Electromagnetic emission experiences using electric propulsion systems: A survey

As electric propulsion systems become ready to integrate with spacecraft systems, the impact of propulsion system radiated emissions are of significant interest. Radiated emissions from electromagnetic, electrostatic, and electrothermal systems have been characterized and results synopsized from the literature describing 21 space flight programs. Electromagnetic radiated emission results from ground tests and flight experiences are presented with particular attention paid to the performance of spacecraft subsystems and payloads during thruster operations. The impacts to transmission of radio frequency signals through plasma plumes are also reviewed

A bifurcation study to guide the design of a landing gear with a combined uplock/downlock mechanism

This paper discusses the insights that a bifurcation analysis can provide when designing mechanisms. A model, in the form of a set of coupled steady-state equations, can be derived to describe the mechanism. Solutions to this model can be traced through the mechanism's state versus parameter space via numerical continuation, under the simultaneous variation of one or more parameters. With this approach, crucial features in the response surface, such as bifurcation points, can be identified. By numerically continuing these points in the appropriate parameter space, the resulting bifurcation diagram can be used to guide parameter selection and optimization. In this paper, we demonstrate the potential of this technique by considering an aircraft nose landing gear, with a novel locking strategy that uses a combined uplock/downlock mechanism. The landing gear is locked when in the retracted or deployed states. Transitions between these locked states and the unlocked state (where the landing gear is a mechanism) are shown to depend upon the positions of two fold point bifurcations. By performing a two-parameter continuation, the critical points are traced to identify operational boundaries. Following the variation of the fold points through parameter space, a minimum spring stiffness is identified that enables the landing gear to be locked in the retracted state. The bifurcation analysis also shows that the unlocking of a retracted landing gear should use an unlock force measure, rather than a position indicator, to de-couple the effects of the retraction and locking actuators. Overall, the study demonstrates that bifurcation analysis can enhance the understanding of the influence of design choices over a wide operating range where nonlinearity is significant

Absolute quantification of the host-to-parasite DNA ratio in Theileria parva-infected lymphocyte cell lines

Theileria parva is a tick-transmitted intracellular apicomplexan pathogen of cattle in sub-Saharan Africa that causes East Coast fever (ECF). ECF is an acute fatal disease that kills over one million cattle annually, imposing a tremendous burden on African small-holder cattle farmers. The pathology and level of T. parva infections in its wildlife host, African buffalo (Syncerus caffer), and in cattle are distinct. We have developed an absolute quantification method based on quantitative PCR (qPCR) in which recombinant plasmids containing single copy genes specific to the parasite (apical membrane antigen 1 gene, ama1) or the host (hypoxanthine phosphoribosyltransferase 1, hprt1) are used as the quantification reference standards. Our study shows that T. parva and bovine cells are present in similar numbers in T. parva-infected lymphocyte cell lines and that consequently, due to its much smaller genome size, T. parva DNA comprises between 0.9% and 3% of the total DNA samples extracted from these lines. This absolute quantification assay of parasite and host genome copy number in a sample provides a simple and reliable method of assessing T. parva load in infected bovine lymphocytes, and is accurate over a wide range of host-to-parasite DNA ratios. Knowledge of the proportion of target DNA in a sample, as enabled by this method, is essential for efficient high-throughput genome sequencing applications for a variety of intracellular pathogens. This assay will also be very useful in future studies of interactions of distinct host-T. parva stocks and to fully characterize the dynamics of ECF infection in the field

Genomic survey of candidate stress-response genes in the estuarine anemone Nematostella vectensis

