2,779 research outputs found

    Life in the Cold

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    Preface; First and Corresponding Author Contact Information; An Evolutionary Framework for Studies of Hibernation and Short-term Torpor -- Gordon C. Grigg; Was Adaptive Hypothermia a Prerequisite for the Colonization of Madagascar By Mammals? -- Barry G. Lovegrove; No Evidence for Torpor in a Small African Mainland Primate: The Lesser Bushbaby, Galago moholi -- Nomakwezi Mzilikazi, Barry G. Lovegrove, and Judith C. Masters; The Origin of Mammalian Heterothermy: A Case for Perpetual Youth? -- Michael B. Harris, Link E. Olson, and William K. Milsom; Passive Rewarming from Torpor in Mammals and Birds: Energetic, Ecological and Evolutionary Implications -- Fritz Geiser, Rebecca L. Drury, Gerhard Kortner, Christopher Turbill, Chris R. Pavey, and R. Mark Brigham; Solar Radiation and the Energetic Cost of Rewarming from Torpor -- Andrew M. McKechnie and Blair O. Wolf; The Role of α-Linolenic Acid (18:3) in Mammalian Torpor -- Craig L. Frank, Wendy R. Hood, and Mary C. Donnelly; Heat Transfer in Humans: Lessons from Large Hibernators -- Dennis Grahn and H. Craig Heller; Factors Influencing the Timing of Dormancy in the Pocket Mouse,Perognathus longimembris -- Alan R. French; The Energetic State-dependency of Autumn Immergence in Eastern Chipmunks -- Murray M. Humphries and Brandon Rodgers; Seasonal Timing of Reproduction and Hibernation in the Edible Dormouse (Glis glis) -- Claudia Bieber and Thomas Ruf; Reproduction and Hibernation in Females: A Comparison of Two Sympatric Ground-Dwelling Rodents -- Eva Millesi, Ilse E. Hoffmann, Anna Aschauer, and Claudia Franceschini; How the Photoperiod Times the Annual Reproductive and Hibernation Cycles -- P. Pevet, M. Saboureau, and P. Klosen; Behaviour, Body Temperature, and Hibernation in Tasmanian Echidnas (Tachyglossus aculeatus) -- Stewart Nicol, Christina Vedel-Smith, and Niels A. Andersen; Metabolic Diversity in Yellow-Bellied Marmots -- Kenneth B. Armitage; Metabolic Rate Reduction During Hibernation and Daily Torpor -- Fritz Geiser; How to Enter Torpor: Thermodynamic and Physiological Mechanisms of Metabolic Depression -- Gerhard Heldmaier and Ralf Elvert; Slow Loss of Protein Integrity During Torpor: A Cause for Arousal? -- Sandra L. Martin, Timothy Dahl, and L. Elaine Epperson; A Technique for Modelling Thermoregulatory Energy Expenditure in Free-ranging Endotherms -- Craig K. R. Willis, Jeffery E. Lane, Eric T. Liknes, David L. Swanson, and R. Mark Brigham; Sex Differences in the Response of Torpor to Exogenous Corticosterone During the Onset of the Migratory Season in Rufous Hummingbirds -- Sara M. Hiebert, John C. Wingfield, Marilyn Ramenofsky, Leah Deni, and Antoinette Grafin zu Elz; The Avian Enigma: “Hibernation” by Common Poorwills (Phalaenoptilus nuttalli) -- Christopher P. Woods and R. Mark Brigham; Shivering Thermogenesis in Birds and Mammals -- Esa Hohtola; The Impact of Social Interactions on Torpor Use in Hummingbirds -- Donald Powers; The Energetics of the Rewarming Phase of Avian Torpor -- Andrew E. McKechnie and Blair O. Wolf; Insect Cold-Hardiness: New Advances Using Gene Screening Technology -- Kenneth B. Storey and David C. McMullen; Advantages and Disadvantages of Freeze-Tolerance and Freeze-Avoidance Overwintering Strategies -- Karl Erick Zachariassen, Sindre Andre Pedersen, and Erlend Kristiansen; Live and Let Diapause: Cell Cycle Regulation During Insect Overwintering -- Savvas c. Pavlides, Kenneth A. Weir, and Steven P. Tammariello; Vertebrate Freeze Tolerance: Role of Freeze-Responsive Gene Expression -- Kenneth B. Storey; Ice, Antifreeze Proteins, and Antifreeze Genes in Polar Fishes -- Arthur L. DeVries; Overwintering in Submerged Turtles -- Donald C. Jackson; Environmental Physiology of Terrestrial Hibernation in Hatchling Turtles -- Patrick J. Baker, Jon P. Costanzo, and Richard E. Lee, Jr.; Overwintering