47 research outputs found
Translating the efficacy of dapagliflozin in chronic kidney disease to lower healthcare resource utilization and costs: a medical care cost offset analysis
No full textAims: Dapagliflozin was approved for use in patients with chronic kidney disease (CKD) based on results of the DAPA-CKD trial, demonstrating attenuation of CKD progression and reduced risk of cardio-renal outcomes and all-cause mortality (ACM) versus placebo, in addition to standard therapy. The study objective was to assess the potential medical care cost offsets associated with reduced rates of cardio-renal outcomes across 31 countries and regions.Materials and methods: A comparative cost-determination framework estimated outcome-related costs of dapagliflozin plus standard therapy versus standard therapy alone over a 3-year horizon based on the DAPA-CKD trial. Incidence rates of end-stage kidney disease (ESKD), hospitalizations for heart failure (HHF), acute kidney injury (AKI), and ACM were estimated for a treated population of 100,000 patients. Associated medical care costs for non-fatal events were calculated using sources from a review of publicly available data specific to each considered setting.Results: Patients treated with dapagliflozin plus standard therapy experienced fewer incidents of ESKD (7,221 vs 10,767; number needed to treat, NNT: 28), HHF (2,370 vs 4,684; NNT: 43), AKI (4,110 vs. 5,819; NNT: 58), and ACM (6,383 vs 8,874; NNT: 40) per 100,000 treated patients versus those treated with standard therapy alone. Across 31 countries/regions, reductions in clinical events were associated with a 33% reduction in total costs, or a cumulative mean medical care cost offset of $264 million per 100,000 patients over 3 years.Limitations and conclusions: This analysis is limited by the quality of country/region-specific data available for medical care event costs. Based on the DAPA-CKD trial, we show that treatment with dapagliflozin may prevent cardio-renal event incidence at the population level, which could have positive effects upon healthcare service delivery worldwide. The analysis was restricted to outcome-associated costs and did not consider the cost of drug treatments and disease management
Hydraulic simulations to evaluate and predict design and operation of the Chashma Right Bank Canal
No full textIrrigation systems / Irrigation canals / Flow control / Velocity / Canal regulation techniques / Hydraulics / Simulation models / Design / Operations / Crop-based irrigation / Distributary canals / Water delivery / Policy / Protective irrigation / Water allocation / Water requirements / Sedimentation / Water distribution / Equity / Water conveyance / Pakistan / Chashma Right Bank Canal
A Contemporary Study in the Theory of Traveling-Wave Tubes
No full textThe traveling-wave tube (TWT) is a widely used amplifier in satellite communications and radar. An electromagnetic signal is fed into one end of the device and is amplified over a distance until it is extracted downstream at the output. The physics behind this spatial amplification of an electromagnetic wave is predicated on the interaction of a linear DC electron beam with the surrounding circuit structure. J. R. Pierce, known as the “father of communications satellites,” was the first to formulate the theory for this beam-circuit interaction, which was since used in other electronic devices such as free-electron lasers, gyrotrons, and Smith-Purcell radiators. In this thesis, we extend the classic Pierce theory in two directions: harmonic generation and the effect of high beam current on both the beam mode and circuit mode.
The classical Pierce theory was formulated for a single (fundamental) frequency, same as the input signal. However, in a TWT with an octave bandwidth or greater, in particular the widely used helix TWT, the second harmonic of the input signal may also be within the amplification band and thus may also be generated and amplified. There is no input at this second harmonic frequency. An extension to the Pierce formulation that incorporates the generation of harmonics, including non-uniform taper, will be presented. We show that the second harmonic arises mostly from a newly discovered dynamic synchronous interaction instead of by the kinematic orbital crowding mechanism that is the most dominant harmonic generation mechanism in a klystron. The methodology provided may be applicable to the bi-frequency recirculating planar magnetron and other high-power microwave sources.
