1,226 research outputs found

    Distribution and Diversity of Archaeal and Bacterial Ammonia Oxidizers in Salt Marsh Sediments

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    Diversity and abundance of ammonia-oxidizing Betaproteobacteria (Ī²-AOB) and archaea (AOA) were investigated in a New England salt marsh at sites dominated by short or tall Spartina alterniflora (SAS and SAT sites, respectively) or Spartina patens (SP site). AOA amoA gene richness was higher than Ī²-AOB amoA richness at SAT and SP, but AOA and Ī²-AOB richness were similar at SAS. Ī²-AOB amoA clone libraries were composed exclusively of Nitrosospira-like amoA genes. AOA amoA genes at SAT and SP were equally distributed between the water column/sediment and soil/sediment clades, while AOA amoA sequences at SAS were primarily affiliated with the water column/sediment clade. At all three site types, AOA were always more abundant than Ī²-AOB based on quantitative PCR of amoA genes. At some sites, we detected 109 AOA amoA gene copies g of sedimentāˆ’1. Ratios of AOA to Ī²-AOB varied over 2 orders of magnitude among sites and sampling dates. Nevertheless, abundances of AOA and Ī²-AOB amoA genes were highly correlated. Abundance of 16S rRNA genes affiliated with Nitrosopumilus maritimus, Crenarchaeota group I.1b, and pSL12 were positively correlated with AOA amoA abundance, but ratios of amoA to 16S rRNA genes varied among sites. We also observed a significant effect of pH on AOA abundance and a significant salinity effect on both AOA and Ī²-Ī‘ĪŸĪ’ abundance. Our results expand the distribution of AOA to salt marshes, and the high numbers of AOA at some sites suggest that salt marsh sediments serve as an important habitat for AOA

    Anisotropic Exchange in LiCu2O2{\bf LiCu_2O_2}

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    We investigate the magnetic properties of the multiferroic quantum-spin system LiCu2_2O2_2 by electron spin resonance (ESR) measurements at XX- and QQ-band frequencies in a wide temperature range (TN1ā‰¤Tā‰¤300(T_{\rm N1} \leq T \leq 300\,K). The observed anisotropies of the gg tensor and the ESR linewidth in untwinned single crystals result from the crystal-electric field and from local exchange geometries acting on the magnetic Cu2+^{2+} ions in the zigzag-ladder like structure of LiCu2_2O2_2. Supported by a microscopic analysis of the exchange paths involved, we show that both the symmetric anisotropic exchange interaction and the antisymmetric Dzyaloshinskii-Moriya interaction provide the dominant spin-spin relaxation channels in this material.Comment: 10 pages, 10 Figure

    Properties of Healthcare Teaming Networks as a Function of Network Construction Algorithms

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    Network models of healthcare systems can be used to examine how providers collaborate, communicate, refer patients to each other. Most healthcare service network models have been constructed from patient claims data, using billing claims to link patients with providers. The data sets can be quite large, making standard methods for network construction computationally challenging and thus requiring the use of alternate construction algorithms. While these alternate methods have seen increasing use in generating healthcare networks, there is little to no literature comparing the differences in the structural properties of the generated networks. To address this issue, we compared the properties of healthcare networks constructed using different algorithms and the 2013 Medicare Part B outpatient claims data. Three different algorithms were compared: binning, sliding frame, and trace-route. Unipartite networks linking either providers or healthcare organizations by shared patients were built using each method. We found that each algorithm produced networks with substantially different topological properties. Provider networks adhered to a power law, and organization networks to a power law with exponential cutoff. Censoring networks to exclude edges with less than 11 shared patients, a common de-identification practice for healthcare network data, markedly reduced edge numbers and greatly altered measures of vertex prominence such as the betweenness centrality. We identified patterns in the distance patients travel between network providers, and most strikingly between providers in the Northeast United States and Florida. We conclude that the choice of network construction algorithm is critical for healthcare network analysis, and discuss the implications for selecting the algorithm best suited to the type of analysis to be performed.Comment: With links to comprehensive, high resolution figures and networks via figshare.co

    Relation between ambient air pollution and low birth weight in the Northeastern United States.

