A Tailored Systems Engineering Process for the Development of CubeSat Class Satellites

The class of small satellites known as CubeSats have grown in popularity and complexity in recent years and have been especially popular with colleges and universities interested in utilizing them both for their value as an educational tool and to conduct science missions. While there have been some tremendously successful CubeSat missions over the years, those that are launched are still more likely than not to be dead on arrival or to fail before accomplishing their objectives. Part of this low success rate, especially of student built CubeSats, may be attributed to the fact that they are often designed in an ad hoc manner, with students working on projects for only a fixed period of time and without a view of the big picture. In contrast, large space-focused organizations utilize Systems Engineering (SE) to standardize processes and improve the odds of mission success. The National Aeronautics and Space Administration (NASA) uses their own SE methodology and it is so complex that the process overview, known as the NASA Project Life Cycle Process Flow can take up an entire wall when printed in full size. While it may not be feasible to apply such a complex SE methodology to most CubeSat developments, they could be improved a great deal by utilizing a rigorous but tailored process of their own. Specifically, CubeSat developers should focus on requirements definition and flow-down, risk analysis and mitigation, cost and schedule management, and integration and interface management. These areas would be aided significantly by developing artifacts such as a Cost Analysis, Risk Analysis, Test and Evaluation Plan, Model Based Architecture, and a Concept of Operations. This paper describes work which aims to develop and implement an optimized SE process for CubeSats intended specifically for student-run projects taking place over the course of a single academic year. It will be implemented on a student CubeSat project at the United States Naval Academy (USNA) and validated by comparing key performance parameters of their project to those of other similar CubeSats developed without using this process. The result of this study will be a tailored SE process that can be applied to virtually any student CubeSat project to improve performance and importantly to increase the chances of mission success

A systematic review and meta-analysis of complementary and alternative medicine in asthma

Asthma is a chronic, inflammatory lung disease affecting around 235 million people worldwide. Conventional medications in asthma are not curative and patients have significant concerns regarding their side effects. Consequently, many asthma patients turn to Complementary and Alternative Medicine (CAM) for a more holistic approach to care. We systematically reviewed the available evidence on the effectiveness of CAM in the management of asthma in adults. We searched MEDLINE, EMBASE, CINAHL, AMED and Cochrane Databases for randomised controlled trials published in English between 1990 to 2016 investigating the effectiveness of oral or topical CAM in asthmatic adults. Quality of the studies was assessed using The Cochrane Risk of Bias Assessment Tool. RevMan 5.3 was used for meta-analysis. In all, 24 eligible trials were identified covering 19 different CAMs. Overall, there was limited evidence on the effectiveness of CAM in adult asthma as most CAMs were assessed in a single trial only. CAMs with multiple trials provided null or inconsistent results. Many of the trials were rated as having high risk of bias. The existing evidence is insufficient to recommend any of the oral and topical CAMs in the management of asthma in adults

Limited polymorphism in Plasmodium falciparum ookinete surface antigen, von Willebrand factor A domain-related protein from clinical isolates

BACKGROUND: As malaria becomes increasingly drug resistant and more costly to treat, there is increasing urgency to develop effective vaccines. In comparison to other stages of the malaria lifecycle, sexual stage antigens are under less immune selection pressure and hence are likely to have limited antigenic diversity. METHODS: Clinical isolates from a wide range of geographical regions were collected. Direct sequencing of PCR products was then used to determine the extent of polymorphisms for the novel Plasmodium falciparum sexual stage antigen von Willebrand Factor A domain-related Protein (PfWARP). These isolates were also used to confirm the extent of diversity of sexual stage antigen Pfs28. RESULTS: PfWARP was shown to have non-synonymous substitutions at 3 positions and Pfs28 was confirmed to have a single non-synonymous substitution as previously described. CONCLUSION: This study demonstrates the limited antigenic diversity of two prospective P. falciparum sexual stage antigens, PfWARP and Pfs28. This provides further encouragement for the proceeding with vaccine trials based on these antigens

