Situations Of Interest Research Articles

Case report of varicose veins treatment in patient with a prosthetic mitral valve

This clinical case may be of interest in situations where a patient with varicose veins of the lower limbs and concomitant heart disease, who is on long-term anticoagulant therapy and is scheduled to undergo minor surgery, may present the possibility of endovenous laser ablation (EVLA) against the background of warfarin use. Patient, G., 68 years old, with rheumatic combined mitral valve disease (mitral valve replacement in 2019, permanent atrial fibrillation), also had varicose vein disease of the lower limbs. History included acute cerebrovascular accident (19.01.2023). Duplex Ultrasonography Screening (DUS) showed failure of the left great saphenous vein valve. Hypocoagulation was also observed in coagulogram and the risk of bleeding on HAS-BLED score was average. On Caprini score, the risk was very high. Endovenous laser ablation of the large saphenous vein on the left side was performed. During follow-up examinations, there were no signs of bleeding from puncture sites. The target trunk was obliterated in dynamics at DUS. Therefore, it is possible to carry out EVLA of a large subcutaneous vein while taking therapeutic doses of warfarin without switching to bridge therapy. Endovascular laser ablation allowed it to be done with less risk of bleeding and, against the background of taking warfarin, reduced the risk of thrombosis.

The impact of quantum correlations on parameter estimation in a spin reservoir

We study the impact of quantum correlations existing within the system-environment thermal equilibrium state while estimating the parameters of the spin reservoir. By employing various physical situations of interest, we present results for the reservoir temperature and its coupling strength with the central two-level system. The central system (probe) interacts with the bunch of randomly oriented spin systems and attains a thermal equilibrium state. We consider a projective measurement which prepares the probe’s initial state, and then the global system (probe and reservoir) evolves unitarily. The reduced density operator encapsulates the information about the spin reservoir which can be extracted by doing measurements on the probe. The precision of such measurement is quantified by quantum Fisher information. We repeat this process if the probe-reservoir initial state is not correlated (product state). We compare the estimation results for both with and without the outturn of initial correlations. In the temperature estimation case, our results are promising as one can significantly improve the accuracy of the estimates by including the effect of initial correlations. A similar trend prevails in the case of coupling strength estimation especially at low temperatures.

One techno-economic analysis to rule them all: Instant prediction of hydrothermal liquefaction economic performance with a machine learned analytic equation

Hydrothermal liquefaction (HTL) has remarkable potential for efficient conversion of abundant, decentralized organic wastes into renewable fuels. Because waste is a highly distributed resource with context-dependent economic viability, selection of optimal deployment sites is slowed by the need to develop detailed techno-economic analyses (TEA) for the thousands of potential deployment locations, each with their own unique combinates of scale, proximity to infrastructure/markets, and feedstock properties. An economic modeling framework that requires only easily obtainable inputs for assessing economic performance would therefore allow multiplexed analysis of many thousands of cases, whereas traditional TEA would not be possible for more than a handful of cases. Within such a context, the present study uses machine learning to guide development of a TEA and modeling framework which provides accurate cost predictions using three key inputs – feedstock cost, biocrude yield, and process scale – to estimate the minimum fuel selling price (MFSP) that an HTL process can achieve. The structure of the proposed framework is informed and based on empirical observations of cost projections made by a detailed TEA over a wide range of feedstock costs, biocrude yields, and process scales. A machine learning guided process was used to identify, train, and test a series of models using auto-generated data for training and independently reported data for testing. The most accurate model consists of three terms and requires 6 adjustable parameters to predict independently published values of MFSP (N = 28) to within an average value of ± 20.4%. It is demonstrated that the reduced-order model’s predictions fall within 40% of the corresponding published values 95% of the time, and in the worst case, the associated discrepancy is 45.9%, suggesting that the accuracy of the machine learned model is indeed comparable to the TEAs that were used to build it. Moreover, the terms in the model are physically interpretable, conferring greater reliability to the use of its predictions. The model can be used to predict the dependence of MSFP on biocrude yield, scale, and feedstock cost; interestingly, MFSP is insensitive to biocrude yield and/or scale under many situations of interest and identifying the critical value for a given application is crucial to optimizing economic performance. The proposed model can be also extended to evaluate economic performance of newly developed HTL-based processes, including catalytic HTL, and the methodological framework used in this study is deemed appropriate for the development of machine learned TEA models in cases of other similar waste-to-energy technologies.