Author Posting. © Marine Biological Laboratory, 2008. This article is posted here by permission of Marine Biological Laboratory for personal use, not for redistribution. The definitive version was published in Biological Bulletin 214 (2008): 233-254.Salt marshes are challenging habitats due to natural variability in key environmental parameters including temperature, salinity, ultraviolet light, oxygen, sulfides, and reactive oxygen species. Compounding this natural variation, salt marshes are often heavily impacted by anthropogenic insults including eutrophication, toxic contamination, and coastal development that alter tidal and freshwater inputs. Commensurate with this environmental variability, estuarine animals generally exhibit broader physiological tolerances than freshwater, marine, or terrestrial species. One factor that determines an organism's physiological tolerance is its ability to upregulate "stress-response genes" in reaction to particular stressors. Comparative studies on diverse organisms have identified a number of evolutionarily conserved genes involved in responding to abiotic and biotic stressors. We used homology-based scans to survey the sequenced genome of Nematostella vectensis, the starlet sea anemone, an estuarine specialist, to identify genes involved in the response to three kinds of insult—physiochemical insults, pathogens, and injury. Many components of the stress-response networks identified in triploblastic animals have clear orthologs in the sea anemone, meaning that they must predate the cnidarian-triploblast split (e.g., xenobiotic receptors, biotransformative genes, ATP-dependent transporters, and genes involved in responding to reactive oxygen species, toxic metals, osmotic shock, thermal stress, pathogen exposure, and wounding). However, in some instances, stress-response genes known from triploblasts appear to be absent from the Nematostella genome (e.g., many metal-complexing genes). This is the first comprehensive examination of the genomic stress-response repertoire of an estuarine animal and a member of the phylum Cnidaria. The molecular markers of stress response identified in Nematostella may prove useful in monitoring estuary health and evaluating coastal conservation efforts. These data may also inform conservation efforts on other cnidarians, such as the reef-building corals.AMR was supported by a Postdoctoral Scholar Program at the Woods Hole Oceanographic Institution, with funding provided by The Beacon Institute for Rivers and Estuaries, and the J. Seward Johnson Fund. NTK was supported by a graduate research training grant from the National Institutes of Health. This research was also supported by NSF grant FP-91656101-0 to JCS and JRF, EPA grant F5E11155 to AMR and JRF, and a grant from the Conservation International Marine Management Area Science Program to JRF

Surgery for constipation : systematic review and practice recommendations : Results II: Hitching procedures for the rectum (rectal suspension)

Aim To assess the outcomes of rectal suspension procedures (forms of rectopexy) in adults with chronic constipation. Method Standardised methods and reporting of benefits and harms were used for all CapaCiTY reviews that closely adhered to PRISMA 2016 guidance. Main conclusions were presented as summary evidence statements with a summative Oxford Centre for Evidence-Based Medicine (2009) level. Results Eighteen articles were identified, providing data on outcomes in 1238 patients. All studies reported only on laparoscopic approaches. Length of procedures ranged between 1.5 to 3.5 h, and length of stay between 4 to 5 days. Data on harms were inconsistently reported and heterogeneous, making estimates of harm tentative and imprecise. Morbidity rates ranged between 5–15%, with mesh complications accounting for 0.5% of patients overall. No mortality was reported after any procedures in a total of 1044 patients. Although inconsistently reported, good or satisfactory outcome occurred in 83% (74–91%) of patients; 86% (20–97%) of patients reported improvements in constipation after laparoscopic ventral mesh rectopexy (LVMR). About 2–7% of patients developed anatomical recurrence. Patient selection was inconsistently documented. As most common indication, high grade rectal intussusception was corrected in 80–100% of cases after robotic or LVMR. Healing of prolapse-associated solitary rectal ulcer syndrome occurred in around 80% of patients after LVMR. Conclusion Evidence supporting rectal suspension procedures is currently derived from poor quality studies. Methodologically robust trials are needed to inform future clinical decision making

Hypermethylation of CpG islands and shores around specific microRNAs and mirtrons is associated with the phenotype and presence of bladder cancer

