Reversible Counterparts Research Articles

Flexible and reversible conversion between extensible records and overloading constraints for ML

Most ML-like functional languages provide records and overloading as unrelated features. Records not only represent data structures, but are also used to implement dictionary passing, whereas overloading produces type constraints that are basically dictionaries subject to compiler-driven dispatching. In this paper we explore how records and overloading constraints can be converted one into the other, allowing the programmer to switch between the two at a very reasonable cost in terms of syntactic overhead. To achieve this we introduce two language constructs, namely inject and eject, performing a type-driven syntactic transformation. The former literally injects constraints into the type and produces a function adding an extra record argument. The latter does the opposite, ejecting a record argument from a function and turning fields into type constraints. The conversion is reversible and can be restricted to a subset of symbols, granting additional control to the programmer. Although what we call inject has already been proposed in literature, making it a language operator and coupling it with its reverse counterpart represent a novel design. The goal is to allow the programmer to switch from a dictionary-passing style to compiler-assisted constraint resolution, and vice versa, enabling reuse between libraries that otherwise would not interoperate.

Bridging multi-level vehicle behavioural patterns with long-term pavement condition: a bidirectional modelling approach for progressively mixed autonomous traffic flow

The increasing of AVs’ market penetration rate (MPR) changes the traffic behavioural pattern and ultimately influences pavement. Pavement condition, in turn, influences microscopic behaviours. The above bidirection influencing mechanism has not been investigated fully yet. This research fill this gap by modelling the linkage between multi-level microscopic behaviour and pavement sustainability. Three levels of behaviour are considered: travel behaviour, microscopic traffic behaviour, and driving behaviour. The latter two are modelled using stochastic lateral movement model, while the former one is captured by a mixed autonomous traffic assignment model. Microscopic behaviours’ influence on pavement is described by a data-driven model, while the reverse counterpart is described by connecting pavement condition with link wandering and disutility. Our analysis results reveal that at link level, AVs can cause extra 50% drop in free flow speed due to pavement deterioration. Neglecting pavement evolution in strategic assignments leads to a 0.2% increase in network cost.

Automatic Regenerative Simulation via Non-Reversible Simulated Tempering

Simulated Tempering (ST) is an MCMC algorithm for complex target distributions that operates on a path between the target and a more amenable reference distribution. Crucially, if the reference enables iid sampling, ST is regenerative and can be parallelized across independent tours. However, the difficulty of tuning ST has hindered its widespread adoption. In this work, we develop a simple nonreversible ST (NRST) algorithm, a general theoretical analysis of ST, and an automated tuning procedure for ST. A core contribution that arises from the analysis is a novel performance metric—Tour Effectiveness (TE)—that controls the asymptotic variance of estimates from ST for bounded test functions. We use the TE to show that NRST dominates its reversible counterpart. We then develop an automated tuning procedure for NRST algorithms that targets the TE while minimizing computational cost. This procedure enables straightforward integration of NRST into existing probabilistic programming languages. We provide extensive experimental evidence that our tuning scheme improves the performance and robustness of NRST algorithms on a diverse set of probabilistic models. Supplementary materials for this article are available online, including a standardized description of the materials available for reproducing the work.

Necessary and sufficient symmetries in Event-Chain Monte Carlo with generalized flows and application to hard dimers.

