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New Method Using Growth Dynamics to Quantify Microbial Contamination of Kaolinite Slurries
- Christopher W. Smith, Christopher M. Babb, Sara J. Snapp, Glenda B. Kohlhagen, Andrei L. Barkovskii
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- Clays and Clay Minerals / Volume 61 / Issue 6 / December 2013
- Published online by Cambridge University Press:
- 01 January 2024, pp. 517-524
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The early and sensitive detection of microbial contamination of kaolinite slurries is needed for timely treatment to prevent spoilage. The sensitivity, reproducibility, and time required by current methods, such as the dip-slide method, do not meet this challenge. A more sensitive, reproducible, and efficient method is required. The objective of the present study was to develop and validate such a method. The new method is based on the measured growth kinetics of indigenous kaolinite-slurry microorganisms. The microorganisms from kaolinite slurries with different contamination levels were eluted and quantified as colony-forming units (CFUs). Known quantities of E. coli (ATCC 11775) were inoculated into sterilized kaolinite slurries to relate kaolinite-slurry CFUs to true microbial concentrations. The inoculated slurries were subsequently incubated, re-extracted, and microbial concentrations quantified. The ratio of the known inoculated E. coli concentration to the measured concentration was expressed as the recovery efficiency coefficient. Indigenous microbial communities were serially diluted, incubated, and the growth kinetics measured and related to CFUs. Using the new method, greater optical densities (OD) and visible microbial growth were measured for greater dilutions of kaolinite slurries with large microbial-cell concentrations. Growth conditions were optimized to maximize the correlation between contamination level, microbial growth kinetics, and OD value. A Standard Bacterial Unit (SBU) scale with five levels of microbial contamination was designed for kaolinite slurries using the experimental results. The SBU scale was validated using a blind test of 50 unknown slurry samples with various contamination levels provided by the Imerys Company. The validation tests revealed that the new method using the SBU scale was more time efficient, sensitive, and reproducible than the dip-slide method.
Helium as a Surrogate for Deuterium in LPI Studies
- Matthias Geissel, Adam J. Harvey-Thompson, Matthew R. Weis, Jeffrey R. Fein, David Ampleford, David E. Bliss, Aaron M. Hansen, Christopher Jennings, Mark W. Kimmel, Patrick Rambo, Jonathon E. Shores, Ian C. Smith, C. Shane Speas, John L. Porter, Fabrizio Consoli
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- Laser and Particle Beams / Volume 2023 / 2023
- Published online by Cambridge University Press:
- 01 January 2024, e2
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Helium or neopentane can be used as surrogate gas fill for deuterium (D2) or deuterium-tritium (DT) in laser-plasma interaction studies. Surrogates are convenient to avoid flammability hazards or the integration of cryogenics in an experiment. To test the degree of equivalency between deuterium and helium, experiments were conducted in the Pecos target chamber at Sandia National Laboratories. Observables such as laser propagation and signatures of laser-plasma instabilities (LPI) were recorded for multiple laser and target configurations. It was found that some observables can differ significantly despite the apparent similarity of the gases with respect to molecular charge and weight. While a qualitative behaviour of the interaction may very well be studied by finding a suitable compromise of laser absorption, electron density, and LPI cross sections, a quantitative investigation of expected values for deuterium fills at high laser intensities is not likely to succeed with surrogate gases.
56 Dunning-Kruger Effect and Anxiety in a Mexican population
- Natalia L. Acosta, Krissy E. Smith, Tara L. Victor, David H. Hardy, Alberto L. Fernandez, Raymundo Cervantes, Ana Paula P. Quiñones, Carolina G. Castañeda, Jill Razani, Isabel D.C. Muñoz, Daniel W. Lopez-Hernandez
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- Journal:
- Journal of the International Neuropsychological Society / Volume 29 / Issue s1 / November 2023
- Published online by Cambridge University Press:
- 21 December 2023, pp. 841-842
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Objective:
The Dunning-Krueger effect is a cognitive bias where individuals tend to overestimate their abilities in areas where they are less competent. The Cordoba Naming Test (CNT) is a 30-item confrontation naming task. Hardy and Wright (2018) conditionally validated a measure of perceived mental workload called the NASA Task Load Index (NASA-TLX). Researchers reported that workload ratings on the NASA-TLX increased with increased task demands on a cognitive task. Anxiety is known as an emotion that can make an individual more susceptible to develop a mental health condition. We examine if the Dunning-Krueger effect occurs in a Mexican population with and without current symptoms of anxiety and possible factors driving individuals to overestimate their abilities on the CNT. We predicted the abnormal symptoms of anxiety (ASA) group would report better CNT performance, report higher perceived workloads on the CNT, and underperform on the CNT compared to the normal symptoms of anxiety (NSA) group. We also predicted the low-performance group would report better CNT performance, report higher perceived workloads on the CNT, and underperform on the CNT compared to the high-performance group.
Participants and Methods:The sample consisted of 192 Mexican participants with NSA (79 low-performance & 113 high-performance) and 74 Mexican participants with ASA (44 low-performance & 30 high-performance). Participants completed the CNT, NASA-TLX, and the Hospital Anxiety and Depression Scale (HADS) in Spanish. The NASA-TLX was used to evaluate perceived workloads after the completion of the CNT. Meanwhile, the HADS was used to create our anxiety groups. Finally, CNT raw scores were converted into T-scores, which then were averaged to create the following two groups: low-performance (CNT T-Score <50) and high-performance (CNT T-Score 50+). A series of 2x2 ANCOVAs, controlling for gender were used to evaluate CNT performance and perceived workloads.
Results:We found a significant interaction where the low-performance ASA and the high-performance NSA groups demonstrated better CNT performance and reported higher perceived workloads (i.e., performance, temporal demand) on the CNT compared to their respective counterparts (i.e., low-performance NSA & high-performance ASA groups), p's<.05, ηp's2=.02. We found a main effect where the high-performance group outperformed the low-performance group on the CNT and reported lower perceived workloads on the CNT, p's<.05, ηp's2 =.04-.46.
Conclusions:The Dunning-Krueger effect did not occur in our sample. Participants that demonstrated better CNT performance also reported higher perceived workloads regardless of their current symptoms of anxiety. A possible explanation can be our sample's cultural norms of what would be considered as abnormal symptoms of anxiety, is a normal part of life, decreasing the possibilities to experience self-efficacy distoritions. Future studies should investigate whether the Dunning-Kruger effect may be influencing other aspects of cognitive functioning subjectively in Mexicans residing in Mexico and the United States with and without current symptoms of anxiety.
