bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparison of the Pulsation Properties of the Rr Lyrae Stars in ω Centauri with those of Classical Cepheids
Authors: Petersen J. O. 
Published: July 2016

In the last few years several studies have shown that Fourier decomposition technique is a powerful method for quantitative description of light curves of pulsation variables. This technique was introduced by Simon & Lee (1981), who showed that amplitude ratios and phase differences provide a very useful description of the Hertzsprung progression for classical Cepheids. Recently, Simon & Teays (1982) discussed 70 RR Lyrae field stars.In the present study I analyse 130 photographic mean light curves of RR Lyrae variables in ω Centauri taken from Martin (1938). I wish (i) to compare the Fourier decomposition parameters of the ω Cen RR Lyrae stars with those of the field variables as studied by Simon & Teays, (ii) to discuss the evidence for progression sequences among the ω Cen variables and (iii) to compare the basic pulsation properties of the RRab variables in ω Cen with those of classical Cepheids.
Infrared Spectroscopy of Cometary Parent Molecules
Authors: Weaver H. A. , Mumma M. J. , Larson H. P. 
Published: July 2016

AbstractMost cometary parent molecules do not strongly fluoresce at ultraviolet and visible wavelengths, and some do not possess permanent electric dipole moments, preventing their study in the radio region as well. However, many of these molecules have strong ro-vibrational transitions in the near infrared (λ ∼ 2 – 5 μm). Since the solar flux at these wavelengths is quite strong, parent molecules in cometary comae can be probed directly via fluorescence in these infrared transitions. The feasibility of this approach was convincingly demonstrated by the detection of H2O in comet Halley (1986 III) from the Kuiper Airborne Observatory and by the detection of H2O, CO2, and H2CO using an infrared spectrometer (IKS) on VEGA. Tentative detections of near infrared lines of CH4 were also reported during ground-based and airborne observations of comets Halley and Wilson (1987 VII). High resolution spectroscopy of the infrared water transitions has yielded a wealth of new information on cometary physics: the absolute line intensities and spatial brightness profiles are used to determine water production rates and lifetimes, the relative line intensities probe the kinetic temperature profile in the coma, the line widths and line positions shed light on coma outflow dynamics, and the temporal variability in the lines provides information on the structure of the nucleus. These observations also allow the determination of the water ortho-to-para ratio, which may provide fundamental insight into the origin and/or evolutionary history of cometary nuclei. Similar observations of other molecules (those mentioned above plus others) will provide important complementary data and will also allow us to compile a volatile inventory for cometary nuclei, but such observations are extremely difficult due to the low abundances of these molecules (≤10% relative to water) and the limitations of present infrared facilities. Recent advances in infrared instrumentation promise to extend sensitivities for parent molecule searches to relative abundances well below 1%, especially if cooled, Earth-orbiting facilities are available.
The Study of Comets at Radio Wavelengths
Authors: Crovisier J. , Schloerb F. P. 
Published: July 2016

AbstractRadio observations of comets complement studies at other wavelengths as well as providing certain kinds of unique information. Studies of continuum emission may probe the thermal emission of the nucleus and large-size dust particles. Spectroscopic observations of gas in the coma allow searches for parent molecular species that have no signatures in the optical spectral range. The 18-cm wavelength spectral lines of the OH radical now are relatively easy to detect, and observations of them permit long-term and short-term monitoring of the cometary gaseous output. Moreover, with the unique spectral resolution of radio techniques, aspects of the kinematics of the coma may be also studied, such as the gas expansion velocity and the anisotropy of gas production from the nucleus. In this review, we present recent results of cometary radio observations, and discuss what may be learned from such studies in the future.
A Review of Radio Interferometric Imaging of Comets
Authors: Pater Imke de , Palmer Patrick , Snyder Lewis E. 
Published: July 2016

