Additional Code Research Articles

Parallel adder-subtractor on elements of neural logic

Modern universal computing machines are capable of implementing any algorithm, but when solving certain tasks in terms of processing speed, they cannot compete with specialized computing modules that can increase the speed of performing arithmetic operations by using parallelism in data processing. The reliability of arithmetic calculators increases due to the use of neural-like elements. Specialized devices effectively solve array processing tasks, artificial intelligence tasks, and are used as control devices. The developed structure of a parallel adder-subtractor based on neural logic elements ensures high performance and reliability. The structural and functional schemes of the adder/subtractor blocks allow to increase the speed in comparison with the known sequential action adder when added in additional codes by at least 2 times, and with a parallel adder with sequential transfer by at least 1.5 times. It is shown that the hardware complexity of the presented adder-subtractor is 1.3 times lower compared to the sequential action adder and 2.8 times lower compared to the parallel adder with sequential transfer. The proposed structure of the adder-subtractor provides an increase in the calculation speed of arithmetic operations due to the implementation of parallelism in data processing.

Manufacturability-Based Design Optimization for Directed Energy Deposition Processes

Additive Manufacturing (AM) is the process of joining materials by selectively depositing them layer upon layer for the purpose of manufacturing parts or assemblies which are based on a 3D digital model. The nature of these processes results in the morphing of complex component geometries, enabling a high degree of design freedom and resulting in lightweight structures with increased performance. These processes, however, experience many limitations regarding manufacturability. The aim of this study is to develop a method and tool that optimizes the design of a component to avoid overhanging geometries and the need for supports during the Additive Manufacturing process. A workflow consisting of steps for topology optimization, orientation optimization, material addition, and machine code generation is described and implemented using Rhinoceros 3D and Grasshopper software. The proposed workflow is compared to a conventional workflow regarding manufacturing Key Performance Indicators (KPIs) such as part volume, support volume, and build time. A significant reduction is observed regarding all the KPIs by using the proposed method. Examining the results from both the conventional workflow and the proposed one, it is clear that the latter has unquestionable advantages in terms of effectiveness. In the particular case study presented, a total volume reduction of around 80% is observed. The reduction in the total volume (including the required support volume) leads to a significant reduction in the material used as well as in the build time, consequently resulting in cost reduction.

Extracting and visualizing hidden activations and computational graphs of PyTorch models with TorchLens

Deep neural network models (DNNs) are essential to modern AI and provide powerful models of information processing in biological neural networks. Researchers in both neuroscience and engineering are pursuing a better understanding of the internal representations and operations that undergird the successes and failures of DNNs. Neuroscientists additionally evaluate DNNs as models of brain computation by comparing their internal representations to those found in brains. It is therefore essential to have a method to easily and exhaustively extract and characterize the results of the internal operations of any DNN. Many models are implemented in PyTorch, the leading framework for building DNN models. Here we introduce TorchLens, a new open-source Python package for extracting and characterizing hidden-layer activations in PyTorch models. Uniquely among existing approaches to this problem, TorchLens has the following features: (1) it exhaustively extracts the results of all intermediate operations, not just those associated with PyTorch module objects, yielding a full record of every step in the model's computational graph, (2) it provides an intuitive visualization of the model's complete computational graph along with metadata about each computational step in a model's forward pass for further analysis, (3) it contains a built-in validation procedure to algorithmically verify the accuracy of all saved hidden-layer activations, and (4) the approach it uses can be automatically applied to any PyTorch model with no modifications, including models with conditional (if–then) logic in their forward pass, recurrent models, branching models where layer outputs are fed into multiple subsequent layers in parallel, and models with internally generated tensors (e.g., injections of noise). Furthermore, using TorchLens requires minimal additional code, making it easy to incorporate into existing pipelines for model development and analysis, and useful as a pedagogical aid when teaching deep learning concepts. We hope this contribution will help researchers in AI and neuroscience understand the internal representations of DNNs.

