Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 153
Filtrar
1.
World J Emerg Surg ; 19(1): 21, 2024 06 05.
Artículo en Inglés | MEDLINE | ID: mdl-38840189

RESUMEN

BACKGROUND: The high rate of stoma placement during emergency laparotomy for secondary peritonitis is a paradigm in need of change in the current fast-track surgical setting. Despite growing evidence for the feasibility of primary bowel reconstruction in a peritonitic environment, little data substantiate a surgeons' choice between a stoma and an anastomosis. The aim of this retrospective analysis is to identify pre- and intraoperative parameters that predict the leakage risk for enteric sutures placed during source control surgery (SCS) for secondary peritonitis. METHODS: Between January 2014 and December 2020, 497 patients underwent SCS for secondary peritonitis, of whom 187 received a primary reconstruction of the lower gastro-intestinal tract without a diverting stoma. In 47 (25.1%) patients postoperative leakage of the enteric sutures was directly confirmed during revision surgery or by computed tomography. Quantifiable predictors of intestinal suture outcome were detected by multivariate analysis. RESULTS: Length of intensive care, in-hospital mortality and failure of release to the initial home environment were significantly higher in patients with enteric suture leakage following SCS compared to patients with intact anastomoses (p < 0.0001, p = 0.0026 and p =0.0009, respectively). Reduced serum choline esterase (sCHE) levels and a high extent of peritonitis were identified as independent risk factors for insufficiency of enteric sutures placed during emergency laparotomy. CONCLUSIONS: A preoperative sCHE < 4.5 kU/L and generalized fecal peritonitis associate with a significantly higher incidence of enteric suture insufficiency after primary reconstruction of the lower gastro-intestinal tract in a peritonitic abdomen. These parameters may guide surgeons when choosing the optimal surgical procedure in the emergency setting.


Asunto(s)
Heces , Peritonitis , Humanos , Femenino , Masculino , Estudios Retrospectivos , Peritonitis/cirugía , Persona de Mediana Edad , Anciano , Suturas , Fuga Anastomótica , Complicaciones Posoperatorias , Factores de Riesgo , Biomarcadores/sangre , Laparotomía/métodos , Laparotomía/efectos adversos
2.
J Cancer Res Clin Oncol ; 149(14): 13051-13064, 2023 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-37470855

RESUMEN

PURPOSE: Immunotherapies have largely failed as treatment options for pancreatic ductal adenocarcinoma (PDAC). In this field, clinical translational studies into personalized treatment are of fundamental importance. In our study, we model tumor-cell immune-cell interactions in a co-culture of primary human PDAC organoids and matched peripheral blood mononuclear cells (PBMCs). METHODS: Using flow cytometry, we evaluated changes in T cell subtypes upon co-culture of patient-derived PDAC organoids and matched PBMCs. RESULTS: After co-culturing PDAC organoids with PBMCs, we observed changes in CD4+, CD8+ and Treg cell populations. We observed favorable clinical outcome in patients whose PBMCs reacted to the co-culture with organoids. CONCLUSION: This experimental model allows to investigate interactions between patient derived PDAC organoids and their PBMCs. This co-culture system could serve as a preclinical platform to guide personalized therapeutic strategies in the future.

3.
Langenbecks Arch Surg ; 408(1): 103, 2023 Feb 24.
Artículo en Inglés | MEDLINE | ID: mdl-36826595

RESUMEN

PURPOSE: The association between sarcopenia of kidney transplant recipients and outcome after kidney transplantation (KT) has not yet been fully understood and is still considered controversial. The aim of our study was to analyze the impact of pre-transplant sarcopenia on graft function, postoperative complication rates, and survival of the patients after renal transplantation. METHODS: In this retrospective single-center study, all patients who underwent KT (01/2013-12/2017) were included. Demographic data, rejection rates, delayed graft function, and graft and patient survival rates were analyzed. Sarcopenia was measured in computed tomography images by the sex-adjusted Hounsfield unit average calculation (HUAC). RESULTS: During the study period, 111 single KTs (38 women and 73 men) were performed. Living donor kidney transplants were performed in 48.6%. In total, 32.4% patients had sarcopenia. Sarcopenic patients were significantly older (59.6 years vs. 49.8 years; p < 0.001), had a higher body mass index (BMI = 27.6 kg/m2 vs. 25.0 kg/m2; p = 0.002), and were more likely to receive deceased donor kidneys (72.2% vs. 41.3%; p = 0.002). Interestingly, 3 years after KT, the creatinine serum levels were significantly higher (2.0 mg/dl vs. 1.5 mg/dl; p = 0.001), whereas eGFR (39.9 ml/min vs. 53.4 ml/min; p = 0.001) and graft survival were significantly lower (p = 0.004) in sarcopenic transplant recipients. Sarcopenic patients stayed in hospital significantly longer postoperatively than those who were non-sarcopenic. CONCLUSIONS: At the time of kidney transplantation, sarcopenia was found to predict reduced long-term graft function and diminished graft survival after KT. The early identification of sarcopenic patients can not only enable an optimized selection of recipients, but also the initiation of pre-habilitation programs during the waiting period.


