54 research outputs found
Fibers and Conductive Films Using Silver Nanoparticles and Nanowires by Near-Field Electrospinning Process
The silver nanowires (AgNWs) and silver nanoparticles (AgNPs) were synthesized. With near-field electrospinning (NFES) process, fibers and thin films with AgNPs and AgNWs were fabricated. In the NFES process, 10 k voltage was applied and the AgNPs and AgNWs fibers can be directly orderly collected without breaking and bending. Then, the characteristics of the fibers were analyzed by four-point probe and EDS. The conductive film was analyzed. When the thickness of films with AgNWs and AgNPs was 1.6 µm, the sheet resistance of films was 0.032 Ω/sq which was superior to that of the commercial ITO. The transmissivity of films was analyzed. The transmissivity was inversely proportional to sheet resistance of the films. In the future, the fibers and films can be used as transparent conductive electrodes
What controls star formation in the central 500 pc of the Galaxy?
The star formation rate (SFR) in the Central Molecular Zone (CMZ, i.e. the central 500 pc) of the Milky Way is lower by a factor of ≥10 than expected for the substantial amount of dense gas it contains, which challenges current star formation theories. In this paper, we quantify which physical mechanisms could be responsible. On scales larger than the disc scaleheight, the low SFR is found to be consistent with episodic star formation due to secular instabilities or possibly variations of the gas inflow along the Galactic bar. The CMZ is marginally Toomre-stable when including gas and stars, but highly Toomre-stable when only accounting for the gas, indicating a low condensation rate of self-gravitating clouds. On small scales, we find that the SFR in the CMZ may be caused by an elevated critical density for star formation due to the high turbulent pressure. The existence of a universal density threshold for star formation is ruled out. The H I–H2 phase transition of hydrogen, the tidal field, a possible underproduction of massive stars due to a bottom-heavy initial mass function, magnetic fields, and cosmic ray or radiation pressure feedback also cannot individually explain the low SFR. We propose a self-consistent cycle of star formation in the CMZ, in which the effects of several different processes combine to inhibit star formation. The rate-limiting factor is the slow evolution of the gas towards collapse – once star formation is initiated it proceeds at a normal rate. The ubiquity of star formation inhibitors suggests that a lowered central SFR should be a common phenomenon in other galaxies. We discuss the implications for galactic-scale star formation and supermassive black hole growth, and relate our results to the star formation conditions in other extreme environments
Discordant identification of pediatric severe sepsis by research and clinical definitions in the SPROUT international point prevalence study
Introduction: Consensus criteria for pediatric severe sepsis have standardized enrollment for research studies. However, the extent to which critically ill children identified by consensus criteria reflect physician diagnosis of severe sepsis, which underlies external validity for pediatric sepsis research, is not known. We sought to determine the agreement between physician diagnosis and consensus criteria to identify pediatric patients with severe sepsis across a network of international pediatric intensive care units (PICUs). Methods: We conducted a point prevalence study involving 128 PICUs in 26 countries across 6 continents. Over the course of 5 study days, 6925 PICU patients <18 years of age were screened, and 706 with severe sepsis defined either by physician diagnosis or on the basis of 2005 International Pediatric Sepsis Consensus Conference consensus criteria were enrolled. The primary endpoint was agreement of pediatric severe sepsis between physician diagnosis and consensus criteria as measured using Cohen's ?. Secondary endpoints included characteristics and clinical outcomes for patients identified using physician diagnosis versus consensus criteria. Results: Of the 706 patients, 301 (42.6 %) met both definitions. The inter-rater agreement (? ± SE) between physician diagnosis and consensus criteria was 0.57 ± 0.02. Of the 438 patients with a physician's diagnosis of severe sepsis, only 69 % (301 of 438) would have been eligible to participate in a clinical trial of pediatric severe sepsis that enrolled patients based on consensus criteria. Patients with physician-diagnosed severe sepsis who did not meet consensus criteria were younger and had lower severity of illness and lower PICU mortality than those meeting consensus criteria or both definitions. After controlling for age, severity of illness, number of comorbid conditions, and treatment in developed versus resource-limited regions, patients identified with severe sepsis by physician diagnosis alone or by consensus criteria alone did not have PICU mortality significantly different from that of patients identified by both physician diagnosis and consensus criteria. Conclusions: Physician diagnosis of pediatric severe sepsis achieved only moderate agreement with consensus criteria, with physicians diagnosing severe sepsis more broadly. Consequently, the results of a research study based on consensus criteria may have limited generalizability to nearly one-third of PICU patients diagnosed with severe sepsis