35 Bilingualism and Time Perspective in Hispanic-Americans Speed Attention
- Daniel W. Lopez-Hernandez, Krissy E. Smith, Isabel D. C. Munoz, Tara L. Victor
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- Journal:
- Journal of the International Neuropsychological Society / Volume 29 / Issue s1 / November 2023
- Published online by Cambridge University Press:
- 21 December 2023, pp. 447-448
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Objective:
Differences between monolinguals and bilinguals have been documented in neuropsychological test performance. Various explanations have been provided to explain why differences exist among these language groups. Hispanic-Americans are individuals born and reside in the United States and have a family background extending to one of the Spanish-speaking countries in Latin America or Spain. Furthermore, Hispanic-American children from Hispanic homes where Spanish is their first language find themselves academically at a disadvantage because their English vocabulary may be lower than English monolinguals. Time perspective (TP) refers to an individual’s orientation towards the past, present, or future. One’s ability to change their TP in order to adapt to changes in cultural context can result in optimal psychological well-being. In one study, researchers reported no relationship existed between ethnicity and TP on cognition. To our knowledge, no study has examined the relationship between language and TP in Hispanic-Americans’ speed attention performance. Therefore, it was predicted that monolinguals would outperform bilinguals on speed attention tasks. Next, it was predicted that monolinguals would report higher scores on future time orientation compared to bilinguals, and bilinguals would report higher scores on past and present time orientation compared to monolinguals. Finally, differences in TP would correlate with speed attention tasks between language groups.
Participants and Methods:The sample consisted of 119 Hispanic-Americans with a mean age of 19.45 (SD = 1.43). Participants were broken into three groups: English first language monolingual (EFLM), English first language bilingual (EFLB), and English second language bilingual (ESLB). The Comalli Stroop part A and B, Trail Making Test part A, and Symbol Digit Modalities Test written and oral parts were used to evaluate speed attention and the Zimbardo Time Perspective Inventory was used to evaluate time orientation in our sample.
Results:ANOVAs revealed the EFLM group outperformed the ESLB group on the Comalli Stroop part B, p = .020, np2 = .07. Next, we also found on the Symbol Digit Modalities Test written part the EFLB group outperformed both bilingual groups, p = .025, np2 = .06. Regarding TP, the EFLB group reported higher past negative orientation compared to the EFLM group, p = .033, np2 = .06. Additionally, we found the bilingual groups reported higher present-fatalistic compared to the EFLM group, p = .023, np2 = .06. Pearson’s correlation revealed no significant correlations between TP and speed attention tasks on any of our language groups.
Conclusions:As expected, the EFLM group outperformed the ESLB group on several speed attention tasks, but the EFLM group only outperformed the EFLB group on the Symbol Digit Modalities Test written part. Additionally, we found that our EFLB sample reported higher orientation of the past and present compared to monolinguals. Our sample level of acculturation could have been a factor influencing the relationship between TP and speed attention. Future studies using larger representative samples should include measures of acculturation and examine if TP influences other cognitive domains (e.g., executive function) in Hispanic-American monolingual and bilingual speakers.
8 The Dunning-Kruger Effect on a Latinx Population
- Carolina Garza Castaneda, Matthew J. Wright, Raymundo Cervantes, Tara L. Victor, Krissy E. Smith, Chelsea McElwee, Adriana Cuello, Alberto L. Fernandez, Isabel D. C. Munoz, David J. Hardy, Daniel W. Lopez-Hernandez
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- Journal:
- Journal of the International Neuropsychological Society / Volume 29 / Issue s1 / November 2023
- Published online by Cambridge University Press:
- 21 December 2023, pp. 423-424
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Objective:
Individuals tend to overestimate their abilities in areas where they are less competent. This cognitive bias is known as the Dunning-Krueger effect. Research shows that Dunning-Krueger effect occurs in persons with traumatic brain injury and healthy comparison participants. It was suggested by Walker and colleagues (2017) that the deficits in cognitive awareness may be due to brain injury. Confrontational naming tasks (e.g., Boston Naming Test) are used to evaluate language abilities. The Cordoba Naming Test (CNT) is a 30-item confrontational naming task developed to be administered in multiple languages. Hardy and Wright (2018) conditionally validated a measure of perceived mental workload called the NASA Task Load Index (NASA-TLX). They found that workload ratings on the NASA-TLX increased with increased task demands on a cognitive task. The purpose of the present study was to determine whether the Dunning-Kruger effect occurs in a Latinx population and possible factors driving individuals to overestimate their abilities on the CNT. We predicted the low-performance group would report better CNT performance, but underperform on the CNT compared to the high-performance group.
Participants and Methods:The sample consisted of 129 Latinx participants with a mean age of 21.07 (SD = 4.57). Participants were neurologically and psychologically healthy. Our sample was divided into two groups: the low-performance group and the high-performance group. Participants completed the CNT and the NASA-TLX in English. The NASA-TLX examines perceived workload (e.g., performance) and it was used in the present study to evaluate possible factors driving individuals to overestimate their abilities on the CNT. Participants completed the NASA-TLX after completing the CNT. Moreover, the CNT raw scores were averaged to create the following two groups: low-performance (CNT raw score <17) and high-performance (CNT raw score 18+). A series of ANCOVA's, controlling for gender and years of education completed were used to evaluate CNT performance and CNT perceived workloads.
Results:We found the low-performance group reported better performance on the CNT compared to the high-performance, p = .021, np2 = .04. However, the high-performance group outperformed the low-performance group on the CNT, p = .000, np2 = .53. Additionally, results revealed the low-performance group reported higher temporal demand and effort levels on the CNT compared to the high-performance group, p's < .05, nps2 = .05.
Conclusions:As we predicted, the low-performance group overestimated their CNT performance compared to the high-performance group. The current data suggest that the Dunning-Kruger effect occurs in healthy Latinx participants. We also found that temporal demand and effort may be influencing awareness in the low-performance group CNT performance compared to the high-performance group. The present study suggests subjective features on what may be influencing confrontational naming task performance in low-performance individuals more than highperformance individuals on the CNT. Current literature shows that bilingual speakers underperformed on confrontational naming tasks compared to monolingual speakers. Future studies should investigate if the Dunning-Kruger effects Latinx English monolingual speakers compared to Spanish-English bilingual speakers on the CNT.
A cluster of three extrapulmonary Mycobacterium abscessus infections linked to well-maintained water-based heater-cooler devices
- Jessica L. Seidelman, Arthur W. Baker, Sarah S. Lewis, Bobby G. Warren, Aaron Barrett, Amanda Graves, Carly King, Bonnie Taylor, Jill Engel, Desiree Bonnadonna, Carmelo Milano, Richard J. Wallace, Matthew Stiegel, Deverick J. Anderson, Becky A. Smith
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- Infection Control & Hospital Epidemiology / Volume 45 / Issue 5 / May 2024
- Published online by Cambridge University Press:
- 21 December 2023, pp. 644-650
- Print publication:
- May 2024
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Background:
Various water-based heater-cooler devices (HCDs) have been implicated in nontuberculous mycobacteria outbreaks. Ongoing rigorous surveillance for healthcare-associated M. abscessus (HA-Mab) put in place following a prior institutional outbreak of M. abscessus alerted investigators to a cluster of 3 extrapulmonary M. abscessus infections among patients who had undergone cardiothoracic surgery.