Asunto(s)
Trasplante de Riñón , Sarcopenia , Masculino , Humanos , Femenino , Trasplante de Riñón/efectos adversos , Supervivencia de Injerto , Estudios Retrospectivos , Receptores de Trasplantes , Donantes de Tejidos , Rechazo de Injerto
4.
Chirurgie (Heidelb) ; 94(4): 333-341, 2023 Apr.
Artículo en Alemán | MEDLINE | ID: mdl-36808498

RESUMEN

In 2019, the World Society of Emergency Surgery (WSES) and the American Association for the Surgery of Trauma (AAST) generated consensus recommendations for the treatment of anorectal emergencies in Parma, Italy, and published a guideline in 2021. This is the first global guideline dealing with this important topic for surgeons' everyday work. Seven anorectal emergencies were discussed and the guideline recommendations were given according to the GRADE (Grading of Recommendations Assessment, Development and Evaluation) system.


Asunto(s)
Urgencias Médicas , Intestino Grueso , Humanos , Estados Unidos , Italia
5.
Urologie ; 62(3): 295-298, 2023 Mar.
Artículo en Alemán | MEDLINE | ID: mdl-36066612

RESUMEN

When taking into consideration the basic principles of fistula surgery, numerous options are available for the surgical repair of rectourethral fistulas. However, there is no standard regarding which surgical method should be used under which circumstances-due to the heterogeneity of this disease. This case report describes the individual adaptation of a surgical technique that is used for the treatment of vesicovaginal fistulas to treat a rectourethral fistula in a patient who had already undergone an unsuccessful fistula closure attempt. Successful closure of the fistula was achieved on the basis of an established method using tissue interposition.


Asunto(s)
Músculo Grácil , Fístula Rectal , Enfermedades Uretrales , Fístula Urinaria , Masculino , Femenino , Humanos , Próstata , Colgajos Quirúrgicos , Fístula Rectal/etiología , Enfermedades Uretrales/etiología , Fístula Urinaria/diagnóstico por imagen
6.
Tech Coloproctol ; 27(3): 209-215, 2023 03.
Artículo en Inglés | MEDLINE | ID: mdl-36050560

RESUMEN

BACKGROUND: Despite significant advances in infection control guidelines and practices, surgical site infections (SSIs) remain a substantial cause of morbidity, prolonged hospitalization, and mortality among patients having both elective and emergent surgeries. D-PLEX100 is a novel, antibiotic-eluting polymer-lipid matrix that supplies a high, local concentration of doxycycline for the prevention of superficial and deep SSIs. The aim of our study was to evaluate the safety and efficacy of D-PLEX in addition to standard of care (SOC) in preventing superficial and deep surgical site infections for patients undergoing elective colorectal surgery. METHODS: From October 10, 2018 to October 6, 2019, as part of a Phase 2 clinical trial, we randomly assigned 202 patients who had scheduled elective colorectal surgery to receive either standard of care SSI prophylaxis or D-PLEX100 in addition to standard of care. The primary objective was to assess the efficacy of D-PLEX100 in superficial and deep SSI reduction, as measured by the incidence of SSIs within 30 days, as adjudicated by both an individual assessor and a three-person endpoint adjudication committee, all of whom were blinded to study-group assignments. Safety was assessed by the stratification and incidence of treatment-emergent adverse events. RESULTS: One hundred and seventy-nine patients were evaluated in the per protocol population, 88 in the intervention arm [51 males, 37 females, median age (64.0 range: 19-92) years] and 91 in the control arm [57 males, 34 females, median age 64.5 (range: 21-88) years]. The SSI rate within 30 day post-index surgery revealed a 64% relative risk reduction in SSI rate in the D-PLEX100 plus standard of care (SOC) group [n = 7/88 (8%)] vs SOC alone [n = 20/91 (22%)]; p = 0.0115. There was no significant difference in treatment-emergent adverse events. CONCLUSIONS: D-PLEX100 application leads to a statistically significant reduction in superficial and deep surgical site infections in this colorectal clinical model without any associated increase in adverse events.