Event-Chain Monte Carlo (ECMC) methods generate continuous-time and non-reversible Markov processes, which often display significant accelerations compared to their reversible counterparts. However, their generalization to any system may appear less straightforward. In this work, our aim is to distinctly define the essential symmetries that such ECMC algorithms must adhere to, differentiating between necessary and sufficient conditions. This exploration intends to delineate the balance between requirements that could be overly limiting in broad applications and those that are fundamentally essential. To do so, we build on the recent analytical description of such methods as generating piecewise deterministic Markov processes. Therefore, starting with translational flows, we establish the necessary rotational invariance of the probability flows, along with determining the minimum event rate. This rate is identified with the corresponding infinitesimal Metropolis rejection rate. Obeying such conditions ensures the correct invariance for any ECMC scheme. Subsequently, we extend these findings to encompass schemes involving deterministic flows that are more general than mere translational ones. Specifically, we define two classes of interest of general flows: the ideal and uniform-ideal ones. They, respectively, suppress or reduce the event rates. From there, we implement a comprehensive non-reversible sampling of a system of hard dimers by introducing rotational flows, which are uniform-ideal. This implementation results in a speed-up of up to ∼3 compared to the state-of-the-art ECMC/Metropolis hybrid scheme.

Bi-Trajectory Hybrid Search to Solve Bottleneck-Minimized Colored Traveling Salesman Problems

A bottleneck-minimized colored traveling salesman problem is an important variant of colored traveling salesman problems. It is useful in handling the planning problems with partially overlapped workspace such as the scheduling transportation resources for timely delivery of goods. In this work, we propose an efficient bi-trajectory hybrid search method for it. The proposed method integrates a route-based crossover operator to generate promising offspring solutions, a multi-neighborhood simulated annealing to perform local optimization, and a stagnation-detect-escape mechanism to help the search escape from local optima. We also propose a bidirectional adjacency solution representation method to encode a solution, which extends the traditional adjacency representation method by additionally employing an array to represent its reverse counterpart. Extensive evaluations on two sets of 58 widely used benchmark instances demonstrate that the proposed method significantly outperforms state-of-the-art algorithms. Investigations on key algorithm modules are performed to confirm the novelty and effectiveness of the proposed ideas and strategies. Finally, we verify the generalization of the proposed method via its use to solve a colored traveling salesman problem with its aim to balance workload among salesmen. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Note to Practitioners</i> —This work is motivated by the problems of scheduling transportation resources for timely delivery of goods. It proposes an effective bi-trajectory hybrid search to tackle bottleneck-minimized colored traveling salesman problem. The proposed approach performs bi-trajectory hybrid evolutionary search by maintaining only two individuals during the whole search process. Extensive numerical experiments and comparisons show that our proposed algorithm significantly outperforms state-of-the-art algorithms and can help decision-makers in designing best-routing solutions.

A novel electrochemical system with adiabatic pre-charging and pre-discharging processes for efficient refrigeration

The extraordinary thermal-to-electricity conversion efficiency of thermally regenerative electrochemical cycle triggers interest in its reverse counterpart, namely thermally regenerative electrochemical refrigerator (TRER), a promising alternative to conventional cooling devices. Nevertheless, due to three fundamental obstacles, the practically feasible TRER model is still absent, which hinders the development of follow-up research. To break this bottleneck, heating by discharging and cooling by charging effects are innovatively utilized to construct TRER models where the electrochemical counterparts of traditional adiabatic compression and expansion processes, namely adiabatic pre-charging and pre-discharging processes, are proposed and introduced. Significantly, the maximum coefficient of performance (COP) and the COP at maximum cooling power are predicted to achieve up to 40% and 5% of Carnot COP, respectively for the given values of parameters. Moreover, the great potential for efficient refrigeration is highlighted by comparing the obtained results with various refrigeration systems. This work lays the foundation for further experimental investigations and opens a new avenue for constructing other novel electrochemical cycles.

Modeling of Excess‐3 to BCD code converter for nano system using quantum‐dot cellular automata technology

AbstractThis work proposes a novel quantum‐dot cellular automata (QCA) layout for an Excess‐3 to BCD code converter for nano systems that is low in cell complexity. The suggested design uses a QCA clock‐phase‐based technique to evaluate integration with other complex circuits. The results obtained using the QCADesigner simulation tool demonstrate the superiority of the recommended layout over prior identical reverse counterpart designs by evaluating the cell numbers used, the space occupied, and the latency as design metrics. The suggested layout has a 56% decrease in occupied space and a 37.5% reduction in delay when compared to similar reverse counterpart scalable designs. In addition, the energy dissipation of the suggested structure was calculated and compared to previous comparable work (reverse equivalent) to confirm its reliability. The suggested circuit may be employed in bigger and more complicated circuits due to its advantage in numerous performance measurement parameters.

