bluuebunny/crossref_metadata_2025 huggingface dataset:
Factors influencing obesity among preschoolers: multilevel approach
Authors: Park S.H. , Park C.G. , Bahorski J.S. , Cormier E.
Published: April 2019

Background

Childhood obesity is a complex and multifaceted problem involving interactions among child, family and community environment.

Aim

The purpose of this study was to examine the contributing factors to early childhood obesity within a multilevel context, including child and family, childcare setting and community.

Methods

A cross‐sectional, quantitative research design was employed. A total of 129 preschoolers and their parents in northwest Florida participated in this study. Child height and weight were measured, and body mass index (BMI) was calculated. Parents and directors of preschools completed survey questionnaires to assess child/family, childcare setting and community factors, respectively. Hierarchical multiple regression was used to evaluate the association of each level of factors with childBMIz‐score.

Results

Twenty‐one per cent of children were overweight or obese (≥85thBMIpercentile). In hierarchical multiple regression, household income, parent beliefs, attitudes and practices for child feeding, family obesogenic environment, child routines (screen time on weekends, sleep hours, bedtime) and physical activity environment were significantly related to childBMIz‐score.

Conclusions

The findings of this study provide a broader understanding of factors that influence childBMIz‐score. Shaping a non‐obesogenic environment by establishing healthy routines for children in the home, childcare setting and community is essential in childhood obesity prevention.

Implications for nursing practice and health policy

Paediatric nurses should routinely assess accurate parental perception of child weight, feeding style and child routines in well‐child care visits. Healthcare professionals and health policymakers should enact policies that build a healthy environment for preschoolers in their childcare setting and community.
At sea vocal repertoire of a foraging seabird
Authors: Thiebault Andréa , Charrier Isabelle , Pistorius Pierre , Aubin Thierry
Published: April 2019

Seabirds spend most of their time at sea, yet our knowledge of their activities and behaviour is limited due to difficulties of in‐situ data collection. In particular, we know virtually nothing about their acoustic communication when at sea. We benefited from the recent development of miniaturised audio‐recording devices to deploy acoustic recorders on breeding Cape gannets Morus capensis to study their vocal activity while foraging. Call sequences were recorded on 1718 occasions, from which acoustic variables were measured on calls with good recording quality. A total of 1348 calls from 18 birds were measured in temporal and frequency domains. Each call was assigned to a behavioural context defined acoustically: sitting on the water, flying, taking off or just before diving. Potential discrimination among calls from different contexts was tested using the random forest algorithm. Within each context, individual stereotypy in the calls was assessed per acoustic variable using a measure of potential of individual coding, and as a combination of variables using a similar multivariate analysis. The acoustic structure differed according to the behavioural context (global accuracy of prediction 75%). Temporal variables (sequence and call duration) were most important to correctly classify the calls among the four contexts. When considering only two contexts, on the water and in the air (merging flying and diving), frequency and spectral variables (percentage of energy below 1200 Hz and fundamental frequency) were of most importance (accuracy 86%). A combination of acoustic variables was necessary to discriminate individuals, but calls from all contexts were not strongly individually distinct (accuracy 41–63%). We provided the first detailed acoustic analysis of a foraging seabird and demonstrated context‐specific acoustic structure in its vocalisations at sea. Our results suggest that seabirds use vocal communication to exchange various types of information that likely improves foraging success.
TSP‐1 is downregulated and inversely correlates with miR‐449c expression in Cushing's disease
Authors: Ren Jie , Gu Changwei , Yang Yong , Xue Jun , Sun Yuhao , Jian Fangfang , Chen Dongjiang , Bian Liuguan , Sun Qingfang
Published: April 2019

The pathogenesis of Cushing's disease, which is caused by pituitary corticotroph adenoma, remains to be studied. Secreted angioinhibitory factor thrombospondin‐1 (TSP‐1) is an adhesive glycoprotein that mediates cell‐to‐cell and cell‐to‐matrix interactions and is associated with platelet aggregation, angiogenesis and tumorigenesis. We have found that the expression of TSP‐1 is significantly lower in human pituitary corticotroph tumours compared with normal adenohypophysis. This study aims to elucidate the role of TSP‐1 in regulating the tumour function of pituitary adenomas. Forced overexpression of TSP‐1 in a murine AtT20 pituitary corticotroph tumour cell line decreased corticotroph precursor hormone proopiomelanocortin (POMC) transcription and adrenocorticotropic hormone (ACTH) secretion. Functional studies showed that TSP‐1 overexpression in pituitary adenoma cells suppressed proliferation, migration and invasion. We have demonstrated that TSP‐1 is a direct target of miR‐449c. Further study showed that miR‐449c activity enhanced tumorigenesis by directly inhibiting TSP‐1 expression. Low expression of lncTHBS1, along with low expression of TSP‐1, was associated with the high expression of miR‐449c in Cushing's disease patients. Furthermore, RNA‐immunoprecipitation associates miR‐449c with lncTHBS1 suggesting that lncTHBS1 might be a negative regulator of miR‐449c. Taken together, this study has demonstrated that lncTHBS1 might function as competing endogenous RNA for miR‐449c, which could suppress the development of Cushing's disease.
No mate preference associated with the supergene controlling social organization in Alpine silver ants
Authors: Avril Amaury , Zahnd Sacha , Djordjevic Jelisaveta , Chapuisat Michel
Published: April 2019

