Fabrication of wide-IF 200–300 GHz superconductor–insulator–superconductor mixers with suspended metal beam leads formed on silicon-on-insulator

We report on a fabrication process that uses SOI substrates and micromachining techniques to form wide-IF SIS mixer devices that have suspended metal beam leads for rf grounding. The mixers are formed on thin 25 µm membranes of Si, and are designed to operate in the 200–300 GHz band. Potential applications are in tropospheric chemistry, where increased sensitivity detectors and wide-IF bandwidth receivers are desired. They will also be useful in astrophysics to monitor absorption lines for CO at 230 GHz to study distant, highly redshifted galaxies by reducing scan times. Aside from a description of the fabrication process, electrical measurements of these Nb/Al–AlNx/Nb trilayer devices will also be presented. Since device quality is sensitive to thermal excursions, the new beam lead process appears to be compatible with conventional SIS device fabrication technology

Position Paper From the Association of Pathology Chairs: Assessing Autopsy Competency in Pathology Residency Training

Declining numbers of hospital autopsies performed in US pathology residency training programs and perceived declining practice of autopsy by many pathologists has caused stakeholder organizations to reassess the role of autopsy training in pathology residency. A working group convened by the stakeholder organizations has delivered the results of a detailed study of current practice of autopsy education in US pathology programs, along with recommendations for the future of autopsy education. Accepting the report of the Working Group, the Association of Pathology Chairs here publishes its position paper on the proposed recommendations

Position Paper From the Association of Pathology Chairs: Surgical Pathology Residency Training

Training in surgical pathology specimen dissection and microscopic diagnosis is an integral part of pathology residency training, as surgical pathology is one of the defining activities of most pathologists. The Accreditation Council for Graduate Medical Education and the American Board of Pathology policies delineate guidelines and requirements for residency training. Both the ACGME and ABP require that residents are ready for “independent practice� upon completion of training (ACGME) and for board eligibility (ABP). This position paper, developed through a consensus process involving the Association of Pathology Chairs, including the Program Directors and Graduate Medical Education committee, expands on these guidelines and the importance of gross dissection as a part of training

Making AlN(x) Tunnel Barriers Using a Low-Energy Nitrogen-Ion Beam

A technique based on accelerating positive nitrogen ions onto an aluminum layer has been demonstrated to be effective in forming thin (<2 nm thick) layers of aluminum nitride (AlN(x)) for use as tunnel barriers in Nb/Al-AlN(x)/Nb superconductor/insulator/ superconductor (SIS) Josephson junctions. AlN(x) is the present material of choice for tunnel barriers because, to a degree greater than that of any other suitable material, it offers the required combination of low leakage current at high current density and greater thermal stability. While ultra-thin AlN films with good thickness and stoichiometry control are easily formed using techniques such as reactive molecular beam epitaxy and chemical vapor deposition, growth temperatures of 900 C are necessary for the dissociative adsorption of nitrogen from either nitrogen (N2) or ammonia (NH3). These growth temperatures are prohibitively high for the formation of tunnel barriers on Nb films because interfacial reactions at temperatures as low as 200 to 300 C degrade device properties. Heretofore, deposition by reactive sputtering and nitridation of thin Al layers with DC and RF nitrogen plasmas have been successfully used to form AlN barriers in SIS junctions. However, precise control over critical current density Jc has proven to be a challenge, as is attaining adequate process reproducibility from system to system. The present ion-beam technique is an alternative to the plasma or reactive sputtering techniques as it provides a highly controlled arrival of reactive species, independent of the electrical conditions of the substrate or vacuum chamber. Independent and accurate control of parameters such as ion energy, flux, species, and direction promises more precise control of film characteristics such as stoichiometry and thickness than is the case with typical plasma processes. In particular, the background pressure during ion-beam nitride growth is 2 or 3 orders of magnitude lower, minimizing the formation of compounds with contaminants, which is critical in devices the performance of which is dictated by interfacial characteristics. In addition, the flux of incoming species can be measured in situ using ion probes so that the dose can be controlled accurately. The apparatus used in the present ion-beam technique includes a vacuum chamber containing a commercial collimated- ion-beam source, a supply of nitrogen and argon, and an ion probe for measuring the ion dose. Either argon or nitrogen can be used as the feed gases for the ion source, depending on whether cleaning of the substrate or growth of the nitride, respectively, is desired. Once the Nb base electrode and Al proximity layer have been deposited, the N2 gas line to the ion beam is vented and purged, and the ion-source is turned on until a stable discharge is obtained. The substrate is moved over the ion-beam source to expose the Al surface layer to the ion beam (see figure) for a specified duration for the formation of the nitride tunnel barrier. Next, the Nb counter-electrode layer is deposited on the nitride surface layer. The Nb/Al- AlN(x)/Nb-trilayer-covered substrate is then patterned into individual devices by use of conventional integrated-circuit processing techniques

