High-fidelity initialization and control of electron and nuclear spins in a four-qubit register.

Single electron spins bound to multi-phosphorus nuclear spin registers in silicon have demonstrated fast (0.8 ns) two-qubit SWAP gates and long spin relaxation times (~30 s). In these spin registers, when the donors are ionized, the nuclear spins remain weakly coupled to their environment, allowing exceptionally long coherence times. When the electron is present, the hyperfine interaction allows coupling of the spin and charge degrees of freedom for fast qubit operation and control. Here we demonstrate the use of the hyperfine interaction to enact electric dipole spin resonance to realize high-fidelity ( F = 10 0 - 6 + 0 %) initialization of all the nuclear spins within a four-qubit nuclear spin register. By controllably initializing the nuclear spins to ⇓ ⇓ ⇓ , we achieve single-electron qubit gate fidelities of F = 99.78 ± 0.07% (Clifford gate fidelities of 99.58 ± 0.14%), above the fault-tolerant threshold for the surface code with a coherence time of T 2 * = 12 µ s .

Characterization of a chromatic confocal displacement sensor integrated with an optical laser head.

In this paper, the results of experimental characterization of an optical system consisting of a chromatic confocal displacement sensor integrated with an optical laser head are presented. As a result of integration, the part of the optical path of the displacement sensor was combined with the optical path of the laser beam. Consequently, a working distance of 250 mm for the optical system was achieved. The main aim of the characterization was to determine the calibration curve, as well as the application parameters of the system. The methodology for spectral data processing with particular emphasis on the effectiveness of various extraction algorithms is presented. The Lorentzian fitting was considered as the optimal algorithm for the optical system. Consequently, a large measuring range of 10 mm was obtained with perfect linear tendency of the calibration curve. The optical system was characterized by high accuracy equal to ±0.11% of the measuring range, as well as 1 µm resolution. Moreover, the functionality of the system was verified on materials commonly used in laser processing and additive manufacturing. Finally, the system was validated through a comparative measurement with a laser profiler.

Design of a chromatic confocal displacement sensor integrated with an optical laser head.

In this paper, the methodology for design of the system consisting of chromatic confocal displacement sensor integrated with an optical laser head was presented. Furthermore, the results of experimental characterization of optical components of the laser head were also included in the numerical analysis. The designed chromatic confocal displacement sensor was analyzed as an assembly of components widely available on the optical market. Nevertheless, the main goal of the numerical optimization was to determine the influence of individual components of the optical path of the system on its parameters, i.e., measuring range, FWHM of the characteristic spectral peak, and intensity that reaches the detector. The optimized solution was characterized in order to determine the calibration curve, as well as other important application parameters of the system. Moreover, taking into consideration the integration aspect the caustic of the laser beam shaped by the laser head was measured. Finally, the versatility of the system was presented and discussed.

Twenty-four hour ex-vivo normothermic machine perfusion in rat livers.

Ex-vivo liver perfusion (EVLP) is an ideal platform to study liver disease, therapeutic interventions, and pharmacokinetic properties of drugs without any patient risk. Rat livers are an ideal model for EVLP due to less organ quality variability, ease of hepatectomy, well-defined molecular pathways, and relatively low costs compared to large animal or human perfusions. However, the major limitation with rat liver normothermic machine perfusion (NMP) is maintaining physiologic liver function on an ex-vivo machine perfusion system. To address this need, our research demonstrates 24-hour EVLP in rats under normothermic conditions. Early (6 hour) perfusate transaminase levels and oxygen consumption of the liver graft are shown to be good markers of perfusion success and correlate with viable 24-hour post-perfusion histology. Finally, we address overcoming challenges in long-term rat liver perfusions such as rising intrahepatic pressures and contamination, and offer future directions necessary to build upon our work.

After Intestinal Transplantation Kidney Function Is Impaired by Downregulation of Epithelial Ion Transporters in the Ileum.

