Analytical Model of Eccentric Induction Machines Using the Conformal Winding Tensor Approach.

Induction machines (IMs) are a critical component of many industrial processes, and their failure can cause large economic losses. Condition-based maintenance systems (CBMs) that are capable of detecting their failures at an incipient stage can reduce these risks by continuously monitoring the IMs' condition. The development and reliable operations of CBMs systems require rapid modeling of the faulty IM. Due to the fault-induced IM asymmetries, these models are much more complex than those used for a healthy IM. In particular, a mixed eccentricity fault (static and dynamic), which can degenerate into rubbing and destruction of the rotor, produces a non-uniform IM air gap that is different for each rotor position, which makes its very difficult to calculate the IM's inductance matrix. In this work, a new analytical model of an eccentric IM is presented. It is based on the winding tensor approach, which allows a clear separation between the air gap and winding-related faults. Contrary to previous approaches, where complex expressions have been developed for obtaining mutual inductances between conductors and windings of an eccentric IM, a conformal transformation is proposed in this work, which allows using the simple inductance expressions of a healthy IM. This novel conformal winding tensor approach (CWFA) is theoretically explained and validated with the diagnosis of two commercial IMs with a mixed eccentricity fault.

Low-Computational-Cost Hybrid FEM-Analytical Induction Machine Model for the Diagnosis of Rotor Eccentricity, Based on Sparse Identification Techniques and Trigonometric Interpolation.

Since it is not efficient to physically study many machine failures, models of faulty induction machines (IMs) have attracted a rising interest. These models must be accurate enough to include fault effects and must be computed with relatively low resources to reproduce different fault scenarios. Moreover, they should run in real time to develop online condition-monitoring (CM) systems. Hybrid finite element method (FEM)-analytical models have been recently proposed for fault diagnosis purposes since they keep good accuracy, which is widely accepted, and they can run in real-time simulators. However, these models still require the full simulation of the FEM model to compute the parameters of the analytical model for each faulty scenario with its corresponding computing needs. To address these drawbacks (large computing power and memory resources requirements) this paper proposes sparse identification techniques in combination with the trigonometric interpolation polynomial for the computation of IM model parameters. The proposed model keeps accuracy similar to a FEM model at a much lower computational effort, which could contribute to the development and to the testing of condition-monitoring systems. This approach has been applied to develop an IM model under static eccentricity conditions, but this may extend to other fault types.

A Review of Techniques Used for Induction Machine Fault Modelling.

Over the years, induction machines (IMs) have become key components in industry applications as mechanical power sources (working as motors) as well as electrical power sources (working as generators). Unexpected breakdowns in these components can lead to unscheduled down time and consequently to large economic losses. As breakdown of IMs for failure study is not economically feasible, several IM computer models under faulty conditions have been developed to investigate the characteristics of faulty machines and have allowed reducing the number of destructive tests. This paper provides a review of the available techniques for faulty IMs modelling. These models can be categorised as models based on electrical circuits, on magnetic circuits, models based on numerical methods and the recently proposed in the technical literature hybrid models or models based on finite element method (FEM) analytical techniques. A general description of each type of model is given with its main benefits and drawbacks in terms of accuracy, running times and ability to reproduce a given fault.

Analytical Model of Induction Machines with Multiple Cage Faults Using the Winding Tensor Approach.

Induction machines (IMs) are one of the main sources of mechanical power in many industrial processes, especially squirrel cage IMs (SCIMs), due to their robustness and reliability. Their sudden stoppage due to undetected faults may cause costly production breakdowns. One of the most frequent types of faults are cage faults (bar and end ring segment breakages), especially in motors that directly drive high-inertia loads (such as fans), in motors with frequent starts and stops, and in case of poorly manufactured cage windings. A continuous monitoring of IMs is needed to reduce this risk, integrated in plant-wide condition based maintenance (CBM) systems. Diverse diagnostic techniques have been proposed in the technical literature, either data-based, detecting fault-characteristic perturbations in the data collected from the IM, and model-based, observing the differences between the data collected from the actual IM and from its digital twin model. In both cases, fast and accurate IM models are needed to develop and optimize the fault diagnosis techniques. On the one hand, the finite elements approach can provide highly accurate models, but its computational cost and processing requirements are very high to be used in on-line fault diagnostic systems. On the other hand, analytical models can be much faster, but they can be very complex in case of highly asymmetrical machines, such as IMs with multiple cage faults. In this work, a new method is proposed for the analytical modelling of IMs with asymmetrical cage windings using a tensor based approach, which greatly reduces this complexity by applying routine tensor algebra to obtain the parameters of the faulty IM model from the healthy one. This winding tensor approach is explained theoretically and validated with the diagnosis of a commercial IM with multiple cage faults.