PURPOSE To analyze the role and translational potential for hypermethylation of CpG islands and shores in the regulation of small RNAs within urothelial cell carcinoma (UCC). To examine microRNAs (miR) and mirtrons, a new class of RNA located within gene introns and processed in a Drosha-independent manner. EXPERIMENTAL DESIGN The methylation status of 865 small RNAs was evaluated in normal and malignant cell lines by using 5-azacytidine and microarrays. Bisulfite sequencing was used for CpG regions around selected RNAs. Prognostic and diagnostic associations for epigenetically regulated RNAs were examined by using material from 359 patients, including 216 tumors and 121 urinary samples (68 cases and 53 controls). Functional analyses examined the effect of silencing susceptible RNAs in normal urothelial cells. RESULTS Exonic/UTR-located miRs and mirtons are most susceptible to epigenetic regulation. We identified 4 mirtrons and 16 miRs with CpG hypermethylation across 35 regions in normal and malignant urothelium. For several miRs, hypermethylation was more frequent and dense in CpG shores than islands (e.g., miRs-9/149/210/212/328/503/1224/1227/1229), and was associated with tumor grade, stage, and prognosis (e.g., miR-1224 multivariate analysis OR = 2.5; 95% CI, 1.3-5.0; P = 0.006). The urinary expression of epigenetically silenced RNAs (miRs-152/328/1224) was associated with the presence of UCC (concordance index, 0.86; 95% CI, 0.80-0.93; ANOVA P < 0.016). CONCLUSIONS Hypermethylation of mirtrons and miRs is common in UCC. Mirtrons appear particularly susceptible to epigenetic regulation. Aberrant hypermethylation of small RNAs is associated with the presence and behavior of UCC, suggesting potential roles as diagnostic and prognostic biomarkers

Social physique anxiety and physical activity in early adolescent girls : the influence of maturation and physical activity motives

This study considered the influence of maturation on social physique anxiety (SPA), the relationship between SPA and current and future physical activity (PA) levels and the influence of motives for physical activity on this relationship in early adolescent girls (n=162; mean age=11.80±0.33 years). Participants completed the Pubertal Development Scale, the modified Social Physique Anxiety Scale and the Motives for Physical Activity Scale at baseline and the Physical Activity Questionnaire for Older Children at baseline and 6 months later. The girls became less active across the 6 months and girls in the early stages of maturation had significantly lower SPA than the girls in the middle and late stages of maturation. SPA was not related to current or future physical activity in the sample as a whole. Cluster analysis identified four groups with different motive profiles and the High Appearance and Fitness group demonstrated a moderate negative relationship between SPA and PA at phase 1, whereas the other groups did not. These findings indicate that SPA may increase with maturation and the relationship between SPA and PA is dependent on reasons for being active. For girls who are motivated to be active primarily by body-related reasons SPA is likely to lead to lower levels of PA

Clinical measurements performed during alfaxalone total intravenous anaesthesia for radiography and neurophysiological investigations in dogs

Objective: To describe clinically relevant, physiological measurements collected during a 3- hour duration alfaxalone total intravenous anaesthesia.Study design: Case series.Animals: A total of 112 client-owned middle aged or older dogs.Methods: Dogs were premedicated with intramuscular acepromazine (0.03 mg kg-1). Anaesthesia was induced and subsequently maintained for up to 3 hours with alfaxalone administered intravenously. Dogs breathed 100% oxygen via an endotracheal tube. Heart rate, respiratory rate, and blood pressure were evaluated 30 minutes after administration of acepromazine and used as baseline values for comparisons of intra-anaesthetic data. Blood glucose was measured one week prior to anaesthesia and every hour during alfaxalone anaesthesia. Quality and duration of recovery were recorded. Mean data for physiological variables were compared over three time points; before induction of anaesthesia, forthe first hour of anaesthesia and from 60 minutes to discontinuation of anaesthesia.Results: Mean induction dose of alfaxalone was 1.4 (95% CI 1.3 - 1.5) mg kg-1. Post induction apnoea for greater than 60 seconds occurred in 13 (11.6%) dogs. Mean alfaxalone infusion rate during the first 60 minutes of anaesthesia was 0.099 mg kg-1 minute-1; from 60 minutes until discontinuation of anaesthesia, mean infusion rate was 0.092 mg kg-1 minute-1. Heart rate was well maintained; hypotension (mean arterial blood pressure less than 60 mmHg) was encountered in 23 (21%) of dogs. Blood glucose levels did not alter during anaesthesia. Median time between discontinuation of alfaxalone infusion and extubation was 17 (7 – 35 minutes), time to assuming sternal recumbency was 75 (58 - 110 minutes), and time to standing was 109 (88 - 140 minutes).Conclusions and clinical relevance: Alfaxalone infusion provided effective anaesthesia in this population. In a minority of cases respiratory and haemodynamic support of the patient was required