Reduced order modelling in multimachine power systems

Conventional techniques used for the assessment of transient and dynamic stability in multimachine power systems require the solution of a large number of ordinary differential equations describing the dynamics of the system generating units. Detailed representation of generating units results in a system of equations that are numerically stiff and of large dimensionality. As a result, the digital simulation of the entire system becomes excessively complex and uneconomical in terms of computer time;It has been recognized that coherency identification is a fundamental step in obtaining reduced order dynamic equivalent models for power systems. Two methods of coherency identification are presented in this dissertation, one based on a slow coherency approach and the other based on modal analysis. Improvements in the slow coherency approach are accomplished by a sensitivity based identification of the set of group-reference generators in the system, leading eventually to the sets of coherent generators. The second method uses the undamped system equations having a system matrix A. The eigenstructure of A is used to obtain a set of coherency indices, based on the root-mean-square values of variations in angular differences between pairs of generators. These coherency indices are compared with a coherency threshold to determine coherent groups of generators. Numerical examples are presented to illustrate and validate both techniques;With regard to the dynamic stability of multimachine power systems, a method based on singular perturbation theory is proposed for the simulation of models of high dimensionality and widely varying time constants. In this method, the state vector is partitioned into subsets of slow and fast variables, a perturbation parameter, (epsilon), is selected and the equations are expressed in their singular perturbation form. The time responses of the system are obtained by the use of the asymptotic expansions of the outer solution and the boundary layer correction of the perturbed equations;A numerical example using a single machine-infinite bus system is used to illustrate and validate the method. While promising results were obtained, the need for additional refinements was made evident

Habitat in El Salvador, processes and spaces that setting it: approach proposal for habitat analysis, the Arcatao Case

La investigación “Procesos sociales y condiciones físico-espaciales que configuran en mayor medida el hábitat en los asentamientos humanos de El Salvador” propone un enfoque de análisis de las condiciones de la producción social del hábitat, a través de un caso de estudio en el municipio de Arcatao. Estructurada a partir del enfoque del pluralismo metodológico crítico, esta investigación, brinda al menos tres resultados claves. Una evaluación con indicadores y cartografía de la producción social del hábitat; Las características principales de los actores, su capacidad de agencia y la forma en que se articulan entre sí; y un análisis histórico de los procesos de producción del hábitat, lo que permite conocer las condiciones estructurales y a capacidad de agencia de un actor o un grupo, necesarias para la emergencia de procesos clave para las transformaciones físico-espaciales del hábitat.This research is Titled: "Social processes and physical-spatial conditions that configure to a greater extent the habitat in the human settlements of El Salvador. This research proposes an approach to analyze the conditions of the social production of habitat in this country, through a case of study in the municipality of Arcatao at the north east of our country. This research proposal is structured on the approach of “critical methodological pluralism”, that allows at least three key results of the municipality studied. First, the evaluation and production of cartography , based on GIS mapping, about the social production of habitat; second, the identification of key stakeholders, their characteristics their agency capability and the sets of networks through which they articulate among themselves; and finally, a historical analysis of the processes regarding the production of habitat, which allows to get a deeper understanding of the key structural conditions and the agency capability of stakeholders, needed for the emergence of the processes underpinning the resulting spatial transformations of the habitat.Peer Reviewe

Large expert-curated database for benchmarking document similarity detection in biomedical literature search

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe

Reduced order modelling in multimachine power systems

Conventional techniques used for the assessment of transient and dynamic stability in multimachine power systems require the solution of a large number of ordinary differential equations describing the dynamics of the system generating units. Detailed representation of generating units results in a system of equations that are numerically stiff and of large dimensionality. As a result, the digital simulation of the entire system becomes excessively complex and uneconomical in terms of computer time;It has been recognized that coherency identification is a fundamental step in obtaining reduced order dynamic equivalent models for power systems. Two methods of coherency identification are presented in this dissertation, one based on a slow coherency approach and the other based on modal analysis. Improvements in the slow coherency approach are accomplished by a sensitivity based identification of the set of group-reference generators in the system, leading eventually to the sets of coherent generators. The second method uses the undamped system equations having a system matrix A. The eigenstructure of A is used to obtain a set of coherency indices, based on the root-mean-square values of variations in angular differences between pairs of generators. These coherency indices are compared with a coherency threshold to determine coherent groups of generators. Numerical examples are presented to illustrate and validate both techniques;With regard to the dynamic stability of multimachine power systems, a method based on singular perturbation theory is proposed for the simulation of models of high dimensionality and widely varying time constants. In this method, the state vector is partitioned into subsets of slow and fast variables, a perturbation parameter, (epsilon), is selected and the equations are expressed in their singular perturbation form. The time responses of the system are obtained by the use of the asymptotic expansions of the outer solution and the boundary layer correction of the perturbed equations;A numerical example using a single machine-infinite bus system is used to illustrate and validate the method. While promising results were obtained, the need for additional refinements was made evident.</p

BET Inhibition as a Rational Therapeutic Strategy for Invasive Lobular Breast Cancer

PURPOSE: Invasive lobular carcinoma (ILC) is a subtype of breast cancer accounting for 10% of breast tumors. The majority of patients are treated with endocrine therapy; however, endocrine resistance is common in estrogen receptor-positive breast cancer and new therapeutic strategies are needed. Bromodomain and extraterminal inhibitors (BETi) are effective in diverse types of breast cancer but they have not yet been assessed in ILC.EXPERIMENTAL DESIGN: We assessed whether targeting the BET proteins with JQ1 could serve as an effective therapeutic strategy in ILC in both 2D and 3D models. We used dynamic BH3 profiling and RNA-sequencing (RNA-seq) to identify transcriptional reprograming enabling resistance to JQ1-induced apoptosis. As part of the RATHER study, we obtained copy-number alterations and RNA-seq on 61 ILC patient samples.RESULTS: Certain ILC cell lines were sensitive to JQ1, while others were intrinsically resistant to JQ1-induced apoptosis. JQ1 treatment led to an enhanced dependence on antiapoptotic proteins and a transcriptional rewiring inducing fibroblast growth factor receptor 1 (FGFR1). This increase in FGFR1 was also evident in invasive ductal carcinoma (IDC) cell lines. The combination of JQ1 and FGFR1 inhibitors was highly effective at inhibiting growth in both 2D and 3D models of ILC and IDC. Interestingly, we found in the RATHER cohort of 61 ILC patients that 20% had FGFR1 amplification and we showed that high BRD3 mRNA expression was associated with poor survival specifically in ILC.CONCLUSIONS: We provide evidence that BETi either alone or in combination with FGFR1 inhibitors or BH3 mimetics may be a useful therapeutic strategy for recurrent ILC patients

coMpliAnce with evideNce-based cliniCal guidelines in the managemenT of acute biliaRy pancreAtitis): The MANCTRA-1 international audit

Background/objectives: Reports about the implementation of recommendations from acute pancreatitis guidelines are scant. This study aimed to evaluate, on a patient-data basis, the contemporary practice patterns of management of biliary acute pancreatitis and to compare these practices with the recommendations by the most updated guidelines. Methods: All consecutive patients admitted to any of the 150 participating general surgery (GS), hepatopancreatobiliary surgery (HPB), internal medicine (IM) and gastroenterology (GA) departments with a diagnosis of biliary acute pancreatitis between 01/01/2019 and 31/12/2020 were included in the study. Categorical data were reported as percentages representing the proportion of all study patients or different and well-defined cohorts for each variable. Continuous data were expressed as mean and standard deviation. Differences between the compliance obtained in the four different subgroups were compared using the Mann-Whitney U, Student's t, ANOVA or Kruskal-Wallis tests for continuous data, and the Chi-square test or the Fisher's exact test for categorical data. Results: Complete data were available for 5275 patients. The most commonly discordant gaps between daily clinical practice and recommendations included the optimal timing for the index CT scan (6.1%, χ2 6.71, P&nbsp;=&nbsp;0.081), use of prophylactic antibiotics (44.2%, χ2 221.05, P&nbsp;&lt;&nbsp;0.00001), early enteral feeding (33.2%, χ2 11.51, P&nbsp;=&nbsp;0.009), and the implementation of early cholecystectomy strategies (29%, χ2 354.64, P&nbsp;&lt;&nbsp;0.00001), with wide variability based on the admitting speciality. Conclusions: The results of this study showed an overall poor compliance with evidence-based guidelines in the management of ABP, with wide variability based on the admitting speciality. Study protocol registered in ClinicalTrials.Gov (ID Number NCT04747990)

Infected pancreatic necrosis: outcomes and clinical predictors of mortality. A post hoc analysis of the MANCTRA-1 international study

The identification of high-risk patients in the early stages of infected pancreatic necrosis (IPN) is critical, because it could help the clinicians to adopt more effective management strategies. We conducted a post hoc analysis of the MANCTRA-1 international study to assess the association between clinical risk factors and mortality among adult patients with IPN. Univariable and multivariable logistic regression models were used to identify prognostic factors of mortality. We identified 247 consecutive patients with IPN hospitalised between January 2019 and December 2020. History of uncontrolled arterial hypertension (p = 0.032; 95% CI 1.135–15.882; aOR 4.245), qSOFA (p = 0.005; 95% CI 1.359–5.879; aOR 2.828), renal failure (p = 0.022; 95% CI 1.138–5.442; aOR 2.489), and haemodynamic failure (p = 0.018; 95% CI 1.184–5.978; aOR 2.661), were identified as independent predictors of mortality in IPN patients. Cholangitis (p = 0.003; 95% CI 1.598–9.930; aOR 3.983), abdominal compartment syndrome (p = 0.032; 95% CI 1.090–6.967; aOR 2.735), and gastrointestinal/intra-abdominal bleeding (p = 0.009; 95% CI 1.286–5.712; aOR 2.710) were independently associated with the risk of mortality. Upfront open surgical necrosectomy was strongly associated with the risk of mortality (p &lt; 0.001; 95% CI 1.912–7.442; aOR 3.772), whereas endoscopic drainage of pancreatic necrosis (p = 0.018; 95% CI 0.138–0.834; aOR 0.339) and enteral nutrition (p = 0.003; 95% CI 0.143–0.716; aOR 0.320) were found as protective factors. Organ failure, acute cholangitis, and upfront open surgical necrosectomy were the most significant predictors of mortality. Our study confirmed that, even in a subgroup of particularly ill patients such as those with IPN, upfront open surgery should be avoided as much as possible. Study protocol registered in ClinicalTrials.Gov (I.D. Number NCT04747990). Graphical abstract: [Figure not available: see fulltext.]