scholarly journals Mainline and water maser observations of OH/IR stars in the Arecibo sky

1997 ◽  
Vol 180 ◽  
pp. 356-356
Author(s):  
B. M. Lewis
Keyword(s):  
Detection Rate ◽  
Planetary Nebulae ◽  
Complete Sample ◽  
Detection Rates ◽  
Ir Stars ◽  
Circumstellar Shells ◽  
Water Masers ◽  
The Many ◽  
Water Maser

A complete sample of color selected IRAS sources with S(25) ≥ 2 Jy in the Arecibo sky and(0° ≤ δ ≤ 37°) was examined previously for 1612 MHz masers. The resulting set of OH/IR stars has now been searched for mainline OH masers at Arecibo (Lewis 1997) and for 22 GHz water masers at Effelsberg (Engels & Lewis 1996). The high overall detection rate of 61.6% for the mainlines and 54.8% for water is partly a result of deployed sensitivity, and partly due to the many blue objects in the sample. But the detectability of both masers improves when S(25)> 20 Jy, as the accompanying tables show. Still the bluest objects exhibit higher (usually ≥80%) detection rates, while there is a clear decrease in detections from redder shells: this decrease begins circa (25–12) μm=–0.55 for mainline masers, and abruptly circa (25–12) μm = −0.35 for water. These trends adhere to the descriptive sequence of the chronological scenario for masers in circumstellar shells, though a few proto planetary nebulae and very red OH/IR stars have water masers and a few mainline masers are detected in shells with (25-12) μm ≥ −0.2.

scholarly journals The Presence of Water Masers in Color-Selected IRAS Sources

1989 ◽  
Vol 131 ◽  
pp. 450-450
Author(s):  
B. M. Lewis ◽  
D. Engels
Keyword(s):  
Point Source ◽  
Detection Rate ◽  
Type Ii ◽  
Maser Emission ◽  
Companion Star ◽  
Alternative Scenario ◽  
Ir Stars ◽  
Circumstellar Shell ◽  
Water Masers ◽  
Water Maser

Eder, Lewis, and Terzian (1987) examined ∼ 400 sources from the IRAS Point Source Catalogue with colors appropriate to OH/IR stars, for the presence of 1612 MHz emission. We examined a proportion of these objects at Effelsberg for the presence of water-maser emission. In sources with |bII| > 10° which are therefore relatively local, we find a 68% detection rate for water-masers among objects associated with 1612 MHz masers, as opposed to a 17% detection rate among sources with similar colors but without 1612 MHz emission. Those conditions in a circumstellar shell that favor the presence of water-masers also favor the presence of a 1612 MHz maser. These results are consistent with most Type II masers being associated with water-masers. Since Cooke and Elitzur (1985) show that water-masers are collisionally excited, this result excludes stirring of the envelope by a companion star with an associated loss of velocity coherence, as the primary cause for the existence of the color-analogue sources without 1612 MHz masers. We discuss an alternative scenario.

Water masers as signposts of extremely young planetary nebulae

2017 ◽  
Vol 13 (S336) ◽  
pp. 377-380
Author(s):  
José F. Gómez ◽  
Luis F. Miranda ◽  
Lucero Uscanga ◽  
Olga Suárez
Keyword(s):  
Planetary Nebulae ◽  
Radio Continuum ◽  
Continuum Emission ◽  
Water Masers ◽  
Water Maser

AbstractOnly five planetary nebulae (PNe) have been confirmed to emit water masers. They seem to be very young PNe. The water emission in these objects preferentially traces circumstellar toroids, although in K 3-35 and IRAS 15103-5754, it may also trace collimated jets. We present water maser observations of these two sources at different epochs. The water maser distribution changes on timescales of months to a few years. We speculate that these changes may be due to the variation of the underlying radio continuum emission, which is amplified by the maser process in the foreground material.