A mechanism for agonist activation of the glucagon-like peptide-1 (GLP-1) receptor through modelling & molecular dynamics.

The receptor for glucagon-like peptide 1 (GLP-1R) is a validated drug target for the treatment of type 2 diabetes and obesity. Recently the first three structures of GLP-1R were published - an X-ray structure of the apo transmembrane domain in the inactive conformation; an X-ray structure of the full-length receptor bound to a truncated peptide agonist; and a cryo-EM structure of the full-length receptor bound with GLP-1 and coupled to the G protein Gs. Since the inactive structure was incomplete, and the two active-state structures shared significant differences, we utilised all available knowledge to build hybrid models of the full length active and inactive state receptors. The two models were simulated using molecular dynamics and the output trajectories analysed and compared to reveal insights into the mechanism for agonist-mediated receptor activation. His-7, Glu-9 and Asp-15 of GLP-1 act together to destabilise transmembrane helix 6 and extracellular loop 3 in order to generate an active conformation of GLP-1R.

Assessing practice pattern differences in the treatment of acute low back pain in the United States Military Health System.

BACKGROUND: Acute low back pain is one of the most common reasons for individuals to seek medical care in the United States. The US Military Health System provides medical care to approximately 9.4 million beneficiaries annually. These patients also routinely suffer from acute low back pain. Within this health system, patients can receive care and treatment from physicians, or physician extenders including physician assistants and nurse practitioners. Given the diversity of provider types and their respective training programs, it would be informative to evaluate variation in care delivery, adherence to clinical guidelines, and differences within the MHS among a complex mix of provider types. METHODS: This study was a retrospective, cross-sectional quantitative analysis that examined variations in treatment between provider types within the Military Health System in 2015 for treatment of acute low back pain using administrative data. In addition to descriptive and summary statistics, binomial logistic regression models were used to assess variation in practice patterns among physicians and mid-level practitioners for prescribing of non-steroidal anti-inflammatory, opioids, plain radiography, computed tomography, and magnetic resonance imaging. RESULTS: With regard to prescribing practices, results indicated that the odds of receiving non-steroidal anti-inflammatory prescriptions increased significantly for both physician assistants and nurse practitioners when compared to physicians. For basic radiological referrals, odds increased significantly for ordering plain radiography for physician assistants and nurse practitioners when compared to physicians. For more advanced imaging, odds significantly decreased for ordering computed tomography (CT) and slightly decreased for magnetic resonance for physician assistants, nurse practitioners and physician residents compared to the physician group. Additionally this study discovered differences in the prescribing patterns between provider categories. Both contractors and civilians had higher odds of prescribing opioids compared to active duty providers. CONCLUSIONS: As physician assistants and nurse practitioners continue to gain popularity as physician extenders in the US and in addressing provider shortages for the Military Health System, further research should be conducted to determine what impact, if any, the differences found in this study have on patient outcomes. In addition, provider type warrants further investigation to determine if labor mix and outsourcing decisions within a single payer system impacts health delivery and value based care.

Longitudinal study of the substantia nigra in Parkinson disease: A high-field (1) H-MR spectroscopy imaging study.

INTRODUCTION: The value of biomarkers in early diagnosis and development of therapeutics in Parkinson's disease (PD) is well established. METHODS: We used proton magnetic resonance spectroscopy in a prospective, longitudinal study of 23 patients with early PD, naïve to dopaminergic therapy, and six age-matched healthy controls to examine the temporal changes in metabolic profile of substantia nigra over a period of 3 months. RESULTS: N-acetyl aspartate to creatine ratio at month 3 was compared with baseline values in the PD and control groups, as well as the side-to-side difference of the ratio at baseline. By month 3, n-acetyl aspartate to creatine ratio had decreased by 4.4% in patients with PD (P = 0.024), without a concomitant change in healthy controls. The side-to-side asymmetry was significantly higher in the PD group (16.7%) vs. healthy controls (1.6%, P = 0.0024). CONCLUSION: Estimation of change in the n-acetyl aspartate to creatine ratio appears to be a fast, quantifiable, and reliable marker of dopaminergic neuronal viability in PD.

Migration-related trauma and PTSD among Latinx parents in the southeast during COVID-19.

OBJECTIVE: Latinx immigrants are at risk for migration-related trauma that can lead to posttraumatic stress disorder (PTSD). Among parents in immigrant families with undocumented family member(s) (i.e., mixed-status), risk for PTSD may be exacerbated by policies that threaten family separation and exclude immigrants from systems of support. Understanding these relationships in context is important to equip practitioners to address traumatic stress in this population. METHOD: Our community-based participatory research (CBPR), mixed-methods study explored migration-related trauma and PTSD among Latinx immigrant parents in a restrictive immigration climate during the COVID-19 pandemic. We conducted 145 surveys with Latinx parents in mixed-status families and conducted multivariable linear analyses to test if immigration policy vulnerability strengthened the relationship between migration-related trauma and PTSD symptoms. Then, we conducted 15 interviews with frontline workers serving Latinx immigrant families to contextualize the relationships between migration-related trauma, immigration-related policies, and PTSD during the COVID-19 pandemic. RESULTS: Parent surveys revealed was no observed relationship between premigration-related trauma and PTSD symptoms (ß = 0.12, p = .15). However, increases in policy vulnerability was associated with PTSD symptoms (ß = 0.25, p < .01) and strengthened the relationship between postmigration trauma and PTSD symptoms (ß = 0.19, p = .03). Frontline workers described how social isolation due to immigration-related policies worsened under the COVID-19 pandemic and deportation fears remained a constant stressor. CONCLUSIONS: Results from our CBPR study highlight the need for policies and practices that address compounding effects of migration-related trauma, policy vulnerability, and the COVID-19 pandemic to promote mental health equity among Latinx immigrant families. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Beyond Infantile Hemangiomas: A Glimpse into Overlapping Rare Syndromes Emphasizing the Vigilant Screening for PHACE and LUMBAR Syndromes.

Infantile hemangiomas are the most common birthmark in newborns. They are clinically diagnosed and usually self-limited. However, there are several exceptions with aggressive types of hemangiomas that can be associated with extracutaneous anomalies, such as PHACE syndrome (posterior fossa anomalies, upper body hemangiomas, arterial anomalies, cardiac anomalies, and eye anomalies) and LUMBAR syndrome (lower body hemangiomas, ulcerations/urogenital anomalies, myelopathies, bony deformities, anorectal malformations/arterial anomalies, and renal anomalies). These two syndromes, described in the literature with distinct features, have rarely been reported in the same patient. We discuss one of the few cases reported with overlapping features of the PHACE and LUMBAR syndromes that initially presented with infantile hemangiomas, as well as other nonspecific skin and systemic findings. Minimal guidance has been described due to the need for more scientific literature. Our aim is to reinforce awareness of these two syndromes and the possibility of an overlap presentation between them. Furthermore, we emphasize the need for an interdisciplinary approach with screening for all known associations to avoid missing essential components of these syndromes that can lead to significant morbidity and lifetime complications.

Facing a dual threat: Pandemic stress and immigration policy vulnerability on mental health among Latinx immigrant parents.

BACKGROUND: Exclusionary immigration policies rooted in structural racism threaten the wellbeing of Latinx families, increasing stress, anxiety, depression, and distress among immigrant parents. The COVID-19 pandemic has had devastating and disproportionate impacts on communities of color with unique impacts on Latinx immigrant parents in mixed-status families. AIMS: From a syndemic theory lens, we explored the convergence of structural racism and the COVID-19 pandemic to explore if the stress of the COVID-19 pandemic may compound harmful immigration-related policies. METHODS: Our community-based participatory research cross-sectional study administered 145 surveys among Latinx immigrant parents in mixed-status families in Georgia. We examined the relationship of pandemic stress and perceived statewide immigration policy vulnerability to depressive, anxiety, and PTSD symptoms. We conducted multiple linear regression analyses to test these relationships and their interaction. RESULTS: We found that that greater perceived policy immigration vulnerability and reported pandemic stress were associated with higher symptoms of depression. Increased PTSD symptoms were also associated with immigration policy vulnerability, but not pandemic stress. Tests to assess if pandemic stress strengthened the relationship between policy vulnerability on depressive, anxiety, and PTSD symptoms revealed no statistically significant interactions. CONCLUSION: Our findings suggest that stress of the COVID-19 pandemic and longstanding anti-immigrant policies in Georgia were salient for and related to the mental health of these Latinx immigrant parents.

The Relationship Between Brain MR Spectroscopy and Disability in Multiple Sclerosis: 20-Year Data from the U.S. Glatiramer Acetate Extension Study.

