730 research outputs found

    Study of conceptual deep space monitor communications systems using a single earth satellite. Volume III - Appendix Final report

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    Condensed technical survey for deep space monitor communications system using earth satellit

    Reinforced oxide throat insert development

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    Wire reinforced zirconium oxide rocket nozzle insert

    List Decoding of Matrix-Product Codes from nested codes: an application to Quasi-Cyclic codes

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    A list decoding algorithm for matrix-product codes is provided when C1,...,CsC_1,..., C_s are nested linear codes and AA is a non-singular by columns matrix. We estimate the probability of getting more than one codeword as output when the constituent codes are Reed-Solomon codes. We extend this list decoding algorithm for matrix-product codes with polynomial units, which are quasi-cyclic codes. Furthermore, it allows us to consider unique decoding for matrix-product codes with polynomial units

    Suction force-suction distance relation during aspiration thrombectomy for ischemic stroke: A computational fluid dynamics study

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    Acute Ischemic Stroke (AIS) is the major type of stroke occurring in patients. Aspiration thrombectomy, which uses suction to remove the thrombosis, is a promising technique in the clinical treatment of AIS patients. In this research a computational fluid dynamics (CFD) analysis was conducted to model the blood flow dynamics in a simplified cerebral model during an aspiration thrombectomy procedure. The flow system being analysed was a typical in vitro cerebral flow model, and the system parameters were set based on the clinical and in vitro data reported in open literature. The simulated flow field features showed good correlation with the in vitro response as reported in literature. The CFD study provides detailed technical data including the peak velocity occurring at the catheter tip and the suction force-suction distance relation during the aspiration thrombectomy procedure, which are useful new knowledge and have the potential to influence future catheter design as well as clinical operational protocols used during thrombectomy intervention

    Treatment evolution in high-risk congenital diaphragmatic hernia: ten years\u27 experience with diaphragmatic agenesis.

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    OBJECTIVE: The objective of this study was to evaluate the impact of newer therapies on the highest risk patients with congenital diaphragmatic hernia (CDH), those with agenesis of the diaphragm. SUMMARY BACKGROUND DATA: CDH remains a significant cause of neonatal mortality. Many novel therapeutic interventions have been used in these infants. Those children with large defects or agenesis of the diaphragm have the highest mortality and morbidity. METHODS: Twenty centers from 5 countries collected data prospectively on all liveborn infants with CDH over a 10-year period. The treatment and outcomes in these patients were examined. Patients were followed until death or hospital discharge. RESULTS: A total of 1,569 patients with CDH were seen between January 1995 and December 2004 in 20 centers. A total of 218 patients (14%) had diaphragmatic agenesis and underwent repair. The overall survival for all patients was 68%, while survival was 54% in patients with agenesis. When patients with diaphragmatic agenesis from the first 2 years were compared with similar patients from the last 2 years, there was significantly less use of ECMO (75% vs. 52%) and an increased use of inhaled nitric oxide (iNO) (30% vs. 80%). There was a trend toward improved survival in patients with agenesis from 47% in the first 2 years to 59% in the last 2 years. The survivors with diaphragmatic agenesis had prolonged hospital stays compared with patients without agenesis (median, 68 vs. 30 days). For the last 2 years of the study, 36% of the patients with agenesis were discharged on tube feedings and 22% on oxygen therapy. CONCLUSIONS: There has been a change in the management of infants with CDH with less frequent use of ECMO and a greater use of iNO in high-risk patients with a potential improvement in survival. However, the mortality, hospital length of stay, and morbidity in agenesis patients remain significant