Asunto(s)
Antibacterianos , Procedimientos Quirúrgicos del Sistema Digestivo , Adulto , Anciano , Anciano de 80 o más Años , Femenino , Humanos , Masculino , Persona de Mediana Edad , Adulto Joven , Antibacterianos/uso terapéutico , Profilaxis Antibiótica , Procedimientos Quirúrgicos del Sistema Digestivo/efectos adversos , Incidencia , Estudios Prospectivos , Infección de la Herida Quirúrgica/etiología , Infección de la Herida Quirúrgica/prevención & control , Infección de la Herida Quirúrgica/epidemiología
7.
Nat Commun ; 13(1): 5219, 2022 09 05.
Artículo en Inglés | MEDLINE | ID: mdl-36064947

RESUMEN

The development dynamics and self-organization of glandular branched epithelia is of utmost importance for our understanding of diverse processes ranging from normal tissue growth to the growth of cancerous tissues. Using single primary murine pancreatic ductal adenocarcinoma (PDAC) cells embedded in a collagen matrix and adapted media supplementation, we generate organoids that self-organize into highly branched structures displaying a seamless lumen connecting terminal end buds, replicating in vivo PDAC architecture. We identify distinct morphogenesis phases, each characterized by a unique pattern of cell invasion, matrix deformation, protein expression, and respective molecular dependencies. We propose a minimal theoretical model of a branching and proliferating tissue, capturing the dynamics of the first phases. Observing the interaction of morphogenesis, mechanical environment and gene expression in vitro sets a benchmark for the understanding of self-organization processes governing complex organoid structure formation processes and branching morphogenesis.


Asunto(s)
Carcinoma Ductal Pancreático , Neoplasias Pancreáticas , Animales , Carcinoma Ductal Pancreático/patología , Ratones , Morfogénesis , Organoides/metabolismo , Páncreas/metabolismo , Neoplasias Pancreáticas/patología , Neoplasias Pancreáticas
8.
Langenbecks Arch Surg ; 407(4): 1315-1332, 2022 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-35307746

RESUMEN

Since the eruption of the worldwide SARS-CoV-2 pandemic in late 2019/early 2020, multiple elective surgical interventions were postponed. Through pandemic measures, elective operation capacities were reduced in favour of intensive care treatment for critically ill SARS-CoV-2 patients. Although intermittent low-incidence infection rates allowed an increase in elective surgery, surgeons have to include long-term pulmonary and extrapulmonary complications of SARS-CoV-2 infections (especially "Long Covid") in their perioperative management considerations and risk assessment procedures. This review summarizes recent consensus statements and recommendations regarding the timepoint for surgical intervention after SARS-CoV-2 infection released by respective German societies and professional representatives including DGC/BDC (Germany Society of Surgery/Professional Association of German Surgeons e.V.) and DGAI/BDA (Germany Society of Anesthesiology and Intensive Care Medicine/Professional Association of German Anesthesiologists e.V.) within the scope of the recent literature. The current literature reveals that patients with pre- and perioperative SARS-CoV-2 infection have a dramatically deteriorated postoperative outcome. Thereby, perioperative mortality is mainly caused by pulmonary and thromboembolic complications. Notably, perioperative mortality decreases to normal values over time depending on the duration of SARS-CoV-2 infection.