Disassortative mating is a powerful mechanism stabilizing polymorphisms at sex chromosomes and other supergenes. The Alpine silver ant, Formica selysi, has two forms of social organization—single‐queen and multiple‐queen colonies—determined by alternate haplotypes at a large supergene. Here, we explore whether mate preference contributes to the maintenance of the genetic polymorphism at the social supergene. With mate choice experiments, we found that females and males mated randomly with respect to social form. Moreover, queens were able to produce offspring irrespective of whether they had mated with a male from the same or the alternative social form. Yet, females originating from single‐queen colonies were more fertile, suggesting that they may be more successful at independent colony founding. We conclude that the pattern of asymmetric assortative mating documented from mature F. selysi colonies in the field is not caused by mate preferences or major genetic incompatibilities between social forms. More generally, we found no evidence that disassortative mate preference contributes to the maintenance of polymorphism at this supergene controlling ant social organization.
Differences in leptin biosynthesis in the stomach and in serum leptin level between men and women
Authors: Kasacka Irena , Piotrowska Żaneta , Niezgoda Michał , Łebkowski Wojciech
Published: April 2019

Background and Aim

Although the stomach has been identified as an important source of leptin, the detailed biosynthesis sites of leptin in human gastrointestinal tract have not been fully elucidated. The study objective was to compare leptin distribution and expression in the stomach and its serum level between healthy men and women.

Methods

Nineteen subjects (organ donors; 10 men and 9 women) with normal gastric mucosa histology were recruited. Research material contained gastric samples from the cardia, fundus, and pyloric regions. Gastric mucosa leptin content and leptin gene expression were determined by immunohistochemistry and real‐time polymerase chain reaction method. Plasma leptin level was measured using ELISA method.

Results

In the stomach of healthy adult subjects, leptin‐immunoreactive cells were mainly found in the fundus, and the number of immunoreactive cells was higher in women than in men. Leptin‐containing cells were less numerous in the cardia and pylorus mucosa. Similarly, leptin gene expression was the highest in the fundus and higher in women than in men. Serum leptin level was higher in women than in men and was found to correlate positively with body mass index and weight in both sexes. A negative correlation between leptin level and age was noted in women, but not in men.

Conclusions

The current study is the first to provide evidence for the presence of leptin‐containing cells in all segments of the human stomach. The differences in gastric leptin biosynthesis and serum leptin levels between men and women suggest that leptin secretion can be controlled by sex hormones or other unknown factors.
Open‐label study assessing the efficacy and tolerability of topical skin care and sun protection alone and in combination with intense pulsed light therapy
Authors: Deaver Peterson Jennifer , Katz Tracy M.
Published: April 2019

Background

Intense pulsed light therapy (IPL) decreases facial erythema and telangiectasias associated with rosacea. Topical skin care products decrease facial erythema by the action of active ingredients and masking effects.

Objectives

To assess the efficacy and tolerability of combining a topical skin care regimen (TSCR) comprised of a multifunctional three‐in‐one facial cream and a mineral‐based brush‐on SPF50 powder sunscreen with a single IPL treatment for treating mild‐to‐severe facial redness associated with rosacea.

Methods

Twenty female subjects with Fitzpatrick skin types I‐III received TSCR monotherapy for 12 weeks. At that time, subjects received a single IPL treatment and continued TSCR for 6 additional weeks. Subjects were evaluated at Baseline and at Weeks 4, 8, 12, and 18.

Results

Using a 7‐point redness scale, the overall mean (SD) redness score significantly improved from 3.05 (0.97) at baseline to 2.05 (0.76) at Week 18 (P < 0.01). There was a decrease in investigator‐rated erythema from baseline (bare skin) to Week 12 (bare skin, before IPL) when TSCR was used as monotherapy which did not achieve significance (P = 0.12). Most subjects (80%) were satisfied or Very satisfied with the TSCR at Week 18. All subjects (100%) agreed that it improved their baseline skin redness and most (85%) would recommend TSCR to others. TSCR was well‐tolerated with no significant changes in skin dryness, scaling, or itching. Mild burning occurred immediately following the IPL treatment at Week 12.

Conclusion

TSCR in combination with a single IPL treatment produced a significant improvement in overall facial redness in patients with rosacea. Longer‐term treatment with TSCR may produce continued improvement.
Knee joint function, walking ability and quality of life within 6 weeks after total knee arthroplasty: A prospective cohort study
Authors: Chang Su‐Yu , Lin Li‐Hwa , Lin Pi‐Chu
Published: April 2019

Aims and objectives

To track changes in patients’ knee function, walking ability and quality of life (QOL) before and after knee arthroplasty surgery and explore factors that influenced these parameters.