    Seismic Structure of Tanaga Island, Alaska

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    Tanaga Island is located in the Central Aleutian Islands and includes four stratovolcanoes: Sajaka, Tanaga, and East Tanaga in the northwest, and Takawangha in the central part of the island. Of these volcanoes, only Tanaga has a record of historical eruptive activity (in 1914). Over 3,000 earthquakes have been recorded beneath the island and the surrounding offshore region since the six-station seismic network was emplaced in 2003. The origin of these earthquakes is not completely understood, and to arrive at this understanding, more accurate hypocenter locations and power spectra need to be determined. A better analyses including improved locations of earthquake hypocenters can provide useful constraints on volcanic and tectonic activity in the region. We use cross-correlation and double-difference methods to relocate Tanaga Island earthquakes from the period 2003–2017. High precision relative relocations show multiple subsurface faults in the Tanaga region related to volcanism and crustal tectonics. In 2005, a large volcanic swarm of nearly 600 volcano-tectonic (VT) events located below the NW portion of the island culminated with a several minute long episode of volcanic tremor. Although there was no verified eruption associated with this swarm, we suggest that this activity is associated with Takawangha volcano due to the shallowing of events towards Takawangha and the inferred location of the tremor signal. In 2008, a M6.6 earthquake was recorded 2.5 km east of Tanaga Island, associated with bookshelf faulting and the northwest translation of the Andreanof region. Shortly after the M6.6 event, two regions on Tanaga Island, 20 and 30 km west of the epicenter became seismically active, suggesting triggering by the M6.6. We also examine a variety of smaller swarms in the Tanaga area. From 2006–2017, we identify activity accommodating the clock-wise rotation of the Delarof Block (Geist et al., 1988), one of five forearc crustal blocks, including a small swarm in 2010. In 2006 heightened seismicity suggests brittle rupture possibly accompanied by fluid movement inferred from the observations of hybrid events 4 km south of Takawangha. In addition, shallow zones of brittle rupture were discovered 8 km south and 25 km southeast of Takawangha. This analysis suggests a complex pattern of earthquake hypocenters that is governed by both volcanic and tectonic processes surrounding Tanaga and Takawangha Volcanoes

    Remission and recovery from first-episode psychosis in adults: systematic review and meta-analysis of long-term outcome studies

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    Background: Remission and recovery rates for people with first-episode psychosis (FEP) remain uncertain. Aims: To assess pooled prevalence rates of remission and recovery in FEP and to investigate potential moderators. Method: We conducted a systematic review and meta-analysis to assess pooled prevalence rates of remission and recovery in FEP in longitudinal studies with more than 1 year of follow-up data, and conducted meta-regression analyses to investigate potential moderators. Results: Seventy-nine studies were included representing 19072 patients with FEP. The pooled rate of remission among 12301 individuals with FEP was 58% (60 studies, mean follow-up 5.5 years). Higher remission rates were moderated by studies from more recent years. The pooled prevalence of recovery among 9642 individuals with FEP was 38% (35 studies, mean follow-up 7.2 years). Recovery rates were higher in North America than in other regions. Conclusions: Remission and recovery rates in FEP may be more favourable than previously thought. We observed stability of recovery rates after the first 2 years, suggesting that a progressive deteriorating course of illness is not typical. Although remission rates have improved over time recovery rates have not, raising questions about the effectiveness of services in achieving improved recovery

    The impact of induced anxiety on affective response inhibition

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    Studying the effects of experimentally induced anxiety in healthy volunteers may increase our understanding of the mechanisms underpinning anxiety disorders. Experimentally induced stress (via threat of unpredictable shock) improves accuracy at withholding a response on the sustained attention to response task (SART), and in separate studies improves accuracy to classify fearful faces, creating an affective bias. Integrating these findings, participants at two public science engagement events (n = 46, n = 55) were recruited to explore the effects of experimentally induced stress on an affective version of the SART. We hypothesized that we would see an improved accuracy at withholding a response to affectively congruent stimuli (i.e. increased accuracy at withholding a response to fearful 'no-go' distractors) under threat of shock. Induced anxiety slowed reaction time, and at the second event quicker responses were made to fearful stimuli. However, we did not observe improved inhibition overall during induced anxiety, and there was no evidence to suggest an interaction between induced anxiety and stimulus valence on response accuracy. Indeed Bayesian analysis provided decisive evidence against this hypothesis. We suggest that the presence of emotional stimuli might make the safe condition more anxiogenic, reducing the differential between conditions and knocking out any threat-potentiated improvement
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