in Tegu Lizards -- Denis V. Andrade, Colin Sanders, William K. Milsom, and Augusto S. Abe; Overwintering in Cold-Submerged Frogs -- Glenn J. Tattersall; Effect of Temperature on Regular and Modified Circannual Rhythms in the European Ground Squirrel Under Free-Running Conditions -- Radoslav K. Andjus, Marina Marjanovic, and Dragoslava Zivadinovic; The Role of the Suprachiasmatic Pacemaker (SCN) in Energy Expenditure During Hibernation of Golden-mantled Ground Squirrels -- Patricia J. DeCoursey; Does Hibernation Violate Biological Laws? -- Andre Malan; The Suprachiasmatic Nucleus Influences Energy Balance of Golden-mantled Ground Squirrels During Hibernation -- Norman E. Ruby; Pesticide Effects on Body Temperature of Torpid/Hibernating Rodents (Peromyscus leucopus and Spermophilus tridecemlineatus) -- Thomas E. Tomasi, Peta Elsken-Lacy, Jean A. Perry, and Kerry Withers; Steroidogenesis and the HPA Axis During Hibernation: Differential Expression of the StAR Protein -- Matthew T. Andrews, Meaghan M. Tredrea, and Aubie K. Shaw; A Quest for the Origin of Mammalian Uncoupling Proteins -- Marton Jastroch, Sigrid Stohr, Kerry Withers, and Martine Klingenspor; Brown-Fat-Derived and Thyroid-Hormone Thermogenesis: Mechanisms and Interactions -- Jan Nedergaard, Valeria Golozoubova, and Barbara Cannon; Alterations in Localization of Hippocampal Protein Kinase Cγ (PKCγ), but Not PKCα, -β1, or –β2, in European Ground Squirrels During Hibernation -- Eddy A. Van der Zee, Jens Stieler, Roelof A. Hut, Martin de Wilde, and Arjen M. Strijkstra; The Role of the Medial Septum in the Control of Hibernation -- Irina Yu. Popova and Yurii M. Kokoz; Proteolysis in Hibernators -- Frank can Breukelen; Post-genomic Approaches to the Mechanisms of Cold Response in Fish and Hibernating Small Mammals -- Daryl Williams, L. Elaine Epperson, Andrew R. Cossins, Jane Fraser, Weizhong Li, Sandra Martin, and Andrew Y. Gracey; Use of Suppression Subtractive Hybridization to Elucidate Novel Gene Products Related to Physiological Events in a Hibernator -- Gregory L. Florant, Chris Pittman, and Scott A. Summers; Clinical Applications and Limitations of Hypothermia -- Philip E. bickler; Hibernation in Mammals: A Model for Alzheimer-type Phosphorylation of the Microtubule-associated Protein Tau -- Thomas Arendt, Jens Stieler, Arjen M. Strijkstriam Roelof A. Hut, Eddy A. Van der Zee, max Holzer, and Woldfgang Hartig; Resistance of Livers to Cold Ischemia/Reperfusion Injury During Hibernation: Involvement of Matrix Metalloproteinase and Nitric Oxide Synthase -- Hannah V. Carey, Timothy M. Piazza, Sarah E. Davis, Susanne L. Lindell, Anna Durranis, Kieran Clarke, and James H. Southard; Anti-Proliferative Effects of Plasma from Hibernating Rodents -- Donna G. Sieckmann, Decheng Cai, Howard Jaffe, John Hallenbeck, and Richard M. McCarron; Antifreeze Proteins in Terrestrial Arthropods -- John G. Duman, Valerie A. Bennett, N. Li, L. Wang, L. Huang, T. Sformo, and B.M. Barnes; Cardiac Conduction and Resistance to Ventricular Fibrillation in Siberian Hibernator Ground Squirrel Citellus undulatus -- Vadim V. Fedorov, Rubin R. Aliev, Alexey V. Glukhov, Andrey V. Resnik, Andrey Anufriev, Irina A. Ivanova, Olga V. Nakipova, Stella G. Kolaeva, Leonid V. Rosenshtraukh, and Igor R. Efimov; The Correlation Between Akt Activity and Hibernation -- Decheng Cai, Richard M. McCarron, Donna Sieckmann, and John M. Hallenbeck; Protection from Traumatic Brain Injury During Hibernation -- Kelly L. Drew, Fang Zhou, Xiongwei Zhu, Rudy J. Castellani, and Mark A. Smith; δ-Opioid Agonists Protect the Rat Liver From Cold Storage and Ischemia/Reperfusion Injury -- Thomas L. Husted, Wen-Jian Chang, Alex B. Lentsch, Steven M. Rudich;Animal Adaptability to Oxidative Stress: Gastropod Estivation and Mammalian Hibernation -- Marcelo Hermes-Lima, Gabriella R. Ramos-Vasconcelos, Luciano A. Cardoso, Adrienne l. Orr, Patricia M. Rivera, and Kelly L. Drew