Background

The number of days as an inpatient for those who undergo joint replacement operations has been greatly reduced in recent years. However, it remains unclear whether shortening the inpatient time has affected patients’ recovery or their QOL.

Design

Prospective cohort study.

Method

In total, 101 participants who underwent total knee arthroplasty (TKA) were enrolled, with data collected preoperatively and at the 2nd and 6th weeks postoperatively. We followed the STROBE checklist to ensure the rigour of our study.

Results

Forty‐nine participants underwent unilateral TKA (UTKA; 48.5%), and 52 underwent simultaneous bilateral TKA (SBTKA; 51.5%). At the 2nd week postoperatively, knee joint function was significantly worse than that preoperatively. However, these patients did not exhibit significant differences in the EQ‐5D utility index (EQ‐5D UI) compared to their preoperative scores. At the 6th week postoperatively, the knee joint function and EQ‐5D UI were significantly better than preoperative values. Participants who underwent UTKA scored higher on the Oxford knee score (OKS) than did SBTKA participants. However, no significant differences were noted between the two groups for the knee flexion angle, the timed up and go (TUG) test, or the EQ‐5D UI score.

Conclusions and suggestions

At the postoperative 6th week, participants exhibited improved knee joint function and QOL, but there was no difference in the walking ability compared to preoperative values. At the 6th week after surgery, patients who underwent SBTKA exhibited poorer joint function than did those who underwent UTKA.

Relevance to clinical practice.

These results can assist nursing staffs and serve as a reference for providing patient education and nursing intervention to TKA patients.
Parents’ journey caring for a preterm infant until discharge from hospital‐based neonatal home care—A challenging process to cope with
Authors: Lundqvist Pia , Weis Janne , Sivberg Bengt
Published: April 2019

Aims and objectives

To present parents’ lived experience of having a preterm infant cared for at the neonatal unit until discharge from hospital‐based neonatal home care (HNHC).

Background

Becoming a parent to a preterm infant has been reported as an experience that may influence the parent's lifeworld also after discharge. Interventions have been implemented at the NICUs, for example introduction of family‐centred care aiming to reduce parent–infant separation, increased integration of the parents, to support them in their altered parental role.

Design

A descriptive phenomenological interview study.

Methods

Six parent couples at a NICU in Sweden were included and interviewed individually after discharge from HNHC. The interviews were analysed from the perspective of caring sciences using a descriptive phenomenological method. The study followed the consolidated criteria for reporting qualitative research (COREQ) checklist.

Result

The journey from birth to discharge from hospital‐based neonatal home care affected the parents’ lifeworld. The parents’ experiences differed. Mothers experienced more physiological reactions that triggered feelings of existential loneliness and guilt and difficulties in combining the role of mother with partner. The fathers faced conflicts managing their partners’ demands, family challenges and employers who claimed their time and energy, which negatively affected their transition into fatherhood.

Both mothers and fathers experienced ambivalent feelings in the relationships with the professional staff, which was more strongly expressed by the mothers.

Conclusion

It is important for healthcare providers to help parents clarify their individual needs and values in caring for a preterm infant to help them achieve parental and family well‐being.

Relevance to clinical practice

These findings can guide healthcare providers to help parents improve care for their preterm infants in the NICU. Integrating a person‐centred approach such as supportive person‐centred dialogues focused on parents’ individual needs might be one way to support parents.
Internal podalic version for delivery of high floating head during cesarean section and neonatal outcome
Authors: Elshwaikh Shereef L. , Elsokary Amal A. , Abuhamama Ashraf M.
Published: April 2019

Aim

To evaluate the technique of internal podalic version for delivery of high floating head during cesarean section as an alternative for other methods for its delivery and its effects on neonatal outcome.

Methods

This study used clinical randomized controlled study design. Three groups of patients each group has 50 patients who attended for elective cesarean section and found to have high floating head during operation, Group I: the babies were delivered by internal podalic version. Group II: the babies were delivered by short curved forceps. Group III: the babies were delivered by vacuum. All groups were compared in regard to time required for delivery of baby, fetal condition, maternal complications, fetal complications and postoperative complications.

Results

Hundred‐and‐fifty patients were selected in the course of preparation of elective cesarean section, all had high floating fetal head, and they were randomly distributed into three groups, each group had 50 patients. There was significant relationship for the favor of Group 1 (study group) as regard the time required for the maneuver as calculated from the end of uterine incision till delivery of whole baby, (24.86, 59.48,54.52 s for Group I, Group II, Group III, respectively) with P‐value <0.00001*. Also there was significant relationship as regard the intraoperative maternal complications for the favor of Group I with P‐value =0.004. While there was an insignificant relationship between the three groups as regard preoperative data, APGAR score, fetal birth weight, postoperative pain and postoperative maternal data. Despite that there was a significant difference as regard the postoperative neonatal complications, with P‐value =0.002*, all these complications were minor and did not need long‐term treatment.

