Ultracold Temperatures Research Articles

Velocity Scanning Tomography for Room-Temperature Quantum Simulation.

Quantum simulation offers an analog approach for exploring exotic quantum phenomena using controllable platforms, typically necessitating ultracold temperatures to maintain the quantum coherence. Superradiance lattices (SLs) have been harnessed to simulate coherent topological physics at room temperature, but the thermal motion of atoms remains a notable challenge in accurately measuring the physical quantities. To overcome this obstacle, we implement a velocity scanning tomography technique to discern the responses of atoms with different velocities, allowing cold-atom spectroscopic resolution within room-temperature SLs. By comparing absorption spectra with and without atoms moving at specific velocities, we can derive the Wannier-Stark ladders of the SL across various effective static electric fields, their strengths being proportional to the atomic velocities. We extract the Zak phase of the SL by monitoring the ladder frequency shift as a function of the atomic velocity, effectively demonstrating the topological winding of the energy bands. Our research signifies the feasibility of room-temperature quantum simulation and facilitates their applications in quantum information processing.

Emergence of subharmonics in a microwave driven dissipative Rydberg gas

Quantum many-body systems near phase transitions respond collectively to externally applied perturbations. We explore this phenomenon in a laser-driven dissipative Rydberg gas that is tuned to a bistable regime. Here two metastable phases coexist, which feature a low and high density of Rydberg atoms, respectively. The ensuing collective dynamics, which we monitor , is characterized by stochastic collective jumps between these two macroscopically distinct many-body phases. We show that the statistics of these jumps can be controlled using a dual-tone microwave field. In particular, we find that the distribution of jump times develops peaks corresponding to subharmonics of the relative microwave detuning. Our study demonstrates the control of collective statistical properties of dissipative quantum many-body systems without the necessity of fine-tuning or of ultracold temperatures. Such robust many-body phenomena may find technological applications in sensing. Published by the American Physical Society 2024

Raman Sideband Cooling of Molecules in an Optical Tweezer Array to the 3D Motional Ground State

Ultracold polar molecules are promising for quantum information processing and searches for physics beyond the standard model. Laser cooling to ultracold temperatures is an established technique for trapped diatomic and triatomic molecules. Further cooling of the molecules to near the motional ground state is crucial for reducing various dephasings in quantum and precision applications. In this work, we demonstrate Raman sideband cooling (RSC) of CaF molecules in optical tweezers to near their motional ground state, with average motional occupation quantum numbers of n¯x=0.16(12), n¯y=0.17(17) (radial directions), and n¯z=0.22(16) (axial direction), and a 3-D motional-ground-state probability of 54±18% of the molecules that survive the RSC. This process paves the way to increase molecular coherence times in optical tweezers for robust quantum computation and simulation applications. Published by the American Physical Society 2024

Dual Optical Cycling Centers Mounted on an Organic Scaffold: New Insights from Quantum Chemistry Calculations and Symmetry Analysis.

Molecules cooled to ultracold temperatures are desirable for applications in fundamental physics and quantum information science. However, cooling polyatomic molecules with more than six atoms has not yet been achieved. Building on the idea of an optical cycling center (OCC), a moiety supporting a set of localized and isolated electronic states within a polyatomic molecule, molecules with two OCCs (bi-OCCs) may afford better cooling efficiency by doubling the photon scattering rate. By using quantum chemistry calculations, we assess the extent of the coupling of the two OCCs with each other and the molecular scaffold. We show that promising coolable bi-OCC molecules can be proposed by following chemical design principles.