Methods:Investigators convened a multidisciplinary team and launched a comprehensive investigation to identify potential sources of M. abscessus in the healthcare setting. Adherence to tap water avoidance protocols during patient care and HCD cleaning, disinfection, and maintenance practices were reviewed. Relevant environmental samples were obtained. Patient and environmental M. abscessus isolates were compared using multilocus-sequence typing and pulsed-field gel electrophoresis. Smoke testing was performed to evaluate the potential for aerosol generation and dispersion during HCD use. The entire HCD fleet was replaced to mitigate continued transmission.
Results:Clinical presentations of case patients and epidemiologic data supported intraoperative acquisition. M. abscessus was isolated from HCDs used on patients and molecular comparison with patient isolates demonstrated clonality. Smoke testing simulated aerosolization of M. abscessus from HCDs during device operation. Because the HCD fleet was replaced, no additional extrapulmonary HA-Mab infections due to the unique clone identified in this cluster have been detected.
Conclusions:Despite adhering to HCD cleaning and disinfection strategies beyond manufacturer instructions for use, HCDs became colonized with and ultimately transmitted M. abscessus to 3 patients. Design modifications to better contain aerosols or filter exhaust during device operation are needed to prevent NTM transmission events from water-based HCDs.
25 Exploring Phonemic and Semantic Fluency Ability Across Multiple Generations
- Krithika Sivaramakrishnan, Dorthy Schmidt, Krissy E Smith, Brittany Heuchert, Adriana C Cuello, Natalia L Acosta, Miriam Gomez, Isabel D Munoz, Yvette D Jesus, Daniel W Lopez-Hernandez
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- Journal:
- Journal of the International Neuropsychological Society / Volume 29 / Issue s1 / November 2023
- Published online by Cambridge University Press:
- 21 December 2023, pp. 438-439
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Objective:
Verbal fluency tasks evaluate executive functioning by requiring a person to provide words within a certain time period that start with a certain letter (phonemic fluency) or category (semantic fluency). Research shows that age impacts test takers’ phonemic and semantic verbal fluency performance. In fact, it has been suggested that phonemic verbal fluency peaks around age 30 to 39 and begins to decline at older ages. In contrast to phonemic fluency, research suggests that semantic fluency increases steadily between test takers until age 12 and begins declining around age 20. A generation is a cohort of people born within a certain period who share age and experiences. Studies show that Generation X individuals (persons born between 1965-1980) outperform Generation Y (persons born between 19811995) and Generation Z individuals (persons born between 1965-1980) on the Cordoba Naming Test. To our knowledge, no study has investigated verbal fluency performance across generational groups. We predicted that Generation X individuals would outperform individuals from Generation Y and Z on both verbal fluency measures.
Participants and Methods:The sample of the present study consisted of 107 participants with a mean age of 27.39 (SD = 9.16). Participants were divided into three groups: Generation X (n = 19), Generation Y (n = 52), and Generation Z (n = 36). The phonemic verbal fluency task consisted of three trials and the semantic verbal fluency task consisted of one trial, one minute each. A series of ANCOVAs with Bonferroni post-hoc tests were used to evaluate verbal fluency performance between generational groups. All participants passed performance validity testing.
Results:We found significant differences between our generational groups on both verbal fluency tasks. Post-hoc tests revealed that the Generation Y group outperformed both Generation X and Z groups on both verbal fluency tasks, p’s <.05, np2 =.11 -.16. No significant differences were found on either verbal fluency task between the Generation X and Z groups.
Conclusions:Contrary to our hypothesis, Generation Y individuals possessed better phonemic and semantic fluency than both Generation X and Z individuals. Meanwhile, Generation X individuals did not significantly differ on any of the verbal fluency tasks compared to Generation Z individuals. Speaking multiple languages has been shown to impact verbal fluency performance. In our sample, the Generation X and Z groups consisted primarily of bilingual speakers compared to the Generation Y group. Examining generational differences is essential to understand the unique characteristics and impact of the times in which various individuals have grown up. Future research, for instance, should evaluate the influence of bilingualism across generational groups on verbal fluency performance.
83 Performance Validity in a Monolingual and Bilingual Undergraduate Population
- Daniel W. Lopez-Hernandez, Krissy E. Smith, Kyle B. Boone, Tara L. Victor
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- Journal:
- Journal of the International Neuropsychological Society / Volume 29 / Issue s1 / November 2023
- Published online by Cambridge University Press:
- 21 December 2023, pp. 756-757
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Objective:
Neuropsychological evaluations are used to examine a person’s current cognitive functioning. Performance validity tests (PVT) are included in neuropsychological test batteries to ensure that examinees are performing to the best of their abilities and identify non-credible performance. There are two types of PVTs: freestanding and embedded. A freestanding PVT is a cognitive test created to evaluate performance validity and do not measure any type of cognition directly. Meanwhile, an embedded PVT is a task design to evaluate some sort of cognition (e.g., memory) by using traditional neuropsychological tests (e.g., Trail Making Test) and performance validity. Research suggests that undergraduate college students are not always performing to the best of their abilities when completing a comprehensive neuropsychological battery. In fact, in one study where an undergraduate college sample was given three PVTs, it was reported that 56% of the participants failed at least one PVT in their first session and 31% in their second session. Research has also shown that speaking multiple languages can influence cognition. The purpose of this study was to identify in three credible language groups of college students what PVTs does bilingualism influence higher failure rates. It was predicted that bilingual college students would significantly demonstrate higher PVTs failure rates compared to monolingual college students.
Participants and Methods:The sample consisted of 70 English first language monolinguals (EFLM), 33 English first language bilinguals (EFLB), and 68 English second language bilinguals (ESLB) that were psychologically and neurologically healthy. All participants completed a comprehensive neuropsychological battery in English. The Rey-Osterrith complex figure copy test, Comalli Stroop part A, B, and C, Trail Making Test part A and B, Symbol Digit Modalities Test written and oral parts, Controlled Oral Word Association Test (COWAT) letter fluency, and Finger Tapping Test were the tasks used as embedded PVTs to evaluate failure rates in our sample. Moreover, all participants were credible (i.e., they did not fail two or more PVTs). PVT cutoff scores were selected for each embedded PVT from previous literature. Chi-square analysis were used to evaluate failure rates between language groups on each PVT.
Results:We found no significant failure rate differences between language groups on any of the PVTs. However, while no significant group differences were found, on the COWAT letter fluency results revealed higher failure rates between the three language groups (i.e., 13% EFLM, 24% EFLB, and 22% ESLB) compared to other PVTs.