Conclusion

Use of internal podalic version for delivery of high floating head during cesarean section is a safe and rapid technique, with less maternal and neonatal complications.
Promoting Math Talk in Adult–Child Interactions Through Grocery Store Signs
Authors: Hanner Erinn , Braham Emily J. , Elliott Leanne , Libertus Melissa E.
Published: April 2019

Young children have better math abilities when their parents engage in more math‐related conversations with them. Yet, previous studies have found that math talk occurs only very infrequently in everyday interactions. In the present study, we sought to promote adult–child conversations about math in a naturalistic context using minimal instructions. We observed 179 adult–child dyads while they shopped in grocery stores with signs prompting them to engage in math‐related conversations (math condition), signs prompting them to talk about other topics (general language condition), or without any signs (baseline condition). In the math condition, more adults talked about math compared to the general language or the baseline condition, and this finding could not be explained by demographic characteristics of the dyad or the overall amount of conversations. This study demonstrates that cost‐effective signs placed in everyday contexts can promote math‐related conversations and potentially provide math learning opportunities for children.
Specialized foraging habits of adult female California sea lions Zalophus californianus
Authors: Rosas‐Hernández Martha P. , Aurioles‐Gamboa David , Hernández‐Camacho Claudia J.
Published: April 2019

Individual foraging specialization occurs when organisms use a small subset of the resources available to a population. This plays an important role in population dynamics since individuals may have different ecological functions within an ecosystem related to habitat use and prey preferences. The foraging habitat fidelity and degree of specialization of California sea lions (Zalophus californianus) were evaluated by analyzing the stable isotopes values of carbon and nitrogen in vibrissae collected from 16 adult females from the reproductive colony on Santa Margarita Island, Magdalena Bay, Mexico, in 2012 and 2013. Based on the degree of individual specialization in δ15N, 62.5% of the females assessed can be considered specialist consumers focusing on the same prey or different prey from the same trophic level. The degree of individual specialization in δ13C indicated that 100% of the individuals showed fidelity to their foraging habitat as some fed in the lagoon, others foraged along the coast, and a third group preferred prey from the pelagic environment during both the breeding and nonbreeding seasons, suggesting diversification of foraging areas. Foraging area fidelity persisted despite the 2°C increase in the sea surface temperature over the course of the study period.
Insights from 180 years of mitochondrial variability in the endangered Mediterranean monk seal (Monachus monachus)
Authors: Gaubert Philippe , Justy Fabienne , Mo Giulia , Aguilar Alex , Danyer Erdem , Borrell Asunción , Dendrinos Panagiotis , Öztürk Bayram , Improta Roberta , Tonay Arda M. , Karamanlidis Alexandros A.
Published: April 2019

Mediterranean monk seals (MMS) are among the most endangered marine mammals on Earth. We screened mitochondrial variability (control region [CR1] and mitogenomes) of the species through a 180‐yr timeframe and extended by 20% (n = 205) the number of samples from a previous investigation, including historical specimens from 1833 to 1975. Although we detected two new, rare CR1 haplotypes, genetic diversity remained extremely low. Fully resolved haplotype median network and rarefaction analysis both suggested low probability for further unscreened haplotypes. There was no clear phylogeographic structure across the 12 marine subdivisions covered by the species’ range. Haplotypes previously considered diagnostic of the extant North Atlantic and eastern Mediterranean populations had their distributions extended into the western Mediterranean and the North Atlantic, respectively, by both historical and recent samples. Our study suggests that MMS have been genetically depauperate since at least the mid‐19th century, and that the massive 1997 die‐off in Western Sahara (North Atlantic) could have caused local haplotype extinctions. Our results support the hypothesis of past metapopulation dynamics across the species range, where the current segregation into geographically distant and genetically depauperate breeding populations (i.e., North Atlantic and eastern Mediterranean Sea) derives from the combined effects of historical extinctions, genetic drift on small breeding groups, and persistently low levels of genetic diversity.
Neurological autoimmune disorders with prominent gastrointestinal manifestations: A review of presentation, evaluation, and treatment
Authors: Blackburn Kyle M. , Kubiliun Maddie , Harris Samar , Vernino Steven
Published: April 2019

Background

The identification of autoantibodies directed against neuronal antigens has led to the recognition of a wide spectrum of neurological autoimmune disorders (NAD). With timely recognition and treatment, many patients with NAD see rapid improvement. Symptoms associated with NAD can be diverse and are determined by the regions of the nervous system affected. In addition to neurological symptoms, a number of these disorders present with prominent gastrointestinal (GI) manifestations such as nausea, diarrhea, weight loss, and gastroparesis prompting an initial evaluation by gastroenterologists.