The Poisson–Boltzmann equation in micro- and nanofluidics: A formulary

The Poisson–Boltzmann (PB) equation provides a mean-field theory of electrolyte solutions at interfaces and in confinement, describing how ions reorganize close to charged surfaces to form the so-called electrical double layer (EDL), with numerous applications ranging from colloid science to biology. This formulary focuses on situations of interest for micro- and nanofluidics, and gathers important formulas for the PB description of a Z:Z electrolyte solution inside slit and cylindrical channels. Different approximated solutions (thin EDLs, no co-ion, Debye–Hückel, and homogeneous/parabolic potential limits) and their range of validity are discussed, together with the full solution for the slit channel. Common boundary conditions are presented, the thermodynamics of the EDL is introduced, and an overview of the application of the PB framework to the description of electrokinetic effects is given. Finally, the limits of the PB framework are briefly discussed, and Python scripts to solve the PB equation numerically are provided.

Syphilis and pregnancy.

•Although congenital syphilis has a known etiological agent, accessible diagnosis and low-cost, effective treatment with low fetal toxicity, it continues to challenge obstetric and antenatal care services. •The increasing rates of syphilis in the general population have direct repercussions on the increase in cases of congenital syphilis, a situation of objective interest for public health. •Although transforming the recording of syphilis and congenital syphilis into notifiable diseases improved the records and has made it possible to measure the occurrence of these diseases and create solutions, no effects on reducing their frequency have been reached yet. •The failure to control syphilis/congenital syphilis is multifactorial, and associates variables that range from the deficiency in teaching about these diseases in schools and in the training system of the various health professional segments, as well as the lack of rigid policies for quality control from antenatal care until the clinical follow-up of children exposed to Treponema pallidum during pregnancy. •To date, benzathine penicillin is the only antimicrobial accepted as effective by the main health authorities on the planet for the treatment of syphilis in pregnant women. •The fear of anaphylaxis in response to the treatment of syphilis with benzathine penicillin is an important factor hindering the prompt and correct treatment of pregnant women with syphilis, even though health authorities have made efforts to face the problem with solid arguments, still insufficient to resolve the question. •Although specific protocols are published, the failure to control the treatment of syphilis in pregnant women is still observed with high frequency, indicating and reinforcing a failure in the quality control of these care principles. The National Specialized Commission on Infectious Diseases of the Brazilian Federation of Gynecology and Obstetrics Associations (Febrasgo) endorses this document. Content production is based on scientific evidence on the proposed topic and the results presented contribute to clinical practice.

Unwilling allies: the USSR, the Communist Party of Argentina, and the military dictatorship in Argentina, 1976–1983

The author of this article aims to explore the complex and contradictory relationship between the Communist Party of Argentina, the Soviet Union, and the military regime in Argentina between 1976 and 1983. It was a period of right-wing military dictatorship domination in the region, characterised by outright terrorist policies against left-wing forces, mass violations of human rights, which put the International Communist Movement in an ambiguous position due to the USSR’s close cooperation with the Argentine military junta. A unique situation of mutual interest between Soviet foreign policy and the military dictatorship developed in the USSR’s relations with the military regime in Argentina. The most important factor in this contradictory situation was the position of the Communist Party of Argentina, supported by the CPSU, on co-operation with a regime that other communist parties and leftist forces qualified as fascist, ultra-reactionary, and anti-communist. The USSR found moral and political justification for its cooperation with the Argentine regime in the policies of local communists who supported the regime, justifying its repression of leftist radical movements, especially the Montoneros. The Argentine Communist Party justified its policy by referring to the junta’s growing cooperation with the USSR. The article explores the reasons for this policy of the Communist Party, which caused tension in the international communist movement and the subsequent isolation of the Argentinian Communist Party. The specific political interests of the USSR were supported by the Argentine communists, who, in turn, saw in them a guarantee of their interests in the conditions of the harsh right-wing military regime in the country. For the first time in historiography, this paper, drawing on records from the archive of the CPSU Central Committee, documents the complex process of reconciling the USSR’s economic and political interests in Argentina during this difficult period of the Cold War.