Cold and ultra-cold chain integrity monitoring via embedded resonant sensor indicators

An increasing number of products require transport at cold and ultra-cold temperatures, < 5 and −60°C respectively. Time-temperature indicators (TTIs) are used to monitor the integrity of the cold chain, however, they are frequently based on colorimetric changes that can be inaccurate for quantification and not possible to read through closed shipment materials. Here, TTIs were prototyped using microfluidic channels containing fluids (oils) that are tuned to melt above target temperatures. By coupling these TTIs to resonant sensors, the time-temperature information can be transmitted wirelessly and quantitatively by observing shifts in resonant frequency. Multiplexed TTIs containing fluids that melt at 9, 13.5, and 19.5°C are demonstrated. When coupled to the resonant sensor, the fluid flows as the temperature increases incrementally and generates a frequency shift of 3.5, 4.5, and 6 MHz at each threshold. TTI for ultra-cold environments were also designed using microfluidic channels with melt responsive fluids (ethanol). The resonant sensor coupled TTI was placed in a Styrofoam container containing dry ice, and over 1 MHz frequency shift is observed when read external to the container as the dry ice evaporates and the temperature exceeds −35°C. This augurs potential uses in inexpensive monitoring of food and pharmaceutical shipments that must remain cold for adequate quality.

Collisional cooling of a Fermi gas with three-body recombination

Evaporative cooling stands as the prevailing method for achieving ultracold temperatures in atomic systems. Current schemes of evaporation selectively remove the hotter atoms near the edge of the trap, as the hotter and colder atoms are distributed in different spatial regions of the trapping potential. However, a long-standing goal is to directly remove the higher momentum atoms, irrespective of their spatial distribution. For this purpose, we demonstrate collisional cooling for a 6Li Fermi gas through inelastic three-body recombination near a narrow Feshbach resonance. Such three-body recombination can induce either heating or cooling effects, and the decay of the quasi-bound Feshbach molecule stirs the hotter atoms away from the trapping potential. When the threshold energy of the Feshbach molecule exceeds the atom’s average kinetic energy of 3/2kBT, the cooling effect becomes more pronounced. Finally, we observe strong temperature dependence in this collisional cooling process, with greater efficiency achieved at lower temperatures.

Toughening epoxy by nano-structured block copolymer to mitigate matrix microcracking of carbon fibre composites at cryogenic temperatures

The incorporation of rigid nanoparticles has proven to enhance microcracking resistance in carbon fibre reinforced polymer (CFRP) composites at cryogenic temperatures, enabling CFRP tanks to store cryogenic liquid like hydrogen without requiring liners. Herein, we investigate efficacy of low-modulus soft nanoparticles in addressing the microcracking challenges inherent in CFRP at cryogenic temperatures. By incorporating a tri-block copolymer (BCP) into an epoxy, nano-structured fillers with an average diameter of approximately 100 nm are formed. Experimental results reveal that, at a 2.5 wt% loading, the BCP significantly increase the fracture energy of the nanocomposite by 392% at −196 °C while maintaining stiffness and strength. More importantly, composite laminates made with the BCP-modified nanocomposite matrix can withstand cryogenic temperatures without matrix microcracking, even when they contain multiple plies with the same orientation, such as [04/904]s, which are known to be highly susceptible to matrix microcracking at cryogenic temperatures. An advanced high-fidelity micromechanical model revealed that the observed toughening effect of nanostructured block copolymer at cryogenic temperatures can be attributed to the increased fracture resistance of the nanocomposite matrix. The findings of this research demonstrate that low concentration of block copolymer can effectively mitigate the initiation and propagation of matrix microcracks in carbon fibre composites at ultra-cold temperatures.

Walking with the Atoms in a Chemical Bond: A Perspective Using Quantum Phase Transition.

Phase transitions happen at critical values of the controlling parameters, such as the critical temperature in classical phase transitions, and system critical parameters in the quantum case. However, true criticality happens only at the thermodynamic limit, when the number of particles goes to infinity with constant density. To perform the calculations for the critical parameters, a finite-size scaling approach was developed to extrapolate information from a finite system to the thermodynamic limit. With the advancement in the experimental and theoretical work in the field of ultra-cold systems, particularly trapping and controlling single atomic and molecular systems, one can ask: do finite systems exhibit quantum phase transition? To address this question, finite-size scaling for finite systems was developed to calculate the quantum critical parameters. The recent observation of a quantum phase transition in a single trapped 171 Yb+ ion indicates the possibility of quantum phase transitions in finite systems. This perspective focuses on examining chemical processes at ultra-cold temperatures, as quantum phase transitions-particularly the formation and dissociation of chemical bonds-are the basic processes for understanding the whole of chemistry.