Purpose

This review provides a general overview of autoantibodies within the nervous system, focusing on three scenarios in which nervous system autoimmunity may initially present with gut symptoms. A general approach to evaluation and treatment, including antibody testing, will be reviewed.
The Austrian UVA‐Network
Authors: Schmalwieser Alois W. , Klotz Barbara , Schwarzmann Michael , Baumgartner Dietmar J. , Schreder Josef , Schauberger Günther , Blumthaler Mario
Published: April 2019

The ultraviolet‐A (UVA) part of the solar spectrum at the Earth's surface is an essential environmental factor but continuous long‐time monitoring of UVA radiation is rarely done. In Austria, three existing stations of the UV monitoring network have been upgraded with UVA broadband instruments. At each station, one instrument measures global UVA irradiance and—in parallel—a second instrument measures diffuse irradiance. Recent and past measurements are available via a web page. This paper describes the used instruments, calibration and quality assurance and control procedures. Global and diffuse UVA measurements during a period of up to 5 years are presented. Data indicate clear annual courses and an increase of UVA with altitude by 8–9% per 1000 m. In the first half of the year, UVA radiation is higher than in the second half, due to less cloudiness. In Vienna (153 m asl), the mean daily global UVA radiant exposure in summer is almost as high as at Mt. Gerlitzen (1540 m asl), equalizing the altitude effect, due to less cloudiness. However, in winter, the UVA radiant exposure at Mt. Gerlitzen is double as high, as in Vienna.
A Review of the Environmental Policy Literature from 2014 to 2017 with a Closer Look at the Energy Justice Field
Authors: Graff Michelle , Carley Sanya , Pirog Maureen
Published: April 2019

This review article documents and analyzes trends within the environmental policy literature published between 2014 and 2017. We find that environmental policy scholarship has recently shifted its focus from more traditional topics, such as watershed and ecosystem management, to other modern issues, such as climate change and energy. The environmental policy literature has increased in complexity and become more interdisciplinary in nature, which we illustrate with a discussion of the energy justice literature. The methodological approaches used by environmental policy scholars have also become increasingly diverse, with a notable uptick in statistical and modeling approaches. We find that some topics, such as policy failure, gender issues, and energy welfare policies are under‐explored, and certain regions within the world, such as developing countries, are less frequently studied. We encourage scholars to consider these gaps in the literature when developing future research.
Loyalty–Competence Trade‐offs for Top U.S. Federal Bureaucratic Leaders in the Administrative Presidency Era
Authors: Krause George A. , O’Connell Anne Joseph
Published: April 2019

We seek to characterize empirically the trade‐off between loyalty and competence that presidents make when appointing individuals to serve in U.S. federal agency leadership positions. These trade‐offs are analyzed from publicly available pre‐nomination information on 1,372 appointees within 39 major government organizations from the Carter through G. W. Bush presidencies. We find that loyalty–competence trade‐offs involving policy‐specific expertise are much stronger than those involving managerial skills. In addition, these loyalty–competence trade‐offs are more acute for top‐level bureaucratic leadership positions relative to subordinate counterparts, as well as for executive branch agencies relative to independent regulatory commissions. We also show that these loyalty–competence trade‐offs become stronger as presidents are less ideologically aligned with the policy activities of federal agencies, and during times of unified partisan control of the appointment process.
Growing up Without Status: The Integration of Children in Mixed‐Status Families
Authors: Hamilton Erin R. , Patler Caitlin C. , Hale Jo Mhairi
Published: April 2019

Over the past three decades, a central new challenge confronting millions of children of immigrants has emerged: growing up in a mixed‐status family in which at least one member lacks legal authorization to live and work in the United States. A body of recent research argues that unauthorized immigrant status is thefundamentaldeterminant of integration for unauthorized immigrants, with intergenerational consequences for their U.S.‐born children. We discuss the immigration and other policies that create the particular social context within which unauthorized immigration status becomes so detrimental for integration. Specifically, we focus on federal and state policies that undermine the very factors thought to protect children and support the integration of new generations of Americans: families and social networks, economic resources and opportunities, and health. We conclude with recommendations for future research.
Self‐Reported Understanding of Ranked‐Choice Voting
Authors: Donovan Todd , Tolbert Caroline , Gracey Kellen
Published: April 2019

Objectives

Ranked‐choice voting (RCV) is relatively complex compared to plurality voting. We test if some voters find it more challenging.

Methods

We conducted surveys in RCV cities and plurality cities to assess how voters reported understanding voting instructions, and how they reported understanding election systems.

Results

Fewer voters reported instructions were easy to understand in RCV cities. Within RCV cities, we found little evidence of race/ethnic differences in reported understanding, but older voters reported less understanding of instructions in RCV cities and less understanding of RCV elections. Across all cities, Asians and women reported less understanding of elections generally, and education correlated with greater reported understanding.