The spiderweb of error-detecting codes in the genetic information

Nature possesses inherent mechanisms for error detection and correction during the translation of genetic information, as demonstrated by the discovery of a self-complementary circular C3-code called X0 in various organisms such as bacteria, eukaryotes, plasmids, and viruses (Arquès and Michel, 1996; Michel, 2015, 2017). Since then, extensive research has focused on circular codes, which are believed to be remnants of ancient comma-free codes. These codes can be regarded as an additional genetic code specifically optimized for detecting and preserving the proper reading frame in protein-coding sequences. A study by Fimmel et al. in 2014 identified that a total of 216 maximal self-complementary C3-codes can be grouped into 27 equivalence classes with eight codes in each class.In this work, we study how the 27 equivalence classes are related to each other. While the codes in each equivalence class obtained by Fimmel et al. in 2014 are permutations of each other, i.e. one code can be obtained from the other by applying a permutation of the bases, it has not been clear how the equvalence classes are connected. We show that there is an ordering of the equivalence classes such that one gets from one class to the next one by substituting only one pair of codon/anticodon in the corresponding codes, i.e. the corresponding codes have a maximal intersection of 18 codons. To perform this analysis, we define two graphs, G216 and G27, whose vertices are, respectively, all 216 maximal self-complementary C3-codes and 27 equivalence classes. Several properties of the graphs are obtained. Most surprisingly, it turns out that G27 contains Hamiltonian paths of length 27. This fact ultimately leads to a representation of the set of all 216 maximal self-complementary C3-codes as a kind of spider web. Finally, we define dinucleotide cuts of such codes by projecting each codon to its first two bases and show that the paths of lengths 27 in G216 can even be chosen so that all the codes contain a special subset of dinucleotides defined by Rumer’s roots. These observations raise a lot of new questions about the biological function of such structures.

Two classes of few-Lee weight [formula omitted]-linear codes using simplicial complexes and minimal codes via Gray map

Recently certain few-Lee weight additive codes over some mixed alphabet rings with optimal or minimal Gray images are constructed using suitable defining sets. Inspired by these works, we construct two special classes of linear codes over Z2[u] with u2=0 by using the mixed alphabet ring Z2Z2[u] and employing simplicial complexes having one or more maximal elements. We show that these codes have few-Lee weights by determining their Lee weight distributions. As applications, we are getting the 1st order binary Reed-Muller codes of length 23m−2 (where m>1) and some infinite families of binary self-orthogonal minimal codes via Gray map.

Outpatient and "Admission-Substituting" Interventions in Vascular Surgery - What is Feasible and Where are the Limits? Previous and New Legal Requirements and their Implementation in Practice

In vascular surgery too, more services and procedures will have to be shifted from the previous inpatient to the outpatient sector in the future. Therefore, the previous and new legal requirements as well as their implementation in vascular surgery will be explained and evaluated. Professional policy analysis from a perspective of medical vascular surgery. The AOP catalog from 01.01.2023 was extended by 208 additional OPS codes. The inpatient performance of services which, according to the AOP contract, must be regularly performed on an outpatient basis, are now to be justified on the basis of context factors.A special sector-equivalent remuneration, which is independent of whether the remunerated service is performed on an outpatient or inpatient basis, is a prerequisite for a cost-covering expansion of outpatient operations and inpatient-replacing services. The rehabilitation of primary varicosis under outpatient conditions is undoubtedly the standard. The majority of AV shunt installations are performed as inpatient procedures. No new OPS codes were added to the 2023 AOP catalog for varicose vein, shunt and endovascular surgery. The shift of inpatient services to the outpatient sector can be a feasible path, based on the experience of other European countries. However, the structures, economic conditions and incentives should first be created to successfully promote transfer to outpatients. Integrated care offers the possibility for the health insurance funds to conclude contracts with the service providers named in §140a of the Social Code, paragraph 3, for special care. The use of telemedicine in the sense of tele-premedication or tele-monitoring can be a way to expand outpatient surgery, especially in rural regions. In order to enable therapy concepts from one expert in vascular medicine, the outpatient service billing of interventional procedures must also be demanded by vascular surgeons and specialists. The potential to transform inpatient services into the outpatient setting of service provision is realisable in vascular surgery in the core areas of varicose vein surgery, shunt surgery and peripheral interventional procedures under specific conditions.

