Nonequilibrium Green's function theory for nonadiabatic effects in quantum electron transport

We develop nonequilibribrium Green's function based transport theory, which includes effects of nonadiabatic nuclear motion in the calculation of the electric current in molecular junctions. Our approach is based on the separation of slow and fast timescales in the equations of motion for the Green's functions by means of the Wigner representation. Time derivatives with respect to central time serves as a small parameter in the perturbative expansion enabling the computation of nonadiabatic corrections to molecular Green's functions. Consequently, we produce series of analytic expressions for non-adiabatic electronic Green's functions (up to the second order in the central time derivatives); which depend not solely on instantaneous molecular geometry but likewise on nuclear velocities and accelerations. Extended formula for electric current is derived which accounts for the non-adiabatic corrections. This theory is concisely illustrated by the calculations on a model molecular junction

Subsurface tropical Pacific nitrogen isotopic composition of nitrate: Biogeochemical signals and their transport

We report measurements of the nitrogen isotopic composition of nitrate (the δ15N of NO3−) across the equatorial Pacific, for zonal transects from 165°E to 95°W and meridional transects across 95° and 110°W. The δ15N of NO3− is similar in the equatorial thermocline (≈100 m) and intermediate depth waters (≈150 to 600 m), averaging (7.1 ± 0.3)‰ and (7.1 ± 0.1)‰, respectively. These values are more than 2‰ higher than subthermocline waters of the Southern and Atlantic Oceans and are ≈1‰ higher than putative source waters in the high latitude South Pacific (Subantarctic Mode Water, SAMW). The combined constraints of nitrate concentration and δ15N of NO3−in the equatorial Pacific require (1) lateral exchange between the high‐latitude source waters and the zones of denitrification in the eastern tropical Pacific and (2) the accumulation of remineralized nutrients at depth. The zonal uniformity of the subsurface equatorial Pacificδ15N of NO3− indicates rapid transport within the equatorial zone, which works to homogenize the δ15N of NO3− across the Pacific basin. Against this backdrop of high δ15N of NO3−in the tropical Pacific, we find a discrete off‐equatorial core of lowerδ15N of NO3− (5.5 ± 0.3)‰ concentrated at 5°S and 150 to 200 m along the 110° and 95°W transects and in apparent association with the Southern Subsurface Counter Current (SSCC). We propose that the remineralized products of nitrogen fixation, at the source of the SSCC in the western south Pacific, are the origin of the low δ15N of NO3− in these waters

New Posterior Auricular Perichondrial Cutaneous Graft for Stable Reconstruction of Nasal Defects

The perichondrial cutaneous graft (PCCG), a reliable composite graft that provides stability, is routinely harvested from the anterior conchal bowl. This established PCCG was simplified by using the less conspicuous posterior auricular donor site, which can be closed without the need of cartilage resection for reconstruction with a postauricular interpolated skin island. Patients with basal cell carcinoma of the nose underwent reconstruction of the nose with a PCCG if parts of the tip cartilage or the fibrofatty tissue were resected. The defect surface area was assessed with a template. Follow-up evaluation included assessment of graft survival, donor-site morbidity, nostril stability, and aesthetic outcome. Of the 14 patients included in the study, whose average defect sizes were 2 cm2 (ala) and 2.5 cm2 (tip), 79% showed primary complete healing. Nostril stability was symmetrical 6 months postoperatively, and no contractions or depressed contour had occurred. In one case, a hyperpigmented area resulted in a slightly imperfect color match. All the donor sites healed without deformity or destabilization of the ear. With the use of this new posterior auricular donor site for graft harvest, functional, stable, and aesthetic reconstruction of the nose can be achieved. The graft- and donor-site morbidity rates are very low, and the results are fully satisfyin

Perforator-Sparing Abdominoplasty Technique in the Presence of Bilateral Subcostal Scars after Gastric Bypass

Background: The number of patients after gastric bypass being referred to plastic surgery units for secondary plastic surgery procedures is increasing. The characteristic abdominal deformity includes a draping apron of panniculus, occasionally associated with previous transverse surgical scars in the upper abdomen. Often a limited abdominoplasty of the low transverse type with limited undermining only up to the level of the umbilicus is performed in order not to compromise blood supply in the zone between the old transverse and the new transverse scar. Method: We propose a new, modified and safe surgical technique to perform a complete abdominoplasty with wide undermining up to the xiphoid process in patients with preexisting transverse subcostal scars after gastric bypass surgery, by selectively dissecting and preserving one to three periumbilical abdominal wall perforator vessels to secure flap blood supply. Vessel tunnelling through the rectus sheath and muscle and ligation of the cephalad branch of the perforator provide sufficient flap mobility without perforator tension or traction. Flap undermining is performed around these perforator vessels. To match dissected flap perforators with blood-flow, we performed postoperative color-flow duplex scanning. Results: We treated two patients according to this new technique. In both cases the postoperative course was uneventful and a good aesthetic result was achieved. Conclusion: We conclude from our experience that with this perforator-sparing abdominoplasty technique, safe and complete abdominoplasty can be performed with no additional risk of complications and that a good cosmetic result can be achieved in patients after open gastric bypass surger