The Assessment of a Novel Endoscopic Ultrasound-Compatible Cryocatheter to Ablate Pancreatic Cancer.

Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal disease that may be treated utilizing thermal therapies. Cryoablation is an effective, minimally invasive therapy that has been utilized for the treatment of various cancers, offering patients a quicker recovery and reduced side effects. Cryoablation has been utilized on a limited basis for the treatment of PDAC. With the recent reports on the success of cryoablation, there is a growing interest in the use of cryoablation as a standalone, minimally invasive procedure to treat PDAC. While offering a promising path, the application of cryoablation to PDAC is limited by current technologies. As such, there is a need for the development of new devices to support advanced treatment strategies for PDAC. To this end, this study investigated the performance of a new endoscopic ultrasound-compatible cryoablation catheter technology, FrostBite. We hypothesized that FrostBite would enable the rapid, effective, minimally invasive delivery of ultra-cold temperatures to target tissues, resulting in effective ablation via an endoscopic approach. Thermal properties and ablative efficacy were evaluated using a heat-loaded gel model, tissue-engineered models (TEMs), and an initial in vivo porcine study. Freeze protocols evaluated included single and repeat 3 and 5 min applications. Isotherm assessment revealed the generation of a 2.2 cm diameter frozen mass with the -20 °C isotherm reaching a diameter of 1.5 cm following a single 5 min freeze. TEM studies revealed the achievement of temperatures ≤ -20 °C at a diameter of 1.9 cm after a 5 min freeze. Fluorescent imaging conducted 24 h post-thaw demonstrated a uniformly shaped ellipsoidal ablative zone with a midline diameter of 2.5 cm, resulting in a total ablative volume of 6.9 cm3 after a single 5 min freeze. In vivo findings consistently demonstrated the generation of ablative areas measuring 2.03 cm × 3.2 cm. These studies demonstrate the potential of the FrostBite cryocatheter as an endoscopic ultrasound-based treatment option. The data suggest that FrostBite may provide for the rapid, effective, controllable freezing of cancerous pancreatic and liver tissues. This ablative power also offers the potential of improved safety margins via the minimally invasive nature of an endoscopic ultrasound-based approach or natural orifice transluminal endoscopic surgery (NOTES)-based approach. The results of this pre-clinical feasibility study show promise, affirming the need for further investigation into the potential of the FrostBite cryocatheter as an advanced, minimally invasive cryoablative technology.

Effect of temperature on the gas-phase reaction of CH3CN with OH radicals: experimental (T = 11.7-177.5 K) and computational (T = 10-400 K) kinetic study.

Acetonitrile (CH3CN) is present in the interstellar medium (ISM) in a variety of environments. However, at the ultracold temperatures of the ISM, radical-molecule reactions are not widely investigated because of the experimental handicap of getting organic molecules in the gas phase by conventional techniques. The CRESU (French acronym for Reaction Kinetics in a Uniform Supersonic Flow) technique solves this problem. For this reason, we present in this work the kinetic study of the gas-phase reaction of CH3CN with one of the most ubiquitous radicals, the hydroxyl (OH) radical, as a function of temperature (11.7-177.5 K). The kinetic technique employed to investigate the CH3CN + OH reaction was the pulsed laser photolysis-laser induced fluorescence. The rate coefficient for this reaction k(T) has been observed to drastically increase from 177.5 K to 107.0 K (about 2 orders of magnitude), while the increase in k(T) from 107.0 K to 11.7 K was milder (around 4 times). The temperature dependent expressions for k(T) are provided in the two distinct T-ranges, excluding the upper limit obtained for k(177.5 K): In addition, the rate coefficients estimated by the canonical competitive unified statistical (CCUS) theory show a similar behaviour to the experimental results, when evaluated within the high-pressure limit. This is consistent with the experimentally observed independence of k(T) with total gas density at selected temperatures. Astrochemical networks, such as the KIDA database or UMIST, do not include the CH3CN + OH reaction as a potential depletion process for acetonitrile in the ISM because the current studies predict very low rate coefficients at IS temperatures. According to the model (T = 10 K), the impact of the titled reaction on the abundances of CH3CN appears to be negligible in dark molecular clouds of the ISM (∼1% of the total depletion reactions included in UMIST network). With respect to the potential formation of the CH2CN radical in those environments, even in the most favourable scenario, where this radical could be formed in a 100% yield from the CH3CN + OH reaction, this route would only contribute around 2% to the current assumed formation routes by the UMIST network.