Construction of Covalent Bisubstrate Inhibitor of Protein Kinase Reacting with Cysteine Residue at Substrate-Binding Site.

Recent clinical success with targeted covalent inhibitors points to new possibilities for development of protein kinase (PK)-targeted drugs by exploiting reactive cysteine residues in and around the ATP-binding site. However, more than 300 human PKs lack cysteine residues in the ATP-binding site. Here, we report the first covalent bisubstrate PK inhibitor whose electrophilic warhead reaches outside the ATP-binding site and reacts with a distant cysteine residue. A series of covalent inhibitors and their reversible counterparts were synthesized and characterized. The most potent reversible inhibitor possessed picomolar affinity and its cysteine-reactive counterpart revealed high value of kinact/KI ratio (6.2 × 107 M-1 s-1) for the reaction with the catalytic subunit of cAMP-dependent PK (PKAc). Under optimized conditions, fluorescent dye-labeled covalent inhibitors demonstrated PKA-selectivity in the cell lysate and reacted with several proteins inside live cells, including PKAc. The disclosed compounds serve as leads for targeting PKs possessing an analogously positioned cysteine residue.

Non-Reversible Parallel Tempering: A Scalable Highly Parallel MCMC Scheme

AbstractParallel tempering (PT) methods are a popular class of Markov chain Monte Carlo schemes used to sample complex high-dimensional probability distributions. They rely on a collection of N interacting auxiliary chains targeting tempered versions of the target distribution to improve the exploration of the state space. We provide here a new perspective on these highly parallel algorithms and their tuning by identifying and formalizing a sharp divide in the behaviour and performance of reversible versus non-reversible PT schemes. We show theoretically and empirically that a class of non-reversible PT methods dominates its reversible counterparts and identify distinct scaling limits for the non-reversible and reversible schemes, the former being a piecewise-deterministic Markov process and the latter a diffusion. These results are exploited to identify the optimal annealing schedule for non-reversible PT and to develop an iterative scheme approximating this schedule. We provide a wide range of numerical examples supporting our theoretical and methodological contributions. The proposed methodology is applicable to sample from a distribution π with a density L with respect to a reference distribution π0 and compute the normalizing constant ∫Ldπ0. A typical use case is when π0 is a prior distribution, L a likelihood function and π the corresponding posterior distribution.

Nonreversible Jump Algorithms for Bayesian Nested Model Selection

Nonreversible Markov chain Monte Carlo methods often outperform their reversible counterparts in terms of asymptotic variance of ergodic averages and mixing properties. Lifting the state-space is a generic technique for constructing such samplers. The idea is to think of the random variables we want to generate as position variables and to associate to them direction variables so as to design Markov chains which do not have the diffusive behavior often exhibited by reversible schemes. In this article, we explore the benefits of using such ideas in the context of Bayesian model choice for nested models, a class of models for which the model indicator variable is an ordinal random variable. By lifting this model indicator variable, we obtain nonreversible jump algorithms, a nonreversible version of the popular reversible jump algorithms. This simple algorithmic modification provides samplers which can empirically outperform their reversible counterparts at no extra computational cost. The code to reproduce all experiments is available online 1 .

