359 research outputs found

    Hyperfine splitting of the dressed hydrogen atom ground state in non-relativistic QED

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    We consider a spin-1/2 electron and a spin-1/2 nucleus interacting with the quantized electromagnetic field in the standard model of non-relativistic QED. For a fixed total momentum sufficiently small, we study the multiplicity of the ground state of the reduced Hamiltonian. We prove that the coupling between the spins of the charged particles and the electromagnetic field splits the degeneracy of the ground state.Comment: 22 page

    The dressed nonrelativistic electron in a magnetic field

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    We consider a nonrelativistic electron interacting with a classical magnetic field pointing along the x3x_{3}-axis and with a quantized electromagnetic field. When the interaction between the electron and photons is turned off, the electronic system is assumed to have a ground state of finite multiplicity. Because of the translation invariance along the x3x_{3}-axis, we consider the reduced Hamiltonian associated with the total momentum along the x3x_{3}-axis and, after introducing an ultraviolet cutoff and an infrared regularization, we prove that the reduced Hamiltonian has a ground state if the coupling constant and the total momentum along the x3x_{3}-axis are sufficiently small. Finally we determine the absolutely continuous spectrum of the reduced Hamiltonian.Comment: typos correction

    The "Real R0": A Resection Margin Smaller Than 0.1 cm is Associated with a Poor Prognosis After Oncologic Esophagectomy.

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    Although resection margin (R) status is a widely used prognostic factor after esophagectomy, the definition of positive margins (R1) is not universal. The Royal College of Pathologists considers R1 resection to be a distance less than 0.1 cm, whereas the College of American Pathologists considers it to be a distance of 0.0 cm. This study assessed the predictive value of R status after oncologic esophagectomy, comparing survival and recurrence among patients with R0 resection (> 0.1-cm clearance), R0+ resection (≤ 0.1-cm clearance), and R1 resection (0.0-cm clearance). The study enrolled all eligible patients undergoing curative oncologic esophagectomy between 2012 and 2018. Clinicopathologic features, survival, and recurrence were compared for R0, R0+, and R1 patients. Categorical variables were compared with the chi-square or Fisher's test, and continuous variables were compared with the analysis of variance (ANOVA) test, whereas the Kaplan-Meier method and Cox regression were used for survival analysis. Among the 160 patients included in this study, 113 resections (70.6%) were R0, 34 (21.3%) were R0+, and 13 (8.1%) were R1. The R0 patients had a better overall survival (OS) and disease-free survival (DFS) than the R0+ and R1 patients. The R0+ resection offered a lower long-term recurrence risk than the R1 resection, and the R status was independently associated with DFS, but not OS, in the multivariate analysis. Both the R0+ and R1 patients had significantly more adverse histologic features (lymphovascular and perineural invasion) than the R0 patients and experienced more distant and locoregional recurrence. Although R status is an independent predictor of DFS after oncologic esophagectomy, the < 0.1-cm definition for R1 resection seems more appropriate than the 0.0-cm definition as an indicator of poor tumor biology, long-term recurrence, and survival

    Involvement of β3-Adrenoceptor in Altered β-Adrenergic Response in Senescent Heart: Role of Nitric Oxide Synthase 1–derived Nitric Oxide

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    Background: In senescent heart, β-adrenergic response is altered in parallel with β1- and β2-adrenoceptor down-regulation. A negative inotropic effect of β3-adrenoceptor could be involved. In this study, the authors tested the hypothesis that β3-adrenoceptor plays a role in β-adrenergic dysfunction in senescent heart.Methods: β-Adrenergic responses were investigated in vivo (echocardiography–dobutamine, electron paramagnetic resonance) and in vitro (isolated left ventricular papillary muscle, electron paramagnetic resonance) in young adult (3-month-old) and senescent (24-month-old) rats. Nitric oxide synthase (NOS) immunolabeling (confocal microscopy), nitric oxide production (electron paramagnetic resonance) and β-adrenoceptor Western blots were performed in vitro. Data are mean percentages of baseline ± SD. Results: An impaired positive inotropic effect (isoproterenol) was confirmed in senescent hearts in vivo (117 ± 23 vs. 162 ± 16%; P < 0.05) and in vitro (127 ± 10 vs. 179 ± 15%; P < 0.05). In the young adult group, the positive inotropic effect was not significantly modified by the nonselective NOS inhibitor NG-nitro-l-arginine methylester (l-NAME; 183 ± 19%), the selective NOS1 inhibitor vinyl-l-N-5(1-imino-3-butenyl)-l-ornithine (l-VNIO; 172 ± 13%), or the selective NOS2 inhibitor 1400W (183 ± 19%). In the senescent group, in parallel with β3-adrenoceptor up-regulation and increased nitric oxide production, the positive inotropic effect was partially restored by l-NAME (151 ± 8%; P < 0.05) and l-VNIO (149 ± 7%; P < 0.05) but not by 1400W (132 ± 11%; not significant). The positive inotropic effect induced by dibutyryl-cyclic adenosine monophosphate was decreased in the senescent group with the specific β3-adrenoceptor agonist BRL 37344 (167 ± 10 vs. 142 ± 10%; P < 0.05). NOS1 and NOS2 were significantly up-regulated in the senescent rat. Conclusions: In senescent cardiomyopathy, β3-adrenoceptor overexpression plays an important role in the altered β-adrenergic response via induction of NOS1-nitric oxide