Development of a Self‐Management Theory‐Guided Discharge Intervention for Parents of Hospitalized Children

Background Parents of hospitalized children, especially parents of children with complex and chronic health conditions, report not being adequately prepared for self‐management of their child\u27s care at home after discharge. Problem No theory‐based discharge intervention exists to guide pediatric nurses\u27 preparation of parents for discharge. Purpose To develop a theory‐based conversation guide to optimize nurses\u27 preparation of parents for discharge and self‐management of their child at home following hospitalization. Methods Two frameworks and one method influenced the development of the intervention: the Individual and Family Self‐Management Theory, Tanner\u27s Model of Clinical Judgment, and the Teach‐Back method. A team of nurse scientists, nursing leaders, nurse administrators, and clinical nurses developed and field tested the electronic version of a nine‐domain conversation guide for use in acute care pediatric hospitals. Conclusions The theory‐based intervention operationalized self‐management concepts, added components of nursing clinical judgment, and integrated the Teach‐Back method. Clinical Relevance Development of a theory‐based intervention, the translation of theoretical knowledge to clinical innovation, is an important step toward testing the effectiveness of the theory in guiding clinical practice. Clinical nurses will establish the practice relevance through future use and refinement of the intervention

Making Wide-IF SIS Mixers with Suspended Metal-Beam Leads

A process that employs silicon-on-insulator (SOI) substrates and silicon (Si) micromachining has been devised for fabricating wide-intermediate-frequency-band (wide-IF) superconductor/insulator/superconductor (SIS) mixer devices that result in suspended gold beam leads used for radio-frequency grounding. The mixers are formed on 25- m-thick silicon membranes. They are designed to operate in the 200 to 300 GHz frequency band, wherein wide-IF receivers for tropospheric- chemistry and astrophysical investigations are necessary. The fabrication process can be divided into three sections: 1. The front-side process, in which SIS devices with beam leads are formed on a SOI wafer; 2. The backside process, in which the SOI wafer is wax-mounted onto a carrier wafer, then thinned, then partitioned into individual devices; and 3. The release process, in which the individual devices are separated using a lithographic dicing technique. The total thickness of the starting 4-in. (10.16-cm)-diameter SOI wafer includes 25 m for the Si device layer, 0.5 m for the buried oxide (BOX) layer, and 350 m the for Si-handle layer. The front-side process begins with deposition of an etch-stop layer of SiO2 or AlN(x), followed by deposition of a Nb/Al- AlN(x) /Nb trilayer in a load-locked DC magnetron sputtering system. The lithography for four of a total of five layers is performed in a commercial wafer-stepping apparatus. Diagnostic test dies are patterned concurrently at certain locations on the wafer, alongside the mixer devices, using a different mask set. The conventional, self-aligned lift-off process is used to pattern the SIS devices up to the wire level

Seed availability and insect herbivory limit recruitment and adult density of native tall thistle

Understanding spatial and temporal variation in factors influencing plant regeneration is critical to predicting plant population growth. We experimentally evaluated seed limitation, insect herbivory, and their interaction in the regeneration and density of tall thistle (Cirsium altissimum) across a topographic ecosystem productivity gradient in tallgrass prairie over two years. On ridges and in valleys, we used a factorial experiment manipulating seed availability and insect herbivory to quantify effects of: seed input on seedling density, insect herbivory on juvenile density, and cumulative impacts of both seed input and herbivory on reproductive adult density. Seed addition increased seedling densities at three of five sites in 2006 and all five sites in 2007. Insect herbivory reduced seedling survival across all sites in both years, as well as rosette survival from the previous year’s seedlings. In both years, insecticide treatment of seed addition plots led to greater adult tall thistle densities in the following year, reflecting the increase in juvenile thistle densities in the experimental year. Seedling survival was not density dependent. Our analytical projection model predicts a significant long-term increase in adult densities from seed input, with a greater increase under experimentally reduced insect herbivory. While plant community biomass and water stress varied significantly between ridges and valleys, the effects of seed addition and insect herbivory did not vary with gradient position. These results support conceptual models that predict seedling and adult densities of short-lived monocarpic perennial plants should be seed limited. Further, the experiment demonstrates that even at high juvenile plant densities, at which density dependence potentially could have overridden herbivore effects on plant survival, insect herbivory strongly affected juvenile thistle performance and adult densities of this native prairie species