Exchange interaction in chirally coupled quantum dots

We present transport measurements on a system of two lateral quantum dots in a perpendicular magnetic field. Due to edge channel formation in an open conducting region, the quantum dots are chirally coupled. When both quantum dots are tuned into the Kondo regime simultaneously, we observe a change in the temperature dependence of the differential conductance. This is explained by the RKKY exchange interaction between the two dots. As a function of bias the differential conductance shows a splitting of the Kondo resonance which changes in the presence of RKKY interaction.DFG/EXC/QUESTNTH School for Contacts in Nanosystem

An Individualized Approach to Abdominoplasty in the Presence of Bilateral Subcostal Scars after Open Gastric Bypass

Background: Patients requiring surgical skin excision after massive weight loss are challenging and require an individualized approach. The characteristic abdominal deformity includes a draping apron of panniculus, occasionally associated with previous transverse surgical scars from open gastric bypass surgery in the upper abdomen, which compromise blood supply of the abdominal skin. Methods: We propose four different surgical techniques for safe abdominal body contouring in the presence of such scars: (1) a limited abdominoplasty of the lower abdomen is performed, and then contouring is completed by a reversed abdominoplasty with scar positioning in the submammary folds; (2) a one-stage procedure characterized by skin resection in the upper and lower abdomen, in which blood supply of the skin island between the submammary and suprapubic incisions is ensured by periumbilical perforators; (3) a perforator-sparing abdominoplasty with selective dissection of periumbilical abdominal wall perforators to secure flap blood supply and allow complete flap undermining up to the xyphoid process; (4) for patients with extensive excess skin, a modified Fleur-de-Lys abdominoplasty performed in such a way that the old transverse scar is transformed into a vertical scar. Results: The treatment of four exemplary patients is described. All techniques yielded good esthetic and functional results through preservation of abdominal blood supply. Conclusion: Through an individualized approach, adequate abdominal body contouring can be performed safely, even in the presence of transverse surgical scars in the upper abdome

Inelastic quantum transport: the self-consistent Born approximation and correlated electron-ion dynamics

A dynamical method for inelastic transport simulations in nanostructures is compared with a steady-state method based on non-equilibrium Green's functions. A simplified form of the dynamical method produces, in the steady state in the weak-coupling limit, effective self-energies analogous to those in the Born Approximation due to electron-phonon coupling. The two methods are then compared numerically on a resonant system consisting of a linear trimer weakly embedded between metal electrodes. This system exhibits enhanced heating at high biases and long phonon equilibration times. Despite the differences in their formulation, the static and dynamical methods capture local current-induced heating and inelastic corrections to the current with good agreement over a wide range of conditions, except in the limit of very high vibrational excitations, where differences begin to emerge.Comment: 12 pages, 7 figure

Determining the unsaturated hydraulic conductivity of a compacted sand-bentonite mixture under constant volume and free-swell conditions

Highly compacted sand-bentonite mixtures are often considered as possible engineered barriers in deep high-level radioactive waste disposals. In-situ, the saturation of these barriers from their initially unsaturated state is a complex hydro-mechanical coupled process in which temperature effects also play a role. The key parameter of this process is the unsaturated hydraulic conductivity of the barrier. In this paper, isothermal infiltration experiments were conducted to determine the unsaturated hydraulic conductivity according to the instantaneous profile method. To do so, total suction changes were monitored at different locations along the soil specimen by using resistivity relative humidity probes. Three constant volume infiltration tests were conducted showing, unexpectedly, a decrease of the hydraulic conductivity during infiltration. One test performed under free-swell conditions showed the opposite and standard trend. These observations were interpreted in terms of microstructure changes during wetting, both under constant volume and free swell conditions

“Was this answer helpful?” – A Taxonomy for Feedback Mechanisms in Customer Service Chatbots

Chatbot technology has rapidly spread, especially in digital customer service. However, the automation potential of chatbots can only be realized if customers are satisfied with their service. Collecting explicit feedback is a promising technique for assessing customer satisfaction and identifying issues with the chatbot. It enables chatbot managers and developers to enhance performance and design of operational chatbots on an informed basis. The evident significance of explicit customer feedback comes with a multitude of design options available. However, there is a lack of research on chatbot feedback mechanisms and practical as well as theoretical clarity. In this paper, we adress this gap by introducing a chatbot feedback taxonomy derived from existing research and a sample of N = 72 real world customer service chatbots. Furthermore, based on a cluster analysis, we identify four archetypes of feedback mechanisms and provide strategic guidelines for the informed use of each of those feedback design variants

Deriving the paradoxical effects of temporal metalepsis

This paper explores a phenomenon, metalepsis, that hasn’t been discussed in linguistics until only recently, but is important because it sheds new light on the semantics of fiction and paradoxical statements. We focus on a particular instance of metalepsis, namely the following sentence from Sylvie by Gérard de Nerval: ‘While the coach is making its way up to the hills, let us piece together the memories of the days when I often visited these parts.’ This sentence exemplifies a temporal paradox since the narrator asks the narratee to join him in doing something that had already happened. Previous analyses of metalepsis have focused on third-person examples, leading to incorrect predictions for such first-person examples. We propose a novel analysis that accounts for both first- and third-person uses, while also accounting for a potential difference in aesthetic import between the two cases