Conclusions:Our data suggested no significant failure rate differences between language groups. It has been suggested in previous studies that linguistic factors impact PVT performance and test interpretation. On the COWAT letter fluency task, it is possible that language is driving higher failure rates between bilingual speakers, even though we found no significant failure rates or performance differences between the three language groups. Future studies should examine language groups and other cultural variables (e.g., time perspective) to determine what may be driving high failure rates on the COWAT letter fluency task in credible participants.
24 The Influence of Acculturation in Neuropsychological Test Performance of Hispanic-Americans
- Krissy E. Smith, Tara L. Victor, Chelsea McElwee, Daniel W. Lopez-Hernandez
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- Journal:
- Journal of the International Neuropsychological Society / Volume 29 / Issue s1 / November 2023
- Published online by Cambridge University Press:
- 21 December 2023, pp. 437-438
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Objective:
Stephenson (2000) suggested that acculturation is a phenomenon that immigrants and refugees ubiquitously experience. The level of acculturation is impacted by a person’s choice to allow how much of their cultural traits they decide to keep while adapting to the dominant society cultural traits. Depending on what immigrants find to be important or unimportant, it can influence future generations (i.e., their children) in how they will be developed and adapt into a dominant society. Hispanic-Americans are individuals that were born and reside in the United States and have a family background that extends to one of the Spanish speaking countries in Latin America or Spain. The typical language spoken by Hispanic families other than English is Spanish. It has been reported that Hispanics that are capable of speaking English may be afforded better and greater opportunities to resources. Research shows that a person level of acculturation can influence their cognition. In fact, in one study using a Mexican-American sample that was divided into two groups: high and low. Researchers found that highly acculturated Mexican-Americans outperformed lower acculturated Mexican-Americans on the Wisconsin Card Sorting Test. We evaluated the influence of acculturation in Hispanic-Americans neuropsychological test performance. It was predicted that highly acculturated Hispanic-Americans to American culture would demonstrate better cognitive abilities compared to lower acculturated Hispanic-Americans.
Participants and Methods:The present study sample consisted of 75 neurologically and psychologically healthy Hispanic-American undergraduate students with a mean age of 19.44 (SD = 1.37). Participants were divided into two acculturation groups: high (n = 39) and low (n = 36). In addition, all the participants completed a comprehensive neuropsychological battery and background questionnaire in English. The Acculturation Rating Scale for Hispanic/Latino Americans is a 20-item scale that was utilized to create our acculturation groups. ANOVAs were used to evaluate cognitive differences between our acculturation groups.
Results:Results revealed that the highly acculturated group outperformed the lower acculturated group on the Weschler Adult Intelligence Scale-Third Edition vocabulary task and the Boston Naming Test, p’s<.05, n.p’s2=.06. Furthermore, results revealed that the lower acculturated group outperformed the highly acculturated group on the Trail Making Test part A and B, and Comalli Stroop part A, p’s<.05, np’s2=.06-.07.
Conclusions:As expected, the highly acculturated group demonstrated better language abilities compared to the lower acculturated group. However, in the opposite direction, the lower acculturated group outperformed the highly acculturated group on several speed attention tasks and one executive functioning task. A possible explanation why the highly acculturated participants demonstrated better language abilities may be attributed that their dominant language is English or they only spoke English. Meanwhile, the opposite could be said for lower acculturated participants that English was not their dominant language or they were bilingual speakers, for that reason they demonstrated better processing speed and executive functioning abilities. Research shows that monolinguals demonstrate better language abilities compared to bilinguals, but the opposite is found on processing speed and executive functioning tasks. Future research should investigate the relationship between bilingualism and acculturation in neuropsychological testing performance of Hispanic-Americans.
42 Lexical Retrieval and Acculturation in Generation Z Mexicans
- Yvette D Jesus, Krissy E Smith, Krithika Sivaramakrishnan, Reymundo Cervantes, Tara L Victor, Brittany Heuchert, Dorthy Schmidt, Diana Palacios, Chelsea McElwee, David J Hardy, Enrique Lopez, Alberto L Fernandez, Daniel W Lopez Hernandez
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- Journal:
- Journal of the International Neuropsychological Society / Volume 29 / Issue s1 / November 2023
- Published online by Cambridge University Press:
- 21 December 2023, p. 453
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Objective:
The Cordoba Naming Test (CNT) is a 30-item lexical retrieval task that was developed to be administered in multiple languages. Research shows that self-identifying Mexicans residing in Mexico outperform self-identifying Mexicans that reside in the United States on the CNT. Studies indicate that the process of acculturation can influence cognitive performance. Previous studies demonstrated that Generation Z individuals (i.e., people born between 1997 and 2012) have underperformed on the CNT compared to Generation Y individuals (i.e., people born between 1981 and 1996). To our knowledge, no study has examined the influence of acculturation on Generation Z Mexicans’ CNT performance. We expected Mexicans residing in Mexico (MRM) to outperform Mexicans residing in the United States on the CNT and to report higher acculturation traits. We also predicted that acculturation would correlate with CNT performance.
Participants and Methods:The present study sample consisted of 285 Generation Z psychologically and neurologically healthy Mexicans with a mean age of 20.32 (SD = 1.60). Participants were divided into three groups: MRM, Mexicans residing in the United States, and Mexican-Americans residing in the United States (MARUS). All participants completed the CNT and acculturation measure in Spanish. Acculturation traits were measured by the Abbreviated Multidimensional Acculturation Scale (AMAS). ANCOVAs were used to evaluate differences in the CNT and AMAS (i.e., Spanish language, Latino competency, Latino identity). Pearson’s correlation coefficient was used to evaluate the relationship between acculturation on CNT performance.
Results:MRM outperformed the Mexicans residing in the United States and MARUS on the CNT, p = .000, np2 = .49. The MRM group reported better Spanish language abilities compared to Mexicans residing in the United States and the MARUS groups, p = .000, np2 = .10. Additionally, MRM reported better Latino competency than the MARUS group, p = .000, np2 = .08. Pearson’s correlation coefficient revealed that the MARUS’s Spanish language abilities impacted CNT performance, p = .000, r = .48. In addition, we found that Latino competency correlated with CNT performance, p’s < .05, r’s = .20-.47, in both the MRM and Mexicans residing in the United States groups. Latino identity did not significantly correlate with CNT performance in any group.
Conclusions:Results confirmed that MRM individuals perform better on the CNT than Mexicans residing in the United States and MARUS. Additionally, we found that several acculturation traits correlated with Mexican groups’ CNT performance. Our research indicates that while all Generation Z individuals of Mexican heritage feel strongly connected to their Latino identity regardless of where they live, MARUS feel less competent in Spanish and Latinx culture than MRM and Mexicans residing in the United States. Future work should further explore these differences for better insight into how acculturative factors influence lexical retrieval performance. Future work with bigger sample sizes can additionally examine CNT performance and acculturation in Generation Z first-generation and non-first-generation Mexicans (e.g., second-generation, third-generation) residing in the United States.
