Coherent and incoherent pumping of electrons in double quantum dots

We propose a new mode of operation of an electron pump consisting of two weakly coupled quantum dots connected to reservoirs. An electron can be transferred within the device at zero bias voltage when it is subjected to electromagnetic radiation, thereby exciting the double dot. The excited state can decay by transferring charge from one lead and to the other lead in one direction. Depending on the energies of the intermediate states in the pumping cycle, which are controlled by the gate voltages, this transport is either incoherent via well-known sequential tunneling processes, or coherent via a inelastic co-tunneling process. The latter novel mode of operation is possible only when interdot Coulomb charging is important. The D.C. transport through the system can be controlled by the frequency of the applied radiation. We concentrate on the resonant case, when the frequency matches the energy difference for exciting an electron from one dot into the other. The resonant peaks in the pumping current should be experimentally observable. We have developed a density matrix approach which describes the dynamics of the system on timescales much larger than the period of the applied irradiation. In contrast to previous works we additionally consider the case of slow modulation of the irradiation amplitude. Harmonic modulation produces additional sidepeaks in the photoresponse, and pulsed modulation can be used to resolve the Rabi frequency in the time-averaged current.Comment: 5 pages, 6 figures. This is an extension of cond-mat/9707310 "A coherent double-quantum-dot electron pump" This version has been accepted for publication in Phys. Rev. B. Changes: Added references. Corrected typos. Changed content mainly the introduction. Regime of device operation is now specified more precisely. A stability diagram has been added as a figure has been adde

Patient-Reported Outcome Measures may optimize shared decision-making for cancer risk management in BRCA mutation carriers

Purpose: The aim of this study was to compare patient-reported outcomes (PROs) of BRCA1/2 mutation carriers, either after bilateral prophylactic mastectomy (BPM) or during breast surveillance, to improve shared decision-making in their cancer risk management. Methods: Unaffected BRCA1/2 mutation carriers at least one year after BPM followed by immediate breast reconstruction (BPM-IBR) or one year under surveillance were eligible. After informed consent, the Hospital Anxiety and Depression Scale (HADS) and BREAST-Q were administered and compared between the different strategies. PROs were also compared to available normative data. Results: Ninety-six participants were analyzed in this study and showed significant differences between strategies in age, age at genetic testing, and time since BPM or starting breast surveillance. All HADS scores were below 8 suggesting no signs of anxiety or depression in both groups. Higher mean ‘Q-physical well-being’ scores were reported by the surveillance group (81.78 [CI 76.99–86.57]) than the BPM group (76.96 [CI 73.16 – 80.75]; p = 0.011). Overall, for both questionnaires better scores were seen when compared to age-matched normative data. Conclusions: No signs of anxiety or depression were seen in the surveillance or BPM-IBR group. Slightly better mean BREAST-Q scores were seen for the surveillance group in comparison to BPM-IBR, except for ‘Q-psychological well-being’. The difference in ‘Q-physical well-being’ was significantly worse for BPM-IBR. Approaches to obtain longitudinal PROs and reference values should be explored in the future, which could add value to shared decision-making in regards to breast cancer risk management in this specific patient population

Electron transport through double quantum dots

Electron transport experiments on two lateral quantum dots coupled in series are reviewed. An introduction to the charge stability diagram is given in terms of the electrochemical potentials of both dots. Resonant tunneling experiments show that the double dot geometry allows for an accurate determination of the intrinsic lifetime of discrete energy states in quantum dots. The evolution of discrete energy levels in magnetic field is studied. The resolution allows to resolve avoided crossings in the spectrum of a quantum dot. With microwave spectroscopy it is possible to probe the transition from ionic bonding (for weak inter-dot tunnel coupling) to covalent bonding (for strong inter-dot tunnel coupling) in a double dot artificial molecule. This review on the present experimental status of double quantum dot studies is motivated by their relevance for realizing solid state quantum bits.Comment: 32 pages, 31 figure

Improving quality of stroke care through benchmarking center performance:why focusing on outcomes is not enough.

Background: Between-center variation in outcome may offer opportunities to identify variation in quality of care. By intervening on these quality differences, patient outcomes may be improved. However, whether observed differences in outcome reflect the true quality improvement potential is not known for many diseases. Therefore, we aimed to analyze the effect of differences in performance on structure and processes of care, and case-mix on between-center differences in outcome after endovascular treatment (EVT) for ischemic stroke. Methods: In this observational cohort study, ischemic stroke patients who received EVT between 2014 and 2017 in all 17 Dutch EVT-centers were included. Primary outcome was the modified Rankin Scale, ranging from 0 (no symptoms) to 6 (death), at 90 days. We used random effect proportional odds regression modelling, to analyze the effect of differences in structure indicators (center volume and year of admission), process indicators (time to treatment and use of general anesthesia) and case-mix, by tracking changes in tau2, which represents the amount of between-center variation in outcome. Results: Three thousand two hundred seventy-nine patients were included. Performance on structure and process indicators varied significantly between EVT-centers (P < 0.001). Predicted probability of good functional outcome (modified Rankin Scale 0–2 at 90 days), which can be interpreted as an overall measure of a center’s case-mix, varied significantly between 17 and 50% across centers. The amount of between-center variation (tau2) was estimated at 0.040 in a model only accounting for random variation. This estimate more than doubled after adding case-mix variables (tau2: 0.086) to the model, while a small amount of between-center variation was explained by variation in performance on structure and process indicators (tau2: 0.081 and 0.089, respectively). This indicates that variation in case-mix affects the differences in outcome to a much larger extent. Conclusions: Between-center variation in outcome of ischemic stroke patients mostly reflects differences in case-mix, rather than differences in structure or process of care. Since the latter two capture the real quality improvement potential, these should be used as indicators for comparing center performance. Especially when a strong association exists between those indicators and outcome, as is the case for time to treatment in ischemic stroke