Seven-Year Efficacy of RTS,S/AS01 Malaria Vaccine among Young African Children

Background The RTS,S/AS01 malaria vaccine candidate is being evaluated for implementation. Methods We conducted 7 years follow-up of children who were randomized at age 5 to 17 months to receive three doses of either the RTS,S/AS01 vaccine or control vaccine (rabies). The endpoint was clinical malaria (temperature ≥37.5°C and infection with Plasmodium falciparum of ≥2500 parasites per µl). Each child’s malaria exposure was estimated using the prevalence of malaria among residents within a 2km radius of their homestead. Vaccine efficacy was defined as 1 minus the hazard ratio (HR) or incidence rate ratios (IRR) of the RTS,S/AS01 vaccinated versus rabies vaccinated groups. Results We identified 1002 clinical malaria episodes among 223 children randomized to RTS,S/AS01 and 992 clinical malaria episodes among 224 children randomized to control vaccination over seven years follow-up. Intention-to-treat vaccine efficacy (VE) was 4.4% (95%CI: -17 to 21.9, p value=0.67) and per-protocol VE was 7.0% (95%CI -14.5 to 24.6%, p=0.5) by negative binomial regression. VE waned over time (p=0.006 for the interaction between vaccination and time), including negative efficacy during the fifth year among children at higher malaria parasite exposure (-43.5%, 95%CI: -100.3 to -2.8, p value=0.033 by intention-to-treat and -56.8%, 95%CI -118.7 to -12.3, p=0.008 per-protocol). Conclusion A 3-dose vaccination with RTS,S/AS01 is initially protective against clinical malaria, but this is offset by rebound in later years in areas with higher malaria parasite exposure. Further data are needed on longer-term outcomes following four-dose vaccinations. </p

Lyme disease in Wisconsin: epidemiologic, clinical, serologic, and entomologic findings.

In 1980-82, 80 individuals (71 Wisconsin residents) had confirmed Lyme disease (LD-c) reported; 39 additional patients had probable or possible LD. All cases of LD-c occurred during May-November; 73 percent occurred during June-July; 54 (68 percent) occurred in males. The mean age was 38.7 years (range, 7-77 years). Among LD-c patients, likely exposure to the presumed vector Ixodes dammini (ID) occurred in 22 different Wisconsin counties. Antibodies to the ID spirochete that causes LD occurred in 33 of 49 LD-c cases versus 0 of 18 in ill controls (p less than .001) and in 13 of 26 LD-c cases treated with penicillin or tetracycline versus 16 of 19 LD-c cases not treated. Early antibiotic therapy appears to blunt the antibody response to the ID spirochete. Regional tick surveys conducted in Wisconsin during each November in 1979-82 have demonstrated regions of greater density of ID. Utilizing comparable tick collection in these surveys, increases were noted in the percentage of deer with ID from 24 percent (31/128) in 1979 to 38 percent (58/152) in 1981, in the standardized mean value of ID/deer from 1.0 in 1979 to 2.2 in 1981, in the percentage of ID of the total ticks collected from 13 percent in 1979 to 71 percent in 1981, or in the ratio of ID to Dermacentor albipictus ticks from 0.14 in 1979 to 2.44 in 1981. However, a reduction in the density of ID/deer was noted generally throughout Wisconsin in 1982 when compared to 1981. LD is widespread in Wisconsin, with ecologic and clinical features similar to those occurring along the eastern seaboard

Maternal immunization against Group B streptococcus: World Health Organization research and development technological roadmap and preferred product characteristics.

Group B streptococcus, found in the vagina or lower gastrointestinal tract of about 10-40% of women of reproductive age, is a leading cause of early life invasive bacterial disease, potentially amenable to prevention through maternal immunization during pregnancy. Following a consultation process with global stakeholders, the World Health Organization is herein proposing priority research and development pathways and preferred product characteristics for GBS vaccines, with the aim to facilitate and accelerate vaccine licensure, policy recommendation for wide scale use and implementation

Effect of human leukocyte antigen heterozygosity on infectious disease outcome: The need for allele-specific measures