22 Cordoba Naming Test Performance and Acculturation in a Geriatric Population
- Isabel C.D. Muñoz, Krissy E. Smith, Santiago I. Espinoza, Diana M. R. Maqueda, Adriana C. Cuello, Ana Paula Pena, Carolina Garza, Raymundo Cervantes, Jill Razani, Tara L. Victor, David J. Hardy, Alberto L. Fernandez, Natalia Lozano Acosta, Daniel W. Lopez-Hernandez
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- Journal:
- Journal of the International Neuropsychological Society / Volume 29 / Issue s1 / November 2023
- Published online by Cambridge University Press:
- 21 December 2023, pp. 335-336
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Objective:
A commonly used confrontation naming task used in the United States is The Boston Naming Test (BNT). Performance differences has been found in Caucasian and ethnic minorities on the BNT. The Cordoba Naming Test (CNT) is a 30-item confrontation naming task developed in Argentina. Past research has shown acculturation levels can influence cognitive performance. Furthermore, one study evaluated geriatric gender differences on CNT performance in Spanish. Researchers reported that older male participants outperformed female participants on the CNT. To our knowledge, researchers have not evaluated ethnic differences on the CNT using a geriatric sample. The purpose of the present study was to examined CNT performance and acculturation in a Latinx and Caucasian geriatric sample. It was predicted the Caucasian group would outperform the Latinx group on the CNT. Moreover, the Caucasian group would report higher acculturation levels on the Abbreviated Multidimensional Acculturation Scale (AMAS) compared to the Latinx group.
Participants and Methods:The sample consisted of 9 Latinx and 11 Caucasian participants with a mean age of 66.80 (SD =6.10), with an average of 14.30 (SD = 2.00) years of education. All participants were neurologically and psychologically healthy and completed the CNT and the AMAS in English. Acculturation was measured via the AMAS English subscales (i.e., English Language, United States. Identity, United States, Competency). A series of ANCOVAs, controlling for years of education completed and gender, was used to evaluate CNT performance and acculturation.
Results:The ethnic groups were not well demographically matched (i.e., years of education and gender).We found that the Caucasian group outperformed the Latinx group on CNT performance p = .012, ηp 2 = .34. Furthermore, the Caucasian group reported higher acculturation levels (i.e., English Language, United States, Identity, United States, Competency) compared to the Latinx group p’s < .05, ηps2 = .42-.64.
Conclusions:To our knowledge, this is the first study to evaluate CNT performance between ethnic groups with a geriatric sample. As expected the Caucasian group outperformed the Latinx group on the CNT. Also, as expected the Caucasian group reported higher English acculturation levels compared to the Latinx group. Our findings are consistent with past studies showing ethnic differences on confrontational naming performance (i.e., The Boston Naming Test), favoring Caucasians. A possible explanation for group differences could have been linguistic factors (e.g., speaking multiple languages) in our Latinx group. Therefore, since our Latinx group reported lower levels of English Language, United States identity, and United States competency the Latinx group assimilation towards United States culture might of influence their CNT performance. Future studies with different ethnic groups (e.g., African-Americans) and a larger sample size should examine if ethnic differences continue to cross-validate in a geriatric sample.
34 The Influence of Bilingualism in Young Adults
- Daniel W. Lopez-Hernandez, Krissy E. Smith, Chelsea McElwee, Tara L. Victor
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- Journal:
- Journal of the International Neuropsychological Society / Volume 29 / Issue s1 / November 2023
- Published online by Cambridge University Press:
- 21 December 2023, pp. 446-447
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Objective:
The research examining the influence of bilingualism on cognition continues to grow. Past research shows that monolingual speakers outperformed bilingual speakers on language, memory, and attention and processing speed tasks. However, the opposite has been found favoring bilingual speakers, when comparing executive functioning abilities. Furthermore, researchers have reported that no differences in executive functioning abilities exist between young adult monolingual speakers compared to young adult bilingual speakers. Moreover, limited research exists examining cognition abilities between monolinguals, bilinguals that learn a language (e.g., English) first, and bilinguals that learn the same language (e.g., English) second. We examined young adult monolinguals cognition abilities (e.g., memory) compared to young adult bilinguals that learned English as a first or second language. It was expected that the monolingual group would outperform both bilingual groups on memory, language, and attention and processing tasks, but no differences would be found on executive functioning tasks.
Participants and Methods:The sample consisted of 149 right-handed undergraduate students with a mean age of 19.58 (SD = 1.90). Participants were neurologically and psychologically healthy and divided into three language groups: English first language (EFL) monolingual speakers, EFL bilingual speakers, and English second language (ESL) bilingual speakers. All the participants completed a background questionnaire and comprehensive neuropsychological battery that included memory, language, executive functioning, and attention and processing speed tasks in English. A series of ANOVA’s were used to evaluate cognitive tasks (e.g., Boston Naming Test, Trail Making Test) between the language groups. Participants demonstrated adequate effort on one performance validity test.
Results:Language groups were well demographically matched. We found the EFL monolingual group outperformed the ESL bilingual group on the Wide Range Achievement Test, fourth edition task and the Controlled Oral Word Association Test (COWAT) phonemic task, p’s < .05, np’s2 = .04-.05. Additionally, results revealed both monolingual groups outperformed the ESL bilingual group on the Wechsler Adult Intelligence Scale, Third edition vocabulary task and the Boston Naming Test, p’s < .05, np’s2 = .06-.15. No significant differences were found on any of the cognitive tasks between the EFL monolingual group and the EFL bilingual group.
Conclusions:As expected, the ESL bilingual group performed worse on language tasks compared to both monolingual groups, specifically the EFL monolingual group. However, in the opposite direction, we found the EFL monolingual demonstrated better phonemic verbal fluency abilities on the COWAT compared to the ESL bilingual group. The current data suggest that bilingualism influences cognitive abilities (e.g., language, executive functioning) more ESL bilingual speakers compared to EFL monolingual speakers. A possible explanation may be due to the type of interaction that ESL bilingual speakers may prefer to have (i.e., mix language conversations) compared to EFL speaking groups. Future studies with a larger bilingual speaking sample should investigate if the Adaptive Control Hypothesis which suggest that different types of conversations may be placing different demands of language control influences cognitive abilities.
