Laboratory evaluation and application of microwave absorption properties under simulated conditions for planetary atmospheres

The recognition of the need to make laboratory measurements of simulated planetary atmospheres over a range of temperatures and pressure which correspond to the altitudes probed by radio occultation experiments, and over a range of frequencies which correspond to both radio occultation experiments and radio astronomical observations, has led to the development of a facility at Georgia Tech which is capable of making such measurements. Construction was completed of the outer planets simulator and measurements were conducted of the microwave absorption and refraction from nitrogen under simulated Titan conditions. The results of these and previous laboratory measurements were applied to a wide range of microwave opacity measurements, in order to derive constituent densities and distributions in planetary atmospheres such as Venus

Laboratory evaluation of microwave absorption properties under simulated conditions for planetary atmospheres

The microwave absorbing properties of gaseous sulfuric acid (H2SO4) under Venus atmospheric conditions are investigated. The results are applied to measurements from Mariner 5, Mariner 10, and Pioneer/Venus Radio Occultation experiments, to determine abundancies of gaseous sulfuric acid in the Venus atmosphere. The microwave properties of the vapors accompanying liquid H2SO4 are studied to estimate the vapor pressure in an atmospheric model

Long-term variations in abundance and distribution of sulfuric acid vapor in the Venus atmosphere inferred from Pioneer Venus and Magellan radio occultation studies

Radio occultation experiments have been used to study various properties of planetary atmospheres, including pressure and temperature profiles, and the abundance profiles of absorbing constituents in those planetary atmospheres. However, the reduction of amplitude data from such experiments to determine abundance profiles requires the application of the inverse Abel transform (IAT) and numerical differentiation of experimental data. These two operations preferentially amplify measurement errors above the true signal underlying the data. A new technique for processing radio occultation data has been developed that greatly reduces the errors in the derived absorptivity and abundance profiles. This technique has been applied to datasets acquired from Pioneer Venus Orbiter radio occultation studies and more recently to experiments conducted with the Magellan spacecraft. While primarily designed for radar studies of the Venus surface, the high radiated power (EIRP) from the Magellan spacecraft makes it an ideal transmitter for measuring the refractivity and absorptivity of the Venus atmosphere by such experiments. The longevity of the Pioneer Venus Orbiter has made it possible to study long-term changes in the abundance and distribution of sulfuric acid vapor, H2SO4(g), in the Venus atmosphere between 1979 and 1992. The abundance of H2SO4(g) can be inferred from vertical profiles of 13-cm absorptivity profiles retrieved from radio occultation experiments. Data from 1979 and 1986-87 suggest that the abundance of H2SO4(g) at latitudes northward of 70 deg decreased over this time period. This change may be due to a period of active volcanism in the late 1970s followed by a relative quiescent period, or some other dynamic process in the Venus atmosphere. While the cause is not certain, such changes must be incorporated into dynamic models of the Venus atmosphere. Potentially, the Magellan spacecraft will extend the results of Pioneer Venus Orbiter and allow the continued monitoring of the abundance of distribution of H2SO4(g) in the Venus atmosphere, as well as other interesting atmospheric properties. Without such measurements it will be difficult to address other issues such as the short-term spatial variability of the abundance of H2SO4(g) at similar latitudes in Venus atmosphere, and the identities of particles responsible for large-scale variations observed in NIR images

Measuring the use of human resources practices and employee attitudes: the linked personnel panel

This paper introduces a new data source available for HRM researchers and personnel economists, the Linked Personnel Panel (LPP). The LPP is a longitudinal and representative employer-employee data set designed for quantitative empirical HR research. The LPP offers a unique structure. First, the data set combines employer and employee surveys that can be matched to each other. Second, it can also be linked to a number of additional administrative data sets. Third, the LPP covers a wide range of firms and workers from different backgrounds. Finally, because of its longitudinal dimension, the LPP should facilitate the study of causal effects of HR practices. The LPP employee survey uses a number of established scales to measure job characteristics, personal characteristics, and employee attitudes. This paper gives an overview of both the employer and employee survey and additionally outlines the definitions, origins and statistical properties of the items used in the individual questionnaire

Disparity Outcomes in Patients Undergoing Pancreas Surgery at an Urban Tertiary Care Center

INTRODUCTION: Previous studies have shown significant disparities in pancreas cancer outcomes in African American (AA) compared to non-AA patients. Pancreas surgery continues to be associated with significant morbidity, however, there is little reported data on pancreas surgical outcomes by race. We sought to evaluate how race would affect surgical outcomes in an urban tertiary care center for patients undergoing pancreas surgery. METHODS: A retrospective single-center analysis of patients undergoing pancreas surgery between January 2013 and September 2021 was performed. Patient demographics and post-surgical complications were collected and stratified by race. Area Deprivation Index (ADI) was used to determine patient socioeconomic status. Charlson Comorbidity Index (CCI) was calculated for comorbidities. Clavien-Dindo (CD) complications, as well as postoperative pancreatic fistula (POPF), delayed gastric emptying (DGE) and postpancreatectomy hemorrhage (PPH) were evaluated. Patient reoperation, readmission, and mortality in the 30- and 90- day period were collected and univariate and multivariate analyses were performed. RESULTS: Among 461 patients, 82% (N = 378) were nonAA and 18% (N = 83) were AA. Age and sex were found to be significantly different between the two groups, while ADI and CCI were not. Length of stay (LOS), POPF, PPH, PPH grade C and intra-abdominal abscess (IAA) were found to be significant on univariate analysis in the AA cohort. On multivariate analysis, LOS (OR 4.0; 95% CI 2.0-5.7; p \u3c 0.001), POPF (OR 0.6; 95% CI 0.4-1.0; p = 0.043), PPH (OR 0.5; 95% CI 0.2-0.9; p = 0.022), PPH grade C (OR 0.2; 95% CI 0.1-0.7; p = 0.017) and IAA (OR 0.4; 95% CI 0.2-0.9; p = 0.017) were still significantly higher in the AA cohort. CONCLUSIONS: AA patients undergoing pancreas surgery were noted to have a longer LOS, higher incidence of POPF, PPH and IAA compared to non-AA patients. However, no significant difference was seen in reoperation rates, major CD complications, or 30- and 90-day readmission. Elucidating patient selection, tumor biology, and preoperative treatment algorithms may shed additional insight on the differences in surgical outcomes in this particular patient cohort