AbstractWe present an overview of cometary observations carried out with the VLA. These include OH imaging observations, studies of other molecules and searches for continuum emission. Primarily, we discuss the OH observations obtained of Comet Halley, a periodic comet, and Comet Wilson, a “new” comet. The emission from Comet Halley is confined to a region a few times 105km. The emission from Comet Wilson shows sporadic blobs at large distances (∼ 106km from the center), which vary abruptly in both position and velocity. The generally accepted picture of excitation by UV pumping in a spherical outflow of cometary gas explains the coarse phenomenology, but other effects seem to cause significant modulations of the OH emission. We suggest that for Comet Halley, collisional effects near the edge of the quenching region, which is coincidently the approximate distance to the cometopause, may be important, and that for Comet Wilson, outgassing from cometesimals ejected from the nucleus may be significant. We further show that asymmetric line profiles are more common than previously thought. Lengthening integration times and lowering the velocity resolution results in a smooth, round shape for the comet’s brightness distribution. In addition, spectral profiles become broader and more symmetric after long integration times and after integration over larger spatial regions. In addition to the OH observations we summarize the H2CO detection experiments for comets Halley and Machholz.
The Modern Role of Visual Observations of Comets
Authors: Larson S.M. , Edberg S.J. , Levy D.H. 
Published: July 2016

AbstractThis paper reviews the role of past and future visual observations in cometary research. The strengths and limitations of visual observations are explored for the benefit of both investigators who might have to use them and observers who wish to make real contributions to the field. We consider the characteristics of the eye-brain combination as a detector and compare them with those of modern detectors. We specifically evaluate visual discoveries, magnitude estimates, and drawings.
Laboratory Simulation of Cometary Processes: Results from First Kosi Experiments
Authors: Grün E. , Bar-Nun A. , Benkhoff J. , Bischoff A. , Düren H. , Hellmann H. , Hesselbarth P. , Hsiung P. , Keller H.U. , Klinger J. , Knölke J. , Kochan H. , Kohl H. , Kölzer G. , Krankowsky D. , Lämmerzahl P. , Mauersberger K. , Neukum G. , Oehler A. , Ratke L. , Roessler K. , Schwehm G. , Spohn T. , Stöffler D. , Thiel K. 
Published: July 2016

AbstractIn situ observations of comet Halley provided the first photographs of a cometary nucleus and yielded information about its environment, including the emitted gas and dust. The relation between these measurements and properties of and processes on the nucleus is established by theoretical modelling, while laboratory experiments may provide some of the physical parameters needed. In addition, laboratory tests can stimulate new ideas for processes that may be relevant to cometary physics. Processes to be studied in detail by large-scale laboratory experiments may include: (1) heat transport phenomena during sublimation of porous ice-dust mixtures, (2) material modification and chemical fractionation caused by the sublimation processes, (3) buildup and destruction of dust mantles, (4) detailed studies of gas release from mixtures of volatile ices, and (S) the investigation of ice and dust particle release mechanisms. The KOSI-team (Kometensimulation) carried out sublimation experiments with ice-mineral mixtures in a large Space Simulator. During initial experiments, cylindrical samples of 30-cm diameter and 15-cm thickness were irradiated with up to 2700–W/m2 light energy. The samples consisted of water-ice or water- and CO2-ice mineral mixtures. The experiments showed the importance of advection for heat transport into the interior. It was found that the sublimation of CO2 advances into the sample at a higher speed than that of water vapor release. Therefore, emission of volatile gases responded to insolation changes with a time lag of several hours. The ratio of the emitted gas species, as well as the dust-to-gas mass ratio, differs significantly from the values within the sample. A partly permeable refractory mantle of minerals and carbonaceous material developed with time. Dust and ice particle emission has been observed to occur from irradiated dirty ices as well as from dust mantles.
End Products of Cometary Evolution: Cometary Origin of Earth-Crossing Bodies of Asteroidal Appearance
Authors: Wetherill G.W. 
Published: July 2016