Monte Carlo Simulation for the Frequency Comb Spectrum of an Atom Laser

A theoretical particle-number conserving quantum field theory based on the concept of imaginary time is presented and applied to the scenario of a coherent atomic laser field at ultra-cold temperatures. The proposed theoretical model describes the analytical derivation of the frequency comb spectrum for an atomic laser realized from modeling a coherent atomic beam of condensate and non-condensate quantum field components released from a trapped Bose–Einstein condensate at a given repetition phase and frequency. The condensate part of the atomic vapor is assumed to be subjected to thermal noise induced by the temperature of the surrounding thermal atomic cloud. This new quantum approach uses time periodicity and an orthogonal decomposition of the quantum field in a complex-valued quantum field representation to derive and model the quantum field's forward- and backward-propagating components as a standing wave field in the same unique time and temperature domain without quantitative singularities at finite temperatures. The complex-valued atom laser field, the resulting frequency comb, and the repetition frequency distribution with the varying shape of envelopes are numerically monitored within a Monte Carlo sampling method, as a function of temperature and trap frequency of the external confinement.Quanta 2023; 12: 171–179.

Self-induced transparency in a semiconductor quantum dot medium at ultracold temperatures

We investigate the feasibility of minimum absorption and minimum broadening of pulse propagation in an inhomogeneously broadened semiconductor quantum dot medium. The phonon interaction is inevitable in studying any semiconductor quantum dot system. We have used the polaron transformation technique to deal with quantum dot phonon interaction in solving system dynamics. We demonstrate that a short pulse can propagate inside the medium with minimal absorption and broadening in pulse shape. The stable pulse area becomes slightly higher than the prediction of the pulse area theorem and is also dependent on the environment temperature. The change in the final pulse shape is explained very well by numerically solving the propagation equation supported by the susceptibility of the medium. Our system also exhibits the pulse breakup phenomena for higher input pulse areas. Therefore, the considered scheme can have important applications in quantum communication, quantum information, and mode-locking with the advantage of scalability and controllability.

Sticking Lifetime of Ultracold CaF Molecules in Triplet Interactions.

A six-dimensional potential energy surface is constructed for the spin-polarized triplet state of CaF-CaF by ab initio calculations at the CCSD(T) level of theory, followed by Gaussian process interpolation. The potential is utilized to calculate the density of states for this bialkaline-earth-halogen system where we find the value 0.038 μK-1, implying a mean resonance spacing of 26 μK in the collision complex. This value implies an associated Rice-Ramsperger-Kassel-Marcus lifetime of 1.8 μs, thus predicting long-lived complexes in collisions at ultracold temperatures.

Full-dimensional quantum mechanical study of three-body recombination for cold 4He-4He-20Ne system.