In beam-circuit interactions, the space-charge effect of the beam is important at high beam currents. In Pierce's TWT theory, this space-charge effect is modeled by the parameter which he called Q in the beam mode. A reliable determination of Q remains elusive for a realistic TWT. In this thesis, the author constructed the first exact small-signal theory of the beam-circuit interaction for the tape helix TWT, from which Q may be unambiguously determined. In the process of doing so, it was discovered that the circuit mode in Pierce's theory must also be modified at high beam current, an aspect overlooked in Pierce’s original analysis. We quantify this circuit mode modification by an entirely new parameter that we call q, introduced here for the first time in TWT theory. For the example using a realistic tape helix TWT, we find that the effect of q is equivalent to a modification of the circuit phase velocity by as much as two percent, which is a significant effect equivalent to a detune of two percent.
Lastly, we apply the theory developed for Q and q to a high-power TWT amplifier of current interest, the disk-on-rod TWT. For this configuration, the exact analytical forms of these parameters are extracted from the exact dispersion relation, which the author has also constructed. Comparisons of the numerical solutions to the analytic results to simulations done in ANSYS HFSS, ICEPIC, and MAGIC are made.PhDNuclear Engineering & Radiological SciencesUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/145994/1/pywong_1.pd
Renal Sympathetic Denervation System via Intraluminal Ultrasonic Ablation: Therapeutic Intravascular Ultrasound Design and Preclinical Evaluation
No full textPlasmapheresis-induced Clinical Improvement in a Patient with Steroid-Resistant Nephrotic Syndrome Due to Podocin (NPHS2) Gene Station
No full textPodocin mutations (NPHS2 gene) are mostly responsible for steroid-resistant nephrotic syndrome (SRNS) of childhood onset. Patients with NPHS2 gene mutations do not respond to corticoids and other immunosuppressive agents; partial remission can be rarely induced by cyclosporin A. We present a boy, where SRNS was diagnosed within first year of life. By the age of 15 years, proteinuria reached 9000 mg/24 h, cholesterolemia 15 mmol/L, albuminemia 19.6 g/L, in spite of combined therapy with cyclosporine A, methylprednisolone, enalapril and losartan. At that time a combined heterozygous form of two NPHS2 gene mutations (p.R138Q and p.V290M) was diagnosed, methylprednisolone was discontinued and patient underwent ten plasmapheresis procedures. This resulted in clinical improvement (proteinuria 3000 mg/24 h, S-cholesterol 6 mmol/L, albumin 30g/L) lasting for three years. In conclusion, plasmapheresis can result in clinical improvement and stabilization of SRNS caused by podocine mutation, before renal replacement therapy is initiated
Harnessing the eccrine sweat glands for the management of interdialytic weight gain – a pilot study
No full textHemodialysis patients are susceptible to excess volume accumulation, particularly over the 2-day interval (long interdialytic gap), resulting in higher interdialytic weight gain (IDWG). We thought to determine whether a novel device designed to enhance fluid and salt loss by activating the eccrine sweat glands can mitigate IDWG. Patients eligible for the study were undergoing regular hemodialysis for ≥3 months, without residual renal function, and with IDWG (as a percentage of IDWG/dry body weight) ≥2.5%. Treatments were administered at the patient’s home. The primary performance endpoint was differences in weight gain over long interdialytic period with the device compared to the control period. Secondary exploratory endpoints included the need for ultrafiltration (UF) rate > 10 mL/kg/h in the post-interval dialysis. Five patients were enrolled into the pilot study (age range 26 to 69 years, 3 women). The hourly mean weight loss from sweat was 186 ± 45 g/h. The average procedure length was 4.5 h with an average fluid loss of 899 ± 283 grams per procedure. The average least-squares mean absolute difference of IDWG between the control and treatment periods was −2.0%; (95% confidence interval [CI], −2.9% to −1.2%, p < 0001). The reduction in IDWG was associated a reduction in UF rates, from 9.23 ± 3.7 mL/kg/h to 5.55 ± 2.45 mL/kg/h between the control and treatment periods (p < 0.001), resulting in a safe UF rate (<10 mL/kg/h) in all post-treatment sessions. We conclude that enhancing sweat rate can mitigate IDWG in hemodialysis patients