Linking information theory and thermodynamics to spatial resolution in photothermal and photoacoustic imaging

In this Tutorial, we combine the different scientific fields of information theory, thermodynamics, regularization theory, and non-destructive imaging, especially for photoacoustic and photothermal imaging. The goal is to get a better understanding of how information gaining for subsurface imaging works and how the spatial resolution limit can be overcome by using additional information. Here, the resolution limit in photoacoustic and photothermal imaging is derived from the irreversibility of attenuation of the pressure wave and of heat diffusion during the propagation of the signals from the imaged subsurface structures to the sample surface, respectively. The acoustic or temperature signals are converted into so-called virtual waves, which are their reversible counterparts and which can be used for image reconstruction by well-known ultrasound reconstruction methods. The conversion into virtual waves is an ill-posed inverse problem, which needs regularization. The reason for that is the information loss during signal propagation to the sample surface, which turns out to be equal to the entropy production. As the entropy production from acoustic attenuation is usually small compared to the entropy production from heat diffusion, the spatial resolution in acoustic imaging is higher than in thermal imaging. Therefore, it is especially necessary to overcome this resolution limit for thermographic imaging by using additional information. Incorporating sparsity and non-negativity in iterative regularization methods gives a significant resolution enhancement, which was experimentally demonstrated by one-dimensional imaging of thin layers with varying depth or by three-dimensional imaging, either from a single detection plane or from three perpendicular detection planes on the surface of a sample cube.

On the Convergence Time of Some Non-Reversible Markov Chain Monte Carlo Methods

It is commonly admitted that non-reversible Markov chain Monte Carlo (MCMC) algorithms usually yield more accurate MCMC estimators than their reversible counterparts. In this note, we show that in addition to their variance reduction effect, some non-reversible MCMC algorithms have also the undesirable property to slow down the convergence of the Markov chain. This point, which has been overlooked by the literature, has obvious practical implications. We illustrate this phenomenon for different non-reversible versions of the Metropolis-Hastings algorithm on several discrete state space examples and discuss ways to mitigate the risk of a small asymptotic variance/slow convergence scenario.

General Method to Design Reversible Universal n-Bit Up/Down Counters

With the growing trend towards reducing the size of electronic devices, reducing power consumption has become one of the major concerns of circuit designers, and designing reversible circuits is one of the approaches proposed for reducing power consumption. Although several studies have been done in the field of synthesizing combinational reversible circuits, little work has been done for designing reversible sequential circuits. Furthermore, many researches in this context use traditional designs which replace latches, flip-flops and associated combinational gates with their reversible counterparts. This traditional technique is not very promising, because it leads to high quantum cost (QC) and garbage outputs. Recently, researchers have proposed direct design of reversible sequential circuits using Reed Muller expressions to obtain next state output. Since most sequential circuits have multiple outputs, using common product terms between multiple outputs might decrease QC significantly. In this paper, a modular and low QC design for a synchronous reversible [Formula: see text]-bit up/down counter with parallel load capability is presented. In this design, the common terms among multiple outputs are used efficiently, which leads to a low QC for the counter. A general formula to evaluate the QC of our proposed reversible counter is presented. This result shows that in our proposed design by increasing the number of bits of counter ([Formula: see text], the QC increases linearly, while in previous works by increasing the number of bits of counter, the QC increases exponentially.

Low-cost and compact design method for reversible sequential circuits

Reversible logic plays an important role in nanotechnology-based systems; therefore, it has become an interesting topic for many researchers in this field. Although many researchers are investigating techniques to synthesize reversible combinational logic, few are working in the field of reversible sequential logic. The traditional method to design a sequential circuit is a replacement technique. In this technique, in order to design a reversible sequential circuit, all parts of an irreversible design (e.g., latches and flip-flops and associated combinational gates) are replaced by their reversible counter parts, which leads to circuits with high quantum cost. In this paper, we propose a direct and compact design of reversible synchronous sequential circuits. The EXOR of Products of EXOR (EPOE) expressions are applied, to reduce the quantum cost of sequential logic circuits. We present designs for some practical sequential circuits, such as state machines, counters and shift registers. To show the efficiency of the proposed method, we have designed a proof of concept of our designs to design a practical sequential system: a reversible self-controlled serial adder. Our designs considerably reduce performance cost factors: including quantum cost, number of constant inputs or the number of garbage outputs and delay.