AbstractBecause there is no necessary connection between the time required to remove the volatile component of a cometary nucleus by solar heating (physical lifetime) and the dynamical lifetime of a comet, it is possible that a comet may evolve into an observable object of asteroidal appearance. Almost all comets have dynamical lifetimes much shorter than their physical lifetimes and in these cases complete loss of volatiles will not occur. Mechanisms do exist, however, whereby a small but significant fraction of comets will have longer dynamical lifetimes, permitting them to evolve first into Jupiter-family short period comets and then into comets with relatively safe decoupled orbits interior to Jupiter’s orbit. Observed Jupiter-family objects of asteroidal appearance (e.g., 1983SA) are much more likely to be of cometary rather than asteroidal origin. “Decoupling” is facilitated by several mechanisms: perturbations by the terrestrial planets, perturbations by Jupiter and the other giant planets (including resonant perturbations) and non-gravitational orbital changes caused by the loss of gas and dust from the comet. The dynamical time scale for decoupling is probably 105–106 years and almost all decoupled comets are likely to be of asteroidal appearance. Once decoupled, the orbits of the resulting Apollo-Amor objects will evolve on a longer (107–108 year) time scale, and the orbital evidence for these objects having originally been comets rather than asteroids will nearly disappear. Statistically, however, a large fraction of the bodies in deep Earth-crossing orbits with semi-major axes ≳ 2.2 AU are likely to be cometary objects in orbits that have not yet diffused into the steady state distribution. For plausible values of the relevant parameters, estimates can be made of the number of cometary Apollo-Amor “asteroids,” the observed number of Earthcrossing active and inactive short period comets, and the production rate of short period comets. These estimates are compatible with other theoretical and observational inferences that suggest the presence of a significant population of Apollo objects that formerly were active comets.
Evolution of Cometary Debris: Physical Aspects
Authors: Hajduk Anton 
Published: July 2016

AbstractCometary dust particles, larger grains, and fragments as products of the disintegration processes are subjected to gravitational and nongravitational forces, causing their dynamical and physical evolution. Critical analysis of some fairly large differences in the observational data obtained for the mass productions, dust/gas ratios, cut-off masses, particle size/mass distributions, erosion factors, bulk densities, and other physical properties of particles leads to a more complex view of the cometary matter than is assumed in some of the current models. This view allows reasonable limits for the dynamical and physical interrelations between the debris and its parent bodies to be obtained.
WASH has a critical role in NK cell cytotoxicity through Lck-mediated phosphorylation
Authors: Huang L , Zhu P , Xia P , Fan Z 
Published: July 2016

AbstractNatural killer (NK) cells are important effector cells of the innate immune system to kill certain virus-infected and transformed cells. Wiskott–Aldrich Syndrome protein (WASP) and SCAR homolog (WASH) has been identified as a member of WASP family proteins implicated in regulating the cytoskeletal reorganization, yet little is known about its function in lymphocytes. Here we demonstrate that WASH is crucial for NK cell cytotoxicity. WASH was found to colocalize with lytic granules upon NK cell activation. Knockdown of WASH expression substantially inhibited polarization and release of lytic granules to the immune synapse, resulting in the impairment of NK cell cytotoxicity. More importantly, our data also define a previously unappreciated mechanism for WASH function, in which Src family kinase Lck can interact with WASH and induce WASH phosphorylation. Mutation of tyrosine residue Y141, identified here as the major site of WASH phosphorylation, partially blocked WASH tyrosine phosphorylation and NK cell cytotoxicity. Taken together, these observations suggest that WASH has a pivotal role for regulation of NK cell cytotoxicity through Lck-mediated Y141 tyrosine phosphorylation.
The Molecular Mechanism of Opening the Helix Bundle Crossing (HBC) Gate of a Kir Channel
Authors: Meng Xuan-Yu , Liu Shengtang , Cui Meng , Zhou Ruhong , Logothetis Diomedes E. 
Published: July 2016

AbstractInwardly rectifying K+ (Kir) channels, serving as natural molecular nanomachines, transport potassium ions across the plasma membrane of the cell. Along the ion permeation pathway, three relatively narrow regions (the selectivity filter (SF), the inner helix bundle crossing (HBC), and the cytosolic G loop) may serve as gates to control ion permeation. Our previous molecular dynamics simulations based on the crystal structure of a Kir3.1 chimera revealed the possible gating mechanism of the G loop gate. Here, we introduced a proline mutation in the inner helix and obtained a channel model of the open HBC gate. The open HBC gate reaches 0.6 nm in diameter, which allows partial hydrated K+ ions to pass through. During the gating process, both the transmembrane helices TM1 and TM2 cooperatively rotate in a counterclockwise direction (viewed from the extracellular side) with the aid of the phospholipid PIP2. Only when all the transmembrane helices adopt a counterclockwise rotation, the HBC gate can be stabilized in the open state. We estimate that introduction of the proline mutation decreases the energy required to open the HBC gate by about 1.4 kcal/mol (ΔΔG).
An Integrative Genetic Study of Rice Metabolism, Growth and Stochastic Variation Reveals Potential C/N Partitioning Loci
Authors: Li Baohua , Zhang Yuanyuan , Mohammadi Seyed Abolghasem , Huai Dongxin , Zhou Yongming , Kliebenstein Daniel J. 
Published: July 2016