Presentation and validation of the internal charging risk forecast in the PAGER framework

The Prediction of Adverse effects of Geomagnetic storms and Energetic Radiation project (PAGER) aims to provide a framework for space weather and related effects forecasts. One of the innovative concepts is to plug, downstream of the environment prediction models, an automatized chain evaluating both surface and internal charging to forecast a charging risk evaluation for spacecraft on GEO and MEO orbits.The evaluation of the internal charging risk induced by electrons of the radiation belts with an energy above ∼0.5 MeV, is carried out throughout an innovating approach, combining different charging models, downstream the environmental ones. The space weather forecast is provided by a simulation of the radiation belt performed with VERB-3D. Downstream, the charging analysis is mainly performed using SPIS-IC, the internal charging branch of the open-source SPIS software (Spacecraft Plasma Interaction Software). SPIS-IC requires the prior computation of the source terms of space charge and dose rates resulting from the transport of primary electrons through the spacecraft structure. This is done beforehand using a 3D direct Monte-Carlo approach. In addition, a simple and fast internal charging 1D code, ICOne has been developed and is also used to evaluate the internal charging risk, based on a semi-empirical deposition rule.The internal charging modeling chain is used to carry out on one hand an evaluation of the electrical risk on a satellite in MEO orbit surrounded by an environment simulated by the VERB-3D Fokker-Plank code, and on the other hand, to reproduce measurements of a charging event of GIOVE-A.

Computer package DIZET v. 6.45

The new version of the DIZET electroweak library is described. Changes and additional code features concerning the previous version are explained. The software allows one to make state-of-the-art theoretical predictions for pseudo-observable quantities, including higher-order radiative corrections. The current version of the DIZET library v. 6.45 incorporates advanced recent results of theoretical calculations. Numerical comparisons with the results of the previous version are performed. Estimates of theoretical uncertainties are discussed. Program summaryProgram Title:DIZET version 6.45CPC Library link to program files:https://doi.org/10.17632/2fr58v92xc.1Code Ocean capsule:https://codeocean.com/capsule/0198682Licensing provisions: GPLv3Programming language: FORTRAN 77/90External routines: AlphaQED http://www-com.physik.hu-berlin.de/~fjeger/software.htmlJournal reference of previous version: Comput. Phys. Commun. 59 (1990) 303Does the new version supersede the previous version?: YesReasons for the new version: Implementation of new options.Summary of revisions: Implemented the complete electroweak two-loop radiative corrections to all the relevant electroweak precision pseudo-observables related to the Z-boson decay. Added support of new library for hadronic contribution to vacuum polarization.Nature of problem: The Z-resonance region is still extremely important for the experimental verification of the Standard Model. The anticipated experimental accuracy on a large variety of observables has to be matched with theory predictions of at least the same level of accuracy to achieve maximum usage of experimental data.Solution method: Theoretical calculations at NNLO in perturbation theory allow to compute higher precision pseudo-observables to verify the Standard Model at high luminosity future colliders. The package includes electroweak two-loop corrections calculated in the on-mass shell renormalization scheme. Pseudo-observables and electroweak form-factors can be calculated in a wide range of input parameters.Additional comments including restrictions and unusual features: The estimate of results at the off-resonance region should be treated with caution as two-loop electroweak corrections were calculated for the Z-resonance peak.

On additive MDS codes with linear projections

We support some evidence that a long additive MDS code over a finite field must be equivalent to a linear code. More precisely, let C be an Fq-linear (n,qhk,n−k+1)qh MDS code over Fqh. If k=3, h∈{2,3}, n>max⁡{qh−1,hq−1}+3, and C has three coordinates from which its projections are equivalent to Fqh-linear codes, we prove that C itself is equivalent to an Fqh-linear code. If k>3, n>q+k, and there are two disjoint subsets of coordinates whose combined size is at most k−2 from which the projections of C are equivalent to Fqh-linear codes, we prove that C is equivalent to a code which is linear over a larger field than Fq.

The association between sociodemographic, clinical, and potentially preventive therapies with oxaliplatin-induced peripheral neuropathy in colorectal cancer patients.

