Relativistic ionization-rescattering with tailored laser pulses

The interaction of relativistically strong tailored laser pulses with an atomic system is considered. Due to a special tailoring of the laser pulse, the suppression of the relativistic drift of the ionized electron and a dramatic enhancement of the rescattering probability is shown to be achievable. The high harmonic generation rate in the relativistic regime is calculated and shown to be increased by several orders of magnitude compared to the case of conventional laser pulses. The energies of the revisiting electron at the atomic core can approach the MeV domain, thus rendering hard x-ray harmonics and nuclear reactions with single atoms feasible

On renormalizability of the massless Thirring model

We discuss the renormalizability of the massless Thirring model in terms of the causal fermion Green functions and correlation functions of left-right fermion densities. We obtain the most general expressions for the causal two-point Green function and correlation function of left-right fermion densities with dynamical dimensions of fermion fields, parameterised by two parameters. The region of variation of these parameters is constrained by the positive definiteness of the norms of the wave functions of the states related to components of the fermion vector current. We show that the dynamical dimensions of fermion fields calculated for causal Green functions and correlation functions of left-right fermion densities can be made equal. This implies the renormalizability of the massless Thirring model in the sense that the ultra-violet cut-off dependence, appearing in the causal fermion Green functions and correlation functions of left-right fermion densities, can be removed by renormalization of the wave function of the massless Thirring fermion fields only.Comment: 17 pages, Latex, the contribution of fermions with opposite chirality is added,the parameterisation of fermion determinant by two parameters is confirmed,it is shown that dynamical dimensions of fermion fields calculated from different correlation functions can be made equal.This allows to remove the dependence on the ultra-violet cut-off by the renormalization of the wave function of Thirring fermion fields onl

Equivalent bosonic theory for the massive Thirring model with non-local interaction

We study, through path-integral methods, an extension of the massive Thirring model in which the interaction between currents is non-local. By examining the mass-expansion of the partition function we show that this non-local massive Thirring model is equivalent to a certain non-local extension of the sine-Gordon theory. Thus, we establish a non-local generalization of the famous Coleman's equivalence. We also discuss some possible applications of this result in the context of one-dimensional strongly correlated systems and finite-size Quantum Field Theories.Comment: 15 pages, latex, no figure

Commission des Communautes Europeennes: Groupe du Porte-Parole. Reunion de la Commission du mercredi 29 octobre 1980 = Commission of European Communities: Spokesman Group. Meeting of the Commission on Wednesday, 29 October 1980. Spokesman Service Note to National Offices Bio No. (80) 432, 30 October 1980

We study strong-field ionization and rescattering beyond the long-wavelength limit of the dipole approximation with elliptically polarized mid-IR laser pulses. Full three-dimensional photoelectron momentum distributions (PMDs) measured with velocity map imaging and tomographic reconstruction revealed an unexpected sharp ridge structure in the polarization plane (2018 Phys. Rev. A 97 013404). This thin line-shaped ridge structure for low-energy photoelectrons is correlated with the ellipticity-dependent asymmetry of the PMD along the beam propagation direction. The peak of the projection of the PMD onto the beam propagation axis is shifted from negative to positive values when the sharp ridge fades away with increasing ellipticity. With classical trajectory Monte Carlo simulations and analytical analysis, we study the underlying physics of this feature. The underlying physics is based on the interplay between the lateral drift of the ionized electron, the laser magnetic field induced drift in the laser propagation direction, and Coulomb focusing. To apply our observations to emerging techniques relying on strong-field ionization processes, including time-resolved holography and molecular imaging, we present a detailed classical trajectory-based analysis of our observations. The analysis leads to the explanation of the fine structure of the ridge and its non-dipole behavior upon rescattering while introducing restrictions on the ellipticity. These restrictions as well as the ionization and recollision phases provide additional observables to gain information on the timing of the ionization and recollision process and non-dipole properties of the ionization process.ISSN:1361-6455ISSN:0368-3508ISSN:0953-4075ISSN:0022-370