Radio Occultation Measurements of Europa's Ionosphere From Juno's Close Flyby

On 29 September 2022 the Juno spacecraft flew within 354 km of Europa's surface while several instruments probed the moon's surroundings. During the close flyby, radio occultations were performed by collecting single-frequency Doppler measurements. These investigations are essential to the study of Europa's ionosphere and represent the first repeat sampling of any set of conditions since the Galileo era. Ingress measurements resulted in a marginal detection with a peak ionospheric density of 4,000 ± 3,700 cm−3 (3σ) at 22 km altitude. A more significant detection emerged on egress, with a peak density of 6,000 ± 3,000 cm−3 (3σ) at 320 km altitude. Comparison with Galileo measurements reveals a consistent picture of Europa's ionosphere, and confirms its dependence on illumination conditions and position within Jupiter's magnetosphere. However, the overall lower densities measured by Juno suggest a dependence on time of observation, with implications for the structure of the neutral atmosphere

Ritonavir blocks AKT signaling, activates apoptosis and inhibits migration and invasion in ovarian cancer cells

<p>Abstract</p> <p>Background</p> <p>Ovarian cancer is the leading cause of mortality from gynecological malignancies, often undetectable in early stages. The difficulty of detecting the disease in its early stages and the propensity of ovarian cancer cells to develop resistance to known chemotherapeutic treatments dramatically decreases the 5-year survival rate. Chemotherapy with paclitaxel after surgery increases median survival only by 2 to 3 years in stage IV disease highlights the need for more effective drugs. The human immunodeficiency virus (HIV) infection is characterized by increased risk of several solid tumors due to its inherent nature of weakening of immune system. Recent observations point to a lower incidence of some cancers in patients treated with protease inhibitor (PI) cocktail treatment known as HAART (Highly Active Anti-Retroviral Therapy).</p> <p>Results</p> <p>Here we show that ritonavir, a HIV protease inhibitor effectively induced cell cycle arrest and apoptosis in ovarian cell lines MDH-2774 and SKOV-3 in a dose dependent manner. Over a 3 day period with 20 μM ritonavir resulted in the cell death of over 60% for MDAH-2774 compared with 55% in case of SKOV-3 cell line. Ritonavir caused G1 cell cycle arrest of the ovarian cancer cells, mediated by down modulating levels of RB phosphorylation and depleting the G1 cyclins, cyclin-dependent kinase and increasing their inhibitors as determined by gene profile analysis. Interestingly, the treatment of ritonavir decreased the amount of phosphorylated AKT in a dose-dependent manner. Furthermore, inhibition of AKT by specific siRNA synergistically increased the efficacy of the ritonavir-induced apoptosis. These results indicate that the addition of the AKT inhibitor may increase the therapeutic efficacy of ritonavir.</p> <p>Conclusion</p> <p>Our results demonstrate a potential use of ritonavir for ovarian cancer with additive effects in conjunction with conventional chemotherapeutic regimens. Since ritonavir is clinically approved for human use for HIV, drug repositioning for ovarian cancer could accelerate the process of traditional drug development. This would reduce risks, limit the costs and decrease the time needed to bring the drug from bench to bedside.</p

Quality Control Measures over 30 Years in a Multicenter Clinical Study: Results from the Diabetes Control and Complications Trial / Epidemiology of Diabetes Interventions and Complications (DCCT/EDIC) Study.

Implementation of multicenter and/or longitudinal studies requires an effective quality assurance program to identify trends, data inconsistencies and process variability of results over time. The Diabetes Control and Complications Trial (DCCT) and the follow-up Epidemiology of Diabetes Interventions and Complications (EDIC) study represent over 30 years of data collection among a cohort of participants across 27 clinical centers. The quality assurance plan is overseen by the Data Coordinating Center and is implemented across the clinical centers and central reading units. Each central unit incorporates specific DCCT/EDIC quality monitoring activities into their routine quality assurance plan. The results are reviewed by a data quality assurance committee whose function is to identify variances in quality that may impact study results from the central units as well as within and across clinical centers, and to recommend implementation of corrective procedures when necessary. Over the 30-year period, changes to the methods, equipment, or clinical procedures have been required to keep procedures current and ensure continued collection of scientifically valid and clinically relevant results. Pilot testing to compare historic processes with contemporary alternatives is performed and comparability is validated prior to incorporation of new procedures into the study. Details of the quality assurance plan across and within the clinical and central reading units are described, and quality outcomes for core measures analyzed by the central reading units (e.g. biochemical samples, fundus photographs, ECGs) are presented