BACKGROUND: Intestinal transplantation is a treatment option for intestinal failure. Although nephrotoxic medication after transplantation is a major cause for posttransplant renal insufficiency, it remains unclear why kidney dysfunction is particularly frequent after intestinal transplantation. METHODS: This study analyzed messenger RNA expression of NHE3, DRA, and CFTR in 404 biopsies obtained between day 2 and 1508 from the terminal ileum of 10 adult intestinal transplant recipients. RESULTS: The time courses of immunosuppression and glomerular filtration rate were correlated. In the first posttransplant year, expression of NHE3 and DRA, which mediate NaCl absorption, was diminished to a greater degree than that of CFTR, which mediates chloride secretion. Reduced NHE3 and DRA expression was associated with high tacrolimus trough levels. Titration of tacrolimus to low levels by year 2 was paralleled by partially restored NHE3 and DRA expression. In cell culture experiments, similar effects of tacrolimus on transporter expression were detected. In patients, both reduced tacrolimus levels and recovery of NHE3 and DRA expression were associated with stabilization of renal function. CONCLUSIONS: Our data strongly suggest that tacrolimus impairs absorption of NaCl and water from the transplanted ileum, leading to volume depletion and impaired renal function. This may be reversible by reduction of tacrolimus to lower levels without increased rates of rejection or chronic graft failure.

Origin of the magnetoelectric coupling effect in Pb(Zr0.2Ti0.8)O{3}/La{0.8}Sr{0.2}MnO{3} Multiferroic heterostructures.

The electronic valence state of Mn in Pb(Zr0.2Ti0.8)O{3}/La{0.8}Sr{0.2}MnO{3} multiferroic heterostructures is probed by near edge x-ray absorption spectroscopy as a function of the ferroelectric polarization. We observe a temperature independent shift in the absorption edge of Mn associated with a change in valency induced by charge carrier modulation in the La0.8Sr0.2MnO3, demonstrating the electronic origin of the magnetoelectric effect. Spectroscopic, magnetic, and electric characterization shows that the large magnetoelectric response originates from a modified interfacial spin configuration, opening a new pathway to the electronic control of spin in complex oxide materials.

Interface-induced polarization and inhibition of ferroelectricity in epitaxial SrTiO3/Si.

We use SrTiO3/Si as a model system to elucidate the effect of the interface on ferroelectric behavior in epitaxial oxide films on silicon. Using both first-principles computations and synchrotron x-ray diffraction measurements, we show that structurally imposed boundary conditions at the interface stabilize a fixed (pinned) polarization in the film but inhibit ferroelectric switching. We demonstrate that the interface chemistry responsible for these phenomena is general to epitaxial silicon-oxide interfaces, impacting on the design of silicon-based functional oxide devices.

Atomic structure of the epitaxial BaO/Si(001) interface.

We present the structure of the interface responsible for epitaxy of crystalline oxides on silicon. Using synchrotron x-ray diffraction, we observe a 2 x 1 unit cell reconstruction at the interface of BaO grown on Si(001) terminated with 1/2 ML of Sr. Since this symmetry is not present in bulk BaO or Si, only the interface contributes to diffracted intensity. First principles calculations accurately predict the observed diffraction and identify the structure of the BaO/Si interface, including the elemental composition and a sub-A rumpling due to epitaxial strain of the 7 adjacent BaO and Si layers.

Role of strontium in oxide epitaxy on silicon (001).

Epitaxial oxide-Si heterostructures, which integrate the functionality of crystalline oxides with Si technology, are made possible by a submonolayer of Sr deposited on Si (001). We find by electron diffraction studies using single termination Si wafers that this Sr submonolayer replaces the top layer of Si when deposited at 650 degrees C. Supported by first-principles calculations, we propose a model for the reaction dynamics of Sr on the Si surface and its effect on oxide epitaxy. This model predicts, and we experimentally confirm, an unexplored 25 degrees C pathway to crystalline oxide epitaxy on Si.

Mass flow of polycyclic musks in two wastewater treatment plants.

Synthetic musks are found in varying amounts in many consumer products. After use, synthetic musks go down the drain into the sewer system and then reach wastewater treatment plants (WWTPs). In this study, mass flows of two synthetic polycyclic musks, 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta[gamma]-2-benzopyran (HHCB) and 7-acetyl-1,1,3,4,4,6-hexamethyl-1,2,3,4-tetrahydronaphthalene (AHTN), along with HHCB-lactone (the oxidation product of HHCB) were examined in two WWTPs. Wastewater and sludge samples were collected at various stages of the treatment process for analysis. HHCB, AHTN, and HHCB-lactone were found in all wastewater samples at concentrations in the ranges of 1780 to 12700, 304 to 2590, and 146 to 4000 ng/L, respectively. The highest concentrations for all compounds were found in sludge samples. Sludge samples contained HHCB at 7.23 to 108 mg/kg dry weight, AHTN at 0.809 to 16.8 mg/kg dry weight, and HHCB-lactone at 3.16 to 22.0 mg/kg dry weight. This is the first study to report HHCB-lactone in wastewater and HHCB, HHCB-lactone, and AHTN in sludge in WWTPs from the United States. HHCB and AHTN concentrations decreased during treatment. However, the concentrations of HHCB-lactone increased in water after treatment. Based on the daily flow rates and mean concentrations of the three compounds in effluent, a WWTP representative of those studied here is expected to release 288 g HHCB, 60.4 g AHTN, and 158 g HHCB-lactone/100,000 people/d. Partitioning HHCB, AHTN, and HHCB-lactone to sludge is the major removal mechanism for polycyclic musks in WWTPs.