AbstractStudying the genetic basis of variation in plant metabolism has been greatly facilitated by genomic and metabolic profiling advances. In this study, we use metabolomics and growth measurements to map QTL in rice, a major staple crop. Previous rice metabolism studies have largely focused on identifying genes controlling major effect loci. To complement these studies, we conducted a replicated metabolomics analysis on a japonica (Lemont) by indica (Teqing) rice recombinant inbred line population and focused on the genetic variation for primary metabolism. Using independent replicated studies, we show that in contrast to other rice studies, the heritability of primary metabolism is similar to Arabidopsis. The vast majority of metabolic QTLs had small to moderate effects with significant polygenic epistasis. Two metabolomics QTL hotspots had opposing effects on carbon and nitrogen rich metabolites suggesting that they may influence carbon and nitrogen partitioning, with one locus co-localizing with SUSIBA2 (WRKY78). Comparing QTLs for metabolomic and a variety of growth related traits identified few overlaps. Interestingly, the rice population displayed fewer loci controlling stochastic variation for metabolism than was found in Arabidopsis. Thus, it is possible that domestication has differentially impacted stochastic metabolite variation more than average metabolite variation.
Kinetic modelling of runaway electrons in dynamic scenarios
Authors: Stahl A. , Embréus O. , Papp G. , Landreman M. , Fülöp T. 
Published: July 2016

Abstract
Improved understanding of runaway-electron formation and decay processes are of prime interest for the safe operation of large tokamaks, and the dynamics of the runaway electrons during dynamical scenarios such as disruptions are of particular concern. In this paper, we present kinetic modelling of scenarios with time-dependent plasma parameters; in particular, we investigate hot-tail runaway generation during a rapid drop in plasma temperature. With the goal of studying runaway-electron generation with a self-consistent electric-field evolution, we also discuss the implementation of a collision operator that conserves momentum and energy and demonstrate its properties. An operator for avalanche runaway-electron generation, which takes the energy dependence of the scattering cross section and the runaway distribution into account, is investigated. We show that the simplified avalanche model of Rosenbluth and Putvinskii (1997 Nucl. Fusion
37 1355) can give inaccurate results for the avalanche growth rate (either lower or higher) for many parameters, especially when the average runaway energy is modest, such as during the initial phase of the avalanche multiplication. The developments presented pave the way for improved modelling of runaway-electron dynamics during disruptions or other dynamic events.
Collective Thomson scattering measurements of fast-ion transport due to sawtooth crashes in ASDEX Upgrade
Authors: Rasmussen J. , Nielsen S.K. , Stejner M. , Galdon-Quiroga J. , Garcia-Munoz M. , Geiger B. , Jacobsen A.S. , Jaulmes F. , Korsholm S.B. , Lazanyi N. , Leipold F. , Ryter F. , Salewski M. , Schubert M. , Stober J. , Wagner D. 
Published: July 2016

Abstract
Sawtooth instabilities can modify heating and current-drive profiles and potentially increase fast-ion losses. Understanding how sawteeth redistribute fast ions as a function of sawtooth parameters and of fast-ion energy and pitch is hence a subject of particular interest for future fusion devices. Here we present the first collective Thomson scattering (CTS) measurements of sawtooth-induced redistribution of fast ions at ASDEX Upgrade. These also represent the first localized fast-ion measurements on the high-field side of this device. The results indicate fast-ion losses in the phase-space measurement volume of about 50% across sawtooth crashes, in good agreement with values predicted with the Kadomtsev sawtooth model implemented in TRANSP and with the sawtooth model in the EBdyna_go code. In contrast to the case of sawteeth, we observe no fast-ion redistribution in the presence of fishbone modes. We highlight how CTS measurements can discriminate between different sawtooth models, in particular when aided by multi-diagnostic velocity-space tomography, and briefly discuss our results in light of existing measurements from other fast-ion diagnostics.
Protocol-Based Resuscitation Bundle to Improve Outcomes in Septic Shock Patients: Evaluation of the Michigan Health and Hospital Association Keystone Sepsis Collaborative*
Authors: Thompson Michael P. , Reeves Mathew J. , Bogan Brittany L. , DiGiovine Bruno , Posa Patricia J. , Watson Sam R. 
Published: July 2016

Objectives:
To evaluate the impact of a multi-ICU quality improvement collaborative implementing a protocol-based resuscitation bundle to treat septic shock patients.