The increase of the number of the two-body recombination channels strongly challenges the numerical calculation of the accurate rates for the three-body recombination (TBR) process and its reverse process, collision-induced dissociation (CID), at ultracold temperatures. By taking the 4He-4He-20Ne collision system as an example, we have obtained the rates for its TBR and CID processes involving all four recombination channels, including the two-body states 4He2 (l = 0) and 4He20Ne (l = 0, 1, 2) with l the rotational quantum number. By using the adiabatic hyperspherical method, we have considered not only total angular momentum J = 0 but also J > 0 in the ultracold collision energies (E = 0.01 - 100mK × kB). It is found that 4He2 (l = 0) is the major product after the TBR process in the ultracold limit (E ≤ 0.1mK × kB). The TBR rate into 4He2 (l = 0) is nearly one order of magnitude larger than the sum of the other three products, 4He20Ne (l = 0, 1, 2). Moreover, the CID rates for the three 4He20Ne (l = 0, 1, 2) + 4He initial states are close to each other and are smaller than that for the 4He2 (l = 0) + 20Ne initial state. Additionally, we have, for the first time, performed the channel-resolved scattering calculation that can explain the above-mentioned findings quantitatively.

MP14-01 EVALUATION OF A NOVEL CYSTOSCOPIC CRYOCATHETER FOR THE IN SITU DESTRUCTION OF BLADDER CANCER

You have accessJournal of UrologyCME1 Apr 2023MP14-01 EVALUATION OF A NOVEL CYSTOSCOPIC CRYOCATHETER FOR THE IN SITU DESTRUCTION OF BLADDER CANCER Anthony Corcoran, Aaron Katz, Anthony Robilotto, Kristi Snyder, Kimberly Santucci, Robert VanBuskirk, John G. Baust, and John Baust Anthony CorcoranAnthony Corcoran More articles by this author , Aaron KatzAaron Katz More articles by this author , Anthony RobilottoAnthony Robilotto More articles by this author , Kristi SnyderKristi Snyder More articles by this author , Kimberly SantucciKimberly Santucci More articles by this author , Robert VanBuskirkRobert VanBuskirk More articles by this author , John G. BaustJohn G. Baust More articles by this author , and John BaustJohn Baust More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003234.01AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: There is a pressing need for the development of new devices facilitating advanced minimally invasive approaches for the in situ treatment of bladder cancer (BC). To this end, a new cystoscopic compatible cryocatheter (UroAblate) has been developed. When paired with the novel Pressurized Subcooled Nitrogen (PSN) cryoconsole, the cryocatheter delivers ultracold ablative temperatures to a targeted tissue in a closed loop manner. In this study, we evaluated cryocatheter performance for its potential use for cystoscopic in situ ablation BC. METHODS: A ∼1 m cryocatheter with a distal 1.5 cm ablation tip (connected to PSN) was passed through the working channel of a Ambu cystoscope. A laparoscopic approach was also utilized to visualize the transmural extension of the ice propagation. Evaluations included a 37°C ultrasound gel model, tissue engineered BC model and a chronic porcine study (4 animals, 7 day survival) wherein 10 lesions/animal were created throughout the bladder (bladder wall, trigone region, UO and distal ureter). Performance assessment included ice ball size, isotherm profile and destruction area. Single and double 0.5, 1, 1.5 and 2 min freeze protocols were evaluated. RESULTS: Bench studies demonstrated the generation of a 1.6cm iceball and the penetration of the -20°C isotherm to 0.87 cm following 2 mins. Analysis of tissue destruction using a BC tumor model revealed the creation of a 350 mm3 and 448 mm3 ablated volume following a single or double 2 min freeze, respectively. Porcine studies demonstrated the consistent generation of transmural lesions following freezing (single or double) for ≥1.5 min regardless of tissue thickness (range: 0.4 cm to 1.2 cm). All animals were found to have good overall health (maintained weight, appetite, mobility, energy levels, etc.) through the recovery period. No significant deviations were noted in CBC and serum chemistry bloodwork with the exception of elevated Creatine Kinase levels. Importantly, no fistulas or bowel/bladder perforations were noted in any animals. CONCLUSIONS: This study demonstrated that the cryocatheter was able to rapidly and effectively freeze targeted tissue via a cystoscopic approach. The results showed the device was able to consistently ablate a >1 cm area using a single 2 minute freeze protocol across all models. Analysis of the ablation efficacy revealed ∼80% destruction within the overall frozen mass. Although further testing and refinement are needed, these studies demonstrated the potential of this new approach to provide a next-generation strategy for the treatment of BC. Source of Funding: National Institutes of Health National Cancer Institute Grant No. 1R43CA210761-01A1 awarded to CPSI Biotech © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e182 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Anthony Corcoran More articles by this author Aaron Katz More articles by this author Anthony Robilotto More articles by this author Kristi Snyder More articles by this author Kimberly Santucci More articles by this author Robert VanBuskirk More articles by this author John G. Baust More articles by this author John Baust More articles by this author Expand All Advertisement PDF downloadLoading ...

