How Valley-Orbit States in Silicon Quantum Dots Probe Quantum Well Interfaces.

The energies of valley-orbit states in silicon quantum dots are determined by an as yet poorly understood interplay between interface roughness, orbital confinement, and electron interactions. Here, we report measurements of one- and two-electron valley-orbit state energies as the dot potential is modified by changing gate voltages, and we calculate these same energies using full configuration interaction calculations. The results enable an understanding of the interplay between the physical contributions and enable a new probe of the quantum well interface.

Coherent Control and Spectroscopy of a Semiconductor Quantum Dot Wigner Molecule.

Semiconductor quantum dots containing more than one electron have found wide application in qubits, where they enable readout and enhance polarizability. However, coherent control in such dots has typically been restricted to only the lowest two levels, and such control in the strongly interacting regime has not been realized. Here we report quantum control of eight different transitions in a silicon-based quantum dot. We use qubit readout to perform spectroscopy, revealing a dense set of energy levels with characteristic spacing far smaller than the single-particle energy. By comparing with full configuration interaction calculations, we argue that the dense set of levels arises from Wigner-molecule physics.

Fabrication process and failure analysis for robust quantum dots in silicon.

We present an improved fabrication process for overlapping aluminum gate quantum dot devices on Si/SiGe heterostructures that incorporates low-temperature inter-gate oxidation, thermal annealing of gate oxide, on-chip electrostatic discharge (ESD) protection and an optimized interconnect process for thermal budget considerations. This process reduces gate-to-gate leakage, damage from ESD, dewetting of aluminum and formation of undesired alloys in device interconnects. Additionally, cross-sectional scanning transmission electron microscopy (STEM) images elucidate gate electrode morphology in the active region as device geometry is varied. We show that overlapping aluminum gate layers homogeneously conform to the topology beneath them, independent of gate geometry and identify critical dimensions in the gate geometry where pattern transfer becomes non-ideal, causing device failure.

Open-Access Single Balloon Enteroscopy: A Tertiary Care Experience.

OBJECTIVES: To compare single balloon enteroscopy (SBE) between patients seen in consultation by a member of our gastroenterology team with those performed as open-access cases. METHODS: Retrospective study of all patients who underwent SBE at a single tertiary care center from April 2008 to January 2012. Open- and closed-access procedures were compared in terms of diagnostic and therapeutic yield, adverse events, and procedural success. RESULTS: A total of 125 SBEs were performed on 125 patients. The mean age was 63.1 (53% men) years. In all, 43 procedures were performed open access and 82 after face-to-face consultation. Indications included anemia/gastrointestinal bleeding (110), abdominal pain (8), and other (7). Diagnostic yield for open- and closed-access procedures was 53% and 60%, respectively (P = 0.501) and therapeutic yield was 37% and 52%, respectively (P = 0.11). Overall technical success was 91% with no difference between the groups (P = 0.27). There were no major adverse events in either group. CONCLUSIONS: SBE can be performed as an open-access procedure without compromise to safety or diagnostic yield.

Blood transfusion practices in upper gastrointestinal bleeding: response to a landmark study.

OBJECTIVE: Lack of clear evidence in red blood cell (RBC) transfusion during gastrointestinal bleeding has led to varied recommendations over the years. However, studies in broad areas of medicine have provided evidence about appropriate RBC transfusion thresholds, and a 'landmark' study published in 2013 provided evidence in patients with upper gastrointestinal (UGI) bleeding. We hypothesized that the response to the evidence would lead to improved RBC transfusion practice. Our aim was to determine the response in RBC transfusion practices at our institution. DESIGN: We examined RBC transfusion practices in patients with UGI bleeding who presented to the Medical University of South Carolina from January 2010 through December 2013. We abstracted extensive clinical data including demographic, medical history (comorbidities), medications, physical examination findings, laboratory data, endoscopic data, and RBC transfusion practices. We considered appropriate RBC transfusion to have occurred when performed for a hemoglobin level of <70 g/L. RESULTS: 270 patients hospitalized with UGI bleeding had 606 RBC transfusions; 355 transfusions in 107 patients were appropriate, and 251 transfusions in 163 were inappropriate. In 2010, 2011, and 2012, the rates of appropriate RBC transfusions were 61/124 (49%), 92/172 (53%), and 84/142 (59%), respectively. There was a statistically significant difference in appropriate transfusions in 2013 (118/168 (70%)) compared with 2012 (84/142 (59%), p=0.003), as well as during 2010-2012 (237/438 (54%), p≤0.003). CONCLUSIONS: The data suggest that there was an improvement in RBC transfusion practices after a landmark study. However, the data also highlight that RBC transfusion practices in UGI bleeding remain imperfect.