Proper Motions of Water Masers in Circumstellar Shells

1998 ◽  
Vol 164 ◽  
pp. 253-254
Author(s):  
K. B. Marvel ◽  
P. J. Diamond ◽  
A. J. Kemball
Keyword(s):  
Circumstellar Envelope ◽  
Proper Motions ◽  
Complex Region ◽  
Circumstellar Shells ◽  
Water Masers ◽  
Water Maser

AbstractWe present measurements of proper motions for circumstellar water maser observations obtained with the VLBA. Results of the observations and modeling indicate that the water masers exist in a kinematically complex region of the circumstellar envelope. A change in position of the maser spots as a function of velocity is discussed.

scholarly journals Imaging the water masers toward the H2O-PN IRAS 18061–2505

2012 ◽  
Vol 8 (S287) ◽  
pp. 258-259
Author(s):  
Yolanda Gómez ◽  
Daniel Tafoya ◽  
Olga Suárez ◽  
Jose F. Gómez ◽  
Luis F. Miranda ◽  
...  
Keyword(s):  
Planetary Nebulae ◽  
Central Star ◽  
Large Array ◽  
Maser Emission ◽  
Very Large Array ◽  
Kinematical Model ◽  
Water Masers ◽  
Central Stars ◽  
Water Maser

AbstractIt has been suggested that the presence of disks or tori around the central stars of pre Planetary Nebulae and Planetary Nebulae is related to the collimation of the jet that are frequently observed in these sources. These disks or tori can be traced by the maser emission of some molecules such as water. In this work we present Very Large Array (VLA) observations of the water maser emission at 22 GHz toward the PN IRAS 18061–2505, for which the masers appear located on one side of the central star. For comparison with the observations, we present a simple kinematical model of a disk rotating and expanding around the central star. The model matches qualitatively the observations. However, since the masers appear only on one side of the disk, these results are not conclusive.

scholarly journals Water Fountains in Pre-Planetary Nebulae: The Case of IRAS16342–3814

2012 ◽  
Vol 8 (S287) ◽  
pp. 225-229 ◽  
Author(s):  
Mark Claussen ◽  
Raghvendra Sahai ◽  
Mark Morris ◽  
Hannah Rogers
Keyword(s):  
General Structure ◽  
Planetary Nebulae ◽  
Large Array ◽  
Very Large Array ◽  
Long Baseline ◽  
Stellar Velocity ◽  
Water Masers ◽  
Very Long Baseline Array ◽  
Water Maser

AbstractWe present a brief review of Very Long Baseline Array (VLBA) observations of water masers in the so-called water fountain pre-planetary nebulae, and report on new VLBA and Very Large Array (VLA) data for the water masers in the prototypical water fountain source IRAS16342–3814, taken approximately monthly in 2008–2009. A new and very strong water maser is found at an LSR velocity of −3 km s−1, which is offset from the central (likely stellar) velocity. The new VLBA observations still show a similar general structure as was observed in 2002, but there are details which are difficult to explain.

scholarly journals Training: improving antenatal detection and outcomes of congenital heart disease

2018 ◽  
Vol 7 (4) ◽  
pp. e000276 ◽  
Author(s):  
Orhan Uzun ◽  
Julia Kennedy ◽  
Colin Davies ◽  
Anthony Goodwin ◽  
Nerys Thomas ◽  
...  
Keyword(s):  
Congenital Heart Disease ◽  
Detection Rate ◽  
Congenital Heart ◽  
Training Programme ◽  
Referral Rate ◽  
Cardiac Anomaly ◽  
Cardiac Ultrasound ◽  
Detection Rates ◽  
Antenatal Detection ◽  
The Uk