Electronic spectroscopy and ionization potentials for YbOH and YbOCH3

The polyatomic molecules YbOH and ${\mathrm{YbOCH}}_{3}$ have been recognized as being of potential value for spectroscopic experiments that explore charge-parity and time-reversal symmetry violation effects. These measurements require very high precision, which, in turn, will necessitate that the molecules be manipulated at ultracold temperatures. Both YbOH and ${\mathrm{YbOCH}}_{3}$ have electronic transitions that appear suitable for laser cooling ($\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{A}{\phantom{\rule{0.16em}{0ex}}}^{2}{\mathrm{\ensuremath{\Pi}}}_{1/2}\text{\ensuremath{-}}\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{X}{\phantom{\rule{0.16em}{0ex}}}^{2}{\mathrm{\ensuremath{\Sigma}}}^{+}$ and $\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{A\phantom{\rule{4pt}{0ex}}}{\phantom{\rule{0.16em}{0ex}}}^{2}{E}_{1/2}\text{\ensuremath{-}}\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{X}{\phantom{\rule{0.16em}{0ex}}}^{2}{A}_{1}$, respectively) but the currently available spectroscopic data are not sufficient to determine the extent to which population leaks may compromise the optical cooling processes. A further complication is that the quantum states of interest for these measurements will need to be selectively populated. The $\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{A}\text{--}\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{X}$ band systems of both YbOH and ${\mathrm{YbOCH}}_{3}$ show evidence of vibronic perturbations, such that there are unassigned vibronic features at energies that are just above the origin bands. In the present study we have recorded spectra for the $\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{A}$ ${}^{2}{\mathrm{\ensuremath{\Pi}}}_{1/2}\text{\ensuremath{-}}\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{X}{\phantom{\rule{0.16em}{0ex}}}^{2}{\mathrm{\ensuremath{\Sigma}}}^{+}$ transition of jet-cooled YbOD to facilitate the vibronic assignments. In addition, spectra for the $\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{B}{\phantom{\rule{0.16em}{0ex}}}^{2}{\mathrm{\ensuremath{\Sigma}}}^{+}\text{\ensuremath{-}}\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{X}{\phantom{\rule{0.16em}{0ex}}}^{2}{\mathrm{\ensuremath{\Sigma}}}^{+}$ transition of YbOH were recorded, establishing the origin band at 20 473.8 $\mathrm{c}{\mathrm{m}}^{\ensuremath{-}1}$. Previously, the reaction of Yb with ${\mathrm{CH}}_{3}\mathrm{OH}$ has been used to generate gas-phase ${\mathrm{YbOCH}}_{3}$. As this reaction also yields YbOH, there have been complications in spectroscopic studies of ${\mathrm{YbOCH}}_{3}$ due to overlap of the $\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{A}\text{--}\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{X}$ band systems. To identify specific regions of overlap, resonantly enhanced two-photon ionization spectra were recorded using mass-resolved detection of the $\mathrm{YbO}{\mathrm{H}}^{+}$ and ${\mathrm{YbOCH}}_{3}^{+}$ ions. These data confirmed the overlap of vibronic bands near 17 640 and 17 680 $\mathrm{c}{\mathrm{m}}^{\ensuremath{-}1}$. Two-photon ionization spectroscopy also provided accurate ionization energies (IE), $\mathrm{IE}(\mathrm{YbOH})=45\phantom{\rule{0.16em}{0ex}}788(10)$ and $\mathrm{IE}({\mathrm{YbOCH}}_{3})=45\phantom{\rule{4pt}{0ex}}283(10)\phantom{\rule{0.16em}{0ex}}\mathrm{c}{\mathrm{m}}^{\ensuremath{-}1}$. The IE for YbOH is relevant to problems encountered in previous attempts to determine the bond-dissociation energy of $\mathrm{YbO}{\mathrm{H}}^{+}$.