Design and Stress Analysis of Screw Shaft for Peanut Oil Screw Press Expeller
The screw press oil expellers are reported to be more efficient than all other methods of oil extraction. The oil seeds fed through the hopper are crushed and transported by a rotating screw in a press barrel. Continuous transport of material by the screw shaft causes the pressure to increase to a level needed, which increases the friction inside the screw press and generates heat which lowers viscosity of the oil in the crushed seeds thereby increasing the oil flow rate. The oil and cake are usually collected at the oil outlet and press cake exit.               Screw shaft is the main component of the oil extraction machine. Existing screw press oil expeller is the JY 200 machine with 220W motor power and 1500rpm. The von-Mises stress of existing screw design is 94.11 MPa and the modified screw design is 89.876 MPa for theoretical. In this research, the modified screw design is considered in order to improve the oil capacity, the efficiency and number of cycles to failure and then to reduce the von-Mises stress, deformation and fatigue stress of automatic oil press machine by changing the pitch of screw shaft for peanut oil screw press expeller. Peanut oil screw press expeller is easy to repair and easy to maintenance. This machine is very suitable for local production and operation
Persistence of High Health Care Costs among VA Patients
ObjectivesTo examine high-cost patients in VA and factors associated with persistence in high costs over time.Data sourcesSecondary data for FY2008-2012.Data extractionWe obtained VA and Medicare utilization and cost records for VA enrollees and drew a 20 percent random sample (N = 1,028,568).Study designWe identified high-cost patients, defined as those in the top 10 percent of combined VA and Medicare costs, and determined the number of years they remained high cost over 4 years. We compared sociodemographics, clinical characteristics, and baseline utilization by number of high-cost years and conducted a discrete time survival analysis to predict high-cost persistence.Principal findingsAmong 105,703 patients with the highest 10 percent of costs at baseline, 68 percent did not remain high cost in subsequent years, 32 percent had high costs after 1 year, and 7 percent had high costs in all four follow-up years. Mortality, which was 47 percent by end of follow-up, largely explained low persistence. The largest percentage of patients who persisted as high cost until end of follow-up was for spinal cord injury (16 percent).ConclusionMost high-cost patients did not remain high cost in subsequent years, which poses challenges to providers and payers to manage utilization of these patients
At-Home Versus In-Clinic INR Monitoring: A Cost-Utility Analysis from The Home INR Study (THINRS).
BackgroundEffective management of patients using warfarin is resource-intensive, requiring frequent in-clinic testing of the international normalized ratio (INR). Patient self-testing (PST) using portable at-home INR monitoring devices has emerged as a convenient alternative. As revealed by The Home INR Study (THINRS), event rates for PST were not significantly different from those for in-clinic high-quality anticoagulation management (HQACM), and a cumulative gain in quality of life was observed for patients undergoing PST.ObjectiveTo perform a cost-utility analysis of weekly PST versus monthly HQACM and to examine the sensitivity of these results to testing frequency.Patients/interventionsIn this study, 2922 patients taking warfarin for atrial fibrillation or mechanical heart valve, and who demonstrated PST competence, were randomized to either weekly PST (n = 1465) or monthly in-clinic testing (n = 1457). In a sub-study, 234 additional patients were randomized to PST once every 4 weeks (n = 116) or PST twice weekly (n = 118). The endpoints were quality of life (measured by the Health Utilities Index), health care utilization, and costs over 2 years of follow-up.ResultsPST and HQACM participants were similar with regard to gender, age, and CHADS2 score. The total cost per patient over 2 years of follow-up was 33,460 for weekly PST, representing a difference of 5566 (95 % CI, -25,142). The incremental cost-effectiveness ratio (ICER) was sensitive to testing frequency: weekly PST dominated PST twice weekly and once every 4 weeks. Compared to HQACM, weekly PST was associated with statistically significant and clinically meaningful improvements in quality of life. The ICER for weekly PST versus HQACM was well within accepted standards for cost-effectiveness, and was preferred over more or less frequent PST. These results were robust to sensitivity analyses of key assumptions.ConclusionWeekly PST is a cost-effective alternative to monthly HQACM and a preferred testing frequency compared to twice weekly or monthly PST
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