Ultrafast Spin Dynamics in Nickel

The spin dynamics in Ni is studied by an exact diagonalization method on the ultrafast time scale. It is shown that the femtosecond relaxation of the magneto-optical response results from exchange interaction and spin-orbit coupling. Each of the two mechanisms affects the relaxation process differently. We find that the intrinsic spin dynamics occurs during about 10 fs while extrinsic effects such as laser-pulse duration and spectral width can slow down the observed dynamics considerably. Thus, our theory indicates that there is still room to accelerate the spin dynamics in experiments.Comment: 4 pages, Latex, 4 postscript figure

Electronic Theory for the Nonlinear Magneto-Optical Response of Transition-Metals at Surfaces and Interfaces: Dependence of the Kerr-Rotation on Polarization and on the Magnetic Easy Axis

We extend our previous study of the polarization dependence of the nonlinear optical response to the case of magnetic surfaces and buried magnetic interfaces. We calculate for the longitudinal and polar configuration the nonlinear magneto-optical Kerr rotation angle. In particular, we show which tensor elements of the susceptibilities are involved in the enhancement of the Kerr rotation in nonlinear optics for different configurations and we demonstrate by a detailed analysis how the direction of the magnetization and thus the easy axis at surfaces and buried interfaces can be determined from the polarization dependence of the nonlinear magneto-optical response, since the nonlinear Kerr rotation is sensitive to the electromagnetic field components instead of merely the intensities. We also prove from the microscopic treatment of spin-orbit coupling that there is an intrinsic phase difference of 90$^{\circ }$ between tensor elements which are even or odd under magnetization reversal in contrast to linear magneto-optics. Finally, we compare our results with several experiments on Co/Cu films and on Co/Au and Fe/Cr multilayers. We conclude that the nonlinear magneto-optical Kerr-effect determines uniquely the magnetic structure and in particular the magnetic easy axis in films and at multilayer interfaces.Comment: 23 pages Revtex, preprintstyle, 2 uuencoded figure

Theory for Spin-Polarized Oscillations in Nonlinear Magneto-Optics due to Quantum Well States

Using an electronic tight-binding theory we calculate the nonlinear magneto-optical response from an x-Cu/1Fe/Cu(001) film as a function of frequency and Cu overlayer thickness (x=3 ... 25). We find very strong spin-polarized quantum well oscillations in the nonlinear magneto-optical Kerr effect (NOLIMOKE). These are enhanced by the large density of Fe $d$ states close to the Fermi level acting as intermediate states for frequency doubling. In good agreement with experiment we find two oscillation periods of 6-7 and 11 monolayers the latter being more pronounced.Comment: 12 pages, Revtex, 3 postscript figure

Efficient Data Averaging for Spin Noise Spectroscopy in Semiconductors

Spin noise spectroscopy (SNS) is the perfect tool to investigate electron spin dynamics in semiconductors at thermal equilibrium. We simulate SNS measurements and show that ultrafast digitizers with low bit depth enable sensitive, high bandwidth SNS in the presence of strong optical background shot noise. The simulations reveal that optimized input load at the digitizer is crucial for efficient spin noise detection while the bit depth influences the sensitivity rather weakly

Serum albumin is an early predictor of complications after liver surgery.

The morbidity associated with liver surgery remained substantially high despite considerable surgical and anesthetic improvements. The unmet need of accurate biomarkers to predict postoperative complications is widely accepted. This pilot study aimed to assess serum albumin as a surrogate marker of surgical stress and to test its potential predictive role for postoperative complications. This retrospective pilot study included 106 patients who underwent liver surgery between 2010 and 2014. Serum albumin levels were measured pre- and post-operatively. Maximal albumin decrease (AlbΔmin) was correlated with complications. Serum albumin rapidly dropped after surgery. AlbΔmin was significantly increased in patients with complications (14.5±6.0g/L vs. 10.3±7.2, p=0.009). On multivariate analysis, ASA III/IV (p=0.016) and AlbΔmin (p=0.037) were the only predictors of overall complications. Early postoperative drop of serum albumin reflects the intensity of the surgical stress and may predict complications after liver surgery. Serum albumin is a biomarker displaying precious features and deserving further prospective investigations

Impact of preoperative risk factors on morbidity after esophagectomy: is there room for improvement?