Smart and user-centric manufacturing information recommendation using multimodal learning to support human-robot collaboration in mixed reality environments

The future manufacturing system must be capable of supporting customized mass production while reducing cost and must be flexible enough to accommodate market demands. Additionally, workers must possess the knowledge and skills to adapt to the evolving manufacturing environment. Previous studies have been conducted to provide customized manufacturing information to the worker. However, most have not considered the worker's situation or region of interest (ROI), so they had difficulty providing information tailored to the worker. Thus, a manufacturing information recommendation system should utilize not only manufacturing data but also the worker's situational information and intent to assist the worker in adjusting to the evolving working environment. This study presents a smart and user-centric manufacturing information recommendation system that harnesses the vision and text dual encoder-based multimodal deep learning model to offer the most relevant information based on the worker's vision and query, which can support human-robot collaboration (HRC) in a mixed reality (MR) environment. The proposed recommendation model can assist the worker by analyzing the manufacturing environment image acquired from smart glasses, the worker's specific question, and the related manufacturing document. By establishing correlations between the MR-based visual information and the worker's query using the multimodal deep learning model, the proposed approach identifies the most suitable information to be recommended. Furthermore, the recommended information can be visualized through MR smart glasses to support HRC. For quantitative and qualitative evaluation, we compared the proposed model with existing vision-text dual models, and the results demonstrated that the proposed approach outperformed previous studies. Thus, the proposed approach has the potential to assist workers more effectively in MR-based manufacturing environments, enhancing their overall productivity and adaptability.

New Constitution in Nepal: Fundamental Freedoms and Educational Rights Provisions, and Implications for Dalits’ Schooling

ABSTRACT When Nepal promulgated a new constitution in 2015, discourse around the ‘New Nepal’, post-monarchical rule, was powerful; the new constitution was perceived as a landmark text to provide a clear vision for New Nepal’s overall development. The poor state of Dalits’ human rights and educational realities were widely cited as critical issues requiring attention and expedited intervention during the constitution-writing process. Almost a decade later, however, no outstanding progress is evident regarding the overall development of the historically marginalized Dalits. This paper aims to interrogate the perpetuation of the dominant ideology, as the basis for the marginalization of people lacking power, in the new constitution’s fundamental and educational provisions by exploring its marginalizing semantic elements. We selected these semantic elements or linguistic categories through reading the new constitution. Our analyses expect to unfold the link between Dalits’ poor state of human rights and educational experiences and the provisions of the new constitution. This study helps expose the roots of inequality, exclusion, and social injustice by appraising policies of public interest in situations where human rights violations, illiteracy, and poverty have distressed the lives of marginalized people, as well as encouraging research on the problems faced by extremely vulnerable population like Dalits, who are not only marginalized in their place of birth but also in the diaspora.

When are You Recovered? Defining Cutoff Points Using the Acute Respiratory Tract Infection Questionnaire

ObjectivesAcute respiratory tract infections (ARTIs) are a heterogenous group of diseases. Often, it is difficult to obtain a precise diagnosis in general practice but also difficult to determine when the patient is recovered. The lack of a precise definition of recovery after ARTI complicates scientific research aiming to optimize diagnostics and compare treatments. The study aimed to define cutoff points to determine the end of an ARTI as a proxy for recovery in patients diagnosed with ARTI in general practice using a validated patient-reported outcome instrument; The ARTI Questionnaire (ARTIQ). MethodsA total of 259 participants was divided in 2 groups—1 with ARTI and 1 without. Histograms and area under the curve were calculated for each of the 5 dimensions within the ARTIQ to evaluate the discriminative effect. For the most discriminative dimensions receiver operating comparison curves were performed to determine relevant cutoff points for having or not having ARTI symptoms and serve as a proxy for recovery in clinical research. ResultsThe highest discriminative effect was found in 2 dimensions: “physical—upper airways” and “physical—lower airways.” When combining these dimensions, the area under the curve was 0.97. Sensitivity, specificity, and predictive values were calculated for selected cutoff points. ConclusionCutoff points serving as proxy for recovery from ARTI using a patient-reported outcome were identified. The specific cutoff point for a certain research project must be selected considering the specific clinical situation of interest.

THE INFLUENCE OF ENJOYMENT, SOCIAL VALUE, AND CONTINUED USE INTENTION TOWARDS BATTLE PASS PURCHASE INTENTION IN GENSHIN IMPACT

This study aims to analyze the influence of enjoyment, social value and continued use intention towards Purchase Intention of a virtual item in a mobile game such as Battle Pass offered in Genshin Impact. This research design is descriptive which describes the variables in a situation of interest of the researcher. The sampling technique used cross-sectional where data was gathered once during a period from a specific group. There were 126 respondents in Jakarta who were consumers/players that have had purchased Battle Pass but only 98 data are valid for analysis. The questionnaires are distributed online and in this research data analysis was carried out using the Partial Least Square - Structural Equation Modeling (PLS-sem) method. Based on the research results, enjoyment, social value and continued use intention can indicate purchase intention positively and significantly. With the results obtained, researchers hope that Genshin Impact developer (Hoyoverse) can get more information in regards to creating a strategy to increase battle pass purchase intention.