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    We evaluated the relation between term low birth weight (LBW) and ambient air levels of carbon monoxide (CO), particulate matter up to 10 microm in diameter (PM(10)), and sulfur dioxide (SO(2)). The study population consisted of singleton, term live births (37-44 weeks of gestation) born between 1 January 1994 and 31 December 1996 in six northeastern cities of the United States: Boston, Massachusetts; Hartford, Connecticut; Philadelphia, Pennsylvania; Pittsburgh, Pennsylvania; Springfield, Massachusetts; and Washington, DC. Birth data were obtained from National Center for Health Statistics Natality Data Sets. Infants with a birth weight < 2,500 g were classified as LBW. Air monitoring data obtained from the U.S. Environmental Protection Agency were used to estimate average trimester exposures to ambient CO, PM(10), and SO(2). Our results suggest that exposures to ambient CO and SO(2) increase the risk for term LBW. This risk increased by a unit increase in CO third trimester average concentration [adjusted odds ratio (AOR) 1.31; 95% confidence interval (CI) 1.06,1.62]. Infants with SO(2) second trimester exposures falling within the 25 and < 50th (AOR 1.21; CI 1.07,1.37), the 50 to < 75th (AOR 1.20; CI 1.08,1.35), and the 75 to < 95th (AOR 1.21; CI 1.03,1.43) percentiles were also at increased risk for term LBW when compared to those in the reference category (< 25th percentile). There was no indication of a positive association between prenatal exposures to PM(10) and term LBW. Increased ambient levels of air pollution may be associated with an increased risk for LBW

    Infraclavicular arterio-arterial prosthetic loop is a safe and effective vascular access technique for haemodialysis in frail patients: a prospective observational study

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    Vascular access failure causes significant morbidity among end stage renal failure patients. With the increased life expectancy and frailty of those patients, maintaining vascular access became a great challenge. In this study, we assess the short and midterm outcomes of infraclavicular arterio-arterial prosthetic loop (IAAPL) as vascular access for haemodialysis in frail patients who have exhausted conventional vascular access methods. A prospective observational study of 43 patients undergoing IAAPL was conducted in a single centre between May 2017 and March 2020. Primary, assisted primary and secondary patency rates were recorded in addition to complications and patient compliance with access. The achieved primary, assisted primary and secondary patency rates at 6 months are 87.5%, 95%, 97.5% respectively, at one year, corresponding rates were 75%, 83.3%, 94.4% and at 18 months they were 68.6%, 77.1%, 85.7% respectively. There was no procedure related mortality and life-threatening complications during the study period. So we can assume that infraclavicular AAPL is a safe and effective method of obtaining alternative vascular access for hemodialysis in frail patients for whom the conventional vascular access for hemodialysis is not suitable or contraindicated

    Analysis of family 24 of the Arabidopsis thaliana J-domain chaperone proteins [abstract]

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    Abstract only availableFaculty Mentor: Dr. Jan Miernyk, Plant BiochemistryThe Arabidopsis thaliana genome includes an unexpectedly large and diverse group of J-domain chaperone proteins. The 93 A. thaliana J-domain protein sequences have been grouped into 51 families, many of which do not have any well-studied counterpart in microbes or mammalian cells. Based upon the results of silico analyses, three proteins, atDjC43, atDjC48, and atDjC49, were assigned to Family 24. Homologous proteins are present in maize, rice, and soybean, and in a variety of animals, but none has been characterized. Members of Family 24 have approximately 300 amino acid residues; besides the J-domain the only prominent structural feature is a predicted transmembrane helix near the C-terminus. Preliminary experiments were conducted to try to understand the multiplicity of plant J-domain proteins, and to address the question of redundancy versus specialization. In order to determine where and when these three J-domain proteins are expressed, primers were designed for semi-quantitative RT-PCR. Total RNA was isolated from the rosette leaves and roots of 4-week old A. thaliana ecotype Columbia plants, and from flowers and green siliques. The results establish a pattern of organ-specific expression. We are also using T-DNA insertion knockout plants for our analyses. We currently have homozygous KO plants for atDjC48, and are in the final stages of screening for atDjC43 knockouts. It is difficult to express eukaryotic integral membrane proteins in bacteria. The sequence encoding the C-terminal transmembrane helix was deleted from the atDjC48 reading frame. The atDjC48ļæ½ļæ½ļæ½C sequence was then cloned into the pCal-n vector for expression in Escherichia coli as a chimera with the CaM-Binding-Peptide. The recombinant protein will be assayed for activity in vitro. Using these diverse strategies, we hope to gain insight into the roles of this Family of molecular chaperone proteins.University of Missouri--Columbia. Office of Undergraduate ResearchPlant Genomics Internship @ M