The purpose of this retrospective cohort study was to evaluate whether several potentially preventive therapies reduced the rate of oxaliplatin-induced peripheral neuropathy (OIPN) in colorectal cancer patients and to assess the relationship of sociodemographic/clinical factors with OIPN diagnosis. Data were obtained from the Surveillance, Epidemiology, and End Results database combined with Medicare claims. Eligible patients were diagnosed with colorectal cancer between 2007 and 2015, ≥ 66years of age, and treated with oxaliplatin. Two definitions were used to denote diagnosis of OIPN based on diagnosis codes: OIPN 1 (specific definition, drug-induced polyneuropathy) and OIPN 2 (broader definition, additional codes for peripheral neuropathy). Cox regression was used to obtain hazard ratios (HR) with 95% confidence intervals (CI) for the relative rate of OIPN within 2years of oxaliplatin initiation. There were 4792 subjects available for analysis. At 2years, the unadjusted cumulative incidence of OIPN 1 was 13.1% and 27.1% for OIPN 2. For both outcomes, no therapies reduced the rate of OIPN diagnosis. The anticonvulsants gabapentin and oxcarbazepine/carbamazepine were associated with an increased rate of OIPN (both definitions) as were increasing cycles of oxaliplatin. Compared to younger patients, those 75-84years of age experienced a 15% decreased rate of OIPN. For OIPN 2, prior peripheral neuropathy and moderate/severe liver disease were also associated with an increased hazard rate. For OIPN 1, state buy-in health insurance coverage was associated with a decreased hazard rate. Additional studies are needed to identify preventive therapeutics for OIPN in cancer patients treated with oxaliplatin.

Euclid: modelling massive neutrinos in cosmology — a code comparison

The measurement of the absolute neutrino mass scale from cosmological large-scale clustering data is one of the key science goals of the Euclid mission. Such a measurement relies on precise modelling of the impact of neutrinos on structure formation, which can be studied with N-body simulations. Here we present the results from a major code comparison effort to establish the maturity and reliability of numerical methods for treating massive neutrinos. The comparison includes eleven full N-body implementations (not all of them independent), two N-body schemes with approximate time integration, and four additional codes that directly predict or emulate the matter power spectrum. Using a common set of initial data we quantify the relative agreement on the nonlinear power spectrum of cold dark matter and baryons and, for the N-body codes, also the relative agreement on the bispectrum, halo mass function, and halo bias. We find that the different numerical implementations produce fully consistent results. We can therefore be confident that we can model the impact of massive neutrinos at the sub-percent level in the most common summary statistics. We also provide a code validation pipeline for future reference.

Development and Internal Validation of Case Definitions for Prevalence Estimation of Microvascular Complications of Diabetes in Routine Data

Surveillance of diabetes requires up-to-date information on the prevalence of diabetes and its complications over time. For this purpose, statutory health insurance (SHI) data is being increasingly used, as the data is available in a timely fashion and case numbers enable detailed estimates also of diabetes complications. The aim of the present study was the development and internal validation of case definitions for the prevalence estimation of diabetic retinopathy (DRP), diabetic polyneuropathy (DPN) and diabetic foot syndrome (DFS). Persons with diabetes differentiated by type 1, type 2, and other diabetes in an age- and sex-stratified sample of persons insured by Barmer SHI in 2018 (n=72,744) comprised the study popuation. Based on the central ICD codes for microvascular complications (DRP: H36.0; DPN: G63.2; DFS: E1X.74/.75), case definitions were developed including additional ICD codes for complications without direct diabetes reference. Subsequently, the case definitions were internally validated. For the validation, coding in the inpatient setting (m1S) or repeatedly in the outpatient setting (m2Q) as well as coding of specific procedures (EBM, OPS) and drug prescriptions or by relevant specialists were considered. Additionally, we analysed the documentation of the diagnoses in the previous years. In 2018, the prevalence of the central ICD codes was 8.4% for DRP (H36.0), 18.9% for DPN (G63.2) and 13.4% for DFS (E1X.74/.75). After inclusion of additional ICD codes in the case definition, prevalence increased significantly for DRP (9.6%) and DPN (20.7%), and barely for DFS (13.5%). Internal validation confirmed the majority of diagnoses (DRP: 96.7%; DPN: 96.5% DFS: 95.8%) and m2Q represented the most relevant criterion. When up to four previous years were considered, prevalences were up to 30% higher for DPN and DFS and up to 64% higher for DRP. The inclusion of additional ICD codes in the case definition of microvascular complications of diabetes appears meaningful, as this increases the sensitivity of the prevalence estimate. Internal validation suggests that the documented diagnoses are plausible. However, not all diagnoses are documented annually, leading to an underestimation of the prevalence using a cross-sectional study design of one year.