ObjectivesThis study describes the design, delivery and efficacy of a regional fetal cardiac ultrasound training programme. This programme aimed to improve the antenatal detection of congenital heart disease (CHD) and its effect on fetal and postnatal outcomes.Design setting and participantsThis was a prospective study that compared antenatal CHD detection rates by professionals from 13 hospitals in Wales before and after engaging in our ‘skills development programme’. Existing fetal cardiac practice and perinatal outcomes were continuously audited and progressive targets were set. The work was undertaken by the Welsh Fetal Cardiovascular Network, Antenatal Screening Wales (ASW), a superintendent sonographer and a fetal cardiologist.InterventionsA core professional network was established, engaging all stakeholders (including patients, health boards, specialist commissioners, ASW, ultrasonographers, radiologists, obstetricians, midwives and paediatricians). A cardiac educational lead (midwife, superintendent sonographer, radiologist, obstetrician, or a fetal medicine specialist) was established in each hospital. A new cardiac anomaly screening protocol (‘outflow tract view’) was created and training on the new protocol was systematically delivered at each centre. Data were prospectively collected and outcomes were continuously audited: locally by the lead fetal cardiologist; regionally by the Congenital Anomaly Register and Information Service in Wales; and nationally by the National Institute for Cardiac Outcomes and Research (NICOR) in the UK.Main outcome measuresPatient satisfaction; improvements in individual sonographer skills, confidence and competency; true positive referral rate; local hospital detection rate; national detection rate of CHD; clinical outcomes of selected cardiac abnormalities; reduction of geographical health inequality; cost efficacy.ResultsHigh levels of patient satisfaction were demonstrated and the professional skill mix in each centre was improved. The confidence and competency of sonographers was enhanced. Each centre demonstrated a reduction in the false-positive referral rate and a significant increase in cardiac anomaly detection rate. According to the latest NICOR data, since implementing the new training programme Wales has sustained its status as UK lead for CHD detection. Health outcomes of children with CHD have improved, especially in cases of transposition of the great arteries (for which no perinatal mortality has been reported since 2008). Standardised care led to reduction of geographical health inequalities with substantial cost saving to the National Health Service due to reduced false-positive referral rates. Our successful model has been adopted by other fetal anomaly screening programmes in the UK.ConclusionsAntenatal cardiac ultrasound mass training programmes can be delivered effectively with minimal impact on finite healthcare resources. Sustainably high CHD detection rates can only be achieved by empowering the regional screening workforce through continuous investment in lifelong learning activities. These should be underpinned by high quality service standards, effective care pathways, and robust clinical governance and audit practices.

scholarly journals Mortality due to primary brain tumours in China and detection rate in people with suspected symptoms: a nationally representative cross-sectional survey

2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Bin Jiang ◽  
Hongmei Liu ◽  
Dongling Sun ◽  
Haixin Sun ◽  
Xiaojuan Ru ◽  
...  
Keyword(s):  
Brain Tumour ◽  
Brain Tumours ◽  
Detection Rate ◽  
Epidemiological Data ◽  
Cross Sectional Survey ◽  
Cross Sectional ◽  
Detection Rates ◽  
Primary Brain Tumours ◽  
Symptom Screening ◽  
Nationally Representative

Abstract Background and purpose Epidemiological data on primary brain tumours (PBTs) are lacking due to the difficulty in case ascertainment among the population. Thus, we aimed to estimate mortality due to PBTs in China nationwide and the detection rate in people with suspected symptoms. Methods A multistage, complex sampling survey regarding mortality due to PBTs in Chinese individuals was carried out by reviewing all causes of death within a year. The detection rates in people with suspected symptoms were estimated based on PBT symptom screening and neurologist reviews and compared between groups by logistic regression analysis. Results Weighted mortality due to PBT was 1.6 (0.8–3.3) per 100,000 population in Chinese individuals, 1.8 (0.7–4.6) per 100,000 population in men, and 1.5 (0.5–4.5) per 100,000 population in women. Among 14,990 people with suspected symptoms, the PBT detection rate was 306.9 (95% CI 224.7–409.3) per 100,000 population in the total population, 233.0 (95% CI 135.7–373.1) per 100,000 population in men, and 376.9 (95% CI 252.4–546.3) per 100,000 population in women. People with an unsteady gait (OR 2.46; 95% CI 1.09–5.51; P=0.029), visual anomalies (3.84; 1.88–7.85; P<0.001), and headache (2.06; 1.10–3.86; P=0.023) were more likely to have a brain tumour than those without corresponding symptoms, while people with dizziness/vertigo were less likely to have a brain tumour than those without corresponding symptoms (0.45; 0.23–0.87; P=0.017). Conclusions Mortality due to PBT in China was low, with a nationwide estimate of 21,215 (10,427–43,165) deaths attributable to PBTs annually. However, the detection rate of PBTs can be greatly improved based on symptom screening in the population.

scholarly journals The Effects of Social Distancing Policies on non-SARS-CoV-2 Respiratory Pathogens