Conclusions

Our evidence is not consistent with concerns about a racial/ethnic bias specific to RCV, but suggests a need for additional voter education.
ABSCESO PROSTATICO: DIAGNÓSTICO Y MANEJO
Authors: Patiño Germán , Peña Murcia Paula Andrea
Published: April 2019

Resumen  El absceso prostático es una entidad urológica con poca evidencia estadísticamente significativa y pocos estudios que permitan realizar una guía de manejo estandarizada. Se define como  la presencia de una o varias colecciones purulentas en la próstata (1), que con un diagnóstico temprano y adecuado manejo médico y/o quirúrgico, tiene una baja morbimortalidad. La presente revisión de tema, reúne los estudios más recientes y sobresalientes en el diagnóstico y manejo de esta patología, de modo que en un futuro se pueda estandarizar el manejo entre los especialistas en esta área.   Abstract Prostatic abscess is an urological entity with few statistical significant evidence that allows us to stablish a standardized management guide. It is defined as one or multiple supurative collections in the prostate, which has a low morbidity and mortality with early diagnosis and appropriate management. The next review, group the most important and recent studies in this pathology, so that in the future we could stablish a standardized managent among tthe urologists.
Generalized Plane Strain Study of Rotational Autofrettage of Thick-Walled Cylinders—Part I: Theoretical Analysis
Authors: Kamal S. M. , Perl M. , Bharali D.
Published: April 2019

In recent years, a few new methods of achieving autofrettage in thick-walled hollow cylinders have been developed. Rotational autofrettage is one of the new methods proposed recently for prestressing thick-walled cylinders. The principle of rotational autofrettage is based on inducing plastic deformation in the cylinder at the inner side and at its neighborhood by rotating the cylinder about its own axis at a certain angular velocity and subsequently bringing down it to zero angular velocity. However, the analysis of the process is still in its nascent stage. In order to establish the rotational autofrettage as a potential design procedure for prestressing thick-walled cylinders, accurate modeling of the process is necessary. In this paper, the rotational autofrettage for thick-walled cylinders is analyzed theoretically based on the generalized plane strain assumption. The closed form analytical solutions of the elasto-plastic stresses and strains and the residual stresses after unloading during the rotational autofrettage of a thick-walled cylinder are obtained. In Part II of the paper, the numerical evaluation of the theoretical model will be presented in order to assess its feasibility.
Aerosol Jet® Direct-Write for Microscale Additive Manufacturing
Authors: Feng James Q. , Renn Michael J.
Published: April 2019

The unique capabilities of Aerosol Jet® technology for noncontact material deposition with in-flight adjustment of ink rheology in microdroplets are explained based on first principles of physics. The suitable range of ink droplet size is determined from the effectiveness for inertial impaction when depositing onto substrate and convenience for pneumatic manipulation, in-flight solvent evaporation, etc. The existence of a jet Reynolds number window is shown by a fluid dynamics analysis of impinging jets for Aerosol Jet® printing with long standoff between nozzle and substrate, which defines the operation range of gas flow rate according to the nozzle orifice diameter. The time scale for ink droplets to remove volatile solvent is shown to just coincide that for them to travel in the nozzle channel toward substrate after meeting the coflowing sheath gas, enabling the in-flight manipulation of ink properties for high aspect-ratio feature printing. With inks being able to solidify rapidly, 3D structures, such as tall micropillars and thin-wall boxes, can be fabricated with Aerosol Jet® printing. Having mist droplets in the range of 1–5 μm also makes it possible to print lines of width about 10 μm.
Accounting for masking of frequency modulation by amplitude modulation with the modulation filter-bank concept
Authors: King Andrew , Varnet Léo , Lorenzi Christian
Published: April 2019

Frequency modulation (FM) is assumed to be detected through amplitude modulation (AM) created by cochlear filtering for modulation rates above 10 Hz and carrier frequencies (fc) above 4 kHz. If this is the case, a model of modulation perception based on the concept of AM filters should predict masking effects between AM and FM. To test this, masking effects of sinusoidal AM on sinusoidal FM detection thresholds were assessed on normal-hearing listeners as a function of FM rate, fc, duration, AM rate, AM depth, and phase difference between FM and AM. The data were compared to predictions of a computational model implementing an AM filter-bank. Consistent with model predictions, AM masked FM with some AM-masking-AM features (broad tuning and effect of AM-masker depth). Similar masking was predicted and observed at fc = 0.5 and 5 kHz for a 2 Hz AM masker, inconsistent with the notion that additional (e.g., temporal fine-structure) cues drive slow-rate FM detection at low fc. However, masking was lower than predicted and, unlike model predictions, did not show beating or phase effects. Broadly, the modulation filter-bank concept successfully explained some AM-masking-FM effects, but could not give a complete account of both AM and FM detection.
Discrimination of changes in spatial configuration for multiple, simultaneously presented sounds
Authors: Yost William A. , Pastore M. Torben , Zhou Yi
Published: April 2019

Listeners discriminated changes in the spatial configuration of two-to-eight consonant-vowel (CV) stimuli spoken by different talkers, all simultaneously presented from different loudspeakers in various azimuthal spatial configurations. The number of CVs, spatial configuration of the sound sources, and similarity of the talkers speaking the CVs were varied. Experiment I used a same–different procedure to determine the discriminability of different spatial configurations of multiple sound sources. In experiment II, listeners determined the direction (clockwise or counterclockwise) of sound source rotation over eight rotational steps. In both experiments, performance declined as the number of sound sources increased beyond two.
Sound propagation in the surface mixed layer and upper ocean: An overview of relevant ocean dynamics and mode scattering theory
Authors: Colosi John A.
Published: April 2019