30 Analyzing Spanish Speakers Cordoba Naming Test Performance
- Raymundo Cervantes, Isabel D.C. Munoz, Estefania J. Aguirre, Natalia Lozano Acosta, Mariam Gomez, Adriana C. Cuello, Krissy E. Smith, Diana I. Palacios Mata, Krithika Sivaramakrishnan, Yvette De Jesus, Santiago I. Espinoza, Diana M. R. Maqueda, David J. Hardy, Tara L. Victor, Alberto L. Fernandez, Daniel W. Lopez-Hernandez
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- Journal:
- Journal of the International Neuropsychological Society / Volume 29 / Issue s1 / November 2023
- Published online by Cambridge University Press:
- 21 December 2023, pp. 443-444
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Objective:
A 30-item confrontation naming test was developed in Argentina for Spanish speakers, The Cordoba Naming Test (CNT). The Boston Naming Test is an established confrontation naming task in the United States. Researchers have used the Boston Naming Test to identify individuals with different clinical pathologies (e.g., Alzheimer’s disease). The current literature on how Spanish speakers across various countries perform on confrontational naming tasks is limited. To our knowledge, one study investigated CNT performance across three Spanish-speaking countries (i.e., Argentina, Mexico, and Guatemala). Investigators found that the Guatemalan group underperformed on the CNT compared to the Argentine and Mexican groups. The purpose of this study was to extend the current literature and investigate CNT performance across five Spanish-speaking countries (i.e., Argentina, Mexico, Guatemala, Colombia, United States). We predicted that the Argentine group would outperform the other Spanish-speaking countries.
Participants and Methods:The present study sample consisted of 502 neurologically and psychologically healthy participants with a mean age of 29.06 (SD = 13.41) with 14.75 years of education completed (SD = 3.01). Participants were divided into five different groups based on their country of birth and current country residency (i.e., United States, Mexico, Guatemala, Argentina, & Colombia). All participants consented to voluntary participation and completed the CNT and a comprehensive background questionnaire in Spanish. The CNT consisted of 30 black and white line drawings, ranging from easy to hard in difficulty. An ANCOVA, controlling for gender, education, and age, was used to evaluate CNT performance between the five Spanish-speaking country groups. Meanwhile, a Bonferroni post-hoc test was utilized to evaluate the significant differences between Spanish-speaking groups. We used a threshold of p < .05 for statistical significance.
Results:Results revealed significant group differences between the five Spanish speaking groups on the CNT, p = .000, np2 = .48. Bonferroni post-hoc test revealed that the United States group significantly underperformed on the CNT compared to all the Spanish-speaking groups. Next, we found the Guatemalan group underperformed on the CNT compared to the Argentinian, Mexican, and Colombian groups. Additionally, we found the Argentinian group outperformed the Mexican, Guatemalan, and United States groups on the CNT. No significant differences were found between the Argentinian group and Colombian group or the Mexican group and Colombian group on the CNT.
Conclusions:As predicted, the Argentinian group outperformed all the Spanish-speaking groups on the CNT except the Colombian group. Additionally, we found that the United States group underperformed on the CNT compared to all the Spanish-speaking groups. A possible explanation is that Spanish is not the official language in the United States compared to the rest of the Spanish-speaking groups. Meanwhile, a possible reason why the Argentinian and Colombian groups demonstrated better CNT performances might have been that it was less culturally sensitive than the United States, Mexican, and Guatemalan groups. Further analysis is needed with bigger sample sizes across other Spanish-speaking countries (e.g., Costa Rica, Chile) to evaluate what variables, if any, are influencing CNT performance.
86 The Examination Between Credible and Non-Credible Groups on Embedded PVT Tests
- Krissy E. Smith, Tara L. Victor, Matthew J. Wright, Kyle B. Boone, Daniel W. Lopez-Hernandez
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- Journal of the International Neuropsychological Society / Volume 29 / Issue s1 / November 2023
- Published online by Cambridge University Press:
- 21 December 2023, pp. 759-760
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Objective:
Performance validity tests (PVTs) are included in neuropsychological testing to ensure examinees are performing to the best of their abilities. There are two types of PVTs: embedded and free standing. Embedded PVTs are tests that are derived from standard neuropsychological tests of various cognitive domains. Freestanding PVTs are tests that are designed with the intention of being a PVT. Research studies show that undergraduate samples do not always performed to the best of their abilities. The purpose of this study was to cross-validate previous research on the topic of performance validity in a college sample. It was predicted that the non-credible group would demonstrate higher failure rates on embedded PVTs compared to the credible group.
Participants and Methods:The sample consisted of 198 neurologically and psychologically healthy undergraduate students with a mean age of 19.69 (SD = 2.11). Participants were broken into two groups: non-credible (i.e., participants that failed two or more PVTs) and credible (i.e., participants that did not failed two or more PVTs). The Rey-Osterrith copy test, Comalli Stroop part A (CSA), B (CSB), and C (CSC), Trail Making Test part A and B, Symbol Digit Modalities Test written (SDMT-W) and oral (SDMT-O) parts, Controlled Oral Word Association Test (COWAT) letter fluency, and Finger Tapping Test were used to evaluate failure rates in our sample. PVT cutoff scores were use from previously validated in the literature. Chi-square analysis was used to evaluate failure rates between the groups.
Results:Chi-square analysis revealed significant failure rate differences between groups on several PVTs. Results revealed that 15% of the non-credible group failed the CSA compared to 1% of the credible group, X2=14.77, p=.000. Meanwhile, 26% of the non-credible group failed the CSB compared to 2% of the credible group, X2=24.72, p=.000. Furthermore, results showed that 11% of the non-credible group failed the CSC compared to 1% of the credible group, X2=13.05, p=.000.Next, 48% of the non-credible group failed the Trail Making Test part A compared to 8% of the credible group, X2=31.61, p=.000. We also found that 15% of the non-credible group failed the SDMT-W part compared to 1% of the credible group,X2=19.18, p=.000. Meanwhile, on the SDMT-O part 19% of the non-credible group failed compared to 1% of the credible group, X2=25.52, p =.000. On the COWAT letter fluency task 74% of the non-credible group failed compared to 19% of the credible group, X2=36.90, p=.000. Finally, results revealed on the Finger Tapping Test 19% of the non-credible group failed compared to 3% of the credible group, X2=10.01, p=.002.
Conclusions:As expected, the non-credible participants demonstrated significantly higher PVT failure rates compared to credible participants. A possible explanation driving higher failure rates in our sample can be due to cultural variables (e.g., bilingualism). It was suggested by researchers that linguistic factors may be impacting higher PVT failure rates and developing a false-positive error. Future research using undergraduate samples need to identify which PVT’s are being impacted by linguist factors.
39 Perceived Workload and Language Order Effects on the Cordoba Naming Test in Spanish-English Bilinguals
- Krissy E. Smith, Isabel D. C. Munoz, Raymundo Cervantes, Andrea R. Preciado, Tara L. Victor, Natalia Garcia, Paula V. Bracho, Enrique Lopez, Alberto L. Fernandez, Yvette De Jesus, Daniel W. Lopez-Hernandez
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- Journal:
- Journal of the International Neuropsychological Society / Volume 29 / Issue s1 / November 2023
- Published online by Cambridge University Press:
- 21 December 2023, pp. 451-452
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The Cordoba Naming Test (CNT) is a 30-item confrontation naming task. The administration of the CNT can be administered in multiple languages. Hardy and Wright (2018) conditionally validated a measure of perceived mental workload called the National Aeronautic Space Administration Task Load Index (NASA-TLX). They found that workload ratings on the NASA-TLX increased with increased demands on a cognitive task. Researchers found interactions in a study examining language proficiency and language (i.e., in which the test was administered) on several tasks of the Golden Stroop Test. Their results revealed that unbalanced bilinguals’ best-spoken language showed significantly better results compared to balanced bilinguals’ where language use did not matter. To our knowledge, no study has examined the order effects of Spanish-English bilingual speakers’ CNT performance and perceived workloads when completed in Spanish first compared to English second and vice-versa. We predicted that persons that completed the CNT in English first would demonstrate better performances and report lower perceived workloads on the CNT compared to completing the CNT in Spanish second. In addition, we predicted that persons that completed the CNT in Spanish first would demonstrate worse performance and higher perceived workloads on the CNT compared to completing the CNT in English second.
Participants and Methods:The sample consisted of 62 Spanish-English healthy and neurologically bilingual speakers with a mean age of 19.94 (SD= 3.36). Thirty-seven participants completed the CNT in English first and then in Spanish (English-to-Spanish) and 25 participants completed the CNT in Spanish first and then in English (Spanish-to-English). The NASA-TLX was used to evaluate CNT perceived workloads. All the participants completed the NASA-TLX in English and Spanish after completing the CNT in the language given, respectfully. A series of paired-samples T-Tests were completed to evaluate groups CNT performance and perceived workload.
Results:We found that the English-to-Spanish group performed better on the CNT in English first than completing it in Spanish second, p = .000. We also found that the English-to-Spanish group reported better performance and less mentally demanding on the CNT when it was completed in English first compared to completing it in Spanish second, p’s < .05. Regarding the Spanish-to-English group, we found participants performed worse when they completed the CNT in Spanish first compared to completing the CNT in English second, p = .000. Finally, the Spanish-to-English group reported worse performance completing the CNT in Spanish first, more temporal demanding, and more frustrating compared to completing the CNT in English second, p’s < .05.
Conclusions:As expected, when participants completed the CNT in English, regardless of the order, they performed better and reported lower perceived workloads compared to completing the CNT in Spanish. Our data suggests that language order effect influenced participants CNT performance possibly due to not knowing specific items in Spanish compared to in English. Future studies using larger sample sizes should evaluate language order effects on the CNT in Spanish-English balanced bilingual speakers compared to unbalanced bilingual speakers.
The Rapid ASKAP Continuum Survey III: Spectra and Polarisation In Cutouts of Extragalactic Sources (SPICE-RACS) first data release
- Alec J. M. Thomson, David McConnell, Emil Lenc, Timothy J. Galvin, Lawrence Rudnick, George Heald, Catherine L. Hale, Stefan W. Duchesne, Craig S. Anderson, Ettore Carretti, Christoph Federrath, B. M. Gaensler, Lisa Harvey-Smith, Marijke Haverkorn, Aidan W. Hotan, Yik Ki Ma, Tara Murphy, N. M. McClure-Griffiths, Vanessa A. Moss, Shane P. O’Sullivan, Wasim Raja, Amit Seta, Cameron L. Van Eck, Jennifer L. West, Matthew T. Whiting, Mark H. Wieringa
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- Journal:
- Publications of the Astronomical Society of Australia / Volume 40 / 2023
- Published online by Cambridge University Press:
- 30 August 2023, e040
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The Australian SKA Pathfinder (ASKAP) radio telescope has carried out a survey of the entire Southern Sky at 887.5 MHz. The wide area, high angular resolution, and broad bandwidth provided by the low-band Rapid ASKAP Continuum Survey (RACS-low) allow the production of a next-generation rotation measure (RM) grid across the entire Southern Sky. Here we introduce this project as Spectral and Polarisation in Cutouts of Extragalactic sources from RACS (SPICE-RACS). In our first data release, we image 30 RACS-low fields in Stokes I, Q, U at 25$^{\prime\prime}$ angular resolution, across 744–1032 MHz with 1 MHz spectral resolution. Using a bespoke, highly parallelised, software pipeline we are able to rapidly process wide-area spectro-polarimetric ASKAP observations. Notably, we use ‘postage stamp’ cutouts to assess the polarisation properties of 105912 radio components detected in total intensity. We find that our Stokes Q and U images have an rms noise of $\sim$80 $\unicode{x03BC}$Jy PSF$^{-1}$, and our correction for instrumental polarisation leakage allows us to characterise components with $\gtrsim$1% polarisation fraction over most of the field of view. We produce a broadband polarised radio component catalogue that contains 5818 RM measurements over an area of $\sim$1300 deg$^{2}$ with an average error in RM of $1.6^{+1.1}_{-1.0}$ rad m$^{-2}$, and an average linear polarisation fraction $3.4^{+3.0}_{-1.6}$ %. We determine this subset of components using the conditions that the polarised signal-to-noise ratio is $>$8, the polarisation fraction is above our estimated polarised leakage, and the Stokes I spectrum has a reliable model. Our catalogue provides an areal density of $4\pm2$ RMs deg$^{-2}$; an increase of $\sim$4 times over the previous state-of-the-art (Taylor, Stil, Sunstrum 2009, ApJ, 702, 1230). Meaning that, having used just 3% of the RACS-low sky area, we have produced the 3rd largest RM catalogue to date. This catalogue has broad applications for studying astrophysical magnetic fields; notably revealing remarkable structure in the Galactic RM sky. We will explore this Galactic structure in a follow-up paper. We will also apply the techniques described here to produce an all-Southern-sky RM catalogue from RACS observations. Finally, we make our catalogue, spectra, images, and processing pipeline publicly available.