Pylorus Resection Does Not Reduce Delayed Gastric Emptying After Partial Pancreatoduodenectomy A Blinded Randomized Controlled Trial (PROPP Study, DRKS00004191)

Objectives: The aim of this study was to investigate the effect of pylorus resection on postoperative delayed gastric emptying (DGE) after partial pancreatoduodenectomy (PD). Background: PD is the standard treatment for tumors of the pancreatic head. Preservation of the pylorus has been widely accepted as standard procedure. DGE is a common complication causing impaired oral intake, prolonged hospital stay, and postponed further treatment. Recently, pylorus resection has been shown to reduce DGE. Methods:Patients undergoing PD for any indication at the University of Heidelberg were randomized to either PD with pylorus preservation (PP) or PD with pylorus resection and complete stomach preservation (PR). The primary endpoint was DGE within 30 days according to the International Study Group of Pancreatic Surgery definition. Results: Ninety-five patients were randomized to PP and 93 patients to PR. There were no baseline imbalances between the groups. Overall, 53 of 188 patients (28.2%) developed a DGE (grade: A 15.5%;B 8.8%;C 3.3%). In the PP group 24 of 95 patients (25.3%) and in the PR group 29 of 93 patients (31.2%) developed DGE (odds ratio 1.534, 95% confidence interval 0.788 to 2.987;P = 0.208). Higher BMI, indigestion, and intraabdominal major complications were significant risk factors for DGE. Conclusions: In this randomized controlled trial, pylorus resection during PD did not reduce the incidence or severity of DGE. The development of DGE seems to be multifactorial rather than attributable to pyloric dysfunction alone. Pylorus preservation should therefore remain the standard of care in PD.Trial Registration:German Clinical Trials Register DRKS0000419

Impact of preoperative patient education on the prevention of postoperative complications after major visceral surgery: the cluster randomized controlled PEDUCAT trial

Background: The prevention of postoperative complications is of prime importance after complex elective abdominal operations. Preoperative patient education may prevent postoperative complications and improve patients’ wellbeing, but evidence for its efficacy is poor. The aims of the PEDUCAT trial were (a) to assess the impact of preoperative patient education on postoperative complications and patient-reported outcomes in patients scheduled for elective complex visceral surgery and (b) to evaluate the feasibility of cluster randomization in this setting. Methods: Adult patients (age ≥ 18 years) scheduled for elective major visceral surgery were randomly assigned in clusters to attend a preoperative education seminar or to the control group receiving the department’s standard care. Outcome measures were the postoperative complications pneumonia, deep vein thrombosis (DVT), pulmonary embolism, burst abdomen, and in-hospital fall, together with patient-reported outcomes (postoperative pain, anxiety and depression, patient satisfaction, quality of life), length of hospital stay (LOS), and postoperative mortality within 30 days after the index operation. Statistical analysis was primarily by intention to treat. Results: In total 244 patients (60 clusters) were finally included (intervention group 138 patients; control group 106 patients). Allocation of hospital wards instead of individual patients facilitated study conduct and reduced confusion about group assignment. In the intervention and control groups respectively, pneumonia occurred in 7.4% versus 8.3% (p = 0.807), pulmonary embolism in 1.6% versus 1.0% (p = 0.707), burst abdomen in 4.2% versus 1.0% (p = 0.165), and in-hospital falls in 0.0% versus 4.2% of patients (p = 0.024). DVT did not occur in any of the patients. Mortality rates (1.4% versus 1.9%, p = 0.790) and LOS (14.2 (+/− 12.0) days versus 16.1 (+/− 15.0) days, p = 0.285) were also similar in the intervention and control groups. Conclusions: Cluster randomization was feasible in the setting of preoperative patient education and reduced the risk of contamination effects. The results of this trial indicate good postoperative outcomes in patients undergoing major visceral surgery without superiority of preoperative patient education compared to standard patient care at a high-volume center. However, preoperative patient education is a helpful instrument not only for teaching patients but also for training the nursing staff. Trial registration: German Clinical Trials Registry, DRKS00004226 . Registered on 23 October 2012. Registered 8 days after the first enrollment