Pseudo-Polyrotaxanes of Cyclodextrins with Direct and Reverse X-Shaped Block Copolymers: A Kinetic and Structural Study

Pseudo-polyrotaxanes (PPRs) are supramolecular host–guest complexes constituted by the reversible threading of a macrocycle along a polymer chain. The resuting dynamic “molecular necklaces” offer potential applications in nanotechnology, drug delivery, and biomaterials. We report the formation of PPRs by threading of cyclodextrins (CDs), cyclic oligosaccharides, onto X-shaped PEO–PPO block copolymers with two opposite presentation of their hydrophobic and hydrophilic blocks: Tetronic 904 (T904) and its reverse counterpart Tetronic 90R4 (T90R4). We assess the effects that relative block position on the polymeric surfactants and cavity size of CD have on the composition, morphology, thermodynamics, and kinetics of PPRs by using a combination of X-ray diffraction, scanning electron microscopy, NMR, UV–vis spectroscopy, and time-resolved small-angle neutron scattering (TR-SANS). Solid PPRs with lamellar microstructure and crystalline channel-like structures are obtained with native CDs and both Tetronics abov...

An Excel Macro for Determining Allelic and Sequence Types of Bacterial Clones in Multilocus Sequence Typing.

BackgroundMultilocus sequence typing (MLST) was designed to overcome the low discriminatory power and poor reproducibility of previous molecular typing schemes, and it is useful for inter-laboratory, inter-regional, and inter-national comparison of pathogenic clones. MLST includes labor-intensive sequencing processes and meticulous allelic/sequence type (ST) determination processes, often prone to error. We developed a free automated MLST determination program (MLST typer) based on the Visual Basic for Applications macro, which runs on Microsoft Excel.MethodsMLST typer imports sequence data in the FASTA format, converts reverse complement counterparts of the reverse sequences, assembles forward and reverse-complement converted sequences, and returns allelic numbers for each gene and ST of each isolate. To evaluate the performance of MLST typer, we tested the sequence data from 200 clinical isolates, each consisting of seven housekeeping gene sequences, with a total of 1,400 allelic number determinations. The results were compared with manual assessment.ResultsMLST typer comprises three worksheets: the Main page, Result page, and Summary page. The Main page console operates the process according to user-specified parameters. The Result and Summary pages provide the allelic type and ST determinations. It took approximately 12 minutes to analyze the sequence data from 200 clinical isolates. Compared with manual assessment, the rate of correct identification was 97.2% (1,361/1,400).ConclusionsMLST typer can be widely used for epidemiological studies owing to its thoroughness in repetitive functions, good compatibility with FASTA type data files, and easy-to-understand outputs for allelic and ST determinations.

Contraceptive Practices in Women With Medical Conditions in the Clinics at the University Hospital of the West Indies [3G

INTRODUCTION: Women with medical comorbidities should optimize their health prior to conception with the consistent use of effective contraceptives. The objective of this study is to assess the contraceptive use among women with chronic diseases at the University Hospital. METHODS: A cross-sectional study was done among 260 participants identified from the medical clinics at the University Hospital, with an interviewer-administrated questionnaire. Candidates were recruited by convenience sampling and those who fit the inclusion criteria were enrolled. Statistical Package for Social Sciences (SPSS Inc., Chicago, IL, USA) was used for data management and statistical analysis. RESULTS: The majority of the patients (200, 76.9%) were between 25-45 years old, employed (114, 43.9%), single (107, 41.2%), nulliparous (24,12.3%) and sexually active (176, 67.7%). Ten persons were pregnant however, only 3 (30%) were planned. The largest representation were in women with Systemic Lupus Erythematous (50, 19.2%), Diabetes Mellitus (48, 18.5%) and Hypertension (45, 17.5%), with the least among those receiving chemotherapy (7, 2.7%). 161 (62%) of the participants were currently using contraceptives. The methods included barrier methods (117, 45%) and oral contraceptive methods (36, 14%). Individuals with sickle cell disease were more likely to be using contraceptives (r=8.14, p=.004). Only 26 (10%) of patients used long acting reversible contraceptives CONCLUSION: Most women with chronic medical illness at the clinics at the University hospital reported current contraceptive use. Mainly short-term methods were used compared to the preferred long acting reversible counterparts. Greater efforts should be made in offering long-term contraception to women with chronic medical disorders.