Design:
A difference-in-differences analysis compared patient outcomes in hospitals participating in the Michigan Health & Hospital Association Keystone Sepsis collaborative (n = 37) with noncollaborative hospitals (n = 50) pre- (2010–2011) and postimplementation (2012–2013). Collaborative hospitals were also stratified as high (n = 19) and low (n = 18) adherence based on their overall bundle adherence.

Setting:
Eighty-seven Michigan hospitals with ICUs.

Patients:
We compared 22,319 septic shock patients in collaborative hospitals compared to 26,055 patients in noncollaborative hospitals using the Michigan Inpatient Database.

Interventions:
Multidisciplinary ICU teams received informational toolkits, standardized screening tools, and continuous quality improvement, aided by cultural improvement.

Measurements and Main Results:
In-hospital mortality and hospital length of stay significantly improved between pre- and postimplementation periods for both collaborative and noncollaborative hospitals. Comparing collaborative and noncollaborative hospitals, we found no additional reductions in mortality (odds ratio, 0.94; 95% CI, 0.87–1.01; p = 0.106) or length of stay (–0.3 d; 95% CI, –0.7 to 0.1 d; p = 0.174). Compared to noncollaborative hospitals, high adherence hospitals had significant reductions in mortality (odds ratio, 0.84; 95% CI, 0.79–0.93; p < 0.001) and length of stay (–0.7 d; 95% CI, –1.1 to –0.2; p < 0.001), whereas low adherence hospitals did not (odds ratio, 1.07; 95% CI, 0.97–1.19; p = 0.197; 0.2 d; 95% CI, –0.3 to 0.8; p = 0.367).

Conclusions:
Participation in the Keystone Sepsis collaborative was unable to improve patient outcomes beyond concurrent trends. High bundle adherence hospitals had significantly greater improvements in outcomes, but further work is needed to understand these findings.
Histological Features, p53, c-Kit, and Poliomavirus Status and Impact on Survival in Merkel Cell Carcinoma Patients
Authors: Husein-ElAhmed Husein , Ramos-Pleguezuelos Francisco , Ruiz-Molina Inmaculada , Civico-Amat Vicente , Solis-García Eduardo , Galán-Gutierrez Manuel , Ruiz-Villaverde Ricardo 
Published: July 2016

Background:Merkel cell carcinoma (MCC) is a rare and aggressive malignancy from neuroendocrine cells in the skin. Despite being one of the most life-threatening of skin cancers, little is known about the potential signaling mechanism that drives carcinogenesis in MCC. The purpose of this study is to assess the impact of Merkel cell polyomavirus (MCPyV), p53, and c-kit on the histological features and clinical prognosis of MCC treated in our regional hospitals.Method:The design was a retrospective study. The specimens were taken between 1993 and 2013 in 2 referral hospitals of Southern Spain. Data were collected retrospectively and analyzed using SPSS software.Results:Thirteen lesions from 13 subjects were included in the study. Positivity for c-kit was associated with the absence of MCPyV viral DNA (P= 0.048) and positivity for p53 (P= 0.002). More rate of mitoses per high-power field was presented significantly in those specimens with: positivity for c-kit (P= 0.046), positivity for p53 (P= 0.05), lesions with infiltrative growth pattern (P= 0.008), and lymphovascular invasion (P= 0.034). We observed an inverse relationship between p53 expression and MCPyV infection (Pearson's coefficient: −0.524;P= 0.046) and between c-kit expression and MCPyV infection (Pearson's coefficient: −0.548;P= 0.05), whereas the relationship was positive between p53 expression and c-kit expression (Pearson's coefficient: 0.884;P< 0.001).Conclusion:We conclude that presence of MCPyV DNA has no effect on overall survival. MCCs with p53 and c-kit expressions are associated with the absence of or low MCPyV DNA showing an inverse relationship. A multifactorial molecular pathogenesis where positivity for p53 and c-kit are associated with other mechanisms different than MCPyV (such as pro-mitotic factors) may lead to aggressive clinical behavior.