Multimodal intervention for avoiding inappropriate cessation of aspirin prior to outpatient endoscopy.

Background and study aims Existing guidelines recommend continuation of aspirin therapy prior to outpatient endoscopic procedures, as it reduces peri-procedural cardiovascular events and is not associated with an increased risk of bleeding. Despite this, many patients at our institution inappropriately alter their aspirin prior to endoscopy. We sought to identify why this occurs and implement an intervention that could reduce improper aspirin alteration. Patients and methods All adult patients undergoing outpatient endoscopy at the Medical University of South Carolina were administered a survey querying demographics, aspirin use, endoscopic procedure, thromboembolic risk factors, and pre-procedural aspirin alteration, if any. An intervention involving revised written and verbal instructions as well as an automated voicemail aimed at ensuring patients adhere to guidelines was then undertaken. The same survey was administered after the intervention to assess for improved adherence. Results A total of 240 patients from the initial survey reported daily aspirin use, of which 114 (47.5 %) inappropriately altered aspirin therapy. A total of 182 patients from the post-intervention survey reported daily aspirin use, of which 66 (36.3 %) inappropriately altered aspirin therapy. This was a statistically significant reduction ( P  = 0.04), which included adjustments for age, sex, procedure type, and thromboembolic risk. Conclusions A high proportion of patients at our institution inappropriately alter aspirin therapy prior to outpatient endoscopy. The reasons for this behavior include patient self-direction, misguidance from staff, and instruction from other physicians. This alteration can be reduced significantly through an intervention that educates both patients and staff on continuation of aspirin therapy prior to outpatient endoscopy.

Small Bowel Mucosal Involvement and Mesenteric Mass Formation in a Young Female with Type 3 Gaucher Disease. A Case Report.

Gaucher Disease arises due to a deficiency in the enzyme glucocerebrosidase and is the most common lysosomal storage disease. This enzyme deficiency leads to the accumulation of glucocerebroside within macrophages (Gaucher cells) and the resulting infiltration of these cells into organs can cause clinical symptoms. There are three types of Gaucher Disease that differ based on the clinical course and the presence or absence of neurological involvement, but classically, Gaucher cell infiltrates impact a patient's spleen, liver, bone marrow and cortex. In this report, we present a case of Type 3 Gaucher Disease involving small bowel mucosa with a mesenteric mass formation. These unusual sites of Gaucher cell deposition likely led directly to uncommonly seen clinical symptoms, including small bowel obstruction and lower gastrointestinal hemorrhage.

Isolation of a monoclonal antibody from a phage display library binding the rhesus macaque MHC class I allomorph Mamu-A1*001.