AD-Related N-Terminal Truncated Tau Is Sufficient to Recapitulate In Vivo the Early Perturbations of Human Neuropathology: Implications for Immunotherapy.

The NH2tau 26-44 aa (i.e., NH2htau) is the minimal biologically active moiety of longer 20-22-kDa NH2-truncated form of human tau-a neurotoxic fragment mapping between 26 and 230 amino acids of full-length protein (htau40)-which is detectable in presynaptic terminals and peripheral CSF from patients suffering from AD and other non-AD neurodegenerative diseases. Nevertheless, whether its exogenous administration in healthy nontransgenic mice is able to elicit a neuropathological phenotype resembling human tauopathies has not been yet investigated. We explored the in vivo effects evoked by subchronic intracerebroventricular (i.c.v.) infusion of NH2htau or its reverse counterpart into two lines of young (2-month-old) wild-type mice (C57BL/6 and B6SJL). Six days after its accumulation into hippocampal parenchyma, significant impairment in memory/learning performance was detected in NH2htau-treated group in association with reduced synaptic connectivity and neuroinflammatory response. Compromised short-term plasticity in paired-pulse facilitation paradigm (PPF) was detected in the CA3/CA1 synapses from NH2htau-impaired animals along with downregulation in calcineurin (CaN)-stimulated pCREB/c-Fos pathway(s). Importantly, these behavioral, synaptotoxic, and neuropathological effects were independent from the genetic background, occurred prior to frank neuronal loss, and were specific because no alterations were detected in the control group infused with its reverse counterpart. Finally, a 2.0-kDa peptide which biochemically and immunologically resembles the injected NH2htau was endogenously detected in vivo, being present in hippocampal synaptosomal preparations from AD subjects. Given that the identification of the neurotoxic tau species is mandatory to develop a more effective tau-based immunological approach, our evidence can have important translational implications for cure of human tauopathies.

First Steps in Creating Online Testable Reversible Sequential Circuits

Synthesis of reversible sequential circuits is a very new research area. It has been shown that such circuits can be implemented using quantum dot cellular automata. Other work has used traditional designs for sequential circuits and replaced the flip-flops and the gates with their reversible counterparts. Our earlier work uses a direct feedback method without any flip-flops, improving upon the replacement technique in both quantum cost and ancilla inputs. We present here a further improved version of the direct feedback method. Design examples show that the proposed method produces better results than our earlier method in terms of both quantum cost and ancilla inputs. We also propose the first technique for online testing of single line faults in sequential reversible circuits.

Studies on the sparsifying operator in compressive digital holography.

In compressive digital holography, we reconstruct sparse object wavefields from undersampled holograms by solving an ℓ1-minimization problem. Applying wavelet transformations to the object wavefields produces the necessary sparse representations, but prior work clings to transformations with too few vanishing moments. We put several wavelet transformations belonging to different wavelet families to the test by evaluating their sparsifying properties, the number of hologram samples that are required to reconstruct the sparse wavefields perfectly, and the robustness of the reconstructions to additive noise and sparsity defects. In particular, we recommend the CDF 9/7 and 17/11 wavelet transformations, as well as their reverse counter-parts, because they yield sufficiently sparse representations for most accustomed wavefields in combination with robust reconstructions. These and other recommendations are procured from simulations and are validated using biased, noisy holograms.