Dissipation and noise in adiabatic quantum pumps

We investigate the distribution function, the heat flow and the noise properties of an adiabatic quantum pump for an arbitrary relation of pump frequency $\omega$ and temperature. To achieve this we start with the scattering matrix approach for ac-transport. This approach leads to expressions for the quantities of interest in terms of the side bands of particles exiting the pump. The side bands correspond to particles which have gained or lost a modulation quantum $\hbar \omega$. We find that our results for the pump current, the heat flow and the noise can all be expressed in terms of a parametric emissivity matrix. In particular we find that the current cross-correlations of a multiterminal pump are directly related a to a non-diagonal element of the parametric emissivity matrix. The approach allows a description of the quantum statistical correlation properties (noise) of an adiabatic quantum pump

Patient-Reported Outcome Measures May Add Value in Breast Cancer Surgery

Purpose: Considering the comparable prognosis in early-stage breast cancer after breast-conserving therapy (BCT) and mastectomy, quality of life should be a focus in treatment decision(s). We retrospectively collected PROs and analyzed differences per type of surgery delivered. We aimed to obtain reference values helpful in shared decision-making. Patients and Methods: pTis-T3N0-3M0 patients operated between January 2005 and September 2016 were eligible if: (1) no chemotherapy was administered < 6 months prior to enrolment, and (2) identical surgeries were performed in case of bilateral surgery. After consent, EQ-5D-5L, EORTC-QLQ-C30/BR23, and BREAST-Q were administered. PROs were evaluated per baseline characteristics using multivariable linear regression models. Outcomes were compared for different surgeries as well as for primary (PBC) and second primary or recurrent (SBC) breast cancer patients using analyses of variance (ANOVAs). Results: The response rate was 68%. PROs in 612 PBC patients were comparable to those in 152 SBC patients. Multivariable analyses showed increasing age to be associated with lower “physical functioning” [β − 0.259, p < 0.001] and “sexual functioning” [β − 0.427, p < 0.001], and increasing time since surgery with less “fatigue” [β − 1.083, p < 0.001]. Mastectomy [β − 13.596, p = 0.003] and implant reconstruction [β − 13.040, p = 0.007] were associated with lower “satisfaction with breast” scores than BCT. Radiation therapy was associated with lower satisfaction scores than absence of radiotherapy. Discussion: PRO scores were associated with age, time since surgery, type of surgery, and radiation therapy in breast cancer patients. The scores serve as a reference value for different types of surgery in the study population and enable prospective use of PROs in shared decision-making

Glucocorticoid receptor mRNA levels are selectively decreased in neutrophils of children with sepsis

Objective: Corticosteroids are used in sepsis treatment to benefit outcome. However, discussion remains on which patients will benefit from treatment. Inter-individual variations in cortisol sensitivity, mediated through the glucocorticoid receptor, might play a role in the observed differences. Our aim was to study changes in mRNA levels of three glucocorticoid receptor splice variants in neutrophils of children with sepsis. Patients and design: Twenty-three children admitted to the pediatric intensive care unit with sepsis or septic shock were included. Neutrophils were isolated at days 0, 3 and 7, and after recovery (>3 months). mRNA levels of the glucocorticoid receptor splice variants GR-α (determining most of the cortisol effect), GR-P (increasing GR-α effect) and GR-β (inhibitor of GR-α) were measured quantitatively. Main results: Neutrophils from sepsis patients showed decreased levels of glucocorticoid receptor mRNA of the GR-α and GR-P splice variants on day 0 compared to after recovery. GR-α and GR-P mRNA levels showed a gradual recovery on days 3 and 7 and normalized after recovery. GR-β mRNA levels did not change significantly during sepsis. GR expression was negatively correlated to interleukin-6 (a measure of disease severity, r = -0.60, P = 0.009). Conclusions: Children with sepsis or septic shock showed a transient depression of glucocorticoid receptor mRNA in their neutrophils. This feature may represent a tissue-specific adaptation during sepsis leading to increased cortisol resistance of neutrophils. Our study adds to understanding the mechanism of cortisol sensitivity in immune cells. Future treatment strategies, aiming at timing and tissue specific regulation of glucocorticoids, might benefit patients with sepsis or septic shock

Gender differences in the use of cardiovascular interventions in HIV-positive persons; the D:A:D Study

Peer reviewe

Surviving Sepsis Campaign: International guidelines for management of severe sepsis and septic shock: 2008

SCOPUS: ar.jinfo:eu-repo/semantics/publishe