This paper presents a First-Order Recurrent Neural Network activated by a wavelet function, in particular a Morlet wavelet, with a fixed set of parameters and capable of identifying multiple chaotic ...systems. By maintaining a fixed structure for the neural network and using the same activation function, the network can successfully identify the three state variables of several different chaotic systems, including the Chua, PWL-Rössler, Anishchenko–Astakhov, Álvarez-Curiel, Aizawa, and Rucklidge models. The performance of this approach was validated by numerical simulations in which the accuracy of the state estimation was evaluated using the Mean Square Error (MSE) and the coefficient of determination (r2), which indicates how well the neural network identifies the behavior of the individual oscillators. In contrast to the methods found in the literature, where a neural network is optimized to identify a single system and its application to another model requires recalibration of the neural algorithm parameters, the proposed model uses a fixed set of parameters to efficiently identify seven chaotic systems. These results build on previously published work by the authors and advance the development of robust and generic neural network structures for the identification of multiple chaotic oscillators.
Quality control processes guarantee the proper product performance prior to its distribution in the market. In particular, the analysis of this process in plastic containers is developed by sensors ...that measure the internal pressure. In this study, an experimental framework for detecting structural damages is proposed. The main contribution lies in the use of passive thermography and digital image processing, where the raw thermographic images are analysed in LabVIEW. The digital interface presents in a user-friendly manner the results of the full process along with the location and characteristics of the structural damage. The results obtained denote an improvement in the quality process by increasing the resolution for the error detection in structural damages around 0.4 mm, which falls out of the scope of classic pressure sensors. The thermographic scans serve as a contrast medium for highlighting the damage in the containers and do not depend on the environmental temperature.
Considering that chaotic systems are immersed in multiple areas of science and nature and that their dynamics are governed by a great sensitivity to the initial conditions and variations in their ...parameters, it is of great interest for the scientific community to have tools to characterize and reproduce these trajectories. Two dynamic chaotic systems whose equations are based on the jerky system are used as benchmarks, i.e., the Memristive Shaking Chaotic System (MSCS) and the Unstable Dissipative System of type I (UDSI). One characteristic common to them is their simple mathematical structure and the complexity of their solutions. Therefore, this paper presents a strategy for identifying chaotic trajectories using a recurrent wavelet first-order neural network (RWFONN) that is trained online with an error filtering algorithm and considering the Morlet-wavelet as an activation function. The parameters of the network are adjusted considering the Euclidean distance between the solutions. Finally, the results depict proper identification of the chaotic systems studied through analysis and numerical simulation to validate the behavior and functionality of the proposed network.
After exposure to SARS-CoV-2 and/or vaccination there is an increase in serum antibody titers followed by a non-linear waning. Our aim was to find out if this waning of antibody titers would fit to a ...mathematical model.
We analyzed anti-RBD (receptor binding domain) IgG antibody titers and the breakthrough infections over a ten-month period following the second dose of the mRNA BNT162b2 (Pfizer-BioNtech.) vaccine, in a cohort of 54 health-care workers (HCWs) who were either never infected with SARS-CoV-2 (naïve, nHCW group, n=27) or previously infected with the virus (experienced, eHCW group, n=27). Two mathematical models, exponential and power law, were used to quantify antibody waning kinetics, and we compared the relative quality of the goodness of fit to the data between both models was compared using the Akaik Information Criterion.
We found that the waning slopes were significantly more pronounced for the naïve when compared to the experienced HCWs in exponential (p-value: 1.801E-9) and power law (p-value: 9.399E-13) models. The waning of anti-RBD IgG antibody levels fitted significantly to both exponential (average-R2: 0.957 for nHCW and 0.954 for eHCW) and power law (average-R2: 0.991 for nHCW and 0.988 for eHCW) models, with a better fit to the power law model. In the nHCW group, titers would descend below an arbitrary 1000-units threshold at a median of 210.6 days (IQ range: 74.2). For the eHCW group, the same risk threshold would be reached at 440.0 days (IQ range: 135.2) post-vaccination.
Two parsimonious models can explain the anti-RBD IgG antibody titer waning after vaccination. Regardless of the model used, eHCWs have lower waning slopes and longer persistence of antibody titers than nHCWs. Consequently, personalized vaccination booster schedules should be implemented according to the individual persistence of antibody levels.