Asunto(s)
COVID-19 , Cuidados Críticos , Procedimientos Quirúrgicos Electivos/efectos adversos , Humanos , Pandemias , SARS-CoV-2
9.
Eur J Med Res ; 27(1): 41, 2022 Mar 18.
Artículo en Inglés | MEDLINE | ID: mdl-35303954

RESUMEN

BACKGROUND: In response to the COVID-19 pandemic, endoscopic societies initially recommended reduction of endoscopic procedures. In particular non-urgent endoscopies should be postponed. However, this might lead to unnecessary delay in diagnosing gastrointestinal conditions. METHODS: Retrospectively we analysed the gastrointestinal endoscopies performed at the Central Endoscopy Unit of Saarland University Medical Center during seven weeks from 23 March to 10 May 2020 and present our real-world single-centre experience with an individualized rtPCR-based pre-endoscopy SARS-CoV-2 testing strategy. We also present our experience with this strategy in 2021. RESULTS: Altogether 359 gastrointestinal endoscopies were performed in the initial period. The testing strategy enabled us to conservatively handle endoscopy programme reduction (44% reduction as compared 2019) during the first wave of the COVID-19 pandemic. The results of COVID-19 rtPCR from nasopharyngeal swabs were available in 89% of patients prior to endoscopies. Apart from six patients with known COVID-19, all other tested patients were negative. The frequencies of endoscopic therapies and clinically significant findings did not differ between patients with or without SARS-CoV-2 tests. In 2021 we were able to unrestrictedly perform all requested endoscopic procedures (> 5000 procedures) by applying the rtPCR-based pre-endoscopy SARS-CoV-2 testing strategy, regardless of next waves of COVID-19. Only two out-patients (1893 out-patient procedures) were tested positive in the year 2021. CONCLUSION: A structured pre-endoscopy SARS-CoV-2 testing strategy is feasible in the clinical routine of an endoscopy unit. rtPCR-based pre-endoscopy SARS-CoV-2 testing safely allowed unrestricted continuation of endoscopic procedures even in the presence of high incidence rates of COVID-19. Given the low frequency of positive tests, the absolute effect of pre-endoscopy testing on viral transmission may be low when FFP-2 masks are regularly used.


Asunto(s)
Prueba de COVID-19/estadística & datos numéricos , COVID-19/diagnóstico , Endoscopía Gastrointestinal/estadística & datos numéricos , Cuidados Preoperatorios/estadística & datos numéricos , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Niño , Preescolar , Femenino , Alemania , Humanos , Lactante , Recién Nacido , Masculino , Persona de Mediana Edad , Pandemias , Estudios Retrospectivos , SARS-CoV-2 , Adulto Joven
10.
Hernia ; 26(1): 259-278, 2022 02.
Artículo en Inglés | MEDLINE | ID: mdl-33713205

RESUMEN

PURPOSE: Trans-hiatal herniation after esophago-gastric surgery is a potentially severe complication due to the risk of bowel incarceration and cardiac or respiratory complaints. However, measures for prevention and treatment options are based on a single surgeon´s experiences and small case series in the literature. METHODS: Retrospective single-center analysis on patients who underwent surgical repair of trans-hiatal hernia following gastrectomy or esophagectomy from 01/2003 to 07/2020 regarding clinical symptoms, hernia characteristics, pre-operative imaging, hernia repair technique and perioperative outcome. RESULTS: Trans-hiatal hernia repair was performed in 9 patients following abdomino-thoracic esophagectomy (40.9%), in 8 patients following trans-hiatal esophagectomy (36.4%) and in 5 patients following conventional gastrectomy (22.7%). Gastrointestinal symptoms with bowel obstruction and pain were mostly prevalent (63.6 and 59.1%, respectively), two patients were asymptomatic. Transverse colon (54.5%) and small intestine (77.3%) most frequently prolapsed into the left chest after esophagectomy (88.2%) and into the dorsal mediastinum after gastrectomy (60.0%). Half of the patients had signs of incarceration in pre-operative imaging, 10 patients underwent emergency surgery. However, bowel resection was only necessary in one patient. Hernia repair was performed by suture cruroplasty without (n = 12) or with mesh reinforcement (n = 5) or tension-free mesh interposition (n = 5). Postoperative pleural complications were most frequently observed, especially in patients who underwent any kind of mesh repair. Three patients developed recurrency, of whom two underwent again surgical repair. CONCLUSION: Trans-hiatal herniation after esophago-gastric surgery is rare but relevant. The role of surgical repair in asymptomatic patients is disputed. However, early hernia repair prevents patients from severe complications. Measures for prevention and adequate closure techniques are not yet defined.