After the fire: A qualitative study of the role of long-term recovery organizations in addressing rural communities’ post-wildfire needs

U.S. wildfire activity has increased over the past several decades, disrupting the systems and infrastructure that support community health and resilience. As the cumulative burden of wildfire damage is projected to increase, understanding an effective community recovery process is critically important. Through qualitative interviews with leaders of long-term recovery organizations (LTROs), a key component of wildfire recovery, we explored barriers and facilitators to LTROs’ ability to support post-wildfire needs among rural communities. Between February-May 2022, we conducted surveys and semi-structured interviews with 18 leaders from six LTROs serving rural communities in Washington, Oregon, and California impacted by wildfires between 2015–2020. The Robert Wood Johnson Foundation’s Culture of Health Framework informed the semi-structured interview guide and a priori codebook, to examine LTROs’ ability to address post-wildfire community needs from a health equity perspective. Additional codes were added through an inductive approach, and emerging themes were identified. Our findings indicate that LTROs face many barriers in addressing community needs post-wildfire, including the policies governing access to and the slow arrival of recovery resources, the intertwined nature of community economic health and built environment restoration, and the challenge of forming a functional LTRO structure. However, participants also identified facilitators of LTROs’ work, including the ability of LTROs and their government partners to adapt policies and procedures, and close collaboration with other community organizations. Factors both internal and external to the community and LTROs’ organizational characteristics influence their ability to address community needs, essential to health, post-wildfire. This study’s findings suggest the need for policy improvements to promote more equitable recovery resource access, that economic recovery should be a core LTRO function, and that recovery planning should be incorporated into community disaster preparedness activities. Future research should focus on LTROs’ role in other contexts and in response to other disasters.

Letter: Commentary: The Anatomy of Disvalued Codes: The 63047 and the 22633.

Letter: Commentary: The Anatomy of Disvalued Codes: The 63047 and the 22633.

Lack of consensus on the definition of severe congenital heart defects for research: A challenge for comparing international studies.

Lack of consensus on the definition of severe congenital heart defects for research: A challenge for comparing international studies.

Patient Perspectives on Adaptation to Inborn Errors of Immunity

IntroductionHealthcare providers aim to facilitate adaptation. However, research is limited on how individuals with inborn errors of immunity (IEI) adapt. We aimed to fill this gap by conducting semi-structured interviews of participants with IEI regarding their experiences of adaptation to their illness. MethodsWe contacted 35 participants with IEI who were 18–40 years old, had above-average scores on an adaptation scale (better adaptation), and reported at least mild anxiety or depression by PROMIS 29 Profile v2.1. Twenty (57.1%) completed semi-structured interviews, which included questions about meaning making, mastery, and mental health. Interviews were recorded and transcribed. Three transcripts were reviewed by two researchers to develop a codebook. All interviews will be analyzed using an inductive, semantic thematic approach. ResultsInterviewees were 32 years old on average and 65% were female. Diagnoses included GATA2 deficiency (n = 5), common variable immune deficiency (n = 5), and others. Seven (35%) participants underwent hematopoietic stem cell transplant.Codes related to meaning making included sympathy for and desire to help others (“My hope is that they find hope through my story.”). Many codes related to mastery described discerning what can and cannot be controlled. Additional codes included sources of anxiety and depression, connections between physical and mental health, and the desire for clinicians to ask about mental health.Many codes related to support. Participants valued when others met their needs (“They came and visited me whenever I was in [the] hospital…That really helped.”). They also described unhelpful relationships with individuals who minimized their symptoms (“No matter how. sick you actually are, they just won’t believe it.”).Other codes included comparison to healthy peers (“That’s something I have to think about and. most people don’t have to.”), attitudes (“I can be so much more than the person that was just a victim to an illness.”), key factors in adaptation (e.g., disrupted goals, symptom severity), and learning about one’s body and how to explain one’s illness. DiscussionAdaptation to IEI involves many factors. Further analysis will explore themes and identify targets for facilitating patient adaptation, such as improving mental health and identifying support needs.

COVID-19 and Severe Acute Respiratory Infections: Monitoring Trends in 421 German Hospitals During the First Four Pandemic Waves.