The mixed layer and upper ocean are a region of immense interest to physical oceanographers, meteorologists, and climate scientists because this is the boundary through which energy, momentum, buoyancy, and gasses are exchanged between the ocean and the atmosphere. The upper ocean is also a rich ecosystem for a vast array of ocean organisms and marine wildlife as well as a region of great Naval tactical importance. Given these factors, it is rather surprising that ocean acoustics has paid little attention to this significant region, aside from very high-frequency studies of bubble properties and gas entrainment. From the standpoint of transmission loss, the major work on the problem seems to go back to the Acoustic, Meteorological, Oceanographic Survey (AMOS) of the mid-50s. Here, a review is presented of relevant ocean processes that may be important for acoustic propagation at frequencies ranging from several hundreds of hertz to several kilohertz, where the foundation of the analysis is normal mode and transport theory. Processes of interest are surface gravity waves including subsurface currents, internal waves and tides, wind driven inertial oscillations and Langmuir circulations, eddies and submesoscale processes, turbulence and spice, bubbles, and fishes.
Ocean remote sensing using passive acoustics
Authors: Sabra Karim G.
Published: April 2019

Conventional acoustic remote sensing techniques typically rely on controlled active sources which can be problematic to deploy and operate over the long term, especially if multiple sources are required to fully illuminate the ocean region of interest. Conversely, receiver arrays are becoming increasingly autonomous, miniaturized, and capable of long term deployment thus enabling passive acoustics for ocean remote sensing applications by taking advantage of uncooperative sources of opportunity (e.g., shipping noise) or the ubiquitous ocean ambient noise which have not typically been used in traditional ocean sensing applications. This fully passive approach can also be advantageous when regulations forbid the use of active sound sources or when no active sources are readily available—e.g., at very low frequencies (~10 Hz) or during covert operations. This presentation will discuss the recent development of ocean remote sensing using passive acoustics notably (1) passive acoustic thermometry to estimate deep ocean temperature variations and internal tides using coherent processing of low-frequency ambient noise; (2) localization of drifting sensor networks using ambient noise to enable random volumetric ad hoc receiver array for tracking underwater targets; and (3) monitoring of the shallow water sound channel using shipping sources of opportunity.
Exploiting ambient noise in polar regions to study ice-ocean interactions
Authors: Deane Grant B.
Published: April 2019

We explore recent developments and future directions for ambient noise cryology: the study of ice-ocean interactions using their underwater noise signatures. The study of ice-ocean interactions is currently spurred by climatic shifts in polar regions and their implications, which include sea level rise and geopolitical stability. There are many important ice-ocean interactions, and a broad range of observational techniques are used to study them, such as satellite remote sensing, ship-based observations with in situ sensors and AUV’s, boreholes, ground-penetrating radar, photogrammetry, seismometry, and differential GPS. Despite such an extensive suite of techniques, submarine calving and ice melting—which play a critical role in the mass balance of ice shelves and marine-terminating glaciers—remain difficult to measure. Progress in quantifying these processes with their underwater noise signatures will be discussed along with future directions for the field.
The measurement of ocean acidity using the depth-dependence of ambient noise
Authors: Barclay David R. , Buckingham Michael J.
Published: April 2019

The absorption of sound in seawater is due to the viscous and chemical relaxation of different compounds. Over the wind noise band of 1–10 kHz, the frequency dependence of the absorption is due to the mechanisms of chemical relaxation for magnesium sulfate (f > 3 kHz) and for boric acid (f < 3 kHz), which involve ionic dissociations activated and deactivated by the condensation and rarefaction of the medium by passing sound waves. Concentrations of both chemicals determine the level at which the sound is absorbed, which makes the process dependent on the salinity, temperature, and pressure in the ocean. The concentration of boric acid in the ocean is a direct measure of pH, while the concentration of magnesium sulfate is independent of pH; thus, a measurement of the frequency dependence of sound absorption may be used to determine ocean acidity. When local winds are strong (> 10 m/s), the ambient noise field is dominated by locally generated surface noise and has a depth-independent directionality and a weakly frequency and depth-dependent intensity, due to sound absorption. By comparing measurements with theory, estimates of ocean acidity can be made from the depth profiles of ambient noise. [Work supported by ONR.]
Three-dimensional multichannel seismic imaging of water columns in the Gulf of Mexico
Authors: Zhang Likun , Zou Zheguang , Rad Parsa , Macelloni Leonardo
Published: April 2019