Asunto(s)
Hernia Hiatal , Laparoscopía , Esofagectomía/efectos adversos , Gastrectomía/efectos adversos , Hernia Hiatal/etiología , Hernia Hiatal/cirugía , Herniorrafia/efectos adversos , Herniorrafia/métodos , Humanos , Laparoscopía/efectos adversos , Complicaciones Posoperatorias/etiología , Complicaciones Posoperatorias/cirugía , Estudios Retrospectivos , Mallas Quirúrgicas/efectos adversos , Resultado del Tratamiento
11.
Chirurg ; 92(11): 1016-1020, 2021 Nov.
Artículo en Alemán | MEDLINE | ID: mdl-34586429

RESUMEN

Different perspectives exist among the various specialist disciplines on the treatment of trauma patients with injuries of the urogenital tract. The multidisciplinary consensus guidelines of the World Society of Emergency Surgery (WSES) and the American Association for the Surgery of Trauma (AAST), which appeared in autumn 2019, are summarized in this article. They should constitute an aid to making decisions on the optimal treatment of trauma patients with urogenital injuries.


Asunto(s)
Sistema Urogenital/lesiones , Humanos , Estados Unidos
12.
Chirurg ; 92(4): 344-349, 2021 Apr.
Artículo en Alemán | MEDLINE | ID: mdl-33666667

RESUMEN

The first edition of the World Society of Emergency Surgeons (WSES) guidelines on the indications and treatment of open abdomen in trauma as well as in non-trauma patients was published at the end of 2018. Publications from 1980 to 2017 were included in the evaluation. Based on the GRADE system each publication was checked for its evidence and evaluated in a Delphi process. In this article the aspects of the guidelines are presented and commented on.


Asunto(s)
Abdomen , Cirujanos , Servicio de Urgencia en Hospital , Humanos
13.
Hernia ; 25(2): 479-489, 2021 04.
Artículo en Inglés | MEDLINE | ID: mdl-32112200

RESUMEN

PURPOSE: Morgagni-Larrey congenital diaphragmatic hernia (MLH) is rare in adult patients and surgery is performed infrequently. The evidence regarding the most beneficial treatment modality is low. Nevertheless, with increasing experience in minimally-invasive surgery, the literature proves the laparoscopic approach as being safely feasible. However, knowledge on the disease as well as treatment options are based on single surgeon's experiences and small case series in the literature. METHODS: Retrospective single-center analysis on adult patients (≥ 18 years) with MLH from 01/2003 to 06/2019 regarding symptoms, hernia sac contents, surgical technique and perioperative outcome. RESULTS: 4.0% of diaphragmatic hernia repair procedures were performed for MLH (n = 11 patients). 27.3% of these patients were asymptomatic. Dyspnea or gastrointestinal symptoms were frequently observed (both in 45.5% of the patients). Colon transversum (63.6%), omentum majus (45.5%) and/or stomach (27.3%) were the most common hernia sac contents. Correct diagnosis was achieved preoperatively in 10/11 patients by cross-sectional imaging. All procedures were performed by trans-abdominal surgery (laparotomy in four and laparoscopy in seven patients). All hernias were reinforced by mesh after primary closure. No differences were observed in the perioperative outcome between patients who underwent hernia repair by laparotomy versus laparoscopy. Pleural complications requiring drainage were the most common postoperative complications. CONCLUSION: MLH repair seems to be safely feasible by laparoscopic surgery. The benefit of mesh augmentation in MLH repair is not clear yet. In contrast to the current literature, all patients in this study received mesh augmentation after primary closure of the hernia. This should be evaluated in larger patient cohorts with long-term follow-up.


Asunto(s)
Hernias Diafragmáticas Congénitas , Laparoscopía , Adulto , Hernias Diafragmáticas Congénitas/cirugía , Herniorrafia/efectos adversos , Humanos , Laparotomía , Estudios Retrospectivos , Mallas Quirúrgicas
16.
Nervenarzt ; 90(12): 1207-1214, 2019 Dec.
Artículo en Alemán | MEDLINE | ID: mdl-31641793

RESUMEN

The breathtaking technological progress in the field of mobile computing, smartphones and wearables offers new opportunities for psychiatric research and therapy. Wearables enable not only the objective assessment of psychiatric symptoms in real time and everyday life but using continuous monitoring and analysis of relevant parameters can also define important situations, contexts and timing during which extended assessment strategies and real-life interventions can be implemented. The momentary effect of inner city green space exposure on well-being, motivational behavior feedback and geofencing for the detection of drinking episodes are used as examples to illustrate the core benefits of real-time analyses and feedback from wearables for psychiatric research and therapy.


