1,994 research outputs found
The kernel of newform Dedekind sums
Newform Dedekind sums are a class of crossed homomorphisms that arise from
newform Eisenstein series. We initiate a study of the kernel of these newform
Dedekind sums. Our results can be loosely described as showing that these
kernels are neither "too big" nor "too small." We conclude with an observation
about the Galois action on Dedekind sums that allows for significant
computational efficiency in the numerical calculation of Dedekind sums.Comment: 8+epsilon pages, 2 figure
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Controllable direction of liquid jets generated by thermocavitation within a droplet.
A high-velocity fluid stream ejected from an orifice or nozzle is a common mechanism to produce liquid jets in inkjet printers or to produce sprays among other applications. In the present research, we show the generation of liquid jets of controllable direction produced within a sessile water droplet by thermocavitation. The jets are driven by an acoustic shock wave emitted by the collapse of a hemispherical vapor bubble at the liquid-solid/substrate interface. The generated shock wave is reflected at the liquid-air interface due to acoustic impedance mismatch generating multiple reflections inside the droplet. During each reflection, a force is exerted on the interface driving the jets. Depending on the position of the generation of the bubble within the droplet, the mechanical energy of the shock wave is focused on different regions at the liquid-air interface, ejecting cylindrical liquid jets at different angles. The ejected jet angle dependence is explained by a simple ray tracing model of the propagation of the acoustic shock wave inside the droplet
Anesthesia Options and the Recurrence of Cancer: What We Know so Far?
Surgery is a critical period in the survival of patients with cancer. While resective surgery of primary tumors has shown to prolong the life of these patients, it can also promote mechanisms associated with metastatic progression. During surgery, patients require general and sometimes local anesthetics that also modulate mechanisms that can favor or reduce metastasis. In this narrative review, we summarized the evidence about the impact of local, regional and general anesthesia on metastatic mechanisms and the survival of patients. The available evidence suggests that cancer recurrence is not significantly impacted by neither regional anesthesia nor volatile or total intravenous anesthesia
Costs Analysis of Fibrin Sealant for Prevention of Anastomotic Leakage in Lower Colorectal Surgery
Introduction: Postoperative anastomotic leaks remain a common and serious complication of colorectal surgeries and are a major cause of mortality and morbidity of these procedures. Anastomotic leaks (AL) have been extensively studied; however, there has been no significant reduction in their prevalence over time. In addition, there is a significant economic burden from AL attributed to the need for repeat surgery, radiologic intervention and lengthened hospital stay. We conducted a comparative cost analysis of patients undergoing colorectal surgery with anastomosis, with the application of fibrin sealant (FS) to the sutured anastomosis versus not treating the sutured anastomosis with FS. Methods: The deterministic decision-tree model was populated with clinical data including operating room time, hospitalization days, occurrence of AL, need for revision surgery, blood products and radiologic interventions to treat the AL in lower colorectal surgery. A systematic literature review was conducted to identify appropriate studies with these variables. Results: The average cost per case treated lower colorectal surgery with fibrin sealant glue 10 mL Tisseel® and those not treated with a fibrin sealant after suturing the anastomoses was €3233 and €4130, respectively, for resource expenses paid by the healthcare system. This would suggest potential savings of €897 per surgery, achieved through the application of FS to the sutured anastomosis for preventing AL following colorectal surgery. Conclusion: Application of FS to the sutured anastomosis in lower colorectal surgery resulted in a decrease in post-operative AL, and cost savings based on a reduction in hospitalization days, a reduction needing: revision surgery, radiologic intervention and blood products to treat AL
Access to Dental Services among Hypertensive Elderly in Peru: Exploring Patterns and Implications
Background: This study was conducted to determine access to dental services in the elderly with hypertension in Peru.
Methods: Observational, analytical, and cross-sectional design. Data used for analysis in this research was collected from the Demographic and Family Health Survey of Peru (ENDES) from 2019 to 2021.
Results: A Poisson regression analysis was performed a weighted sample for calculating prevalence ratio (PR) with their 95% confidence intervals (95%CI). The multiple regression analysis did not find among the factors associated with the probability of using the dental health service, since neither the time less than two years of hypertension (PR=0.74, 95%CI 0.53 – 1.02); nor from 2 to 4 years (PR = 0.97, CI 95% 0.86 – 1.09); neither a time of hypertension from 5 years or more (PR = 0.94, CI 95% 0.85 – 1.03) were associated.
