Quantum Mpemba Effect in a Quantum Dot with Reservoirs.

We demonstrate the quantum Mpemba effect in a quantum dot coupled to two reservoirs, described by the Anderson model. We show that the system temperatures starting from two different initial values (hot and cold) cross each other at finite time (and thereby reverse their identities; i.e., hot becomes cold and vice versa) to generate thermal quantum Mpemba effect. The slowest relaxation mode believed to play the dominating role in Mpemba effect in Markovian systems does not contribute to such anomalous relaxation in the present model. In this connection, our analytical result provides necessary condition for producing quantum Mpemba effect in the density matrix elements of the quantum dot, as a combined effect of the remaining relaxation modes.

Harnessing the potential of blood donors negative for high prevalence Rh antigens: A database initiative for thalassaemia care.

BACKGROUND AND OBJECTIVES: With increasing life expectancy and prevalence of thalassaemia, it has led to a greater need for safe blood, yet the current supply from voluntary donors is insufficient to meet this demand. Thalassaemia recipients face a significant risk of alloimmunization because of repeated exposure to foreign red cell antigens. Study aims to determine high prevalent Rh antigen negative donors in western India donor population along with what percentage of these donors are willing to become dedicated voluntary donors for thalassaemia patients. Study also aims to examine factors influencing their willingness and challenges faced in mobilizing dedicated donors. METHOD: 700 whole blood donors from western India, following screening for inclusion & exclusion criteria as per Drugs and Cosmetic Act (DCA) 2020 amendment guidelines & were sero-negative for transfusion transmitted infections were enrolled for the study. Red cell phenotyping was performed using Conventional Tube Technique (CTT) for "D", "C", "E", "c", "e" and "K" antigen using known antisera. Donors that were "C" AND/OR "e" antigen negative were contacted telephonically and were counseled and motivated for becoming voluntary blood donors. Statistical analysis assessed correlation between donation frequency, donor's occupation and education. RESULT: Among 700 donors, 96.6% (n = 676) were males and 3.4% (n = 24) were females. The most predominant blood group was B > O > A > AB. Rh(D) antigen was present in 91.44% (n = 640) and absent in 8.6% (n = 60). Prevalence of other Rh antigens is as follows: "e" (99%) > "C" (85.4%) > "c" (59.1%) > "E" (18.0%). Only 1.15% had "K" antigen positive. The commonest Rh phenotype R1R1 (DCe/DCe) was expressed by 40.57% (n = 283), and the least common r″r (cE/ce), r″r″ (cE/cE) and r'r' (Ce/Ce) was found in 0.14% (n = 1), respectively. 'C' negative, 'e' negative, 'C' and 'e' antigen negative donors constituted 14.8% (n = 104) with 93.2% (n = 97) C-antigen negative, 1.92% (n = 2) e-antigen negative and 4.8% (n = 5) both "C" and "e" antigen negative donors. The commonest phenotypes among C-antigen and e-antigen negative donors were rr (50%) and RzR2 (1.94%) respectively. Likewise, the most common phenotype amongst both C- and e-antigens negative donors was R2R2 (3.84%). 61.5% of the donors agreed to enroll for voluntary blood donation following telephonic invitation, while 6.8% of them refused permanently. Approximately, 3.9% of the blood donors were willing to donate blood only when needed and 27.8% of them could not be contacted. CONCLUSION: Creating a database of voluntary donors with known phenotype, especially who lack very common antigens like "C" and "e" and are willing to become dedicated, regular voluntary donors for thalassemic patients can ensure timely administration of safe blood. One of the major challenges for this noble initiative was lack of awareness which can be circumvent effectively with proper counseling efforts.

Anti-A and anti-B titers in A, B and O whole blood donors: Beyond "dangerous O".

BACKGROUND AND OBJECTIVES: Hemolytic transfusion reactions (HTRs) pose significant risks in transfused patients, with anti-A and anti-B antibodies in donor plasma being potential contributing factors. Despite advancements in component preparation, HTRs remain a concern, particularly with apheresis-derived platelets. This study aimed to determine the prevalence of high anti-A and anti-B titers among A, B, and O blood group donors and to explore factors associated with high titers. MATERIALS AND METHODS: A cross-sectional observational study was conducted over 18 months, enrolling 978 participants from a tertiary care teaching hospital in Western India. Anti-A and anti-B titers were determined using the Conventional Tube Technique (CTT). Statistical analysis assessed correlations between high titers and demographic factors. RESULTS: The majority of participants were young males (98.8%). Prevalence of high titers for IgM anti-A was 12.2% and IgG anti-A was 2.5%. For anti-B, IgM titers were 2.3% and IgG titers were 0.2%. The prevalence of dangerous O was found to be 14.1%, while 3.52% and 10.5% of A and B blood group donors were found to have high titers, respectively. Factors associated with high titers included female gender, vegetarian diet, age <30 years, and O blood group. CONCLUSION: The study sheds additional light and provides supplementary information regarding the prevalence and correlation of high anti-A and anti-B titers among O, A and B blood donors. Understanding these factors is crucial for optimizing transfusion safety protocols, including selective screening of platelet units and tailored transfusion strategies based on donor characteristics.

Counterflow-induced clustering: Exact results.