Slow-stimulated multifocal ERG in high- and normal-tension glaucoma.

PURPOSE: To study the ability and sensitivity of the slow stimulation multifocal ERG (mfERG) to detect glaucomatous damage. METHODS: Right eyes of 20 patients with normal-tension glaucoma (NTG), 15 patients with high-tension glaucoma (HTG) and 15 healthy volunteers underwent testing with the mfERG (VERIS 4.1). The central 50 degrees of the retina were stimulated by 103 hexagons (m-sequence: 2(13)-1, Lmax: 100 cd/m(2), Lmin: 1 cd/m(2), background: 50 cd/m(2)). Each m-sequence step was followed by 3 black frames (Lmax: < 1 cd/m(2)). Five response averages of the first order response component (KI) were analyzed: the central 7.5 degrees and the 4 adjoining quadrants. The amplitudes from the first minimum, N1, to the first maximum, P1, and from P1 to the second minimum, N2, were analyzed as well as the latencies of N1, P1, N2 and the latencies of 3 multifocal oscillatory potentials (mfOPs) with their maxima at about 73, 80 and 85 ms. RESULTS: For each parameter the percentage of deviation from the mean of the control group was calculated. These values were then added for each individual to form a deviation index (DI). Seventeen patients (85.0%) with NTG and 3 patients (20.0%) with HTG showed a DI outside the normal range. The major changes were observed in the mfOPs of the NTG patients. MfOPs were then selectively filtered at 100-300 Hz and their scalar product was analyzed over an epoch of 68-105 ms. This confirmed that mfOPs differed significantly from the control in the central 7.5 degrees and, for NTG, in the nasal field. With a logistic regression analysis the mfOPs had a sensitivity to differentiate 85% of the NTG patients and 73% of the HTG patients from normal. CONCLUSIONS: Under these conditions, the slow-stimulated mfERG can detect glaucomatous dysfunction in NTG (85.0%). The differences observed between NTG and HTG are in support of a different underlying pathomechanism.

Preoperative embolization in spinal and pelvic metastases.

The role of preoperative embolization should be evaluated for the surgical treatment of spinal and pelvic metastases. Selective embolization was performed in 32 patients (19 men, 13 women; mean age 63.4 years) before surgery by anterior resection of spinal metastases (n = 21) or pelvic metastases (n = 11). Evaluation parameters consisted of the intraoperative blood loss, the need for blood replacement, and the operating time. There was a significant difference in blood loss and transfusion requirements in the spinal group (P = 0.02) as well as in the pelvic group (P = 0.05) compared to a nonembolized control group of spinal (n = 20) and pelvic (n = 10) metastases. The operating time in the embolized group was shorter, but the difference was not significant. Surgical revision was required in two cases in the embolized spinal group owing to necrosis of the psoas muscle. No neurological deficit was observed that could be attributed to the embolization procedure. Preoperative embolization is thus a suitable method for reducing intraoperative blood loss and transfusion requirements in hypervascularized spinal and pelvic metastases.

Genetic instability in primary leiomyosarcoma of bone.

Primary leiomyosarcoma (LMS) of bone is an exceedingly rare entity on which to date no molecular data have been reported. In a series of 6 tumors (5 grade IIB, 1 grade IIA), we assessed the prevailing genetic stability by microsatellite analysis at 7 loci. The IIB tumors demonstrated a rate of genomic loss as high as 90%, accompanied by an intratumoral heterogeneity in 30% of conspicuous markers. High microsatellite instability in the severe type was not observed, although hMLH1 immunostaining was consistently negative. We assume that intraosseous LMS pertains to "deletor phenotype" tumors. We did observe a locus-specific MSI in our marker linked with hMSH2. Immunostaining and allelotyping indicated a knock-out of pRb in all cases, confirming its major role in sarcomas. Only the stage IIB tumors (4 of 5) pointed to p53 inactivation. In addition, the human telomerase subunit-linked markers exhibited high rates of chromosomal loss. The stage IIA tumor still confined to the bone displayed no genetic instability. Moreover, the proliferation index made a clear distinction between the IIA and IIB tumors (5% vs 30%). We propose to further investigate the usefulness of loss of heterozygosity as a progression marker in this entity.