2021 ◽  
Author(s):  
Jeff Nawrocki ◽  
Katherine Olin ◽  
Martin C Holdrege ◽  
Joel Hartsell ◽  
Lindsay Meyers ◽  
...  
Keyword(s):  
Public Health ◽  
Influenza A ◽  
Detection Rate ◽  
Respiratory Illness ◽  
Respiratory Pathogens ◽  
Public Health Response ◽  
Mixed Effect ◽  
Detection Rates ◽  
Social Distancing ◽  
The Impact

Abstract Background The initial focus of the US public health response to COVID-19 was the implementation of numerous social distancing policies. While COVID-19 was the impetus for imposing these policies, it is not the only respiratory disease affected by their implementation. This study aimed to assess the impact of social distancing policies on non-SARS-CoV-2 respiratory pathogens typically circulating across multiple US states. Methods Linear mixed-effect models were implemented to explore the effects of five social distancing policies on non-SARS-CoV-2 respiratory pathogens across nine states from January 1 through May 1, 2020. The observed 2020 pathogen detection rates were compared week-by-week to historical rates to determine when the detection rates were different. Results Model results indicate that several social distancing policies were associated with a reduction in total detection rate, by nearly 15%. Policies were associated with decreases in pathogen circulation of human rhinovirus/enterovirus and human metapneumovirus, as well as influenza A, which typically decrease after winter. Parainfluenza viruses failed to circulate at historical levels during the spring. Total detection rate in April 2020 was 35% less than historical average. Many of the pathogens driving this difference fell below historical detection rate ranges within two weeks of initial policy implementation. Conclusion This analysis investigated the effect of multiple social distancing policies implemented to reduce transmission of SARS-CoV-2 on non-SARS-CoV-2 respiratory pathogens. These findings suggest that social distancing policies may be used as an impactful public health tool to reduce communicable respiratory illness.

scholarly journals Comparison of colonoscopy after colonic diverticulitis and positive fecal immunochemical tests for the detection of colorectal neoplasia

2021 ◽  
Vol 09 (03) ◽  
pp. E331-E337
Author(s):  
Dai Nakamatsu ◽  
Tsutomu Nishida ◽  
Shinji Kuriki ◽  
Li-sa Chang ◽  
Kazuki Aochi ◽  
...  
Keyword(s):  
Detection Rate ◽  
Colorectal Neoplasia ◽  
Acute Diverticulitis ◽  
Colonic Diverticulitis ◽  
Detection Rates ◽  
Positive Group ◽  
Asymptomatic Patients ◽  
Polyp Detection Rate ◽  
Adenoma Detection ◽  
Acute Colonic Diverticulitis

Abstract Background and study aims The relationship between acute colonic diverticulitis and colorectal cancer (CRC) is unclear, but colonoscopy is recommended to exclude malignancy. We compared the detection rates for colorectal neoplasia in patients with colonic diverticulitis and asymptomatic patients who had positive fecal immunochemical tests (FITs). Patients and methods In total, 282 patients with acute colonic diverticulitis were hospitalized in our hospital from February 2011 to December 2019. Of them, 143 patients with diverticulitis and 1819 with positive FITs patients during the same period underwent colonoscopy without a prior colonoscopy within 5 years. We retrospectively compared these patients in terms of the invasive CRC rate, advanced neoplasia detection rate (ANDR), adenoma detection rate (ADR), and polyp detection rate (PDR). Results Compared to the diverticulitis group, the FIT-positive group had a significantly higher CRC rate (0 vs 2.7 %, P = 0.0061), ANDR (5.6 vs. 14.0 %, P = 0.0017), ADR (19.6 vs. 53.2 %, P < .0001), and PDR (44.1 vs. 91.0 %, P < .0001). Using 1:1 propensity score matching based on age and sex, we obtained 276 matched patients in both groups. After matching, no difference was found in the CRC rate (0 vs 0.7 %) or ANDR (5.8 vs 7.3 %) between groups, but the ADR and PDR were significantly higher in the FIT-positive group (20.3 vs 43.5 %, P < .0001; 45.7 % vs 86.2 %, P < .0001). Conclusion Patients with acute diverticulitis had lower ADRs and PDRs than patients with positive FITs.

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