Postoperative irradiation for squamous cell carcinoma of head and neck: Retrospective comparison of accelerated radiochemotherapy and standard radiotherapy

Background: Comparison of accelerated radiochemotherapy (aRCT) and standard radiotherapy (sRT) in postoperative treatment after macroscopically complete resection of squamous cell cancers of head and neck. Material and Methods: 229 patients treated within the same period had either (no randomization) postoperative radiotherapy with conventional fractionation (60-70 Gy, 2.0 Gy per day) or received 2 fractions of 2.1 Gy per day, 8 times\textbackslash{}week, up to a total dose of 56.7 Gy with a treatment split after 2 weeks and simultaneous low dose cisplatin or carboplatin on treatment clays (cumulative dose >66 mg/m(2) or 550 mg/m(2) in 83% of patients). Results: 65 patients completed their course of twice-daily irradiations within a maximum of 35 days and therefore had aRCT; their 3-year locoregional tumor control (Kaplan-Meier estimate) was 86%, whereas that of 42 patients with prolonged twice-daily radiochemotherapy was 65% (p=0.0509). After sRT, i.e. 1 fraction daily and treatment time up to 45 days, locoregional tumor control was 67%, this result being significantly inferior to that after aRCT (p=0.0282). In multivariate analysis, pN stage, tumor site oral cavity/floor of mouth, high/moderate differentiation of squamous cell carcinoma and conventional surgery (versus CO2-laser surgery) were significantly predictive of locoregional failure. Whereas nodal status, the strongest prognostic factor, was evenly distributed among aRCT and sRT patients, there was a misbalance of 3 risk factors favoring the aRCT collective. Superior tumor control after aRCT was confirmed unilaterally for nearly each subgroup (significant for recurrent tumors, close margins, pN1/2a-b). For pN2c/pN3 nodal stage, the results after aRCT were by tendency worse than after sRT, possibly due to a particularly long interval between surgery and start of radio(chemo)therapy for the patients with aRCT (mean 58.0 days vs. 43.8 days, p=0.037). Among the total of patients the 3-year hazard for late toxicity Ill-IV was 31% after twice-daily treatment and 17% after conventionally fractionated radiotherapy (p=0.083). Conclusions:This retrospective analysis provides some evidence that accelerated radiotherapy with simultaneous chemotherapy is more potent than standard radiotherapy. However, as multivariate analysis misses significance and the influence of misbalance of some prognostic factors among aRCT and sRT patients remains unclear, only a randomized trial with stratification according to risk factors as well as a defined interval between surgery and initiation of RT can provide more evidence

Исследование остаточных углеводородов в ходе деструкции гептана углеводородокисляющими микроорганизмами рода Pseudomonas и Rodococcus

Molding of micro structures by injection molding leads to special requirements for the molds e.g. regarding wear resistance and low release forces of the molded components. At the same time it is not allowed to affect the replication precision. Physical vapor deposition (PVD) is one of the promising technologies for applying coatings with adapted properties like high hardness, low roughness, low Young's modulus and less adhesion to the melt of polymers. Physical vapor deposition technology allows the deposition of thin films on micro structures. Therefore, the influence of these PVD layers on the contour accuracy of the replicated micro structures has to be investigated. For this purpose injection mold inserts were laser structured with micro structures of different sizes and afterwards coated with two different coatings, which were deposited by a magnetron sputter ion plating PVD technology. After deposition, the coatings were analyzed by techniques regarding hardness, Young's modulus and morphology. The geometries of the micro structures were analyzed by scanning electron microscopy before and after coating. Afterwards, the coated mold inserts were used for injection molding experiments. During the injection molding process, a conventional and a variothermal temperature control of the molds were used. The molded parts were analyzed regarding roughness, structure height and structure width by means of laser microscopy