaneous Localization model based on rotational optomechanics
The Continuous Spontaneous Localization (CSL) model is the best known and
studied among collapse models, which modify quantum mechanics and identify the
fundamental reasons behind the unobservability of quantum superpositions at the
macroscopic scale. Albeit several tests were performed during the last decade,
up to date the CSL parameter space still exhibits a vast unexplored region.
Here, we study and propose an unattempted non-interferometric test aimed to
fill this gap. We show that the angular momentum diffusion predicted by CSL
heavily constrains the parametric values of the model when applied to a
macroscopic object
The pattern of breathing and chest wall movements at different levels of pressure support and PEEP
Comparison of the P/V curve obtained by the supersyringe and the optoelectronic plethysmography
Nonequilibrium Quantum Thermodynamics of a Particle Trapped in a Controllable Time-Varying Potential
Many advanced quantum techniques feature non-Gaussian dynamics, and the ability to manipulate the system in that domain is the next stage in many experiments. One example of meaningful non-Gaussian dynamics is that of a double-well potential. Here we study the dynamics of a levitated nanoparticle undergoing the transition from a harmonic potential to a double well in a realistic setting, subjected to both thermalization and localization. We characterize the dynamics of the nanoparticle from a thermodynamic point of view, investigating the dynamics with the Wehrl entropy production and its rates. Furthermore, we investigate coupling regimes where the the quantum effect and thermal effect are of the same magnitude, and look at suitable squeezing of the initial state that provides the maximum coherence. The effects and the competitions of the unitary and the dissipative parts onto the system are demonstrated. We quantify the requirements to relate our results to a bonafide experiment with the presence of the environment, and discuss the experimental interpretations of our results in the end
Contribution of red blood cells to the compensation for hypocapnic alkalosis through plasmatic strong ion difference variations
Introduction Chloride shift is the movement of chloride between red
blood cells (RBC) and plasma (and vice versa) caused by variations in
pCO2. The aim of our study was to investigate changes in plasmatic
strong ion diff erence (SID) during acute variations in pCO2 and their
possible role in the compensation for hypocapnic alkalosis.Methods Patients admitted in this year to our ICU requiring extracorporeal
CO2 removal were enrolled. Couples of measurements
of gases and electrolytes on blood entering (v) and leaving (a) the
respiratory membrane were analyzed. SID was calculated as [Na+]
+ [K+] + 2[Ca2+] \u2013 [Cl\u2013] \u2013 [Lac\u2013]. Percentage variations in SID (SID%)
were calculated as (SIDv \u2013 SIDa) x 100 / SIDv. The same calculation was
performed for pCO2 (pCO2%). Comparison between v and a values was
performed by paired t test or the signed-rank test, as appropriate.
Results Analysis was conducted on 205 sample-couples of six enrolled
patients. A signifi cant diff erence (P <0.001) between mean values of
v\u2013a samples was observed for pH (7.41 \ub1 0.05 vs. 7.51 \ub1 0.06), pCO2
(48 \ub1 6 vs. 35 \ub1 7 mmHg), [Na+] (136.3 \ub1 4.0 vs. 135.2 \ub1 4.0 mEq/l), [Cl\u2013]
(101.5 \ub1 5.3 vs. 102.8 \ub1 5.2 mEq/l) and therefore SID (39.5 \ub1 4.0 vs.
36.9 \ub1 4.1 mEq/l). pCO2% and SID% signifi cantly correlated (r2 = 0.28,
P <0.001). Graphical representation by quartiles of pCO2% is shown in
Figure 1.
Conclusions As a reduction in SID decreases pH, the observed
movement of anions and cations probably limited the alkalinization
caused by hypocapnia. In this model, the only source of electrolytes
are blood cells (that is, no interstitium and no infl uence of the kidney
is present); it is therefore conceivable to consider the observed
phenomenon as the contribution of RBC for the compensation of acute
hypocapnic alkalosi
- …