Asunto(s)
Psiquiatría , Dispositivos Electrónicos Vestibles , Humanos , Trastornos Mentales/diagnóstico , Psiquiatría/instrumentación , Psiquiatría/tendencias
17.
Langenbecks Arch Surg ; 404(3): 257-271, 2019 May.
Artículo en Inglés | MEDLINE | ID: mdl-30685836

RESUMEN

PURPOSE: The abdomen is the second most common source of sepsis and is associated with unacceptably high morbidity and mortality. Recently, the essential definitions of sepsis and septic shock were updated (Third International Consensus Definitions for Sepsis and Septic Shock, Sepsis-3) and modified. The purpose of this review is to provide an overview of the changes introduced by Sepsis-3 and the current state of the art regarding the treatment of abdominal sepsis. RESULTS: While Sepsis-1/2 focused on detecting systemic inflammation as a response to infection, Sepsis-3 defines sepsis as a life-threatening organ dysfunction caused by a dysregulated host response to infection. The Surviving Sepsis Campaign (SSC) guideline, which was updated in 2016, recommends rapid diagnosis and initiating standardized therapy. New diagnostic tools, the establishment of antibiotic stewardship programs, and a host of new-generation antibiotics are new landmark changes in the sepsis literature of the last few years. Although the "old" surgical source control consisting of debridement, removal of infected devices, drainage of purulent cavities, and decompression of the abdominal cavity is the gold standard of surgical care, the timing of gastrointestinal reconstruction and closure of the abdominal cavity ("damage control surgery") are discussed intensively in the literature. The SSC guidelines provide evidence-based sepsis therapy. Nevertheless, treating critically ill intensive care patients requires individualized, continuous daily re-evaluation and flexible therapeutic strategies, which can be best discussed in the interdisciplinary rounds of experienced surgeons and intensive care medicals.


Asunto(s)
Medicina Basada en la Evidencia/normas , Infecciones Intraabdominales/terapia , Sepsis/terapia , Terapia Combinada , Diagnóstico Precoz , Humanos , Infecciones Intraabdominales/clasificación , Infecciones Intraabdominales/diagnóstico , Puntuaciones en la Disfunción de Órganos , Guías de Práctica Clínica como Asunto , Factores de Riesgo , Sepsis/clasificación , Sepsis/diagnóstico
18.
HNO ; 66(4): 280-289, 2018 Apr.
Artículo en Alemán | MEDLINE | ID: mdl-29222682

RESUMEN

The human nose takes primary responsibility for preconditioning inhaled air. Numerous pathologies can affect the physiology of the nose. The beginnings of flow analyzes were carried out with three-dimensional casting models and differently colored liquids. Temperature and humidity could not be taken into account. Today, much more complex analyzes are possible using computational fluid dynamics (CFD), which are based on three-dimensional models generated from computed tomography (CT) or magnetic resonance imaging (MRI) datasets. Here, flow velocities, temperature, humidity, and pressure differences can be simulated and displayed in high-resolution videos as a function of multiple boundary conditions. The analysis of pathological changes or surgical interventions is thereby possible.


Asunto(s)
Hidrodinámica , Nariz , Simulación por Computador , Humanos , Imagenología Tridimensional , Imagen por Resonancia Magnética , Modelos Anatómicos , Nariz/diagnóstico por imagen , Nariz/fisiología , Tomografía Computarizada por Rayos X
19.
Eur Phys J C Part Fields ; 78(4): 336, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-30996660

RESUMEN

The asymptotic safety scenario in gravity is accessed within the systematic vertex expansion scheme for functional renormalisation group flows put forward in Christiansen et al. (Phys Lett B 728:114, 2014), Christiansen et al. (Phy Rev D 93:044036, 2016), and implemented in Christiansen et al. (Phys Rev D 92:121501, 2015) for propagators and three-point functions. In the present work this expansion scheme is extended to the dynamical graviton four-point function. For the first time, this provides us with a closed flow equation for the graviton propagator: all vertices and propagators involved are computed from their own flows. In terms of a covariant operator expansion the current approximation gives access to Λ , R, R 2 as well as R µ ν 2 and higher derivative operators. We find a UV fixed point with three attractive and two repulsive directions, thus confirming previous studies on the relevance of the first three operators. In the infrared we find trajectories that correspond to classical general relativity and further show non-classical behaviour in some fluctuation couplings. We also find signatures for the apparent convergence of the systematic vertex expansion. This opens a promising path towards establishing asymptotically safe gravity in terms of apparent convergence.