SARS-CoV-2 vaccines are an invaluable resource against COVID-19. Current vaccine shortage makes it necessary to prioritize distribution to the most appropriate segments of the population.
This is a ...prospective cohort study of 63 health care workers (HCWs) from a General Hospital. We compared antibody responses to two doses of BNT162b2 mRNA COVID-19 vaccine between HCWs with previous SARS-CoV-2 infection (experienced HCWs) and HCWs without previous infection (naïve HCWs).
Seven days after the first vaccine dose, HCWs with previous infection experienced a 126-fold increase in antibody levels (p<0·001). However, in the HCW naïve group, response was much lower and only five showed positive antibody levels (>50 AU). After the second dose, no significant increase in antibody levels was found in experienced HCWs, whereas in naïve HCWs, levels increased by 16-fold (p<0·001). Approximately two months post-vaccination, antibody levels were much lower in naïve HCWs compared to experienced HCWs (p<0·001).
The study shows that at least ten months post-COVID-19 infection, the immune system is still capable of producing a rapid and powerful secondary antibody response following one single vaccine dose. Additionally, we found no further improvement in antibody response to the second dose in COVID-19 experienced HCWs. Nonetheless, two months later, antibody levels were still higher for experienced HCWs. These data suggest that immune memory persists in recovered individuals; therefore, the second dose of the COVID-19 vaccine in this group could be postponed until immunization of the remaining population is complete.
•Imatinib has shown antiviral and immunomodulatory properties in preclinical models.•Imatinib could potentially be helpful in COVID-19.•This is the first case series of COVID-19 patients treated with ...imatinib.•Imatinib is a well-known drug whose safety profile seems acceptable in COVID-19.
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Abstract
Background
COVID-19 has emerged as a global public health emergency and has been the main cause of intensive care admission during the pandemic. COVID-19-associated pulmonary aspergillosis ...(CAPA) has been reported in case series of critically ill patients. However, the criteria for CAPA diagnosis has been inconsistent among most of the reports. Mexico has been widely affected by SARS-CoV-2. We present a series of CAPA cases at a teaching hospital in Mexico City.
Methods
We performed a retrospective analysis of COVID-19 patients admitted to the ABC Medical Center from May 1st, 2020, to May 1st, 2021. Including only those with critical COVID-19 who required invasive mechanical ventilation (IMV). Patients with a diagnosis of CAPA were analyzed. We followed the 2020 ECMM/ISHAM consensus criteria for CAPA diagnosis. Aspergillus antigen testing in tracheal aspirate and serum was done with Aspergillus-specific galactomannoprotein (GP) ELISA (Euroimmun Medizinische Labordiagnostika).
Results
Among the 230 admitted patients who required IMV, we identified 49 (21.3%) cases of CAPA, 46 probable CAPA and 3 proven CAPA. Nineteen (38%) of those died in the hospital. The mean age was 64.5 ± 12.6 years and 11 were female. Proven CAPA was diagnosed with culture in three cases (one A. niger, one A. terreus and one A. fumigatus). Probable CAPA was diagnosed by a positive serum GP in 27 (55.1%) patients and by a positive bronchoalveolar lavage (BAL) GP in 29 (59.2%) cases. Seven patients had both serum and BAL positive GP. Forty-six (93.9%) patients received corticosteroids, and 22 (49.9%) were treated with tocilizumab before CAPA diagnosis. All but one received isavuconazole as CAPA treatment. We detected 35 (71.4%) patients who had a bacterial co-infection. Eighteen of those died (51.4%) compared to only one dead in the subgroup without coinfections (7.1%). The mean time from hospital admission to CAPA diagnosis was 6.2 days (SD 7.1) among those who survived compared to 13.2 (SD 6.3) days in those who died p< 0.01.
Conclusion
CAPA had a lower prevalence than previously reported in other series. However, it appears to be linked to high mortality when it occurs with other bacterial coinfections and when it is diagnosed late from admission.