    Controlling Second Harmonic Efficiency of Laser Beam Interactions

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    A method is provided for controlling second harmonic efficiency of laser beam interactions. A laser system generates two laser beams (e.g., a laser beam with two polarizations) for incidence on a nonlinear crystal having a preferred direction of propagation. Prior to incidence on the crystal, the beams are optically processed based on the crystal's beam separation characteristics to thereby control a position in the crystal along the preferred direction of propagation at which the beams interact

    Multiple-wavelength tunable laser

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    A tunable laser includes dispersion optics for separating generated laser pulses into first and second wavelength pulses directed along first and second optical paths. First and second reflective mirrors are disposed in the first and second optical paths, respectively. The laser's output mirror is partially reflective and partially transmissive with respect to the first wavelength and the second wavelength in accordance with provided criteria. A first resonator length is defined between the output mirror and the first mirror, while a second resonator length is defined between the output mirror and the second mirror. The second resonator length is a function of the first resonator length

    Coronal Emission Measures and Abundances for Moderately Active K Dwarfs Observed by Chandra

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    We have used Chandra to resolve the nearby 70 Oph (K0 V+K5 V) and 36 Oph (K1 V+K1 V) binary systems for the first time in X-rays. The LETG/HRC-S spectra of all four of these stars are presented and compared with an archival LETG spectrum of another moderately active K dwarf, Epsilon Eri. Coronal densities are estimated from O VII line ratios and emission measure distributions are computed for all five of these stars. We see no substantial differences in coronal density or temperature among these stars, which is not surprising considering that they are all early K dwarfs with similar activity levels. However, we do see significant differences in coronal abundance patterns. Coronal abundance anomalies are generally associated with the first ionization potential (FIP) of the elements. On the Sun, low-FIP elements are enhanced in the corona relative to high-FIP elements, the so-called "FIP effect." Different levels of FIP effect are seen for our stellar sample, ranging from 70 Oph A, which shows a prominent solar-like FIP effect, to 70 Oph B, which has no FIP bias at all or possibly even a weak inverse FIP effect. The strong abundance difference exhibited by the two 70 Oph stars is unexpected considering how similar these stars are in all other respects (spectral type, age, rotation period, X-ray flux). It will be difficult for any theoretical explanation for the FIP effect to explain how two stars so similar in all other respects can have coronae with different degrees of FIP bias. Finally, for the stars in our sample exhibiting a FIP effect, a curious difference from the solar version of the phenomenon is that the data seem to be more consistent with the high-FIP elements being depleted in the corona rather than a with a low-FIP enhancementComment: 35 pages, 8 figures, AASTEX v5.0 plus EPSF extensions in mkfig.sty; accepted by Ap

    SMART Cables for Observing the Global Ocean: Science and Implementation

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    The ocean is key to understanding societal threats including climate change, sea level rise, ocean warming, tsunamis, and earthquakes. Because the ocean is difficult and costly to monitor, we lack fundamental data needed to adequately model, understand, and address these threats. One solution is to integrate sensors into future undersea telecommunications cables. This is the mission of the SMART subsea cables initiative (Science Monitoring And Reliable Telecommunications). SMART sensors would “piggyback” on the power and communications infrastructure of a million kilometers of undersea fiber optic cable and thousands of repeaters, creating the potential for seafloor-based global ocean observing at a modest incremental cost. Initial sensors would measure temperature, pressure, and seismic acceleration. The resulting data would address two critical scientific and societal issues: the long-term need for sustained climate-quality data from the under-sampled ocean (e.g., deep ocean temperature, sea level, and circulation), and the near-term need for improvements to global tsunami warning networks. A Joint Task Force (JTF) led by three UN agencies (ITU/WMO/UNESCO-IOC) is working to bring this initiative to fruition. This paper explores the ocean science and early warning improvements available from SMART cable data, and the societal, technological, and financial elements of realizing such a global network. Simulations show that deep ocean temperature and pressure measurements can improve estimates of ocean circulation and heat content, and cable-based pressure and seismic-acceleration sensors can improve tsunami warning times and earthquake parameters. The technology of integrating these sensors into fiber optic cables is discussed, addressing sea and land-based elements plus delivery of real-time open data products to end users. The science and business case for SMART cables is evaluated. SMART cables have been endorsed by major ocean science organizations, and JTF is working with cable suppliers and sponsors, multilateral development banks and end users to incorporate SMART capabilities into future cable projects. By investing now, we can build up a global ocean network of long-lived SMART cable sensors, creating a transformative addition to the Global Ocean Observing System

