Extended Phase Research Articles

An extended phase graph-based framework for DANTE-SPACE simulations including physiological, temporal, and spatial variations.

The delay alternating with nutation for tailored excitation (DANTE)-sampling perfection with application-optimized contrasts (SPACE) sequence facilitates 3D intracranial vessel wall imaging with simultaneous suppression of blood and CSF. However, the achieved image contrast depends closely on the selected sequence parameters, and the clinical use of the sequence is limited in vivo by observed signal variations in the vessel wall, CSF, and blood. This paper introduces a comprehensive DANTE-SPACE simulation framework, with the aim of providing a better understanding of the underlying contrast mechanisms and facilitating improved parameter selection and contrast optimization. An extended phase graph formalism was developed for efficient spin ensemble simulation of the DANTE-SPACE sequence. Physiological processes such as pulsatile flow velocity variation, varying flow directions, intravoxel velocity variation, diffusion, and effects were included in the framework to represent the mechanisms behind the achieved signal levels accurately. Intravoxel velocity variation improved temporal stability and robustness against small velocity changes. Time-varying pulsatile velocity variation affected CSF simulations, introducing periods of near-zero velocity and partial rephasing. Inclusion of diffusion effects was found to substantially reduce the CSF signal. Blood flow trajectory variations had minor effects, but differences along the trajectory reduced DANTE efficiency in low- areas. Introducing low-velocity pulsatility of both CSF and vessel wall helped explain the in vivo observed signal heterogeneity in both tissue types. The presented simulation framework facilitates a more comprehensive optimization of DANTE-SPACE sequence parameters. Furthermore, the simulation framework helps to explain observed contrasts in acquired data.

Comparing a fecal immunochemical test and circulating tumor DNA blood test for colorectal cancer screening adherence.

Colorectal cancer (CRC) screening programs are most effective at reducing disease incidence and mortality through sustained screening participation. A novel blood test modality is being explored for CRC screening, but it is unclear whether it will provide sustained screening participation. This study aimed to investigate whether a circulating tumor DNA (ctDNA) blood test improved CRC screening re-participation when compared with a fecal immunochemical test (FIT) and to define the predictors of sustained CRC screening in an Australian population. South Australians who initially participated in CRC screening using a ctDNA blood test (n=36) or FIT (n=547) were offered the same CRC screening test approximately 2years later through an extended phase of a randomized controlled trial. Surveys collected demographic, psychosocial, and clinical information. Predictors of CRC screening re-participation were explored using chi-square, Wilcoxon tests, and logistic regression. Participants offered a second ctDNA blood test were equally likely to re-participate in CRC screening as those who completed a FIT in the first round and who were offered the same test (61% vs 66% re-participation respectively, P=0.6). CRC fatalism, health activation, and self-efficacy were associated with repeated screening participation. Test awareness was predictive of repeated FIT-based CRC screening. Targeted interventions to improve CRC screening awareness and increase patient health activation may improve CRC screening adherence. A ctDNA blood test may be a suitable CRC screening option to maintain CRC screening adherence in people who do not participate in screening with FIT.

Investigation of the benefits of the oxazolidinium cation for plastic crystal and ionic liquid electrolytes

Organic ionic plastic crystals (OIPCs) are promising for developing safer energy storage electrolytes. However, there remains a significant knowledge gap regarding how different cation-anion combinations influence their core properties, and cyclic ether-based cations have received limited attention. This study reports the synthesis and characterization of OIPCs based on the N-ethyl-N-methyl-oxazolidinium cation [C2moxa]+ and demonstrates the first instance of oxazolidinium OIPCs being combined with lithium salts to create electrolytes. The [C2moxa]+ cation was paired with [FSI]-, [TFSI]-, [BF4]-, [PF6]- and [FTFSI]- anions. A study of the thermal, transport and electrochemical properties was performed. Among the new salts developed, [C2moxa][BF4] exhibited the most promising characteristics, including the lowest entropy of melting (ΔS = 7 J mol−1 K−1), an extended phase I range (10°C–130°C), the highest conductivity of 8 x 10−6 S cm−1 at 30°C, and an electrochemical stability window of 4.8 V. When the [C2moxa][BF4] and [C2moxa][FSI] were mixed with lithium salts (10, 20 and 50 mol% Li+) of the same anion, the highest conductivity of 2 x 10−3 S cm−1 at 30°C was found for the 20 mol% LiFSI/[C2moxa][FSI] electrolyte. Finally, preliminary lithium plating/stripping experiments and coulombic efficiency (CE) measurements demonstrate stability for lithium cycling for all four [C2moxa]+ electrolytes.

Thermodynamics and Phase Transitions of Dyonic AdS Black Holes in Gauss-Bonnet-Scalar Gravity

In this paper, by treating the cosmological constant as a thermodynamic pressure, we study the thermodynamics and phase transitions of the dyonic AdS black holes in Gauss-Bonnet-Scalar gravity, where the conformal scalar field is considered. In a more general extended phase space, we first verified the first law of black hole thermodynamics, and find that it is always true. Meanwhile, the corresponding Smarr relation is also obtained. Then, we found that this black hole exhibits interesting critical behaviors in six dimensions, i.e., two swallowtails can be observed simultaneously. Interestingly, in a specific parameter space, we observed the small/intermediate/large black hole phase transitions, with the triple point naturally appearing. Additionally, the small/large black hole phase transition, similar to the liquid/gas phase transition of the van der Waals fluids, can also be found in other parameter regions. Moreover, we note that the novel phase structure composed of two separate coexistence curves discovered in the dyonic AdS black holes in Einstein-Born-Infeld gravity disappears in Gauss-Bonnet-Scalar gravity. This suggests that this novel phase structure may be related to gravity theory, and importantly, it is generally observed that the triple point is a universal property of dyonic AdS black holes. On the other hand, we calculated the critical exponents near the critical points and found that they share the same values as in mean field theory. Finally, it is true that these results will provide some deep insights into the interesting thermodynamic properties of the dyonic AdS black holes in the background of conformal scalar fields.

Optimization of flip angle and radiofrequency pulse phase to maximize steady-state magnetization in three-dimensional missing pulse steady-state free precession.

Missing pulse (MP) steady-state free precession (SSFP) is a magnetic resonance imaging (MRI) pulse sequence that is highly tolerant to the magnetic field inhomogeneity. In this study, optimal flip angle and radiofrequency (RF) phase scheduling in three-dimensional (3D) MP-SSFP is introduced to maximize the steady-state magnetization while keeping broadband excitation to cover widely distributed frequencies generated by inhomogeneous magnetic fields. Numerical optimization based on extended phase graph (EPG) simulation was performed to maximize the MP-SSFP steady-state magnetization. To limit the specific absorption rate (SAR) associated with the broadband excitation in 3D MP-SSFP, SAR constraint was introduced in the numerical optimization. Optimized flip angle and RF phase settings were experimentally tested by introducing a linear inhomogeneous magnetic field in a range of 10-20 mT/m and using a phantom with known T1/T2 relaxation and diffusion parameters at 3 T. The experimental results were validated through comparisons with EPG simulation. Image contrasts and molecular diffusion effects were investigated in in vivo human brain imaging with 3D MP-SSFP with the optimal flip angle and RF phase settings. In the phantom measurements, the optimal flip angle and RF phase settings improved the MP-SSFP steady-state magnetization/signal-to-noise ratio by up to 41% under the fixed SAR conditions, which matched well with EPG simulation results. In vivo brain imaging with the optimal RF pulse settings provided T2-like image contrasts. Diffusion effects were relatively minor with the linear inhomogeneous field of 10-20 mT/m for white and gray matter, but cerebrospinal fluid showed conspicuous signal intensity attenuation as the linear inhomogeneous field increased. Numerical optimization achieved significant improvement in the steady-state magnetization in MP-SSFP compared with the RF pulse settings used in previous studies. The proposed flip angle and RF phase optimization is promising to improve 3D MP-SSFP image quality for MRI in inhomogeneous magnetic fields.

Renormalized electric and magnetic charges for O(rn) large gauge symmetries

In this work we present the construction of a renormalized symplectic form on an extended phases space where the higher order large gauge transformations (LGT) act canonically. The expressions of the subn-leading electric charges associated with each O(rn) LGT are then obtained, in agreement with the expressions previously proposed in [1] by means of the tree-level subn-leading formulas. We also present the duality extension of the extended phase space, computing the full electromagnetic charge algebra, showing a tower of central extensions.

Crossed products, extended phase spaces and the resolution of entanglement singularities

We identify a direct correspondence between the crossed product construction which plays a crucial role in the theory of Type III von Neumann algebras, and the extended phase space construction which restores the integrability of non-zero charges generated by gauge symmetries in the presence of spatial substructures. This correspondence provides a blue-print for resolving singularities which are encountered in the computation of entanglement entropy for subregions in quantum field theories. The extended phase space encodes quantities that would be regarded as ‘pure gauge’ from the perspective of the full theory, but are nevertheless necessary for gluing together, in a path integral sense, physics in different subregions. These quantities are required in order to maintain gauge covariance under such gluings. The crossed product provides a consistent method for incorporating these necessary degrees of freedom into the operator algebra associated with a given subregion. In this way, the extended phase space completes the subregion algebra and subsequently allows for the assignment of a meaningful, finite entropy to states therein.

A high‐integration dual‐resonance element with independent frequency tuning for wideband reflectarrays

AbstractIn this letter, a novel design methodology of dual‐resonance elements for wideband reflectarrays is proposed for the first time. The alluring merits of this design lie in the compact common‐via dual‐resonance element with weak inner coupling and independent frequency tuning. To improve compactness, a traditional dipole is terminated by a metallic via connected to the ground plane. The element operates in monopole mode, decreasing the size by half. To realize a high‐integration dual‐resonance element, two monopoles operating at different frequencies are adopted to construct an asymmetric common‐via element, with an equivalent size to the traditional dipole resonating at merely one frequency. The first‐ever proposed element embodies superiorities of compactness, independent frequency tuning, and low profile. The proof‐of‐concept is validated by a fabricated reflectarray. The elaborately designed element with a compact size of 0.42 λ × 0.105 λ × 0.0737 λ exhibits an extended phase range of 484° at 14 GHz. The measured 3‐dB gain bandwidth is 36% (12.5–18 GHz) with a maximum gain of 26.9 dBi. The design strategy is capable of integrating more resonant structures in a compact area, rendering it suitable for broadband reflectarrays.

Analysis, Modeling and Cascade Operation of Wind Energy Fed Dual Active Bridge Converter Operating in Extended Phase Shift and Single Phase Shift Modes: A Comparative Study

In this work, cascade control of wind energy conversion System (WECS) fed Dual Active Bridge (DAB) converter is presented. The Permanent Magnet Synchronous Generator (PMSG) is used to feed the DAB. The real time wind speed data of Muppandal, Tamilnadu, India is fed to the PMSG. The DAB is operated in Extended Phase Shift (EPS) and Single-Phase Shift (SPS) control modes. An outer voltage controller in cascade with an inner current controller is used for closed loop operation of the DAB. The proposed controller is tested for small wind speed variations (13 m/s to 10 m/s) with a step load change and wide changes in wind speed (13 m/s to 8 m/s) accompanied with a step load change. DAB controls the power flow from the WECS to resistive load and its power carrying capability when controlled via the proposed controller is exhibited in the presented work. The proposed configuration controlled via the new cascade EPS controller draws lower power (100 Watts) and offers superior efficiency (85.10%) when compared with cascade SPS controlled microgrid configuration. The cascade controller is tested in MATLAB/Simulink environment and a prototype of DAB is developed in lab for which the cascade controller is tested through the TI-Piccolo-F280049 microcontroller.

Thermodynamic geometry of dyonic black holes in AdS in extended phase space

Ruppeiner scalar curvature can be considered as an empirical tool to explore the nature of interaction among the microstructures of black holes. In the extended phase space, the phase transitions and criticality are investigated for the dyonic black holes in an ensemble, where the electric potential [Formula: see text] is fixed. At first, we described the thermodynamic properties of dyonic black holes to investigate the [Formula: see text] criticality. Further, the Ruppeiner scalar curvature is calculated in an ensemble with fixed [Formula: see text] utilizing the fluctuation coordinates [Formula: see text]. The behavior of interactions among the microstructures of the dyonic black holes in AdS is studied where the dominance of attractive or repulsive interaction is found to be dependent on the values of electric potential [Formula: see text].

Provoked vs minimally provoked vs unprovoked VTE: does it matter?

Venous thromboembolism (VTE) is a multifactorial disease, and its risk depends on exposure to risk factors and predisposing conditions. Based on their strength of association with a VTE episode, risk factors are classified as major or minor and determined using a temporal pattern to be transient or persistent. All patients with VTE should receive anticoagulant treatment for at least 3 months in the absence of an absolute contraindication. Beyond this period, selected patients may be candidates for an extended phase of anticoagulation aimed at secondary VTE prevention. The risk of recurrent VTE if anticoagulation is discontinued is probably the main driver of decision-making regarding extended treatment. The risk of recurrence after VTE associated with major risk factors is low if the risk factor is no longer present. In this case, treatment can be discontinued. If the major risk factor is persistent, anticoagulation should be continued. After VTE occurring in the absence of risk factors, anticoagulation should probably be continued indefinitely if the risk for bleeding is low and preferably with minimal effective doses of anticoagulants. VTE occurring after exposure to minor risk factors is probably the most challenging situation, especially if the clinical manifestation was acute pulmonary embolism. Understanding the actual role of minor risk factors in the occurrence of VTE helps in estimating the risk of recurrence and avoiding the dangers associated with unnecessary anticoagulation. The availability of safer strategies for anticoagulation could allow personalized strategies for secondary prevention of VTE.

Thermodynamic topology of black holes from bulk-boundary, extended, and restricted phase space perspectives

In this article, we investigate the thermodynamic topology of some black holes, namely AdS Reissner Nordstrom (R–N), AdS Einstein–Gauss–Bonnet (EGB), and AdS Einstein-power-Yang–Mills (EPYM), from different frameworks: bulk-boundary (BB) and restricted phase space (RPS). Using the generalized off-shell Helmholtz free energy method, we calculate the thermodynamic topology of the selected black holes in each space separately and determine their topological classifications. We show that the addition of GB terms, dimensions, and other factors do not affect the topological classes of black holes in both spaces. The calculations and plots indicate that the AdS R–N and AdS EGB black holes show similar behavior and their topological numbers sets in both spaces, i.e., BB and RPS, are similar and equal to (W=+1). However, AdS EPYM black holes show an interesting behavior. In addition to BBT and RPS, we also consider the extended phase space thermodynamics (EPST) and evaluate the thermodynamic topology for AdS EPYM black hole. The changing (r−τ) in both spaces shows similar behavior. Also, the topological number and the total topological numbers for this black hole in the BB, RPS and EPS thermodynamics are completely same, i,e., (ωBBT=ωRPS=ωEPST=+1,−1) or WBBT=WRPS=WEPST=0. An important point is that the Einstein–Yang–Mills black hole has thermodynamic topology equivalence in three spaces. The present result may be due to the non-linear YM charge parameter and the difference between the gauge and gravity corrections in the above black holes.

Hermitian realizations of the Yang model

The Yang model is an example of noncommutative geometry on a background spacetime of constant curvature. We discuss the Hermitian realizations of its associated algebra on phase space in a perturbative expansion up to sixth order. We also discuss its realizations on extended phase spaces, that include additional tensorial and/or vectorial degrees or freedom.

Simplifying molecular testing through electronic order entry

Abstract Our solid-tumor molecular laboratory receives more than 3,000 orders each year, with about two-thirds coming from internal providers. Before this project, molecular tests were ordered using one of two different paper forms, which the care team then faxed or e-mailed to the Genetics Preanalytical Service (GPS). These requests led to frequent modifications and cancellations due to the complexity of molecular testing. A small fraction of requisitions were lost due to transmission errors. We undertook a project to design, develop, and implement computerized physician order entry (CPOE) in Epic (Epic Systems Corp., Verona, WI) and Sunquest (Clinisys, Tucson, AZ). We conducted extensive interviews with the directors of the molecular lab, laboratory medicine IT, GPS, anatomic pathology staff, laboratory scientists, laboratory genetic counselors, oncologists, clinicians, and nurse coordinators. The order itself and other technical changes underwent iterative review and testing by a subset of interviewees. Five oncologists participated in formal beta-testing. The user interviews allowed us to produce a detailed process diagram that drew attention to specific areas of repetition or risk. We proposed a new workflow that would eliminate repetition, provide redundant order-tracking, and automate some lab processes. Once approved, we built the electronic order in Epic and modified existing laboratory programs and interfaces as needed. The process of placing an order, which previously typically involved both nurses and doctors over several calendar days, was now being completed in fewer than 5 minutes by a single practitioner. Requisition status events were no longer created manually in Sunquest by GPS. Certain data-entry tasks were eliminated through the incorporation of label printers. Within one month of launch, more than 50% of somatic molecular orders arrived via CPOE, increasing to 90% within six months. At a rate of 125 CPOE orders per month, time savings range from 20 hours per month for GPS staff, 50 hours per month for nursing, and 20 hours per month for physicians. The success of this project demonstrates the feasibility of replacing a paper-based process for a complex test menu with CPOE. Due to the intricacies of molecular testing, such a change will undoubtedly involve multiple divisions. We attribute the success of this project to early involvement by key stakeholder groups, including developers; an extended testing phase to ensure reliability at roll-out; creation of straightforward reference documents; and rapid response to user questions, especially during the first weeks post-launch.

The conformational phase diagram of charged polymers in the presence of attractive bridging crowders.

Using extensive molecular dynamics simulations, we obtain the conformational phase diagram of a charged polymer in the presence of oppositely charged counterions and neutral attractive crowders for monovalent, divalent, and trivalent counterion valencies. We demonstrate that the charged polymer can exist in three phases: (1) an extended phase for low charge densities and weak polymer-crowder attractive interactions [Charged Extended (CE)]; (2) a collapsed phase for high charge densities and weak polymer-crowder attractive interactions, primarily driven by counterion condensation [Charged Collapsed due to Intra-polymer interactions [(CCI)]; and (3) a collapsed phase for strong polymer-crowder attractive interactions, irrespective of the charge density, driven by crowders acting as bridges or cross-links [Charged Collapsed due to Bridging interactions [(CCB)]. Importantly, simulations reveal that the interaction with crowders can induce collapse, despite the presence of strong repulsive electrostatic interactions, and can replace condensed counterions to facilitate a direct transition from the CCI and CE phases to the CCB phase.

Extended phase space in general gauge theories

In a recent paper, it was shown that in diffeomorphism-invariant theories, the symplectic vector fields induced by spacetime diffeomorphisms are integrable if one introduces an extended phase space. In this paper we extend the notion of extended phase space to all gauge theories with arbitrary combinations of internal and spacetime local symmetries. We formulate this in terms of a corresponding Atiyah Lie algebroid, a geometric object derived from a principal bundle which features internal symmetries and diffeomorphisms on an equal footing. In this language, gauge transformations are understood as morphisms between Atiyah Lie algebroids that preserve the geometric structures encoded therein. The extended configuration space of a gauge theory can subsequently be understood as the space of pairs (φ,Φ), where φ is a Lie algebroid morphism and Φ is a field configuration in the non-extended sense. Starting from this data, we outline a very powerful, manifestly geometric approach to the extended phase space. Using this approach, we find that the action of the group of gauge transformations and diffeomorphisms on the symplectic geometry of any covariant theory is integrable. We motivate our construction by carefully examining the need for extended phase space in Chern-Simons gauge theories and display its usefulness by re-computing the charge algebra. We also describe the implementation of the configuration algebroid in Einstein-Yang-Mills theories.

Alkylbenzoic and Alkyloxybenzoic Acid Blending for Expanding the Liquid Crystalline State and Improving Its Rheology.

Thermotropic mesogens typically exist as liquid crystals (LCs) in a narrow region of high temperatures, making lowering their melting point with the temperature expansion of the mesophase state an urgent task. Para-substituted benzoic acids can form LCs through noncovalent dimerization into homodimers via hydrogen bonds, whose strength and, consequently, the temperature region of the mesophase state can be potentially altered by creating asymmetric heterodimers from different acids. This work investigates equimolar blends of p-n-alkylbenzoic (kBA, where k is the number of carbon atoms in the alkyl radical) and p-n-alkyloxybenzoic (kOBA) acids by calorimetry and viscometry to establish their phase transitions and regions of mesophase existence. Non-symmetric dimerization of acids leads to the extension of the nematic state region towards low temperatures and the appearance of new monotropic and enantiotropic phase transitions in several cases. Moreover, the crystal-nematic and nematic-isotropic phase changes have a two-step character for some acid blends, suggesting the formation of symmetric and asymmetric associates from heterodimers. The mixing of 6BA and 8OBA most strongly extends the region of the nematic state towards low temperatures (from 95-114 °C and 108-147 °C for initial homodimers, respectively, to 57-133 °C for the resulting heterodimer), whereas the combination of 4OBA and 5OBA gives the most extended high-temperature nematic phase (up to 156 °C) and that of 6BA and 9OBA (or 12OBA) provides the existence of a smectic phase at the lowest temperatures (down to 51 °C).

Nonadiabatic simulations of photoisomerization and dissociation in ethylene using abinitio classical trajectories.

We simulate the nonadiabatic dynamics of photo-induced isomerization and dissociation in ethylene using abinitio classical trajectories in an extended phase space of nuclear and electronic variables. This is achieved by employing the linearized semiclassical initial value representation method for nonadiabatic dynamics, where discrete electronic states are mapped to continuous classical variables using either the Meyer-Miller-Stock-Thoss representation or a more recently introduced spin mapping approach. Trajectory initial conditions are sampled by constraining electronic state variables to a single initial excited state and by drawing nuclear phase space configurations from a Wigner distribution at a finite temperature. An ensemble of classical abinitio trajectories is then generated to compute thermal population correlation functions and analyze the mechanisms of isomerization and dissociation. Our results serve as a demonstration that this parameter-free semiclassical approach is computationally efficient and accurate, identifying mechanistic pathways in agreement with previous theoretical studies and also uncovering dissociation pathways observed experimentally.

Experimental and theoretical investigation of the dry ice sublimation temperature for varying far-field pressure and CO2 concentration

Solid carbon dioxide, also known as dry ice, is extensively used in various applications, such as cleaning large telescopes, refrigeration, spray cooling, and biological processes like cryopreservation. In standard atmospheric conditions, dry ice sublimates continuously because the triple point pressure of carbon dioxide is higher than the atmospheric pressure. While the sublimation temperature of dry ice at atmospheric pressure is widely reported in the literature to be approximately −78.5∘C, this value is only conditionally true as it refers to dry ice exposed to an ambient saturated with its vapor. In reality, dry ice is mainly utilized in an unsaturated atmosphere. This study investigates the effect of the atmosphere on the sublimation temperature of a dry ice sphere, both experimentally and theoretically. Specifically, the far-field pressure is varied from 0.6 bar to 1.3 bar in steps of 0.1 bar, and the far-field CO2 concentration is varied from 100%vol to 0%vol in steps of 20%vol. The results show that the sublimation temperature reduces and reaches a lower thermodynamic wet-bulb temperature when the far-field CO2 concentration is lowered from the previously set value at a given ambient pressure. The lowest value of the sublimation temperature, for the ambient pressure of 1 atm and 0%vol CO2 concentration, is measured to be −97.3∘C, which deviates from the commonly quoted value in the literature by approximately 19∘C. Finally, the results are presented in the form of an extended phase diagram showing the solid-vapor coexistence line for various far-field CO2 concentrations in comparison to the standard coexistence line present on the phase diagram. A mathematical model that considers heat and mass transport phenomena in the surroundings of a dry ice sphere is developed, and its predictions are found to be in encouraging agreement with the experimental results. This study provides important insights into the behavior of dry ice under different atmospheric conditions and can be useful in various industrial and scientific applications.

Thermodynamic geometry of STU black holes

This work investigates the phase structure of STU black holes with uniform charges by utilizing the New Thermodynamic Geometry (NTG) approach. The study explores the intriguing relationship between heat capacity phase transitions and curvature singularities, employing the NTG formalism. The analysis encompasses an examination of phase transitions along the T − S and Q − Φ planes, a study of critical exponents, and an assessment of black hole stability. The NTG geometry is applied in both the normal and extended phase spaces, revealing valuable insights into the thermodynamic behavior and stability of STU black holes. Meanwhile, a closer examination of NTG geometry shows a positive correlation in the sign between the extrinsic curvature and the heat capacity, which is incompatible with the curvature singularity. Overall, this study contributes to our understanding of the phase transitions and thermodynamic properties of STU black holes, shedding light on the intricate interplay between curvature singularities and the stability of black holes in diverse thermodynamic scenarios.