The Southern-sky MWA Rapid Two-metre (SMART) pulsar survey—II. Survey status, pulsar census, and first pulsar discoveries – ADDENDUM
- N. D. R. Bhat, N. A. Swainston, S. J. McSweeney, M. Xue, B.W. Meyers, S. Kudale, S. Dai, S. E. Tremblay, W. van Straten, R. M. Shannon, K. R. Smith, M. Sokolowski, S. M. Ord, G. Sleap, A. Williams, P. J. Hancock, R. Lange, J. Tocknell, M. Johnston-Hollitt, D. L. Kaplan, S. J. Tingay, M. Walker
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- Journal:
- Publications of the Astronomical Society of Australia / Volume 40 / 2023
- Published online by Cambridge University Press:
- 18 July 2023, e031
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WALLABY pilot survey: The diversity of HI structural parameters in nearby galaxies
- T. N. Reynolds, B. Catinella, L. Cortese, N. Deg, H. Dénes, A. Elagali, B.-Q. For, P. Kamphuis, D. Kleiner, B. S. Koribalski, K. Lee-Waddell, C. Murugeshan, W. Raja, J. Rhee, K. Spekkens, L. Staveley-Smith, J. M. van der Hulst, J. Wang, T. Westmeier, O. I. Wong, F. Bigiel, A. Bosma, B. W. Holwerda, D. A. Leahy, M. J. Meyer
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- Publications of the Astronomical Society of Australia / Volume 40 / 2023
- Published online by Cambridge University Press:
- 08 June 2023, e032
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We investigate the diversity in the sizes and average surface densities of the neutral atomic hydrogen (H i) gas discs in $\sim$280 nearby galaxies detected by the Widefield ASKAP L-band Legacy All-sky Blind Survey (WALLABY). We combine the uniformly observed, interferometric H i data from pilot observations of the Hydra cluster and NGC 4636 group fields with photometry measured from ultraviolet, optical, and near-infrared imaging surveys to investigate the interplay between stellar structure, star formation, and H i structural parameters. We quantify the H i structure by the size of the H i relative to the optical disc and the average H i surface density measured using effective and isodensity radii. For galaxies resolved by $>$$1.3$ beams, we find that galaxies with higher stellar masses and stellar surface densities tend to have less extended H i discs and lower H i surface densities: the isodensity H i structural parameters show a weak negative dependence on stellar mass and stellar mass surface density. These trends strengthen when we limit our sample to galaxies resolved by $>$2 beams. We find that galaxies with higher H i surface densities and more extended H i discs tend to be more star forming: the isodensity H i structural parameters have stronger correlations with star formation. Normalising the H i disc size by the optical effective radius (instead of the isophotal radius) produces positive correlations with stellar masses and stellar surface densities and removes the correlations with star formation. This is due to the effective and isodensity H i radii increasing with mass at similar rates while, in the optical, the effective radius increases slower than the isophotal radius. Our results are in qualitative agreement with previous studies and demonstrate that with WALLABY we can begin to bridge the gap between small galaxy samples with high spatial resolution H i data and large, statistical studies using spatially unresolved, single-dish data.
The Southern-sky MWA Rapid Two-metre (SMART) pulsar survey—II. Survey status, pulsar census, and first pulsar discoveries
- N. D. R. Bhat, N. A. Swainston, S. J. McSweeney, M. Xue, B.W. Meyers, S. Kudale, S. Dai, S. E. Tremblay, W. van Straten, R. M. Shannon, K. R. Smith, M. Sokolowski, S. M. Ord, G. Sleap, A. Williams, P. J. Hancock, R. Lange, J. Tocknell, M. Johnston-Hollitt, D. L. Kaplan, S. J. Tingay, M. Walker
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- Journal:
- Publications of the Astronomical Society of Australia / Volume 40 / 2023
- Published online by Cambridge University Press:
- 11 April 2023, e020
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In Paper I, we presented an overview of the Southern-sky MWA Rapid Two-metre (SMART) survey, including the survey design and search pipeline. While the combination of MWA’s large field-of-view and the voltage capture system brings a survey speed of ${\sim} 450\, {\textrm{deg}}^{2}\,\textrm{h}^{-1}$, the progression of the survey relies on the availability of compact configuration of the Phase II array. Over the past few years, by taking advantage of multiple windows of opportunity when the compact configuration was available, we have advanced the survey to 75% of the planned sky coverage. To date, about 10% of the data collected thus far have been processed for a first-pass search, where 10 min of observation is processed for dispersion measures out to 250 ${\textrm{pc cm}}^{-3}$, to realise a shallow survey that is largely sensitive to long-period pulsars. The ongoing analysis has led to two new pulsar discoveries, as well as an independent discovery and a rediscovery of a previously incorrectly characterised pulsar, all from ${\sim} 3\% $ of the data for which candidate scrutiny is completed. In this sequel to Paper I, we describe the strategies for further detailed follow-up including improved sky localisation and convergence to timing solution, and illustrate them using example pulsar discoveries. The processing has also led to re-detection of 120 pulsars in the SMART observing band, bringing the total number of pulsars detected to date with the MWA to 180, and these are used to assess the search sensitivity of current processing pipelines. The planned second-pass (deep survey) processing is expected to yield a three-fold increase in sensitivity for long-period pulsars, and a substantial improvement to millisecond pulsars by adopting optimal de-dispersion plans. The SMART survey will complement the highly successful Parkes High Time Resolution Universe survey at 1.2–1.5 GHz, and inform future large survey efforts such as those planned with the low-frequency Square Kilometre Array (SKA-Low).
The Southern-sky MWA Rapid Two-metre (SMART) pulsar survey—I. Survey design and processing pipeline
- N. D. R. Bhat, N. A. Swainston, S. J. McSweeney, M. Xue, B.W. Meyers, S. Kudale, S. Dai, S. E. Tremblay, W. van Straten, R. M. Shannon, K. R. Smith, M. Sokolowski, S. M. Ord, G. Sleap, A. Williams, P. J. Hancock, R. Lange, J. Tocknell, M. Johnston-Hollitt, D. L. Kaplan, S. J. Tingay, M. Walker
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- Publications of the Astronomical Society of Australia / Volume 40 / 2023
- Published online by Cambridge University Press:
- 05 April 2023, e021
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We present an overview of the Southern-sky MWA Rapid Two-metre (SMART) pulsar survey that exploits the Murchison Widefield Array’s large field of view and voltage-capture system to survey the sky south of 30$^{\circ}$ in declination for pulsars and fast transients in the 140–170 MHz band. The survey is enabled by the advent of the Phase II MWA’s compact configuration, which offers an enormous efficiency in beam-forming and processing costs, thereby making an all-sky survey of this magnitude tractable with the MWA. Even with the long dwell times employed for the survey (4800 s), data collection can be completed in $<$100 h of telescope time, while still retaining the ability to reach a limiting sensitivity of $\sim$2–3 mJy (at 150 MHz, near zenith), which is effectively 3–5 times deeper than the previous-generation low-frequency southern-sky pulsar survey, completed in the 1990s. Each observation is processed to generate $\sim$5000–8000 tied-array beams that tessellate the full $\sim 610\, {\textrm{deg}^{2}}$ field of view (at 155 MHz), which are then processed to search for pulsars. The voltage-capture recording of the survey also allows a multitude of post hoc processing options including the reprocessing of data for higher time resolution and even exploring image-based techniques for pulsar candidate identification. Due to the substantial computational cost in pulsar searches at low frequencies, the survey data processing is undertaken in multiple passes: in the first pass, a shallow survey is performed, where 10 min of each observation is processed, reaching about one-third of the full-search sensitivity. Here we present the system overview including details of ongoing processing and initial results. Further details including first pulsar discoveries and a census of low-frequency detections are presented in a companion paper. Future plans include deeper searches to reach the full sensitivity and acceleration searches to target binary and millisecond pulsars. Our simulation analysis forecasts $\sim$300 new pulsars upon the completion of full processing. The SMART survey will also generate a complete digital record of the low-frequency sky, which will serve as a valuable reference for future pulsar searches planned with the low-frequency Square Kilometre Array.