    Enlisting in the Military: The Influential Role of Genetic Factors

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    Given that enlistment in the U.S. military is completely voluntary, there has been a great deal of interest in identifying the various factors that might explain why some people join the military, whereas others do not. The current study expanded on this line of literature by estimating the extent to which genetic and environmental factors explained variance in the liability for lifetime participation in the military. Analysis of twin pairs drawn from the National Longitudinal Study of Adolescent to Adult Health (Add Health) revealed that 82% of the variance was the result of genetic factors, 18% of the variance was the result of nonshared environmental factors, and none of the variance was accounted for by shared environmental factors. In light of a number of limitations, replication studies are needed to determine the robustness of these findings and whether they are generalizable to other samples and populations

    Optical Properties of Tm(3+) Ions in Alkali Germanate Glass

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    Tm-doped alkali germanate glass is investigated for use as a laser material. Spectroscopic investigations of bulk Tm-doped germanate glass are reported for the absorption, emission and luminescence decay. Tm:germanate shows promise as a fiber laser when pumped with 0.792 m diodes because of low phonon energies. Spectroscopic analysis indicates low nonradiative quenching and pulsed laser performance studies confirm this prediction by showing a quantum efficiency of 1.69

    MEF2C regulates outflow tract alignment and transcriptional control of Tdgf1

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    Congenital heart defects are the most common birth defects in humans, and those that affect the proper alignment of the outflow tracts and septation of the ventricles are a highly significant cause of morbidity and mortality in infants. A late differentiating population of cardiac progenitors, referred to as the anterior second heart field (AHF), gives rise to the outflow tract and the majority of the right ventricle and provides an embryological context for understanding cardiac outflow tract alignment and membranous ventricular septal defects. However, the transcriptional pathways controlling AHF development and their roles in congenital heart defects remain incompletely elucidated. Here, we inactivated the gene encoding the transcription factor MEF2C in the AHF in mice. Loss of Mef2c function in the AHF results in a spectrum of outflow tract alignment defects ranging from overriding aorta to double-outlet right ventricle and dextro-transposition of the great arteries. We identify Tdgf1, which encodes a Nodal co-receptor (also known as Cripto), as a direct transcriptional target of MEF2C in the outflow tract via an AHFrestricted Tdgf1 enhancer. Importantly, both the MEF2C and TDGF1 genes are associated with congenital heart defects in humans. Thus, these studies establish a direct transcriptional pathway between the core cardiac transcription factor MEF2C and the human congenital heart disease gene TDGF1. Moreover, we found a range of outflow tract alignment defects resulting from a single genetic lesion, supporting the idea that AHF-derived outflow tract alignment defects may constitute an embryological spectrum rather than distinct anomalies

    A Quantitative Genetic Analysis of the Associations Among Language Skills, Peer Interactions, and Behavioral Problems in Childhood: Results From a Sample of Twins

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    A body of empirical research has revealed that there are associations among language skills, peer interactions, and behavioral problems in childhood. At the same time, however, there has been comparatively less research devoted to exploring the mutual unfolding of these factors over the first few years of life. The current study is designed to partially address this gap in the literature by examining how language skills, negative peer interactions, and behavioral problems are interrelated in a sample of twins drawn from the Early Childhood Longitudinal Study–Birth Cohort (ECLS-B). Employing a quantitative genetic framework, the results of the current study revealed that variance in language skills, negative peer interactions, and externalizing behavioral problems were all due to a combination of genetic and environmental factors. Bivariate Cholesky models indicated that most of the covariance among language skills, negative peer interactions, and externalizing behavioral problems was due to common genetic factors. Additional analyses using a modified DeFries–Fulker approach nested within a path model revealed a bidirectional association between negative peer interactions and externalizing behavioral problems, wherein there appeared to be feedback loops between the two. Implications of the results are discussed and avenues for future research are offered

    Big events, little change: Extreme climatic events have no region-wide effect on Great Barrier Reef governance

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    Extreme climatic events trigger changes in ecosystems with potential negative impacts for people. These events may provide an opportunity for environmental managers and decision-makers to improve the governance of social-ecological systems, however there is conflicting evidence regarding whether these actors are indeed able to change governance after extreme climatic events. In addition, the majority of research to date has focused on changes in specific policies or organizations after crises. A broader investigation of governance actors’ activities is needed to more fully understand whether or not crises trigger change. Here we demonstrate the use of a social network analysis of management and decision-making forums (e.g. meetings, partnerships) to reveal the effects of an extreme climatic event on governance of the Great Barrier Reef over an eight-year period. To assess potential shifts in action, we examine the topics of forums and the relative participation and influence of diverse governance actors before, during, and after two back-to-back mass coral bleaching events in 2016 and 2017. Our analysis reveals that there is little change in the topics that receive attention, and in the relative participation and influence of different actor groups in the region. Our research demonstrates that network analysis of forums is useful for analyzing whether or not actors’ activities and priorities evolve over time. Our results provide empirical evidence that governance actors struggle to leverage extreme climate events as windows of opportunity and further research is needed to identify alternative opportunities to improve governance
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