#1353 Apathy and fatigue in patients treated with haemodialysis and peritoneal dialysis

Abstract Background and Aims Apathy is a distinct syndrome manifesting with a loss of interest in social or emotional situations, lack of sense of purpose, low energy levels and detachment from life and personal events. Previous studies showed that apathy is associated with vascular impairment and consequent cognitive dysfunction, reduced quality of life and increased hospitalization, institutionalization, healthcare costs and death. So far there has been little research on the prevalence of apathy among dialysis patients although this population could be considered at risk for this condition due to increasing age, and disease and treatment burden. Fatigue is also common in dialyzed patients and impacts daily living, impairs the quality of life, increases the risk of cardiovascular events and negatively influences survival. This study aimed to explore the link between apathy and fatigue among hemodialysis (HD) and peritoneal dialysis (PD) patients. Method We conducted a cross-sectional cohort study which included 75 HD (57.3% male, median age 64 years) and 62 PD patients (48.4% male, median age 61 years) from two dialysis centres. Apathy status was assessed by the Apathy Evaluation Scale (AES) by Starkstein. Fatigue was evaluated with the Functional Assessment of Chronic Illness Therapy (FACIT) scale. AES score of 14 and higher denotes the presence of apathy, while a FACIT score of less than 30 indicates severe fatigue. Demographic, clinical and laboratory data were obtained by a focused questionnaire and from electronic medical records. Data were analyzed with T-test, Hi-square, ANOVA and Pearson correlation as applicable. Results HD patients were significantly longer on dialysis than PD patients (p=0.046). Apathy was more frequent among PD patients compared to the HD group (64.5% vs 48%), but the difference was not statistically significant (p = 0.053). Severe fatigue was more frequent in the HD group (33.8% vs 27.4%), but the difference was not statistically significant (p = 0.424). Elderly patients had a higher prevalence of apathy in both HD (70.3% vs 29.7%, p<0.001) and PD groups (84.2% vs 16.3%, p = 0.008), and a significantly higher prevalence of severe fatigue in the HD group (68% vs 32%, p = 0.017). Among HD patients higher education level was significantly associated with higher FACIT and lower apathy scores (p = 0.002 and p = 0.001 respectively). HD patients taking psychotropic medication had significantly lower FACIT (27.2±13.5 vs 35.0 ± 11.9, p = 0.03). Also, the presence of apathy was significantly associated with lower hemoglobin levels (101.7±9.7 vs 110.3±11.2, p = 0.001), red blood cells count (3.2±0.2 vs 3.5±0.6, p = 0.004), lower serum creatinine (900.0±149.1 vs 1001.5±266.4, p = 0.047) and lower Kt/V (1.35±0.22 vs 1.49±0.24, p = 0.008) in the HD group, while PD patients with severe fatigue had significantly higher creatinine levels (796.7±176.9 vs 646.4±200.0, p = 0.009). Gender, dialysis vintage, primary renal disease, and comorbidities were not significantly associated with either apathy or fatigue in either group of patients. Apathy and fatigue were significantly correlated in both the HD (p = 0.04) and the PD (p = 0.001) groups. Conclusion Apathy is a highly prevalent and often overlooked condition among dialyzed patients regardless of dialysis modality. Longitudinal studies should explore whether apathy is a causative factor for fatigue in these populations.

Quantum Circuits with Multiterminal Josephson-Andreev Junctions

We explore superconducting quantum circuits where several leads are simultaneously connected beyond the tunneling regime, such that the fermionic structure of Andreev bound states in the resulting multiterminal Josephson junction influences the states of the full circuit. Using a simple model of single-channel contacts and a single level in the middle region, we discuss different circuit configurations where the leads are islands with finite capacitance and/or form loops with finite inductance. We find situations of practical interest where the circuits can be used to define noise-protected qubits, which map to the bifluxon and 0−π qubits in the tunneling regime. We also point out the subtleties of the gauge choice for a proper description of these quantum circuit dynamics. Published by the American Physical Society 2024