BACKGROUND AND PURPOSE: Conventional MRI techniques do not necessarily provide information about multiple sclerosis (MS) disease pathology or progression. Nonconventional MRI techniques, including proton magnetic resonance spectroscopy (1 H-MRS), are increasingly used to improve the qualitative and quantitative specificity of MR images. This study explores potential correlations between MRI measures of disease and disability progression as measured by the Expanded Disability Status Scale (EDSS), Functional Systems (FS), and ambulation index scores in a unique cohort of MS patients treated with glatiramer acetate that has been closely monitored for over 20 years. METHODS: This was a multicenter, open-label, cross-sectional MRI substudy among participants in the GA-9004 open-label extension of the 36-month, double-blind GA-9001 study, timed to coincide with the prospectively planned 20-year clinical exam. RESULTS: Of 64 patients who participated in the MRI substudy, results are presented for the 39 patients (61%) who had a 1 H-MRS assessment at 20 years of treatment. Both total N-acetylaspartate relative to total creatinine (tNAA/tCr) concentration ratio and T1 lesion volume were found to be robustly associated with disability levels with different statistical approaches. Gray matter (GM) volume was found to be a more consistent parameter than white matter (WM) volume for disability allocation. The elastic net algorithm showed a trade-off between WM and GM volumes for disability estimation when different disability definitions were used. CONCLUSIONS: Among patients with MS receiving long-term glatiramer acetate therapy, consistent effects on disability levels indicated by EDSS and pyramidal FS score thresholds were found for tNAA/tCr concentration ratio and T1 lesion volume.

Gestational trophoblastic disease in ectopic pregnancy: A case series.

OBJECTIVE: To describe 6 cases of gestational trophoblastic disease (GTD) in ectopic pregnancy admitted to Hospital Universitario de Caracas (HUC). STUDY DESIGN: Medical records of 6 patients admitted to the Obstetrics and Gynecology Department, HUC, from 1996 to 2004 were reviewed. They underwent surgery with a diagnosis of ectopic pregnancy, and histologic analysis revealed GTD. Clinical trends were analyzed. RESULTS: The prevalence of GTD in ectopic pregnancy was 0.16:1,000 deliveries. The mean patient age was 29 years. The preceding gestation was a term delivery in 4 and abortion in 2. The mean gestational age at admission was 8 weeks. All patients complained of abdominal pain, and 3 of them also had vaginal bleeding. Ultrasound revealed an adnexal tumor in 5 cases; this tumor and hemoperitoneum (6 cases) were the most frequent surgical findings. Histopathologic diagnosis was partial mole in 5 and choriocarcinoma in 1. Four patients were lost to follow-up. CONCLUSION: In this series the prevalence of ectopic GTD was high. The condition can mimic the usual symptoms of ectopic pregnancy, especially when a hemoperitoneum is present. It is important to apply strict histologic criteria for GTD when a sample of ectopic pregnancy is analyzed and to monitor those patients with careful human chorionic gonadotropin follow-up.

Characterizing retinal structure injury in African-Americans with multiple sclerosis.

To examine retinal structure injury in African-Americans (AA) with Multiple Sclerosis (MS) compared to Caucasians (CA) with MS, we used spectral domain optical-coherence tomography (OCT) in this cross sectional study. The peripapillary retinal nerve fiber layer (pRNFL) and macular volume of 234 MS patients (149 CA; 85 AA) and 74 healthy controls (60 CA; 17 AA) were measured. Intra-retinal segmentation was performed to obtain retinal nerve fiber (RNFL), ganglion cell (GCL), inner plexiform (IPL), inner nuclear (INL), outer plexiform (OPL), outer nuclear (ONL), retinal pigment epithelium (RPE), and photoreceptor (PR) layer volumes. Study was approved by IRB, and informed consent obtained from all participants. We found that pRNFL was thicker in AA v. CA healthy controls (100.9 vs 97.00µm, p=0.004). Compared to HC, MS patients demonstrated thinner pRNFL (p<0.0001), and lower TMV (p<0.001), macular RNFL (p<0.0001), GCL (p<0.0001), and IPL (p<0.0001). AAMS patients had thinner pRNFL (87.2 vs 90.0µm, and lower TMV (8.2 vs 8.4mm(3), p=0.0001), RNFL (0.73 vs 0.79mm(3), p=0.0001), and GCL (0.94 vs 0.98mm(3), p=0.007) than CAMS patients. Sub-analysis of patients without history of AON showed thinner pRNFL (88.9 vs 93.1µm) and TMV (8.2 vs. 8.5mm(3), p<0.0001) in AAMS compared to CAMS patients. In conclusion, this cross-sectional study provides evidence supporting greater retinal structure injury in AAMS compared to CAMS patients, irrespective of history of AON. Our findings are consistent with other studies demonstrating a more severe CNS tissue injury in AAMS patients.