Childhood and adolescent factors shaping vulnerability to underage entry into sex work: a quantitative hierarchical analysis of female sex workers in Nairobi, Kenya

OBJECTIVE: To explore factors associated with early age at entry into sex work, among a cohort of female sex workers (FSWs) in Nairobi, Kenya. BACKGROUND: Younger age at sex work initiation increases the risk of HIV acquisition, condom non-use, violence victimisation and alcohol and/or substance use problems. This study aimed to understand factors in childhood and adolescence that shape the vulnerability to underage sex work initiation. DESIGN: Building on previous qualitative research with this cohort, analysis of behavioural-biological cross-sectional data using hierarchical logistic regression. PARTICIPANTS AND MEASURES: FSWs aged 18-45 years were randomly selected from seven Sex Workers Outreach Programme clinics in Nairobi, and between June and December 2019, completed a baseline behavioural-biological survey. Measurement tools included WHO Adverse Childhood Experiences, Alcohol, Smoking and Substance Involvement Screening Test and questionnaires on sociodemographic information, sexual risk behaviours and gender-based violence. Descriptive statistics and logistic regression were conducted using hierarchical modelling. RESULTS: Of the 1003 FSWs who participated in the baseline survey (response rate 96%), 176 (17.5%) initiated sex work while underage (<18 years). In the multivariable analysis, factors associated with entering sex work while underage included incomplete secondary school education (aOR=2.82; 95% CI=1.69 to 4.73), experiencing homelessness as a child (aOR=2.20; 95% CI=1.39 to 3.48), experiencing childhood physical or sexual violence (aOR=1.85; 95% CI=1.09 to 3.15), young age of sexual debut (≤15 years) (aOR=5.03; 95% CI=1.83 to 13.79) and being childless at time of sex work initiation (aOR=9.80; 95% CI=3.60 to 26.66). CONCLUSIONS: Lower education level and childhood homelessness, combined with sexual violence and sexual risk behaviours in childhood, create pathways to underage initiation into sex work. Interventions designed for girls and young women at these pivotal points in their lives could help prevent underage sex work initiation and their associated health, social and economic consequences

Enhanced Discrimination of Malignant from Benign Pancreatic Disease by Measuring the CA 19-9 Antigen on Specific Protein Carriers

The CA 19-9 assay detects a carbohydrate antigen on multiple protein carriers, some of which may be preferential carriers of the antigen in cancer. We tested the hypothesis that the measurement of the CA 19-9 antigen on individual proteins could improve performance over the standard CA 19-9 assay. We used antibody arrays to measure the levels of the CA 19-9 antigen on multiple proteins in serum or plasma samples from patients with pancreatic adenocarcinoma or pancreatitis. Sample sets from three different institutions were examined, comprising 531 individual samples. The measurement of the CA 19-9 antigen on any individual protein did not improve upon the performance of the standard CA 19-9 assay (82% sensitivity at 75% specificity for early-stage cancer), owing to diversity among patients in their CA 19-9 protein carriers. However, a subset of cancer patients with no elevation in the standard CA 19-9 assay showed elevations of the CA 19-9 antigen specifically on the proteins MUC5AC or MUC16 in all sample sets. By combining measurements of the standard CA 19-9 assay with detection of CA 19-9 on MUC5AC and MUC16, the sensitivity of cancer detection was improved relative to CA 19-9 alone in each sample set, achieving 67–80% sensitivity at 98% specificity. This finding demonstrates the value of measuring glycans on specific proteins for improving biomarker performance. Diagnostic tests with improved sensitivity for detecting pancreatic cancer could have important applications for improving the treatment and management of patients suffering from this disease