Virtual Reality for Spatial Planning and Emergency Situations: Challenges and Solution Directions

The notion of the smart city involves embedding Industry 4.0 technologies to improve the lives of inhabitants in urban environments. Within this context, smart city data layers (SCDLs) concern the integration of extra tiers of information for the purposes of improving communication potential. Under the Industry 4.0 technology grouping, advanced communication technologies, such as virtual reality (VR), further the opportunities to model, recreate, evaluate and communicate scenarios that potentially improve citizens lives at multiple SCDL scales in a smart cities context. The use of added contextual information in SCDLs is of special interest for emergency planning situations at the building scale. In this research, a literature review to understand the current approaches for the use, development and evaluation of VR applications in the context of emergency planning was conducted. The results indicated four main categories of relevant challenges for these types of applications, for which recommendations and a roadmap for VR development are presented. In total, the study identified 10 commonly occurring challenges (e.g., optimization and discomfort) and 19 solution directions (e.g., model construction and spatial directions) in related articles when considering the development of VR for spatial planning and emergency situations.

H.M. Naqvi's Home Boy: A Socio-Cultural Conflict Analysis in the Context of Disruption and Multiculturalism

Through the lens of multiculturalism, this inquiry examines Home Boy by H.M. Naqvi. In particular, this study will look at how the selected literary work portrays several types of socio-cultural conflict that make it hard for the protagonists to blend in with their new communities. Concerns about intergroup tensions are at the forefront of multicultural communities' minds. According to this research, "socio-cultural conflict" describes when two or more cultures clash in areas such as politics, economics, religion, and society. The current study focuses on the book in question as an example of the socio-cultural conflict that might arise in heterogeneous society. Summing up the current human condition and the difficulties people face in a diverse city like New York is offered here. Characters in that society suffer as a result of these tensions as a result of immigration struggles, terrorist attacks, and identity issues. Cultural priorities, as shown in the book, lead to the denial of rights to many people in heterogeneous societies. Terrorist attacks and other forms of discrimination against them serve to solidify their inferiority complex. The facts on the hardships experienced by people in New York's postcolonial multicultural society are unearthed via the use of qualitative content analysis. Home Boy faces a plethora of socio-cultural conflicts and shows an interest in the real-life situations of the people living in such civilizations, according to the study. Their socioeconomic position is deteriorated by the prevailing culture, and H. M. Naqvi has communicated this misery via this work.

New geographic location data on the occurrence and abundance of carrion insects of forensic interest.

The world's forensic entomologists have much in common. They face similar research challenges, apply the same scientific methodology, study the same kinds of evidence, and access global research databases. Nevertheless, some regional heterogeneity inevitably exists. For most countries, and particularly those that have complex and diverse ecosystems, the current priority is to stimulate use of forensic entomology by establishing open access databases with time series data using standardised protocols for occurrence, abundance, distribution, niche preferences, life cycle, and identification characteristics for the key regional species that may be encountered in forensic entomology cases. Even in countries where forensic entomology is routinely used as a tool in reconstructing the history of corpses found on crime scenes in accordance with principles found in the rapidly developing body of literature, there is still much to learn about forensically useful insects. Examples of regional gaps include the taxonomy of lesser-known carrion insect species, seasonal occurrence of carrion species in the country's various geographical regions, and rates of development of the local species modeled in the many site situations of forensic interest. The first published study of carrion insects found in Athens, Greece published in this journal is an example of entomologists in a region taking the necessary first step towards establishing baseline data about native and introduced species and hence, physiological and behavioural responses to local environmental conditions, including life cycles and likelihood of occurrence or absence in the region.

Revealing ultrafast phonon mediated inter-valley scattering through transient absorption and high harmonic spectroscopies

Processes involving ultrafast laser driven electron-phonon dynamics play a fundamental role in the response of quantum systems in a growing number of situations of interest, as evinced by phenomena such as strongly driven phase transitions and light driven engineering of material properties. To show how these processes can be captured from a computational perspective, we simulate the transient absorption spectra and high-harmonic generation signals associated with valley selective excitation and intraband charge-carrier relaxation in monolayer hexagonal boron nitride. We show that the multitrajectory Ehrenfest dynamics approach, implemented in combination with real-time time-dependent density-functional theory and tight-binding models, offers a simple, accurate, and efficient method to study ultrafast electron-phonon coupled phenomena in solids under diverse pump-probe regimes which can be easily incorporated into the majority of real-time software packages. Published by the American Physical Society 2024

Effect of an Electric Field on the Structure and Stability of Atmospheric Clusters.