    Mean-field evolution of fermions with singular interaction

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    We consider a system of N fermions in the mean-field regime interacting though an inverse power law potential V(x)=1/xαV(x)=1/|x|^{\alpha}, for α(0,1]\alpha\in(0,1]. We prove the convergence of a solution of the many-body Schr\"{o}dinger equation to a solution of the time-dependent Hartree-Fock equation in the sense of reduced density matrices. We stress the dependence on the singularity of the potential in the regularity of the initial data. The proof is an adaptation of [22], where the case α=1\alpha=1 is treated.Comment: 16 page

    Preoperative hiatal hernia in esophageal adenocarcinoma; does it have an impact on patient outcomes?

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    The impact of hiatal hernia (HH) on oncologic outcomes of patients with esophageal adenocarcinoma (AC) remains unclear. The aim of this study was to assess the effect of pre-existing HH (≥3 cm) on histologic response after neoadjuvant treatment (NAT), overall (OS) and disease-free survival (DFS). All consecutive patients with oncological esophagectomy for AC from 2012 to 2018 in our center were eligible for assessment. Categorical variables were compared with the X <sup>2</sup> or Fisher's test, continuous ones with the Mann-Whitney-U test, and survival with the Kaplan-Meier and log-rank test. Overall, 101 patients were included; 33 (32.7%) had a pre-existing HH. There were no baseline differences between HH and non-HH patients. NAT was used in 81.8% HH and 80.9% non-HH patients (p = 0.910), most often chemoradiation (63.6% and 57.4% respectively, p = 0.423). Good response to NAT (TRG 1-2) was observed in 36.4% of HH versus 32.4% of non-HH patients (p = 0.297), whereas R0 resection was achieved in 90.9% versus 94.1% respectively (p = 0.551). Three-year OS was comparable for the two groups (52.4% in HH, 56.5% in non-HH patients, p = 0.765), as was 3-year DFS (32.7% for HH versus 45.6% for non-HH patients, p = 0.283). HH ≥ 3 cm are common in patients with esophageal AC, concerning 32.7% of all patients in this series. However, its presence was neither associated with more advanced disease upon diagnosis, worse response to NAT, nor overall and disease-free survival. Therefore, such HH should not be considered as risk factor that negatively affects oncological outcome after multimodal treatment of esophageal AC

    Absence of Ground States for a Class of Translation Invariant Models of Non-relativistic QED

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    We consider a class of translation invariant models of non-relativistic QED with net charge. Under certain natural assumptions we prove that ground states do not exist in the Fock space

    A Comprehensive Review of Prognostic Factors in Patients with Gastric Adenocarcinoma.

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    Gastric adenocarcinoma remains associated with a poor long-term survival, despite recent therapeutical advances. In most parts of the world where systematic screening programs do not exist, diagnosis is often made at advanced stages, affecting long-term prognosis. In recent years, there is increasing evidence that a large bundle of factors, ranging from the tumor microenvironment to patient ethnicity and variations in therapeutic strategy, play an important role in patient outcome. A more thorough understanding of these multi-faceted parameters is needed in order to provide a better assessment of long-term prognosis in these patients, which probably also require the refinement of current staging systems. This study aims to review existing knowledge on the clinical, biomolecular and treatment-related parameters that have some prognostic value in patients with gastric adenocarcinoma

    Expression profiling of metalloproteinases and tissue inhibitors of metalloproteinases in normal and degenerate human achilles tendon

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    To profile the messenger RNA (mRNA) expression for the 23 known genes of matrix metalloproteinases (MMPs), 19 genes of ADAMTS, 4 genes of tissue inhibitors of metalloproteinases (TIMPs), and ADAM genes 8, 10, 12, and 17 in normal, painful, and ruptured Achilles tendons. Tendon samples were obtained from cadavers or from patients undergoing surgical procedures to treat chronic painful tendinopathy or ruptured tendon. Total RNA was extracted and mRNA expression was analyzed by quantitative real-time reverse transcription–polymerase chain reaction, normalized to 18S ribosomal RNA. In comparing expression of all genes, the normal, painful, and ruptured Achilles tendon groups each had a distinct mRNA expression signature. Three mRNA were not detected and 14 showed no significant difference in expression levels between the groups. Statistically significant (P < 0.05) differences in mRNA expression, when adjusted for age, included lower levels of MMPs 3 and 10 and TIMP-3 and higher levels of ADAM-12 and MMP-23 in painful compared with normal tendons, and lower levels of MMPs 3 and 7 and TIMPs 2, 3, and 4 and higher levels of ADAMs 8 and 12, MMPs 1, 9, 19, and 25, and TIMP-1 in ruptured compared with normal tendons. The distinct mRNA profile of each tendon group suggests differences in extracellular proteolytic activity, which would affect the production and remodeling of the tendon extracellular matrix. Some proteolytic activities are implicated in the maintenance of normal tendon, while chronically painful tendons and ruptured tendons are shown to be distinct groups. These data will provide a foundation for further study of the role and activity of many of these enzymes that underlie the pathologic processes in the tendon
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