We analyze the cluster formation in a nonergodic stochastic system as a result of counterflow, with the aid of an exactly solvable model. To illustrate the clustering, a two species asymmetric simple exclusion process with impurities on a periodic lattice is considered, where the impurity can activate flips between the two nonconserved species. Exact analytical results, supported by Monte Carlo simulations, show two distinct phases, free-flowing phase and clustering phase. The clustering phase is characterized by constant density and vanishing current of the nonconserved species, whereas the free-flowing phase is identified with nonmonotonic density and nonmonotonic finite current of the same. The n-point spatial correlation between n consecutive vacancies grows with increasing n in the clustering phase, indicating the formation of two macroscopic clusters in this phase, one of the vacancies and the other consisting of all the particles. We define a rearrangement parameter that permutes the ordering of particles in the initial configuration, keeping all the input parameters fixed. This rearrangement parameter reveals the significant effect of nonergodicity on the onset of clustering. For a special choice of the microscopic dynamics, we connect the present model to a system of run-and-tumble particles used to model active matter, where the two species having opposite net bias manifest the two possible run directions of the run-and-tumble particles, and the impurities act as tumbling reagents that enable the tumbling process.

Dynamical regimes of finite-temperature discrete nonlinear Schrödinger chain.

We show that the one-dimensional discrete nonlinear Schrödinger chain (DNLS) at finite temperature has three different dynamical regimes (ultralow-, low-, and high-temperature regimes). This has been established via (i) one-point macroscopic thermodynamic observables (temperature T, energy density ε, and the relationship between them), (ii) emergence and disappearance of an additional almost conserved quantity (total phase difference), and (iii) classical out-of-time-ordered correlators and related quantities (butterfly speed and Lyapunov exponents). The crossover temperatures T_{l-ul} (between low- and ultra-low-temperature regimes) and T_{h-l} (between the high- and low-temperature regimes) extracted from these three different approaches are consistent with each other. The analysis presented here is an important step forward toward the understanding of DNLS which is ubiquitous in many fields and has a nonseparable Hamiltonian form. Our work also shows that the different methods used here can serve as important tools to identify dynamical regimes in other interacting many-body systems.

Spatiotemporal spread of perturbations in a driven dissipative Duffing chain: An out-of-time-ordered correlator approach.

Out-of-time-ordered correlators (OTOCs) have been extensively used as a major tool for exploring quantum chaos, and recently there has been a classical analog. Studies have been limited to closed systems. In this work, we probe an open classical many-body system, more specifically, a spatially extended driven dissipative chain of coupled Duffing oscillators using the classical OTOC to investigate the spread and growth (decay) of an initially localized perturbation in the chain. Correspondingly, we find three distinct types of dynamical behavior: the sustained chaos, transient chaos, and nonchaotic region, as clearly exhibited by different geometrical shapes in the OTOC heat map. To quantify such differences, we look at instantaneous speed (IS), finite-time Lyapunov exponents (FTLEs), and velocity-dependent Lyapunov exponents (VDLEs) extracted from OTOCs. Introduction of these quantities turns out to be instrumental in diagnosing and demarcating different regimes of dynamical behavior. To gain control over open nonlinear systems, it is important to look at the variation of these quantities with respect to parameters. As we tune drive, dissipation, and coupling, FTLEs and IS exhibit transition between sustained chaos and nonchaotic regimes with intermediate transient chaos regimes and highly intermittent sustained chaos points. In the limit of zero nonlinearity, we present exact analytical results for the driven dissipative harmonic system, and we find that our analytical results can very well describe the nonchaotic regime as well as the late-time behavior in the transient regime of the Duffing chain. We believe that this analysis is an important step forward towards understanding nonlinear dynamics, chaos, and spatiotemporal spread of perturbations in many-particle open systems.

Negative differential mobility in interacting particle systems.

Driven particles in the presence of crowded environment, obstacles, or kinetic constraints often exhibit negative differential mobility (NDM) due to their decreased dynamical activity. Based on the empirical studies of conserved lattice gas model, two species exclusion model and other interacting particle systems we propose a new mechanism for complex many-particle systems where slowing down of certain non-driven degrees of freedom by the external field can give rise to NDM. To prove that the slowing down of the non-driven degrees is indeed the underlying cause, we consider several driven diffusive systems including two species exclusion models, misanthrope process, and show from the exact steady state results that NDM indeed appears when some non-driven modes are slowed down deliberately. For clarity, we also provide a simple pedagogical example of two interacting random walkers on a ring which conforms to the proposed scenario.

Phase coexistence and spatial correlations in reconstituting k-mer models.

In reconstituting k-mer models, extended objects that occupy several sites on a one-dimensional lattice undergo directed or undirected diffusion, and reconstitute-when in contact-by transferring a single monomer unit from one k-mer to the other; the rates depend on the size of participating k-mers. This polydispersed system has two conserved quantities, the number of k-mers and the packing fraction. We provide a matrix product method to write the steady state of this model and to calculate the spatial correlation functions analytically. We show that for a constant reconstitution rate, the spatial correlation exhibits damped oscillations in some density regions separated, from other regions with exponential decay, by a disorder surface. In a specific limit, this constant-rate reconstitution model is equivalent to a single dimer model and exhibits a phase coexistence similar to the one observed earlier in totally asymmetric simple exclusion process on a ring with a defect.