20.
Braz. j. biol ; 77(2): 361-366, Apr.-June 2017. tab, graf
Artículo en Inglés | LILACS | ID: biblio-888752

RESUMEN

Abstract The soybean (Glycine max (L.): Fabaceae) is considered the most important agricultural crop in Brazil. Phytophagous tetranychid mites as Mononychellus planki McGregor, Tetranychus ludeni Zacher and T. urticae Koch have been considered pest in soybean crops. Neoseiulus idaeus Denmark & Muma (Phytoseiidae) is a predatory mite of T. ludeni and T. urticae. The aim of the present study was to evaluate the biological performance of N. idaeus when fed on T. urticae, T. ludeni and M. planki, coming from the Northwest region of Rio Grande do Sul state, Brazil. The study was conducted in the laboratory with individual predators supplied with different preys. The mean duration (days) of N. idaeus egg-adult development was similar independently of supplied prey (T. ludeni - 5.29±0.03; M. planki - 5.34±0.05 and T. urticae - 5.23±0.03 days). Female viability was 90% when fed on M. planki and 100% when fed on T. ludeni and T. urticae. Mean fecundity of N. idaeus was lower when fed on M. planki (4.6±1.58 eggs/female) and higher when fed on T. ludeni (21.8±3.22) and T. urticae (26.2±2.41). The mean generation time (T) was lower when N. idaeus fed on M. planki than when fed on T. ludeni and T. urticae. The net reproductive rate (Ro) was 4.42±0.49 on M. planki, 17.77±0.55 on T. ludeni and 20.59±0.48 on T. urticae. The innate capacity for increase (rm) was lower when N. idaeus was fed on M. planki (0.09) and higher when such predator was fed on T. ludeni (0.20) and T. urticae (0.22 females/females/day). These results demonstrated that N. idaeus is able to reach the complete development feeding on all the three tetranychid species. Mononychellus planki demonstrated to provide a sub-optimal diet if compared to T. ludeni and T. urticae.


Resumo Soja (Glycine max (L.): Fabaceae) é a mais importante cultura agrícola brasileira. Tetraniquídeos fitófagos são pragas na cultura, Mononychellus planki McGregor, Tetranychus ludeni Zacher e T. urticae Koch. Neoseiulus idaeus Denmark & Muma (Phytoseiidae) é o ácaro predador de T. ludeni e T. urticae. Este estudo teve como objetivo avaliar o desempenho biológico de N. idaeus quando alimentado com T. urticae, T. ludeni e M. planki da região noroeste do Rio Grande do Sul, Brasil. O estudo foi realizado em laboratório com predadores individualizados com diferentes presas. A duração média (dias) de N. idaeus desenvolvimento ovo-adulto foi semelhante independentemente da presa fornecida (T. ludeni - 5.29 ± 0.03; M. planki - 5.34 ± 0.05 e T. urticae - 5.23 ± 0.03 dias). Viabilidade feminina foi de 90% quando alimentados com M. planki e 100% em T. ludeni e T. urticae. Fecundidade de N. idaeus foi menor com M. planki (4.6 ± 1.58 ovos / fêmea) e maior com T. ludeni e T. urticae, 21.8 ± 3.22 e 26.2 ± 2.41, respectivamente. O tempo médio de uma geração (T) foi menor quando N. idaeus alimentados com M. planki do que quando em T. ludeni e T. urticae. A taxa líquida de reprodução (Ro) foi de 4.42 ± 0.49 em M. planki, 17.77 ± 0.55 em T. ludeni e 20.59 ± 0.48 no T. urticae. A capacidade inata de aumento (rm) foi menor em M. planki (0.09) e maior quando alimentados com T. ludeni (0.20) e T. urticae (0.22 fêmeas / fêmea / dia). Estes resultados demonstraram que N. idaeus é capaz de utilizar e desenvolver em todas as três espécies de tetraniquídeos. Mononychellus planki demonstrou ser a presa menos adequada para este predador do que T. urticae e T. ludeni.


Asunto(s)
Animales , Masculino , Femenino , Glycine max , Control Biológico de Vectores , Ácaros/fisiología , Reproducción , Brasil , Productos Agrícolas , Tetranychidae/crecimiento & desarrollo , Tetranychidae/fisiología , Fertilidad , Ácaros/crecimiento & desarrollo
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA