7,334 research outputs found

    Fundamental Parameters of Cepheids: Masses and Multiplicity

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    Masses determined from classical Cepheids in binary systems are a primary test of both pulsation and evolutionary calculations. The first step is to determine the orbit from ground-based radial velocities. Complementary satellite data from Hubble, FUSE, IUE, and Chandra provide full information about the system. A summary of recent results on masses is given. Cepheids have also provided copious information about the multiplicity of massive stars, as well as the distribution of mass ratios and separations. This provides some important constraints for star formation scenarios including differences between high and low mass results and differences between close and wide binaries

    Genome-wide association study for calving performance using high-density genotypes in dairy and beef cattle

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    peer-reviewedBackground Calving difficulty and perinatal mortality are prevalent in modern-day cattle production systems. It is well-established that there is a genetic component to both traits, yet little is known about their underlying genomic architecture, particularly in beef breeds. Therefore, we performed a genome-wide association study using high-density genotypes to elucidate the genomic architecture of these traits and to identify regions of the bovine genome associated with them. Results Genomic regions associated with calving difficulty (direct and maternal) and perinatal mortality were detected using two statistical approaches: (1) single-SNP (single nucleotide polymorphism) regression and (2) a Bayesian approach. Data included high-density genotypes on 770 Holstein-Friesian, 927 Charolais and 963 Limousin bulls. Several novel or previously identified genomic regions were detected but associations differed by breed. For example, two genomic associations, one each on chromosomes 18 and 2 explained 2.49 % and 3.13 % of the genetic variance in direct calving difficulty in the Holstein-Friesian and Charolais populations, respectively. Imputed Holstein-Friesian sequence data was used to refine the genomic regions responsible for significant associations. Several candidate genes on chromosome 18 were identified and four highly significant missense variants were detected within three of these genes (SIGLEC12, CTU1, and ZNF615). Nevertheless, only CTU1 contained a missense variant with a putative impact on direct calving difficulty based on SIFT (0.06) and Polyphen (0.95) scores. Using imputed sequence data, we refined a genomic region on chromosome 4 associated with maternal calving difficulty in the Holstein-Friesian population and found the strongest association with an intronic variant in the PCLO gene. A meta-analysis was performed across the three breeds for each calving performance trait to identify common variants associated with these traits in the three breeds. Our results suggest that a portion of the genetic variation in calving performance is common to all three breeds. Conclusion The genomic architecture of calving performance is complex and mainly influenced by many polymorphisms of small effect. We identified several associations of moderate effect size but the majority were breed-specific, indicating that breed-specific alleles exist for calving performance or that the linkage phase between genotyped allele and causal mutation varies between breeds

    Using the Cornell Note-taking System Can Help Eighth Grade Students Alleviate the Impact of Interruptions While Reading at Home

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    A large group of eighth-grade social studies students (N=-101) received instruction and practice using the Cornell note-taking system and were assigned to one of three note-taking groups or one non-note-taking group. Students were asked to read an article about persuasion and use their assigned note-taking system to take notes at home. A 10-question multiple choice reading comprehension test and questionnaire were given. A one-way ANOVA found a significance in the group’s means and a Tukey HSD found significant differences between each note-taking group and the non-note-taking group. The students’ self-reported feelings of preparedness, their time spent reading and taking notes, overall comments about their experience and their reporting of interruptions were analyzed using constant comparisons and questioning strategies. Two conclusions can be drawn from these results. First, middle school students must take some form of notes to benefit from the encoding process while reading. Secondly, middle school teachers should not fear giving their students reading and note-taking homework assignments. This study provides evidence that supports the idea that the Cornell system can be used to increase student confidence and alleviate the impact interruptions have on students’ working memories while reading at home

    Time Traveling with Timelines: Web Apps for Storytelling in Libraries

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    From online embeds to interactive displays, timelines can serve many purposes and tell powerful stories. At the University of Georgia’s Law Library we have teamed up with faculty and staff to bring history to life, engage students, and preserve scholarly and institutional milestones. Through trial and error we have found a variety of tools for creating timelines digitally. In this article we share our four favorite web-based applications for creating timelines including Tiki-Toki, TimeToast, Prezi and Piktochart

    An Early Bronze Age Urned Burial from Crowmeole, Shrewsbury, Shropshire

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    An early Bronze Age urned burial was revealed in July 2015 during archaeological investigations on land to the west of Crowmeole Lane, on the south-western side of Shrewsbury, Shropshire. A small oval pit contained an inverted urn which had survived undisturbed and fully intact up to the point of discovery. The classification of this urn is challenging: it may belong to the wider Collared Urn tradition based on form, but in strict typological terms can be considered a Food Vessel Urn/ Collared Urn hybrid. Enclosed within was a cremation deposit, probably once bagged, as well as a burnt and fractured worked stone knife. The vessel also exhibited an internal charred residue, thought to relate to earlier use. Scientific dating of the residue, along with the cremated bone, suggested that the burial took place around 2000BC. The cremation deposit included the remains of an individual adult, probably a female, and mainly comprised bone, rather than pyre material, indicative of carefully managed collection. As a result, the recorded weight of bone is amongst the highest for a single cremation burial from the British Isles for any period, and in the upper regions of the consistently high range of weights for Bronze Age deposits

    Optimization of photomixers and antennas for continuous-wave terahertz emission

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    We have studied terahertz emission from interdigitated finger photomixers coupled to planar antenna structures. Using both pulsed and continuous-wave excitation, polarization measurements reveal that the antenna design dominates the properties of the radiated output at frequencies below 0.6 THz, while the efficiency at higher frequencies is additionally dependent on the design of the photomixer fingers. We have produced terahertz maps of the device, characterizing the photomixer by measuring the generated power as a function of the excitation position. Together, these measurements have allowed us to understand better the distinct roles of the photomixer and antenna in emission at different fre

    A Time Lord, a Timeline and Legal Instruction

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    From online embeds to interactive displays, timelines can serve many purposes and tell powerful stories. In this session librarians team up with an archivist and a clinician to bring history to life, engage students, and preserve the scholarly and institutional milestones. A variety of tools for creating digital timelines and gathering content will be shared including TikiToki, TimeToast, and Piktochart. Comparisons will be given based on cost, technical limitations, collaborative potential, and general ease of use. Potential applications for timelines will also be shared in the form of examples including: a TimeToast embedded timeline tribute for individual faculty scholarship as a part of research guides a TikiToki multi-media timeline celebrating the growth of clinical and experiential learning programs over the course of 50 years a Piktochart timeline for classroom slides or printed display illustrating a series of significant trials Time permitting, a live demo will guide attendees through the creation of a timeline with one of the tools. This session will be of interest to technologists, librarians and faculty alike. Attendees will walk away with an overview of the tools available for making timelines, ideas for how they could be used for instructional purposes, and a guide including examples and resources

    Time Lords & Timelines Panel

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    From self-guided online embeds to immersive live displays, timelines can serve many purposes and tell powerful stories. In this panel three members of UGA\u27s Law Library shared how they bring history to life, engage students, and preserve the scholarly and institutional milestones of the Law School with timelines by enhancing guide and repository collections, complimenting physical item displays and interacting with patrons at special events using multimedia. A variety of tools for creating digital timelines and gathering content were discussed including our four favorite applications: Prezi, TimeToast, Tiki-Toki, and Piktochart. Comparisons were given based on cost, technical limitations, collaborative potential, and general ease of use. Handouts were provided and the session was followed with an opportunity to ask questions of panelists
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