Pressão arterial elevada em servidores de universidades públicas no norte do brasil / High blood pressure in public university employees in northern brazil / High blood pressure in public university employees in northern brazil

RESUMO Objetivo: identificar o perfil de pressão arterial elevada em servidores públicos. Método: estudo de prevalência, realizado com 223 servidores das Pró-Reitorias de duas universidades públicas de Manaus. A coleta consistiu em entrevista para levantamento das condições sociodemográficas, estilo de vida e medida da pressão arterial sistêmica, durante o período de janeiro a março de 2018. Foi aplicado teste Qui-quadrado e considerada significância de 5%. Resultados: o percentual de participantes com pressão arterial elevada foi de 5,4%. As comorbidades mais autorreferidas foram hipertensão [41,7% (p=0,002)], diabetes mellitus [25% (p=0,001)] e obesidade [58,3% (p=0,0001)]. A maioria dos participantes informou não praticar atividade física regularmente. Conclusão: os resultados deste estudo poderão contribuir como subsídios para a implementação de ações preventivas, controle de agravos e ações que garantam o tratamento eficaz nos indivíduos com Hipertensão Arterial Sistêmica, sobretudo no âmbito da saúde do trabalhador.

RESUMEN Objetivo: identificar el perfil de hipertensión arterial en empleados públicos. Método: estudio de prevalencia realizado con 223 empleados de las Oficinas del Decano de dos universidades públicas de Manaos. El proceso de recolección de datos consistió en una entrevista para recopilar las condiciones sociodemográficas, el estilo de vida y la medición de la presión arterial sistémica, entre enero y marzo de 2018. Se aplicó la prueba de chi-cuadrado y se consideró un nivel de significancia del 5%. Resultados: el porcentaje de participantes con hipertensión arterial fue del 5,4%. Las comorbilidades más autodeclaradas fueron las siguientes: hipertensión [41,7% (p=0,002)], diabetes mellitus [25% (p=0,001)] y obesidad [58,3% (p=0,0001)]. La mayoría de los participantes declaró no practicar actividad física regularmente. Conclusión: los resultados de este estudio podrán servir como apoyo para implementar acciones preventivas, control de enfermedades y acciones que garanticen un tratamiento eficaz de las personas con Hipertensión Arterial Sistémica, especialmente en el ámbito de la salud ocupacional.

ABSTRACT Objective: to identify the profile of high blood pressure in public employees. Method: a prevalence study, carried out with 223 employees working in the Dean Offices of two public universities in Manaus. Collection consisted of an interview to survey the sociodemographic conditions, lifestyle and systemic blood pressure measurement, from January to March 2018. The Chi-square test was applied and 5% significance was considered. Results: the percentage of participants with high blood pressure was 5.4%. The most frequently self-reported comorbidities were hypertension [41.7% (p=0.002)], diabetes mellitus [25% (p=0.001)] and obesity [58.3% (p=0.0001)]. Most of the participants reported not practicing regular physical activity. Conclusion: the results of this study may contribute as subsidies for the implementation of preventive actions, disease control and actions that ensure effective treatment for individuals with Systemic Arterial Hypertension, especially in the context of worker's health.

Spinal cord atrophy in multiple sclerosis and relationship with disability across clinical phenotypes.

BACKGROUND: Several studies have shown a relationship between spinal cord atrophy and clinical disability in patients with multiple sclerosis (MS). OBJECTIVES: We examined the correlation between cervical cord cross-sectional area at the C2 vertebral level (CSA-C2) and the expanded disability status scale (EDSS) in patients with relapsing-remitting and progressive forms of MS. The latter included both secondary and primary progressive MS patients. METHODS: A total of 150 patients with MS were recruited from the Wayne State University MS clinic. Ninety-three had relapsing-remitting MS and 57 patients had progressive MS. MRI scan of the cervical cord was obtained for each patient. Correlation studies and multivariate regression analysis was performed, blinded to clinical status. RESULTS: The mean age was 41.3 year old, 64.6% were women, mean disease duration was 11.2 years, CSA-C2 was 80.2mm(2) and mean EDSS was 3.8. There was significant correlation between CSA-C2 and EDSS (r -0.75, p<0.0001). Sub-group analysis showed CSA-C2 was 68.6mm(2) and 87.3mm(2) in the progressive and relapsing-remitting groups, respectively (p<0.0001). Multivariable regression showed that CSA-C2 was a significant predictor of disability independent of disease duration, and phenotype. CONCLUSIONS: Our study demonstrates that CSA-C2 has a strong correlation with clinical disability in both RRMS and progressive MS. Greater spinal cord atrophy was seen in patients with progressive than relapsing-remitting MS. CSA-C2, disease duration, and phenotype are independent predictors of disability.