Future mission studies: Forecasting solar flux directly from its chaotic time series

The mathematical structure of the programs written to construct a nonlinear predictive model to forecast solar flux directly from its time series without reference to any underlying solar physics is presented. This method and the programs are written so that one could apply the same technique to forecast other chaotic time series, such as geomagnetic data, attitude and orbit data, and even financial indexes and stock market data. Perhaps the most important application of this technique to flight dynamics is to model Goddard Trajectory Determination System (GTDS) output of residues between observed position of spacecraft and calculated position with no drag (drag flag = off). This would result in a new model of drag working directly from observed data

Nonlinear techniques for forecasting solar activity directly from its time series

This paper presents numerical techniques for constructing nonlinear predictive models to forecast solar flux directly from its time series. This approach makes it possible to extract dynamical in variants of our system without reference to any underlying solar physics. We consider the dynamical evolution of solar activity in a reconstructed phase space that captures the attractor (strange), give a procedure for constructing a predictor of future solar activity, and discuss extraction of dynamical invariants such as Lyapunov exponents and attractor dimension

Future mission studies: Preliminary comparisons of solar flux models

The results of comparisons of the solar flux models are presented. (The wavelength lambda = 10.7 cm radio flux is the best indicator of the strength of the ionizing radiations such as solar ultraviolet and x-ray emissions that directly affect the atmospheric density thereby changing the orbit lifetime of satellites. Thus, accurate forecasting of solar flux F sub 10.7 is crucial for orbit determination of spacecrafts.) The measured solar flux recorded by National Oceanic and Atmospheric Administration (NOAA) is compared against the forecasts made by Schatten, MSFC, and NOAA itself. The possibility of a combined linear, unbiased minimum-variance estimation that properly combines all three models into one that minimizes the variance is also discussed. All the physics inherent in each model are combined. This is considered to be the dead-end statistical approach to solar flux forecasting before any nonlinear chaotic approach

Future missions studies: Combining Schatten's solar activity prediction model with a chaotic prediction model

K. Schatten (1991) recently developed a method for combining his prediction model with our chaotic model. The philosophy behind this combined model and his method of combination is explained. Because the Schatten solar prediction model (KS) uses a dynamo to mimic solar dynamics, accurate prediction is limited to long-term solar behavior (10 to 20 years). The Chaotic prediction model (SA) uses the recently developed techniques of nonlinear dynamics to predict solar activity. It can be used to predict activity only up to the horizon. In theory, the chaotic prediction should be several orders of magnitude better than statistical predictions up to that horizon; beyond the horizon, chaotic predictions would theoretically be just as good as statistical predictions. Therefore, chaos theory puts a fundamental limit on predictability

Changes in consumer purchasing behavior due to COVID-19 pandemic

Due to the COVID-19 pandemic, the world is facing historical challenges without prior preparation. Because of the unavoidable economic crisis for the shutdown of numerous trade and industrial activities the COVID-19 pandemic has triggered substantial modifications in the habits of consumers all over the world. The pandemic has led to key changes in consumers purchasing and consumption behavior as the result of lockdown, social distancing, and uncertainty about the future due to its infectious nature. This study investigated the impact of the pandemic outbreak on consumers’ purchasing and consumption behavior in a developing country such as Bangladesh. An online survey was conducted for collecting data about the changes in buying behavior through a structured questionnaire. The research targeted 200 respondents belonging to different age-gender segments, qualifications & occupations, and household monthly income. The 191 completed responses had received and analyzed among 200 distributed structured questionnaires. The Partial Least Squares (PLS-SEM) method was applied, with the Smart PLS software v.3.3.2 for analyzing the proposed theoretical model and to test the developed hypotheses. The outcomes of the research strongly indicate that the health and safety concern, imposed restrictions, financial condition, surrounding environment-people, and other realities caused a remarkable change in consumer buying behavior. The outcomes of this study provide significant guidance to policy interventions, marketing decisions, and strategies for doing business as usual during and after the pandemic and perhaps add to the understanding of this unprecedented and ongoing phenomenon

The Wiener, Eccentric Connectivity and Zagreb Indices of the Hierarchical Product of Graphs

Let G1 = (V1, E1) and G2 = (V2, E2) be two graphs having a distinguished or root vertex, labeled 0. The hierarchical product G2 ⊓ G1 of G2 and G1 is a graph with vertex set V2 × V1. Two vertices y2y1 and x2x1 are adjacent if and only if y1x1 ∈ E1 and y2 = x2; or y2x2 ∈ E2 and y1 = x1 = 0. In this paper, the Wiener, eccentric connectivity and Zagreb indices of this new operation of graphs are computed. As an application, these topological indices for a class of alkanes are computed. ACM Computing Classification System (1998): G.2.2, G.2.3.The research of this paper is partially supported by the University of Kashan under grant no 159020/12

Use of Α-Interferon, Amantadin and Isoprinosine in Subacute Sclerosing Panencephalitis (Sspe): Comparing the Effectiveness