Capture and release of a conditional state of a cavity QED system by quantum feedback.

Detection of a single photon escaping an optical cavity QED system prepares a nonclassical state of the electromagnetic field. The evolution of the state can be modified by changing the drive of the cavity. For the appropriate feedback, the conditional state can be captured (stabilized) and then released. This is observed by a conditional intensity measurement that shows suppression of vacuum Rabi oscillations for the length of the feedback pulse and their subsequent return.

Absence of telomerase activity in malignant bone tumors and soft-tissue sarcomas.

PURPOSE: Telomerase activity appears to play a crucial role in the development of many tumors. More than 80% of all malignant human tumors show an increased telomerase activity. However, conflicting results have been reported about telomerase activity in sarcomas. The aim of the study was to obtain more information about telomerase activity in sarcomas based on a large number of cases. METHODS: Telomerase activity was measured in 69 different tumor samples (33 malignant bone tumors and 36 soft tissue sarcomas). Tumor samples were obtained intraoperatively and frozen immediately in liquid nitrogen. Telomerase activity was detected by the telomeric repeat amplification assay (TRAP-assay). RESULTS: Only 7% of the samples showed telomerase activity. No correlation between staging and telomerase activity could be observed. DISCUSSION: The fact that only five out of 69 examined tumor samples showed a telomerase activity provides experimental evidence that in sarcomas the reactivation of telomerase may play a subordinate role. Our results suggest that alternative mechanisms for cell immortalization, yet to be determined, seem to be involved in the development and/or maintenance of soft-tissue sarcomas and malignant bone tumors.

Standardized terminological services enabling semantic interoperability between distributed and heterogeneous systems.

The interconnection of heterogeneous computer applications in medicine raises the issue of semantic interoperability, going beyond traditional approaches of terminological standardization in basically three aspects. First, the variety of medical vocabularies that currently coexist in different domains is a major barrier for the integration of autonomously developed applications. Fortunately, with the Unified Medical Language System (UMLS) there are machine-readable terminological sources that cover and integrate most of the existing medical vocabularies. Second, the exchanged data need to be processed by a machine for different purposes like patient data integration, access to literature and knowledge bases as well as clinical audit and research. Medical vocabularies provided as passive dictionaries are no longer sufficient. Software system developers should take advantage of terminological services for refining user queries, for mapping the user's terms to appropriate medical vocabularies etc. Third, the services should be accessible uniformly and transparently. In the CORBAmed initiative a proposal for a standardized interface for querying and accessing computerized medical terminology resources was created. Based on the mentioned principles the MUSTANG system (Medical UMLS based Terminology Server for Authoring, Navigating and Guiding the Retrieval to Heterogeneous Knowledge Sources) has been developed. It is implemented on a Windows NT platform using the ORACLE database management and development software. The terminological services are accessible via multiple interfaces. The MUSTANG-System and the experiences with using terminological services in practice are described. Opposed to other levels of standardization like syntactical message standards there is much more a hesitation in the use of standardized terminology.

Predictors of left ventricular function after acute myocardial infarction: effects of time to treatment, patency, and body mass index: the GUSTO-I angiographic experience.

BACKGROUND: Despite the significant survival benefit associated with successful reperfusion therapy for acute myocardial infarction, global indices of outcome left ventricular function, such as ejection fraction, have often demonstrated little or no improvement. Although these measurements are confounded by numerous clinical, physiologic, and angiographic variables, no comprehensive analysis of this issue in a large series of patients is available. We used the Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries (GUSTO-I) database to better understand this phenomenon by determining independent predictors of left ventricular function and their interplay with regard to outcome ventricular function and improvement in function during the initial postinfarction week. METHODS: Ninety-minute and 5- to 7-day posttreatment global and regional indices derived from left ventriculograms were analyzed from a population of 676 patients. These observations were combined with clinical data to describe independent determinants of ventricular function outcome. RESULTS: Clinical factors predictive of global and regional ventricular function as well as improvement in function between 90 minutes and 5 to 7 days included time to treatment, early infarct-related artery flow grade, and body mass index. These same factors contribute significantly to compensatory hyperkinesis of the noninfarct zone, which is critical to maintenance of global ventricular function during this time period. CONCLUSIONS: The ventricular function benefits of early complete reperfusion after myocardial infarction are readily demonstrable after adjustment for multiple covariables and include (1) maintenance of global ventricular function and (2) prevention or delay in ventricular dilatation.