Conclusion: The study concluded that hypertensive patient over 60 years of age, despite a previous diagnosis of hypertension or not, does not attend dental service, reflecting a lack of interest and a greater risk exposure to cardiovascular complications associated with oral health
Recent and Rapid Radiation of the Highly Endangered Harlequin Frogs (Atelopus) into Central America Inferred from Mitochondrial DNA Sequences
Populations of amphibians are experiencing severe declines worldwide. One group with the most catastrophic declines is the Neotropical genus Atelopus (Anura: Bufonidae). Many species of Atelopus have not been seen for decades and all eight Central American species are considered “Critically Endangered”, three of them very likely extinct. Nonetheless, the taxonomy, phylogeny, and biogeographic history of Central American Atelopus are still poorly known. In this study, the phylogenetic relationships among seven of the eight described species in Central America were inferred based on mitochondrial DNA sequences from 103 individuals, including decades-old museum samples and two likely extinct species, plus ten South American species. Among Central American samples, we discovered two candidate species that should be incorporated into conservation programs. Phylogenetic inference revealed a ladderized topology, placing species geographically furthest from South America more nested in the tree. Model-based ancestral area estimation supported either one or two colonization events from South America. Relaxed-clock analysis of divergence times indicated that Atelopus colonized Central America prior to 4 million years ago (Ma), supporting a slightly older than traditional date for the closure of the Isthmus. This study highlights the invaluable role of museum collections in documenting past biodiversity, and these results could guide future conservation efforts
Contribution of advanced regeneration of Pinus Radiata D. Don. to transpiration by a fragment of Native forest in central Chile is out of proportion with the contribution to sapwood area
The transpiration of Nothofagus glauca (Phil.) Krasser and advanced Pinus radiata D. Don. regeneration was measured in a fragment of native N. glauca forest. Over the eight months of this study, P. radiata contributed approximately 60% of the total stand transpiration. This was out of proportion with the approximately 34% of the stand sapwood area contributed by P. radiata. This was due to the significantly greater sap flux density of the P. radiata compared to the N. glauca between May and October. Though the results are from a small study conducted as part of a larger experiment, it is argued that they suggest that invasion by P. radiata may substantially increase the risk from climate change to reserves of N. glauca forest in the Maule region of central Chile. In some reserves of N. glauca forest, Forestal Arauco S.A. manually removed P. radiata that regenerated after the wildfire of January 2017. This was a costly operation and there is a need for indices to assess competition. The ratio of sapwood area to leaf area is suggested as a potential index for assessing competition to identify stands at risk. © 2020 by the author
Contribution of advanced regeneration of Pinus Radiata D. Don. to transpiration by a fragment of Native forest in central Chile is out of proportion with the contribution to sapwood area
The transpiration of Nothofagus glauca (Phil.) Krasser and advanced Pinus radiata D. Don. regeneration was measured in a fragment of native N. glauca forest. Over the eight months of this study, P. radiata contributed approximately 60% of the total stand transpiration. This was out of proportion with the approximately 34% of the stand sapwood area contributed by P. radiata. This was due to the significantly greater sap flux density of the P. radiata compared to the N. glauca between May and October. Though the results are from a small study conducted as part of a larger experiment, it is argued that they suggest that invasion by P. radiata may substantially increase the risk from climate change to reserves of N. glauca forest in the Maule region of central Chile. In some reserves of N. glauca forest, Forestal Arauco S.A. manually removed P. radiata that regenerated after the wildfire of January 2017. This was a costly operation and there is a need for indices to assess competition. The ratio of sapwood area to leaf area is suggested as a potential index for assessing competition to identify stands at risk. © 2020 by the author
