Thoughts and Progress

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75183/1/j.1525-1594.1999.06248.x.pd

Photon noise from chaotic and coherent millimeter-wave sources measured with horn-coupled, aluminum lumped-element kinetic inductance detectors

We report photon-noise limited performance of horn-coupled, aluminum lumped-element kinetic inductance detectors at millimeter wavelengths. The detectors are illuminated by a millimeter-wave source that uses an active multiplier chain to produce radiation between 140 and 160 GHz. We feed the multiplier with either amplified broadband noise or a continuous-wave tone from a microwave signal generator. We demonstrate that the detector response over a 40 dB range of source power is well-described by a simple model that considers the number of quasiparticles. The detector noise-equivalent power (NEP) is dominated by photonnoise when the absorbed power is greater than approximately 1 pW, which corresponds to NEP ≈ 2×10^(−17) W Hz^(−1/2), referenced to absorbed power. At higher source power levels, we observe the relationships between noise and power expected from the photon statistics of the source signal: NEP∝P for broadband (chaotic) illumination and NEP∝P^(1/2) for continuous-wave (coherent) illumination

International practice patterns and factors associated with non-conventional hemodialysis utilization

<p>Abstract</p> <p>Background</p> <p>The purpose of our study was to determine characteristics that influence the utilization of non-conventional hemodialysis (NCHD) therapies and its subtypes (nocturnal (NHD), short daily (SDHD), long conventional (LCHD) and conventional hemodialysis (CHD) as well as provider attitudes regarding the evidence for NCHD use.</p> <p>Methods</p> <p>An international cohort of subscribers of a nephrology education website <url>http://www.nephrologynow.com</url> was invited to participate in an online survey. Non-conventional hemodialysis was defined as any forms of hemodialysis delivered > 3 treatments per week and/or > 4 hours per session. NHD and SDHD included both home and in-centre. Respondents were categorized as CHD if their centre only offered conventional thrice weekly hemodialysis. Variables associated with NCHD and its subtypes were determined using multivariate logistic regression analysis. The survey assessed multiple domains regarding NCHD including reasons for initiating and discontinuing, for not offering and attitudes regarding evidence.</p> <p>Results</p> <p>544 surveys were completed leading to a 15.6% response rate. The final cohort was limited to 311 physicians. Dialysis modalities utilized among the respondents were as follows: NCHD194 (62.4%), NHD 83 (26.7%), SDHD 107 (34.4%), LCHD 81 (26%) and CHD 117 (37.6%). The geographic regions of participants were as follows: 11.9% Canada, 26.7% USA, 21.5% Europe, 6.1% Australia/New Zealand, 10% Africa/Middle East, 10.9% Asia and 12.9% South America. Variables associated with NCHD utilization included NCHD training (OR 2.47 CI 1.25-4.16), government physician reimbursement (OR 2.66, CI 1.11-6.40), practicing at an academic centre (OR 2.28 CI 1.25-4.16), higher national health care expenditure and number of ESRD patients per centre. Hemodialysis providers with patients on NCHD were significantly more likely to agree with the statements that NCHD improves quality of life, improves nutritional status, reduces EPO requirements and is cost effective. The most common reasons to initiate NCHD were driven by patient preference and the desire to improve volume control and global health outcomes.</p> <p>Conclusion</p> <p>Physician attitudes toward the evidence for NCHD differ significantly between NCHD providers and conventional HD providers. Interventions and health policy targeting these areas along with increased physician education and training in NCHD modalities may be effective in increasing its utilization.</p

PMC-Turbo: a balloon-borne Mission to image gravity waves and turbulence in polar mesospheric clouds