BACKGROUND: Despite progress in multidisciplinary treatment of esophageal cancer, oncologic esophagectomy is still the cornerstone of therapeutic strategies. Several scoring systems are used to predict postoperative morbidity, but in most cases they identify nonmodifiable parameters. The aim of this study was to identify potentially modifiable risk factors associated with complications after oncologic esophagectomy. METHODS: All consecutive patients with complete data sets undergoing oncologic esophagectomy in our department during 2001-2011 were included in this study. As potentially modifiable risk factors we assessed nutritional status depicted by body mass index (BMI) and preoperative serum albumin levels, excessive alcohol consumption, and active smoking. Postoperative complications were graded according to a validated 5-grade system. Univariate and multivariate analyses were used to identify preoperative risk factors associated with the occurrence and severity of complications. RESULTS: Our series included 93 patients. Overall morbidity rate was 81 % (n = 75), with 56 % (n = 52) minor complications and 18 % (n = 17) major complications. Active smoking and excessive alcohol consumption were associated with the occurrence of severe complications, whereas BMI and low preoperative albumin levels were not. The simultaneous presence of two or more of these risk factors significantly increased the risk of postoperative complications. CONCLUSIONS: A combination of malnutrition, active smoking and alcohol consumption were found to have a negative impact on postoperative morbidity rates. Therefore, preoperative smoking and alcohol cessation counseling and monitoring and improving the nutritional status are strongly recommended

Nonlinear Magneto-Optical Response of ss- and dd-Wave Superconductors

The nonlinear magneto-optical response of $s$- and $d$-wave superconductors is discussed. We carry out the symmetry analysis of the nonlinear magneto-optical susceptibility in the superconducting state. Due to the surface sensitivity of the nonlinear optical response for systems with bulk inversion symmetry, we perform a group theoretical classification of the superconducting order parameter close to a surface. For the first time, the mixing of singlet and triplet pairing states induced by spin-orbit coupling is systematically taken into account. We show that the interference of singlet and triplet pairing states leads to an observable contribution of the nonlinear magneto-optical Kerr effect. This effect is not only sensitive to the anisotropy of the gap function but also to the symmetry itself. In view of the current discussion of the order parameter symmetry of High-T$_c$ superconductors, results for a tetragonal system with bulk singlet pairing for various pairing symmetries are discussed.Comment: 21 pages (REVTeX) with 8 figures (Postscript

Is standardized care feasible in the emergency setting? A case matched analysis of patients undergoing laparoscopic cholecystectomy.

Immediate laparoscopic cholecystectomy is the accepted standard for the treatment of acute cholecystitis. The aim of the present study was to evaluate the feasibility of a standardized approach with tailored care maps for pre- and postoperative care by comparing pain, nausea and patient satisfaction after elective and emergent laparoscopic cholecystectomy. From January 2014 until April 2015, data on pain and nausea management were prospectively recorded for all elective and emergency procedures in the department of visceral surgery. This prospective observational study compared consecutive laparoscopic elective vs. emergency cholecystectomies. Visual analogue scales (VAS) were used to measure pain, nausea, and satisfaction from recovery room until 96 hours postoperatively. Final analysis included 168 (79%) elective cholecystectomies and 44 (21%) emergent procedures. Demographics (Age, gender, BMI and ASA-scores) were comparable between the 2 groups. In the emergency group, patients did not receive anxiolytic medication (0% vs.13%, p = 0.009) and less postoperative nausea and vomiting (PONV) prophylaxis (77% vs. 97% p = <0.001). Perioperative pain management was similar in terms of opioid consumption (median amount of fentanyl 450ug [IQR 350-500] vs. 450ug [375-550], p = 0.456) and wound infiltration rates (24% vs. 25%, p = 0.799). Postoperative consumption of paracetamol, metamizole and opiod medications were similar between the 2 groups. VAS scores for pain (p = 0.191) and nausea (p = 0.392) were low for both groups. Patient satisfaction was equally high in both clinical settings (VAS 8.5 ± 1.1 vs. 8.6 ± 1.1, p = 0.68). A standardized pathway allows equally successful control of pain and nausea after both elective and emergency laparoscopic cholecystectomy. This study was retrospectively registered by March 01, 2016 in the following trial register: www.researchregistry.com (UIN researchregistry993)