Disclosures
All Authors: No reported disclosures
Abstract
Background
Over the past few years, it has been shown that T cells play an essential role in antiviral immunity, in the course of the COVID-19 pandemic some studies reported an association ...between lymphocytopenia and exhaustion of the surviving remaining T cells which are apparently functional in patients with acute COVID-19, specially in those with severe forms of presentation. Some studies have reported an association where less than 800 CD4 + T cells are negatively related to the survival of seriously ill patients with COVID -19.
Methods
We included 19 patients admitted to our hospital (ABC Medical Center) from May 7 to 15, 2020 with a confirmed diagnosis of COVID-19 and were randomized into 2 groups according to the severity of the presentation (severe or critical) A determination of CD4 + T cells was made at admission, we also reported the need for invasive mechanical ventilation at some point of the hospitalization for each group, all patients were followed until their hospital discharge. One patient was excluded because he was still admitted at the time of the analysis.
Results
Of the 18 patients included, 9 (50%) fulfilled criteria of severe and 9 (50%) of critical. The mean of CD4 + T cell was 455 (256–697) for the severe and 285.44 (145–430) for the critical (CI 95% P 0.46), the determination of CD8+ T cell was 212 (88–392) for the severe and 201 (59–534) for the critical (CI 95% P 1.19), of the critical patients 8 (88.9%) required invasive mechanical ventilation and only one non-invasive mechanical ventilation, while the severe patients only required support with supplemental oxygen by nasal cannula (9 (100%)).The mean lenght of hospitalization was 12.73 days (3–34) and all the patients survived until they were discharged home.
Conclusion
As it has been reported in some studies, the pathogenesis of SARS-CoV-2 infection in humans is associated with a reduction and functional exhaustion of T cells in patients with COVID-19.In this study we presume that lower levels of CD4+T cells can be associated with critical forms of COVID 19 as the majority of critical patients in our report had < 300 CD4 +T cell count, while we need further studies with a greater number of patients and follow-up to establish reliable determinations, we propose than the levels of CD4+T cell count could be use as a good predictor of severity in COVID-19
Disclosures
All Authors: No reported disclosures
Abstract
Background
COVID-19, caused by SARS-CoV-2, has emerged as a global public health emergency and has been the main cause of intensive care admission during the pandemic. Invasive pulmonary ...aspergillosis (IPA) superinfection has been reported in case series of critically ill patients. Mexico has been widely affected by SARS-CoV-2. We present a case series of COVID-19-associated IPA at a teaching hospital in Mexico City.
Methods
We performed a retrospective analysis of COVID-19 patients admitted to the ABC Medical Center from March 13 to June 1, 2020. Only those with severe or critical COVID-19 were hospitalized. Patients with a diagnosis of putative IPA were analyzed. SARS-CoV-2 was diagnosed by Real-Time PCR from nasopharyngeal swabs. Aspergillus antigen testing in tracheal aspirate and serum was done with Aspergillus-specific galactomannoprotein (GP) ELISA (Euroimmun Medizinische Labordiagnostika).The study was approved by the hospital ethics committee.
Results
Among the 47 admitted patients who required invasive mechanical ventilation (IMV), we identified seven (14.9%) cases of IPA. The mean age was 59.7 ± 17.8 years and five were male. All our patients had comorbidities, but none were under previous immunosuppressive treatment. All had critical COVID-19 pneumonia requiring IMV. All but one patient received corticosteroids, and five patients were treated with tocilizumab before IPA diagnosis. Putative IPA was diagnosed in six cases (86%) by a positive GP in tracheal aspirate, additionally in one of these, the tracheal aspirate culture also grew Aspergillus niger. The remaining one (14%) had a positive serum GP. The median time from COVID-19 to IPA diagnosis was 10 days. There were five bacterial co-infections, three with Pseudomonas aeruginosa, one with Stenotrophomonas maltophilia, and one with Mycobacterium tuberculosis. Six patients were treated with isavuconazole and one voriconazole. As of June 17, 2020, three patients had died, two patients had been discharged, and two were still in the intensive care unit receiving IMV.
Aspergillus niger isolated from a tracheal aspirate of a critically-ill COVID-19 patient
Conclusion
COVID-19-associated IPA had a lower prevalence than previously reported in other series. However, it appears to be linked to high mortality and could be associated with other bacterial coinfections.
Disclosures
All Authors: No reported disclosures
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