BACKGROUND: Doherty and Zinkernagel, who discovered that antigen presentation is restricted by the major histocompatibility complex (MHC, called HLA in humans), hypothesized that individuals heterozygous at particular MHC loci might be more resistant to particular infectious diseases than the corresponding homozygotes because heterozygotes could present a wider repertoire of antigens. The superiority of heterozygotes over either corresponding homozygote, which we term allele-specific overdominance, is of direct biological interest for understanding the mechanisms of immune response; it is also a leading explanation for the observation that MHC loci are extremely polymorphic and that these polymorphisms have been maintained through extremely long evolutionary periods. Recent studies have shown that in particular viral infections, heterozygosity at HLA loci was associated with a favorable disease outcome, and such findings have been interpreted as supporting the allele-specific overdominance hypothesis in humans. METHODS: An algebraic model is used to define the expected population-wide findings of an epidemiologic study of HLA heterozygosity and disease outcome as a function of allele-specific effects and population genetic parameters of the study population. RESULTS: We show that overrepresentation of HLA heterozygotes among individuals with favorable disease outcomes (which we term population heterozygote advantage) need not indicate allele-specific overdominance. On the contrary, partly due to a form of confounding by allele frequencies, population heterozygote advantage can occur under a very wide range of assumptions about the relationship between homozygote risk and heterozygote risk. In certain extreme cases, population heterozygote advantage can occur even when every heterozygote is at greater risk of being a case than either corresponding homozygote. CONCLUSION: To demonstrate allele-specific overdominance for specific infections in human populations, improved analytic tools and/or larger studies (or studies in populations with limited HLA diversity) are necessary

Accelerating to Zero: Strategies to Eliminate Malaria in the Peruvian Amazon.

AbstractIn February 2014, the Malaria Elimination Working Group, in partnership with the Peruvian Ministry of Health (MoH), hosted its first international conference on malaria elimination in Iquitos, Peru. The 2-day meeting gathered 85 malaria experts, including 18 international panelists, 23 stakeholders from different malaria-endemic regions of Peru, and 11 MoH authorities. The main outcome was consensus that implementing a malaria elimination project in the Amazon region is achievable, but would require: 1) a comprehensive strategic plan, 2) the altering of current programmatic guidelines from control toward elimination by including symptomatic as well as asymptomatic individuals for antimalarial therapy and transmission-blocking interventions, and 3) the prioritization of community-based active case detection with proper rapid diagnostic tests to interrupt transmission. Elimination efforts must involve key stakeholders and experts at every level of government and include integrated research activities to evaluate, implement, and tailor sustainable interventions appropriate to the region

Evolution, revolution and heresy in the genetics of infectious disease susceptibility

Infectious pathogens have long been recognized as potentially powerful agents impacting on the evolution of human genetic diversity. Analysis of large-scale case–control studies provides one of the most direct means of identifying human genetic variants that currently impact on susceptibility to particular infectious diseases. For over 50 years candidate gene studies have been used to identify loci for many major causes of human infectious mortality, including malaria, tuberculosis, human immunodeficiency virus/acquired immunodeficiency syndrome, bacterial pneumonia and hepatitis. But with the advent of genome-wide approaches, many new loci have been identified in diverse populations. Genome-wide linkage studies identified a few loci, but genome-wide association studies are proving more successful, and both exome and whole-genome sequencing now offer a revolutionary increase in power. Opinions differ on the extent to which the genetic component to common disease susceptibility is encoded by multiple high frequency or rare variants, and the heretical view that most infectious diseases might even be monogenic has been advocated recently. Review of findings to date suggests that the genetic architecture of infectious disease susceptibility may be importantly different from that of non-infectious diseases, and it is suggested that natural selection may be the driving force underlying this difference

Volatile Anesthetic and Outcome in Acute Trauma Care: Planned Secondary Analysis of the PROPPR Study

BACKGROUND: This retrospective analysis of prospectively collected data from the PROPPR study describes volatile anesthetic use in severely injured trauma patients undergoing anesthesia. METHODS: After exclusions, 402 subjects were reviewed of the original 680, and 292 had complete data available for analysis. Anesthesia was not protocolized, so analysis was of contemporary practice. RESULTS: The small group who received no volatile anesthetic (n = 25) had greater injury burden (Glasgow Coma Scale CONCLUSION: In this acutely injured trauma population, choice of volatile anesthetic did not appear to influence short-term mortality and morbidity. Subjects who received no volatile were more severely injured with greater mortality, representing hemodynamic compromise where volatile agent was limited until stable. As anesthetic was not protocolized, these findings that choice of specific volatile was not associated with short-term survival require prospective, randomized evaluation