Association between the temperature difference and acute exacerbations of chronic obstructive pulmonary disease: A time-series analysis with 143,318 hospital admissions in Beijing, China.

Acute exacerbation of chronic obstructive pulmonary disease (AECOPD) has the adverse influence on quality of life and creates significant healthcare costs. However, there were sparse studies investigating the correlation between AECOPD hospital admissions and temperature change. Therefore, it is noteworthy to investigate the impact of various temperature differences and recognize the susceptible population. The purpose of this study was to investigate the impact of temperature differences on AECOPD hospital admissions, and to give potentially helpful material for disease preventative efforts. The distributed lag non-linear model was adopted to characterize the exposure-response relationship and to assess the impact of temperature difference. The stratified analysis and sensitivity analysis were also conducted to determine the susceptible populations and examine the robustness of the results. There were 143,318 AECOPD hospital admissions overall during the study period. The AECOPD hospital admissions had significant association with the daily mean temperature difference (DTDmean) such as the extreme-cold temperature difference (1st DTDmean), the ultra-cold temperature difference (5th DTDmean), the ultra-hot temperature difference (95th DTDmean) and the extreme-hot temperature difference (99th DTDmean). Besides, there was the "U-shaped" association between DTDmean and 21 days cumulative relative risk of AECOPD. The AECOPD hospital admissions was correlated with the DTDmean temperature differences, especially the extreme-cold and extreme-hot temperature difference. Moreover, people older than 65 years were more susceptible to the extreme-hot and extreme-cold temperature difference.

Tapered LADs: Acquiring Cryogenic Liquid Propellants in Deep Space

To carry out complex manoeuvres such as orbit insertion, large spacecraft on long voyages must carry tanks of liquid propellants, kept at ultra-cold temperatures. In existing designs, however, heat leaking into these tanks can form unwanted vapour bubbles in the channels required to extract their contents – which are especially difficult to remove in the microgravity environment of deep space. In their research, a team at the Southwest Research Institute presents a simple solution to this problem – through which the sides of these extraction channels are tapered, allowing vapour bubbles to escape. Results from recent microgravity testing of this technology could lead to exciting new opportunities for future space missions.

Accelerated motional cooling with deep reinforcement learning

A proposed machine-learning-based method demonstrates how artificial controllers can be used to discover nonintuitive, intelligent pulse sequences that can cool a mechanical object from a high temperature to the quantum regime at ultracold temperatures faster than other standard methods, showing the utility of artificial machine intelligence in the development of quantum technologies.

Solitary waves explore the quantum-to-classical transition

How the classical appearance of our environment arises from the underlying quantum many-body theory is an open fundamental question. We propose that phenomena involved in the quantum-to-classical transition can be probed in collisions of bright solitary waves in Bose-Einstein condensates, where thousands of atoms form a large compound object at ultra cold temperatures. For the experimentally most relevant quasi-1D regime, where integrability is broken through effective three-body interactions, we find that ensembles of solitary waves exhibit complex interplay between phase coherence and entanglement generation in beyond mean-field simulations using the truncated Wigner method: An initial state of two solitons with a well-defined relative phase looses that phase coherence in the ensemble, with its single-particle two-mode density matrix exhibiting similar dynamics as a decohering two-mode superposition. This apparent decoherence is a prerequisite for the formation of entangled superpositions of different atom numbers in a subsequent soliton collision. The necessity for the solitons to first decohere is explained based on the underlying phase-space of the quintic mean-field equation. We show elsewhere that superpositions of different atom numbers later further evolve into spatially entangled solitons. Loss of ensemble phase coherence followed by system internal entanglement generation appear in an unusual order in this closed system, compared to a typical open quantum system.