Using the Kalman Filter to Smooth the Shocks of a Dynamic Stochastic General Equilibrium Model
Impacto del equipo multidisciplinario “ECMO Team” en el pronóstico de pacientes sometidos a membrana de oxigenación extracorpórea venoarterial por choque cardiogénico o paro cardiorrespiratorio refractario
Objectives. Veno-arterial Extracorporeal membrane oxygenation (VA ECMO) is a salvage intervention in patients with cardiogenic shock (CS), and cardiac arrest (CA) refractory to standard therapies. The design of ECMO Teams has achieved the standardization of processes, although its impact on survival and prognosis is unknown. Objective: We aimed to analyze whether the creation of an ECMO Team has modified the prognosis of patients undergoing VA ECMO for refractory CS or CA. Materials and methods. We conducted a single-center retrospective cohort study. Patients with refractory CS or CA who underwent VA ECMO were divided in two consecutive periods: from 2014 to April 2019 (pre-ECMO T) and from May 2019 to December 2022 (Post ECMO T). The main outcomes were survival on ECMO, in-hospital survival, complications, and annual ECMO volume. Results. Eighty-three patients were included (36 pre-ECMO T and 47 post-ECMO T). The mean age was 53 +/-13 years. The most common reason for device indication was different: postcardiotomy shock (47.2%) pre-ECMO T and refractory cardiogenic shock (29.7%) post-ECMO T. The rate of extracorporeal cardiopulmonary resuscitation was 14.5%. The median duration of VA ECMO was longer after ECMO team implementation: 8 days (IQR 5-12.5) vs. five days (IQR 2-9, p=0.04). Global in-hospital survival was 45.8% (38.9% pre-ECMO T vs. 51.1% post-ECMO T; p=0.37), and the survival rate from VA ECMO was 60.2% (55.6% pre-ECMO T vs 63.8% post-ECMO T; p= 0.50). The volume of VA ECMO implantation was significantly higher in the post-ECMO team period (13.2 +/3.5 per year vs. 6.5 +/-3.5 per year, p: 0.02). The rate of complications was similar in both groups. Conclusions. After the implementation of an ECMO team, there was no statistical difference in the survival rate of patients treated with VA ECMO. However, a significant increase in the number of patients supported per year was observed after the implementation of this multidisciplinary team. Post-ECMO T, the most common reason for device indication was cardiogenic shock, with longer run times and a higher rate of extracorporeal cardiopulmonary resuscitation.Introducción. La oxigenación por membrana extracorpórea venoarterial (ECMO VA) es una intervención de rescate utilizada en choque cardiogénico (CC) o paro cardiorrespiratorio (PCR) refractario. La creación de equipos multidisciplinarios ECMO Teams (ECMO T), ha permitido la estandarización de procesos, aunque se desconoce su impacto en sobrevida y pronóstico. Objetivo: El propósito es analizar si la creación del ECMO Team ha modificado el pronóstico de los pacientes sometidos a ECMO VA por CC o PCR refractario. Materiales y métodos. Estudio observacional, unicéntrico, retrospectivo, que comparó los resultados del implante de ECMO VA por CC o PCR refractario en dos períodos consecutivos: entre 2014 y abril de 2019 (pre-ECMO T), y entre mayo de 2019 y diciembre de 2022 (pos-ECMO T). Como puntos finales, se evaluó la sobrevida intrahospitalaria y en ECMO, complicaciones, y volumen de ECMO anual. Resultados. Se analizaron 83 pacientes (36 pre-ECMO T, y 47 pos-ECMO T), con edad de 53 +/-13 años. La causa más frecuente de asistencia fue: poscardiotomía pre-ECMO T (47,2%) y CC refractario pos-ECMO T (29,7%). En el 14,5% se realizó ECMO en PCR. La mediana de asistencia fue mayor pos-ECMO T (8 días, RIC 5-12,5 vs. 5 días, RIC 2-9 pre-ECMO T; p:0,04). La supervivencia al alta fue del 45,8% (38,9% pre-ECMO T vs. 51,1% pos-ECMO T;p:0,37) y en ECMO VA del 60,2% (55,6% pre-ECMO T y 63,8% pos-ECMO T; p:0,50). El volumen de ECMO VA fue significativamente mayor pos-ECMO T (13,2+/3,5 por año vs. 6,5+/-3,5 por año, p: 0,02). La tasa de complicaciones fue similar en ambos períodos. Conclusiones.Luego de la implementación del ECMO Team no se observó una diferencia significativa en la sobrevida en pacientes asistidoscon ECMO VA. Sin embargo, luego de su creación se evidenció un aumento significativo del volumen de pacientes asistidos por año. Pos-ECMO T se asistió mayor número de pacientes por choque cardiogénico, en PCR y con más días de asistencia
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