ObjectiveSub acute Sclerosing Pan Encephalitis (SSPE), a progressive neurological disorder characterized by inflammation of the brain (encephalitis), is the result of an inappropriate immune response to the measles virus or measles vaccination.SSPE usually develops 2 to 10 years after the original viral attack. Some of the major signs and symptoms are mental deterioration, jerky movements, and seizures specially myoclonic type, involuntary movements, and/or behavioral changes, difficulty in walking, speech, and loss of cognition, respiratory distress and death.Materials and MethodsDuring the ten years, from July 1991 to July 2001, we admitted 45 cases of (SSPE), at different stages of the disorder. Regardless of their stage of disease, for intervention, randomly, we used one of three drugs; Amantadin, Interferon alfa and Isoprinosine, administered to the patients, for between one month to one year. Fourteen cases received Amantadin, 15 Alfa interferon, and 16 were given Isoprinosine.ResultsWhile the results show all three drugs to be relatively effective, Isoprinosine showed four times more effectiveness than Amantadin and twice as much as Interferon.ConclusionThe results showed Isoprinosine to be much more effective than Amantadin and Alfa interferon in treating the condition

Incidentally detected stenoses proximal to grafts originating below the common femoral artery: Do they affect graft patency or warrant repair in asymptomatic patients?

AbstractObjective: Stenoses in infrainguinal arteries proximal to a lower extremity vein graft may reduce flow velocity through the bypass graft and are thought to predispose to graft occlusion. Repair of these lesions has been recommended to preserve graft function. This study was undertaken to better define the natural history of grafts below inflow lesions and to evaluate the necessity of repair to preserve graft patency. Methods: From 1994 through 1999, patients undergoing lower extremity vein grafts by a single surgeon at a university hospital and an affiliated teaching hospital were placed in a prospective protocol for proximal infrainguinal native artery and graft surveillance through use of duplex scanning. The records of those patients with grafts originating distal to the common femoral artery were evaluated; they form the basis for this report. Arteriograms were obtained before bypass grafting, and no patient had a stenosis greater than 50% diameter reduction proximal to the graft origin. Follow-up scans were obtained from the common femoral artery through the graft and outflow artery. The peak systolic velocity and velocity ratio in an infrainguinal native artery proximal to the graft origin were recorded, as were the location and the time interval since the bypass graft. Repair of these proximal lesions was not performed during the course of this study. Revision of the bypass graft or its anastomoses was undertaken according to preestablished duplex scan criteria. Results: During this time, 288 autogenous infrainguinal bypass grafts were performed, of which 159 originated below the common femoral artery; of these, 74 were from the superficial femoral artery, 29 from the profunda femoris artery, 49 from the popliteal artery, and 7 from a tibial artery. The maximum peak systolic velocity proximal to the graft origin was more than 250 in 38 arteries (25%) and more than 300 in 26 arteries (16%). The velocity ratio was 3.0 or more in 32 arteries at the same location as the peak systolic velocity and 3.5 or more in 23 arteries (15%), confirming hemodynamically significant stenoses at these sites. The location of peak systolic velocity was the common femoral artery in 81 patients (51%), the superficial femoral artery in 50 (31%), the popliteal artery in 22 (14%), and a tibial artery in 6 (4%). Follow-up ranged from 8 to 60 months (mean, 35 months). During follow-up, 19 patients died, 18 with patent grafts. Overall, nine grafts occluded. One of the occluded grafts had a velocity ratio greater than 3.0; this may have contributed to graft thrombosis. The other occlusions resulted from an unrepaired graft lesion in 2 patients, graft infection in 2 patients, and graft ligation necessitated by below-knee amputation in 2 patients. No cause for the occlusion could be identified in two of the grafts (neither had evidence of proximal arterial stenosis). Assisted primary patency rates were 95% and 91% at 3 and 5 years, respectively. Conclusions: For grafts originating distal to the common femoral artery, stenoses proximal to the graft do not affect bypass graft patency and do not require repair to prevent graft occlusion. Surveillance of these lesions may therefore be unnecessary, inasmuch as the repair of proximal lesions should not be undertaken to preserve graft function. (J Vasc Surg 2000;32:1180-9.

Study on age-related bioaccumulation of some heavy metals in the soft tissue of rock oyster (Saccostrea cucullata) from Laft Port – Qeshm Island, Iran

Heavy metals widely enter into aquatic ecosystems, and cause various environmental problems due to bioaccumulation and biomagnification in food chains. The accumulation of heavy metals in bivalve tissues is affected by a number of intrinsic and extrinsic factors such as physiological conditions, growth, seasonal changes, pH, salinity, temperature, genera and age. The present study investigated the effects of age of the rock oyster Saccostrea cucullata on the accumulation of Ni, Cd and Pb in the Laft Port coast located on the Qeshm Island. 200 oysters were collected and their age was determined, then they were classified into four age categories and 15 oysters from each category were selected. Samples were dry digested and the metal concentrations were measured by an ICP-OES (PerkinElmer, USA) instrument. Results revealed that the accumulation of Ni and Pb in one year old oysters (immature) was more than those in mature oysters (two, three and four year old oysters). Significant differences were observed between concentrations of Ni and Pb in mature and immature oysters. The results suggested that aging has a negative effect on bioaccumulation of Ni and Pb in S. cucullata; while it has no effect on bioaccumulation of Cd