Nonstationary statistical theory for multipactor
No full text[EN] This work presents a new and general approach to the real dynamics of the multipactor process: the nonstationary statistical multipactor theory. The nonstationary theory removes the stationarity assumption of the classical theory and, as a consequence, it is able to adequately model electron exponential growth as well as absorption processes, above and below the multipactor breakdown level. In addition, it considers both double-surface and single-surface interactions constituting a full framework for nonresonant polyphase multipactor analysis. This work formulates the new theory and validates it with numerical and experimental results with excellent agreement. (C) 2010 American Institute of Physics.The authors would like to thank ESA/ESTEC for having funded this research activity through the Contract "Study of High Order Modes and Fringing Fields in Multipactor Effect" (Contract No. 1-5918/08/NL/GLC) and to the Ministerio de Ciencia e Innovacion (Spain) for the support through the "Programa Torres Quevedo" Contract No. PTQ05-02-02759.Anza, S.; Vicente, C.; Gil, J.; Boria Esbert, VE.; Gimeno, B.; Raboso, D. (2010). Nonstationary statistical theory for multipactor. Physics of Plasmas. 17(6):1-11. https://doi.org/10.1063/1.3443128S111176Farnsworth, P. T. (1934). Television by electron image scanning. Journal of the Franklin Institute, 218(4), 411-444. doi:10.1016/s0016-0032(34)90415-4Starting potentials of high-frequency gas discharges at low pressure. (1948). Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences, 192(1030), 446-463. doi:10.1098/rspa.1948.0018Vaughan, J. R. M. (1988). Multipactor. 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Physics of Plasmas, 2(8), 3194-3213. doi:10.1063/1.871151Kishek, R. A., Lau, Y. Y., Ang, L. K., Valfells, A., & Gilgenbach, R. M. (1998). Multipactor discharge on metals and dielectrics: Historical review and recent theories. Physics of Plasmas, 5(5), 2120-2126. doi:10.1063/1.872883Gilardini, A. L. (1992). New breakdown modes of the multipacting discharge. Journal of Applied Physics, 71(9), 4629-4631. doi:10.1063/1.350767Kryazhev, A., Buyanova, M., Semenov, V., Anderson, D., Lisak, M., Puech, J., … Sombrin, J. (2002). Hybrid resonant modes of two-sided multipactor and transition to the polyphase regime. Physics of Plasmas, 9(11), 4736-4743. doi:10.1063/1.1514969Semenov, V. E., Rakova, E., Udiljak, R., Anderson, D., Lisak, M., & Puech, J. (2008). Conformal mapping analysis of multipactor breakdown in waveguide irises. Physics of Plasmas, 15(3), 033501. doi:10.1063/1.2884712Semenov, V. E., Rakova, E. I., Anderson, D., Lisak, M., & Puech, J. (2007). Multipactor in rectangular waveguides. 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(2005). Effect of emission velocity spread of secondary electrons in two-sided multipactor. Physics of Plasmas, 12(5), 053102. doi:10.1063/1.1881532Kossyi, I. A., Lukyanchikov, G. S., Semenov, V. E., Rakova, E. I., Anderson, D., Lisak, M., & Puech, J. (2008). Polyphase (non-resonant) multipactor in rectangular waveguides. Journal of Physics D: Applied Physics, 41(6), 065203. doi:10.1088/0022-3727/41/6/065203Vaughan, J. R. M. (1989). A new formula for secondary emission yield. IEEE Transactions on Electron Devices, 36(9), 1963-1967. doi:10.1109/16.34278C. Vicente, M. Mattes, D. Wolk, H. L. Hartnagel, J. R. Mosig, and D. Raboso, Proceedings of the 5th International Workshop on Multipactor, RF and DC Corona and Passive Intermodulation in Space RF Hardware (ESTEC, Noordwijk, The Netherlands, 2005), pp. 11–17.Gilardini, A. L. (1995). Multipacting discharges: Constant‐ktheory and simulation results. Journal of Applied Physics, 78(2), 783-795. doi:10.1063/1.360336A. 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Anemia and iron deficiency in COPD patients: prevalence and the effects of correction of the anemia with erythropoiesis stimulating agents and intravenous iron
No full textCare of undocumented-uninsured immigrants in a large urban dialysis unit
No full textAbstract Background: Medical, ethical and financial dilemmas may arise in treating undocumented-uninsured patients with end-stage renal disease (ESRD). Hereby we describe the 10-year experience of treating undocumented-uninsured ESRD patients in a large public dialysis-unit
When the chimney is blocked: malignant renovascular hypertension after endovascular repair of abdominal aortic aneurysm
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