Seismic reflection profiling technique, previously used to image the sediments beneath the seafloor, is herein used to image the ocean’s water columns, namely, seismic oceanography. The imaging has a much higher lateral resolution (~10 m) than traditional oceanographic measurements such as CTD (usually >100 m). Prior work on seismic oceanography was limited on imaging in two dimensional vertical transects. This work develops the three-dimensional (3D) seismic oceanography technique to image the 3D dynamic processes of water columns. 3D multichannel seismic survey data in a seismic volume of 625 km3 in the Gulf of Mexico are processed and produce images containing detailed 3D water-column structures near the continental slope. Some mesoscale and sub-mesoscale structures are visualized from different viewing angles. Spectral analyses of the seismic images reveal 3D spatial features of the structures, suggesting the potential of 3D seismic oceanography. [Work supported by NOAA.]
The soud of light: Towards ocean acoustic sensing with an optical breakdown transducer
Authors: Athanassiadis Athanasios G.
Published: April 2019

When a high-power laser is focused to a small spot in a fluid, nonlinear interactions at the focus can excite a plasma that evolves and glows according to the properties of the breakdown medium. This phenomenon—optical breakdown—is commonly used for underwater chemical measurements in a technique called Laser-Induced Breakdown Spectroscopy (LIBS). However, LIBS generally operates at short ranges and only leverages the optical emission of the plasma for sensing. If instead, the laser systems were tuned to amplify the mechanical effects of optical breakdown, then it could be deployed as a versatile source for broadband acoustic sensing. The optical breakdown acoustic source is simultaneously compact (mm-scale), loud (MPa peak pressures), ultra-broadband (10 kHz–4 MHz), and geometrically reconfigurable. Here, I will describe the physics governing optical breakdown transduction and then show how can this be tuned to enable new single-vehicle sensing strategies in the ocean.
Overview of acoustic detection for counter unmanned aircraft systems
Authors: Bishop Brian B. , Tufariello Justin
Published: April 2019

Integration of unmanned aircraft systems (UAS) into the National Airspace System (NAS) is currently a major problem for government and industry. The detection of unauthorized UAS activity is a concern. There is a need for effective low-cost sensor technology to detect and track unauthorized UAS operations. Acoustic sensor systems have potential to improve counter UAS (C-UAS) sensing capabilities at greatly reduced cost relative to traditional sensors such as radar and optical systems, but the commercially available acoustic sensing technology is still lacking. The MITRE Corporation has been a leader in advising the United States’ Federal Government on the issues around integration of UAS into the NAS and C-UAS technologies. Research done by MITRE on acoustic sensing of UAS will be presented. The current state of commercially available acoustic sensor systems will be briefly reviewed. Recommendations that MITRE has developed on how to design acoustic sensor systems for C-UAS will be discussed. Future research directions in topics such as acoustic beamforming, array design, and outdoor sound propagation will be recommended. Approved for Public Release; Distribution Unlimited 18-4035
Combining psychophysics and modeling to probe suprathreshold auditory processing efficiently
Authors: Ponsot Emmanuel
Published: April 2019

The ability to understand speech in noise differs considerably among people. Even “normal-hearing” individuals, i.e., with normal audiograms, exhibit a variety of performances in speech-in-noise listening tests. The number of studies investigating the underlying causes of this variability, not captured by current audiological measures, has exploded over the last few years. However, we still lack an overall computational account of suprathreshold auditory processing that would incorporate enough flexibility to capture these idiosyncratic differences. We propose to uncover the psychophysical mechanisms of suprathreshold processing trough its variability among individuals, by combining noise-based psychophysical methods and computational tools. This approach is illustrated in the case of spectrotemporal modulation processing in normal and impaired hearing. Experimental results collected show how listeners modulate their tuning characteristics depending on the task and reveal that hearing-impaired listeners with similar audiometric losses exhibit a large variety of computational strategies for such tasks, which our modeling approach have the potential to connect with specific computational elements. Overall, this shows how a signal-detection theory framework combined with efficient experimental methods and modeling tools should be considered as a powerful approach to further understand the respective contributions of sensory coding and read-out inefficiencies in human suprathreshold processing.
Midbrain sensitivity to spectral cues for sound-source localization: A modeling study
Authors: Wang Yuxiang , Carney Laurel H.
Published: April 2019

The features of head-related transfer functions (HRTFs) are a key topic in the field of spatial auditory displays. Neural encoding of HRTFs is not well understood; their sharp spectral peaks and notches are not well represented by average rates of relatively widely tuned auditory-nerve (AN) fibers, and phase-locking to the temporal fine structure is not adequate to encode features at high-frequencies. However, low-frequency fluctuations in cochlear responses to wideband stimuli are encoded in time-varying rates of AN fibers across all frequency channels. Here, we focus on modeling the profile of amplitude fluctuations in response to spectral cues across the population of AN channels. The fluctuation profile across AN responses sets up an average-rate profile across inferior colliculus (IC) neurons, which are sensitive to envelope-related low-frequency fluctuations. Both unilateral and bilateral IC model responses indicate that rather than responding to spectral peaks in a given HRTF, IC responses are more sensitive to fluctuations in frequency channels near steep spectral slopes. The influence of the spatial location and stimulus level on model IC responses was examined. Using statistical methods, psychoacoustical thresholds of discrimination of sounds that differ in the source location were estimated and compared to trends in the existing perceptual results.