    Phelan-McDermid syndrome: a review of the literature and practice parameters for medical assessment and monitoring

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    The purpose of this study is to contribute to a deeper understanding about how placement discontinuities of children in foster care affect their learning. The aim is to find out more about their learning and what role school plays in their life. A life-world perspective is used and theories mainly developed by Alfred SchĆ¼tz (2002) build the theoretical framework. The empirical research is mainly based on narratives of a pair of twins at 19 years of age, who agreed to share their life stories and experiences of their time in school. Meetings were arranged separately with Alex, the boy, and Helena, the girl, both eager to participate. They felt that their stories could contribute to knowledge. The stories show that placement discontinuities in their early childhood made memories and their perspective of time blurry. They both suffered severe neglect in two of their foster care placements. School offered them a safe place throughout their adolescent years. However, despite this, they are critical to the teachers who saw that they suffered neglect at home but never acted upon that knowledge. Hence their first-hand experiences suggest that teachers, considered important in earlier research studies, are not as important as friend made or the daily routines that provide certain security in an otherwise uncertain life. The social services didnā€™t listen or support them. Alex and Helena felt that they had to take care of themselves. Their stories show that both of them are goal-oriented and that they highly value a good education. This is evident since they have always taken responsibility to complete set homework and to make school a functional place where they have also learned to know themselves. Furthermore, it is obvious that the twins have played a tremendous role for each other when their life-world time after time has changed. Alex and Helenaā€™s stories and experiences can give the social services a deeper understanding of what lies behind the statistics. A teacher, who listens, shows support and has ambitious expectations regarding the childrenā€™s academic performance, has been confirmed in previous research to be of significant importance. In addition, the study shows that teachers should learn more about children in foster care. A life-world perspective and life-world theories can contribute to an alternative point of view regarding learning in life-world discontinuities. Learning can be reflected on by using SchĆ¼tz theory about ā€œstrangersā€ as a way of understanding learning in a wider range, especially when there are discontinues in the life-world. The reflections made in this study point out the possibility that schools, as organizations, seem to have independent cultures that can be transferred between one another. In fact there seems to be certain variables that are the same for schools in general and hence it is of significant value to recognize school as a regional life-world. The expectations of how you act as a student and among friends are important for the sense of belonging. It is possible that Alex and Helena succeeded in school partly because some of the things they learned about the first school could be transferred to their new school. The study contributes with two new concepts; ā€œlivsvƤrldsbrottā€- life-world-disruption and ā€œlivsvƤrldsbevarandeā€- life-world-preservation

    Food Science Challenge: Translating the Dietary Guidelines for Americans to Bring About Real Behavior Change

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    Food scientists and nutrition scientists (dietitians and nutrition communicators) are tasked with creating strategies to more closely align the American food supply and the public's diet with the Dietary Guidelines for Americans (DGA). This paper is the result of 2 expert dialogues to address this mandate, which were held in Chicago, Illinois, and Washington, D.C., in early October 2010 between these 2 key scientific audiences. It is an objective that has largely eluded public health experts over the past several decades. This document takes the perspective of food scientists who are tasked with making positive modifications to the food supply, both in innovating and reformulating food products, to respond to both the DGA recommendations, and to consumer desires, needs, and choices. The paper is one of two to emerge from those October 2010 discussions; the other article focuses on the work of dietitians and nutrition communicators in effecting positive dietary change
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