PMC-Turbo is a balloon-borne experiment that will fly at an altitude between 35 and 40 km. It is designed to record gravity wave events in polar mesospheric clouds with high spatial and temporal resolution as they unfold across a large field of the sky. The project is motivated by the serendipitous observation of PMCs during the balloon flight of EBEX, an observational cosmology experiment which flew in 2013 at an altitude of about 35 km. EBEX included two star cameras, each of which had a field of view of 4 by 3 degrees, a resolution of 2.5 m at 80 km altitude, and an image cadence of 30 seconds. Even though EBEX was not designed to observe PMCs, instability and turbulent structures were visible with features at scales down to 20 m in the star camera images. However, it is difficult to put the images in context due to the inconsistent pointing, slow image cadence, and the narrow field of view. PMC-Turbo was designed leverage the strengths of the EBEX star cameras to observe gravity wave events at various length scales. This requires capturing a wide view while remaining sensitive to small features, as well as recording images at a high cadence. It carries seven cameras, four of which are wide field cameras that together cover a field of view of about 150 by 40 degrees with an 8 m per pixel resolution. Cameras with narrow field lenses provide smaller fields of view of 10 by 15 degrees with about 3 m per pixel resolution and are situated within in the larger field of view. The cameras can sustain 3.5 frames per second and can capture bursts of images up to 8 frames per second. The payload also carries BOLIDE, a Rayleigh lidar from the DLR Institute of Atmospheric Physics and an airglow camera from Utah State University. These instruments will provide additional context to observed events in the form of thermal profiles and infrared mapping. The Balloon Lidar Experiment BOLIDE is a miniaturized Rayleigh backscatter lidar developed for PMC-Turbo that will provide observations of PMC with unprecedented resolution and signal to noise ratio. PMC-Turbo is scheduled to fly next year from either Sweden or Antarctica. We anticipate a fourteen day flight over Antarctica, and we expect to capture about 14 million images. An arctic flight would last around 5 days, but we anticipate several gravity wave events during this time. In addition to lab testing of our equipment, we have had opportunities to collect data with the PMC-Turbo instruments in the field. This December we will fly one camera as a piggyback on the Super Tiger payload from Antarctica. In July, we used several cameras on the ground to capture PMC images in High Level, Alberta. We hope to resolve tomography from the images captured during that campaign. If we fly from Sweden, we plan to coordinate ground-based tomographic imaging with the balloon flight

Infusion fluids contain harmful glucose degradation products

PURPOSE: Glucose degradation products (GDPs) are precursors of advanced glycation end products (AGEs) that cause cellular damage and inflammation. We examined the content of GDPs in commercially available glucose-containing infusion fluids and investigated whether GDPs are found in patients' blood. METHODS: The content of GDPs was examined in infusion fluids by high-performance liquid chromatography (HPLC) analysis. To investigate whether GDPs also are found in patients, we included 11 patients who received glucose fluids (standard group) during and after their surgery and 11 control patients receiving buffered saline (control group). Blood samples were analyzed for GDP content and carboxymethyllysine (CML), as a measure of AGE formation. The influence of heat-sterilized fluids on cell viability and cell function upon infection was investigated. RESULTS: All investigated fluids contained high concentrations of GDPs, such as 3-deoxyglucosone (3-DG). Serum concentration of 3-DG increased rapidly by a factor of eight in patients receiving standard therapy. Serum CML levels increased significantly and showed linear correlation with the amount of infused 3-DG. There was no increase in serum 3-DG or CML concentrations in the control group. The concentration of GDPs in most of the tested fluids damaged neutrophils, reducing their cytokine secretion, and inhibited microbial killing. CONCLUSIONS: These findings indicate that normal standard fluid therapy involves unwanted infusion of GDPs. Reduction of the content of GDPs in commonly used infusion fluids may improve cell function, and possibly also organ function, in intensive-care patients

Doctor can I buy a new kidney? I've heard it isn't forbidden: what is the role of the nephrologist when dealing with a patient who wants to buy a kidney?

Organ trafficking is officially banned in several countries and by the main Nephrology Societies. However, this practice is widespread and is allowed or tolerated in many countries, hence, in the absence of a universal law, the caregiver may be asked for advice, placing him/her in a difficult balance between legal aspects, moral principles and ethical judgments. In spite of the Istanbul declaration, which is a widely shared position statement against organ trafficking, the controversy on mercenary organ donation is still open and some experts argue against taking a negative stance. In the absence of clear evidence showing the clinical disadvantages of mercenary transplantation compared to chronic dialysis, self-determination of the patient (and, with several caveats, of the donor) may conflict with other ethical principles, first of all non-maleficence. The present paper was drawn up with the participation of the students, as part of the ethics course at our medical school. It discusses the situation in which the physician acts as a counselor for the patient in the way of a sort of “reverse” informed consent, in which the patient asks advice regarding a complex personal decision, and includes a peculiar application of the four principles (beneficence, non-maleficence, justice and autonomy) to the donor and recipient parties