Reliable surveillance systems to monitor trends of COVID-19 case numbers and the associated healthcare burden play a central role in efficient pandemic management. In Germany, the federal government agency Robert-Koch-Institute uses an ICD-code-based inpatient surveillance system, ICOSARI, to assess temporal trends of severe acute respiratory infection (SARI) and COVID-19 hospitalization numbers. In a similar approach, we present a large-scale analysis covering four pandemic waves derived from the Initiative of Quality Medicine (IQM), a German-wide network of acute care hospitals. Routine data from 421 hospitals for the years 2019-2021 with a "pre-pandemic" period (01-01-2019 to 03-03-2020) and a "pandemic" period (04-03-2020 to 31-12-2021) was analysed. SARI cases were defined by ICD-codes J09-J22 and COVID-19 by ICD-codes U07.1 and U07.2. The following outcomes were analysed: intensive care treatment, mechanical ventilation, in-hospital mortality. Over 1.1 million cases of SARI and COVID-19 were identified. Patients with COVID-19 and additional codes for SARI were at higher risk for adverse outcomes when compared to non-COVID SARI and COVID-19 without any coding for SARI. During the pandemic period, non-COVID SARI cases were associated with 28%, 23% and 27% higher odds for intensive care treatment, mechanical ventilation and in-hospital mortality, respectively, compared to pre-pandemic SARI. The nationwide IQM network could serve as an excellent data source to enhance COVID-19 and SARI surveillance in view of the ongoing pandemic. Future developments of COVID-19/SARI case numbers and associated outcomes should be closely monitored to identify specific trends, especially considering novel virus variants.

Analisis Ketepatan Kode Diagnosis pada Kasus Persalinan Pasien Rawat Inap di Rumah Sakit Patria Ikkt Tahun 2022

Diagnostic coding must comply with ICD-10 rules. According to WHO, the coding of delivery cases consists of the code for the mother's condition (O00-O75), the method of delivery (O80-084), and the Outcome of delivery Z37.-., while the code is Z37.-. used as an additional code to determine the outcome of labor. So that the coder officer must have knowledge in setting the diagnosis code. Coding accuracy is very necessary because it is used as a reporting material. To determine the Standard Operating Procedure (SOP), the percentage of accuracy of the diagnosis code for inpatient labor cases based on 3M (complications, delivery method, and outcome of delivery) and the cause of the inaccuracy of the diagnosis code for labor cases. Descriptive research type with a quantitative approach. The population is medical records of inpatients in labor cases with a sample of 100 medical records. The sampling technique is by systematic random sampling. Collecting data by means of observation, interviews, and documentation. Research results: SOPs already exist, but not yet complete. The percentage of accuracy of the correct diagnosis code for labor cases is 22.33% while the incorrect diagnosis code is 77.67%. The cause of the inaccuracy of the ICD-10 code for delivery cases is that the diagnosis does not include the method of delivery and the outcome of delivery, and has never been done. evaluation or audit coding. The accuracy of the diagnosis of labor cases is still incomplete. Improve the SOP entry and complete the delivery method and outcome of delivery in medical records and registers.

A systematic review of barriers and enablers that health professionals experience to the delivery of type 2 diabetes care for adults with severe mental illness.

People with severe mental illness have a heightened risk for type 2 diabetes. They also experience poorer outcomes, including more diabetes complications, more emergency admissions, lower quality of life and excess mortality. This systematic review aimed to identify health professionals' barriers to and enablers of delivering and organising type 2 diabetes care for people with severe mental illness. Searches were conducted in Medline, EMBASE, PsycInfo, CINAHL, OVID Nursing, Cochrane Library, Google Scholar, OpenGrey, PsycExtra, Health Management Information Consortium and Ethos in March 2019, with updates in September 2019 and January 2023. There were no restrictions on study design, but studies were excluded if they did not include the perspective of health professionals or were not in English. Barriers and/or enablers of type 2 diabetes care for people with a severe mental illness were organised using the theoretical domains framework with additional inductive thematic coding. Twenty-eight studies were included in the review. Overall, eight domains were identified as important with barriers and enablers identified at individual, interpersonal and organisational levels. Focussing on providing a collaborative healthcare environment which actively supports type 2 diabetes care, fostering improved communication both between professionals and service users, ensuring clear boundaries around roles and responsibilities as well as individual skill and knowledge support alongside confidence building all offer opportunities to improve type 2 diabetes care.

Correction to: Multi-twisted additive codes over finite fields

Correction to: Multi-twisted additive codes over finite fields