We study the influence of an applied electric field on the structure and stability of some common bimolecular clusters that are found in the atmosphere. These clusters play an important role in new particle formation (NPF). For low values of the electric field (i.e., |E| ≤ 0.01 V Å-1), we demonstrate that the field response of the clusters can be predicted from simply calculating the dipole moment of the cluster and the dipole moments of the constituent molecules and that the influence on the association energy of the cluster is minimal (i.e., <0.5 kcal mol-1). For higher field strengths |E| > 0.2 V Å-1, there can be more dramatic effects on both structure and energetics, as the induced dipole, charge transfer, and geometric distortion play a larger role. Although such large fields are not very relevant in the atmosphere, they do exist in some situations of experimental interest, such as near interfaces and in intense laser fields.

Geological significance of the spatial clustering and alignment of vents in zones of distributed volcanism: A critical review

The spatial distribution of volcanic activity has been the subject of scientific enquiry for more than 350 years. Nevertheless, it has been only until recently that modern techniques of analysis started to be used to characterize such distribution. As a result, in the past 40 years many methods were devised, or adopted from other fields of study, aiming to achieve that purpose. Ironically, the plethora of now available methodologies has made problematic the selection of one method of study to characterize the spatial distribution of volcanic vents. In addition, given the diversity of methods, and their underlying assumptions, there are issues concerning the form in which the results of any specific method should be interpreted in a volcanic context. In this work I make emphasis on the relationship between the embedded assumptions of several common methods of study with the concept of a “natural partition”. Throughout this work it is remarked that 1) it is extremely important to gain conscience about the several assumptions implicit on each method of analysis, 2) never loose sight that not all volcanic systems are equal, and 3) that it is a myth that any quantitative method can provide reliable information about any system. The convenience of assessing more than one conceptual model to explain the formation of a cluster-subcluster structure is also mentioned. Overall, it is shown that the complexity of volcanic phenomena cannot be encapsulated by using a single method of study, or an automatized selection of parameters. Thus, given the complexity and diversity of volcanic phenomena, there is no particular method, nor set of methods, that can be recommended to be used on every situation of interest. Yet, as a golden rule, it is suggested that more than one method of analysis is used at every location of study, looking for congruency of results within a range of spatial scales.

Knowledge in real-world contexts: not glamorous, but indispensable

During the past several decades, many epistemologists have argued for and contributed to a paradigm shift according to which knowledge is central to assertion, action, and interaction. This general position stands in sharp contrast to several recently developed accounts regarding specific epistemic contexts. These specific accounts resist applying traditional epistemic norms, including strong knowledge norms, to real-world situations of interest. In particular, I consider recent arguments about the epistemic standards for scientific pronouncements, expert testimony in a political context, and interactive reasoning. I argue, firstly, that knowledge does have a crucial role to play in each case, contrary to appearances. Clarifying the role of knowledge fills gaps in our understanding left open by the existing accounts. Secondly, I show that combining the insights from the knowledge-centric approach and from the more specific accounts provides a new perspective on the open problem of developing an account of knowledge-based decisions. Specifically, I argue that the biggest open problem regarding knowledge-based decisions is not how we respond to uncertainty, but rather how we assess the relevance of our many disparate pieces of knowledge, choosing which to integrate, and how. A strong case emerges for a procedural solution to this part of the problem of how to make knowledge-based decisions.

DNA superhelicity.

Closing each strand of a DNA duplex upon itself fixes its linking number L. This topological condition couples together the secondary and tertiary structures of the resulting ccDNA topoisomer, a constraint that is not present in otherwise identical nicked or linear DNAs. Fixing L has a range of structural, energetic and functional consequences. Here we consider how L having different integer values (that is, different superhelicities) affects ccDNA molecules. The approaches used are primarily theoretical, and are developed from a historical perspective. In brief, processes that either relax or increase superhelicity, or repartition what is there, may either release or require free energy. The energies involved can be substantial, sufficient to influence many events, directly or indirectly. Here two examples are developed. The changes of unconstrained superhelicity that occur during nucleosome attachment and release are examined. And a simple theoretical model of superhelically driven DNA structural transitions is described that calculates equilibrium distributions for populations of identical topoisomers. This model is used to examine how these distributions change with superhelicity and other factors, and applied to analyze several situations of biological interest.