Monoclonal antibodies that bind to human leukocyte antigen (HLA) are useful tools for HLA-typing, tracking donor-recipient chimerisms after bone marrow transplants, and characterizing specific major histocompatibility complexes (MHC) on cell surfaces. Unfortunately, equivalent reagents are not available for rhesus macaques, which are commonly used animal as models in organ transplant and infectious disease research. To address this deficiency, we isolated an antibody that recognizes the common Indian rhesus macaque MHC class I molecule, Mamu-A1*001. We induced Mamu-A1*001-binding antibodies by alloimmunizing a female Mamu-A1*001-negative rhesus macaque with peripheral blood mononuclear cells (PBMC) from a male Mamu-A1*001-positive donor. A Fab phage display library was constructed with PBMC from the alloimmunized macaque and panned to isolate an antibody that binds to Mamu-A1*001 but not to other common rhesus macaque MHC class I molecules. The isolated antibody distinguishes PBMC from Mamu-A1*001-positive and -negative macaques. Additionally, the Mamu-A1*001-specific antibody binds the cynomolgus macaque MHC class I ortholog Mafa-A1*001:01 but not variants Mafa-A1*001:02/03, indicating a high degree of binding specificity. The Mamu-A1*001-specific antibody will be useful for identifying Mamu-A1*001-positive rhesus macaques, for detecting Mamu-A1*001-positive cells in populations of Mamu-A1*001-negative cells, and for examining disease processes that alter expression of Mamu-A1*001 on cell surfaces. Moreover, the alloimmunization process we describe will be useful for isolating additional MHC allomorph-specific monoclonal antibodies or antibodies against other polymorphic host proteins which are difficult to isolate with traditional technologies.

Comparison of the reusable standard GlideScope® video laryngoscope and the disposable cobalt GlideScope® video laryngoscope for tracheal intubation in an academic emergency department: a retrospective review.

OBJECTIVES: The objective was to compare the first-pass success and clinical performance characteristics of the reusable standard GlideScope® video laryngoscope (sGVL) and the disposable Cobalt GlideScope® video laryngoscope (cGVL). METHODS: This was a retrospective analysis of prospectively collected data recorded into a continuous quality improvement database at an urban academic emergency department (ED). The intent of the database is to evaluate operator performance and to track practice patterns used for intubation in the ED. Between July 1, 2007, and June 30, 2013, operators recorded all consecutive intubations performed in the ED. The database included patient demographics and detailed information about each intubation, such as device(s) used, reason for device selection, method of intubation, difficult airway characteristics, number of intubation attempts, and outcome of each attempt. The operator also evaluated the presence of lens fogging and extent of lens contamination. The primary outcome measure was first-pass success. Secondary outcome measures were ultimate success, Cormack-Lehane (CL) view of the airway, presence of lens fogging, and extent of lens contamination. Only adult patients age 18 years or older intubated with the sGVL or cGVL using a stylet, and who had data forms completed at the time of intubation, were included in this study. RESULTS: A total of 583 intubations were included in the study, 504 with the sGVL and 79 with cGVL. First pass success was achieved in 81.0% (95% confidence interval [CI]=77.3% to 84.3%) of patients in the sGVL group and in 58.2% (95% CI=46.6% to 69.2%) of patients in the cGVL group. In a multivariate logistic regression analysis, the sGVL was associated with a higher first pass success than the cGVL (odds ratio [OR]=3.3, 95% CI=1.9 to 5.8). The ultimate success of the sGVL was 92.1% (95% CI=89.4% to 94.3%) and the cGVL was 72.2% (95% CI=60.9% to 81.7%). A CL grade I or II view was obtained in 93.2% (95% CI=90.7% to 95.3%) in the sGVL group and 86.1% (95% CI=76.5% to 92.8%) in the cGVL group. Lens fogging occurred in 33.3% (95% CI=29.2% to 37.6%) of the cases in the sGVL group and 59.5% (95% CI=47.9% to 70.4%) of the cases in the cGVL group. Significant lens contamination occurred in 5.0% (95% CI=3.2% to 7.2%) of the sGVL group and 21.5% (95% CI=13.1% to 32.2%) of the cGVL group. CONCLUSIONS: In this observational study, the sGVL had higher first pass and overall success than the disposable cGVL. The cGVL had significantly higher incidence of lens fogging and contamination, which may partially account for its lower success. A prospective randomized trial is needed to confirm these findings.