536 research outputs found

    Bringing Families In: Recommendations of the Incarceration, Reentry and Family Roundtables

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    Building on the findings of the New Jersey Reentry Roundtable and a growing concern around the state about how to improve outcomes for the more than 70,000 individuals expected to return home from prison over the next five years, the roundtable examined the complex role that families – broadly defined – play in the lives of prisoners during incarceration and after their release. This document presents a set of recommendations emerging directly from roundtable sessions and provides a road map for individual and collaborative efforts accepted by a range of key players in New Jersey, including government officials, community and faith based service agencies, advocacy groups, family members and formerly incarcerated people

    Nuclear Thermometers for Classical Novae

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    Classical novae are stellar explosions occurring in binary systems, consisting of a white dwarf and a main sequence companion. Thermonuclear runaways on the surface of massive white dwarfs, consisting of oxygen and neon, are believed to reach peak temperatures of several hundred million kelvin. These temperatures are strongly correlated with the underlying white dwarf mass. The observational counterparts of such models are likely associated with outbursts that show strong spectral lines of neon in their shells (neon novae). The goals of this work are to investigate how useful elemental abundances are for constraining the peak temperatures achieved during these outbursts and determine how robust "nova thermometers" are with respect to uncertain nuclear physics input. We present updated observed abundances in neon novae and perform a series of hydrodynamic simulations for several white dwarf masses. We find that the most useful thermometers, N/O, N/Al, O/S, S/Al, O/Na, Na/Al, O/P, and P/Al, are those with the steepest monotonic dependence on peak temperature. The sensitivity of these thermometers to thermonuclear reaction rate variations is explored using post-processing nucleosynthesis simulations. The ratios N/O, N/Al, O/Na, and Na/Al are robust, meaning they are minimally affected by uncertain rates. However, their dependence on peak temperature is relatively weak. The ratios O/S, S/Al, O/P, and P/Al reveal strong dependences on temperature and the poorly known 30P(p,g)31S rate. We compare our model predictions to neon nova observations and obtain the following estimates for the underlying white dwarf masses: 1.34-1.35 solar masses (V838 Her), 1.18-1.21 solar masses (V382 Vel), <1.3 solar masses (V693 CrA), <1.2 solar masses (LMC 1990#1), and <1.2 solar masses (QU Vul).Comment: 12 pages, 7 figures, accepted to Ap

    On Presolar Stardust Grains from CO Classical Novae

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    About 30% to 40% of classical novae produce dust 20-100 days after the outburst, but no presolar stardust grains from classical novae have been unambiguously identified yet. Although several studies claimed a nova paternity for certain grains, the measured and simulated isotopic ratios could only be reconciled assuming that the grains condensed after the nova ejecta mixed with a much larger amount of close-to-solar matter. However, the source and mechanism of this potential post-explosion dilution of the ejecta remains a mystery. A major problem with previous studies is the small number of simulations performed and the implied poor exploration of the large nova parameter space. We report the results of a different strategy, based on a Monte Carlo technique, that involves the random sampling over the most important nova model parameters: the white dwarf composition; the mixing of the outer white dwarf layers with the accreted material before the explosion; the peak temperature and density; the explosion time scales; and the possible dilution of the ejecta after the outburst. We discuss and take into account the systematic uncertainties for both the presolar grain measurements and the simulation results. Only those simulations that are consistent with all measured isotopic ratios of a given grain are accepted for further analysis. We also present the numerical results of the model parameters. We identify 18 presolar grains with measured isotopic signatures consistent with a CO nova origin, without assuming any dilution of the ejecta. Among these, the grains G270 2, M11-334-2, G278, M11-347-4, M11-151-4, and Ag2 6 have the highest probability of a CO nova paternity.Comment: 8 figure

    Nuclear Mixing Meters for Classical Novae

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    Classical novae are caused by mass transfer episodes from a main sequence star onto a white dwarf via Roche lobe overflow. This material forms an accretion disk around the white dwarf. Ultimately, a fraction of this material spirals in and piles up on the white dwarf surface under electron-degenerate conditions. The subsequently occurring thermonuclear runaway reaches hundreds of megakelvin and explosively ejects matter into the interstellar medium. The exact peak temperature strongly depends on the underlying white dwarf mass, the accreted mass and metallicity, and the initial white dwarf luminosity. Observations of elemental abundance enrichments in these classical nova events imply that the ejected matter consists not only of processed solar material from the main sequence partner but also of material from the outer layers of the underlying white dwarf. This indicates that white dwarf and accreted matter mix prior to the thermonuclear runaway. The processes by which this mixing occurs require further investigation to be understood. In this work, we analyze elemental abundances ejected from hydrodynamic nova models in search of elemental abundance ratios that are useful indicators of the total amount of mixing. We identify the abundance ratios Σ\SigmaCNO/H, Ne/H, Mg/H, Al/H, and Si/H as useful mixing meters in ONe novae. The impact of thermonuclear reaction rate uncertainties on the mixing meters is investigated using Monte Carlo post-processing network calculations with temperature-density evolutions of all mass zones computed by the hydrodynamic models. We find that the current uncertainties in the 30^{30}P(pp,γ\gamma)31^{31}S rate influence the Si/H abundance ratio, but overall the mixing meters found here are robust against nuclear physics uncertainties. A comparison of our results with observations of ONe novae provides strong constraints for classical nova models

    Cyclic di-GMP: second messenger extraordinaire

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    Cyclic dinucleotides (CDNs) are highly versatile signalling molecules that control various important biological processes in bacteria. The best-studied example is cyclic di-GMP (c-di-GMP). Known since the late 1980s, it is now recognized as a near-ubiquitous second messenger that coordinates diverse aspects of bacterial growth and behaviour, including motility, virulence, biofilm formation and cell cycle progression. In this Review, we discuss important new insights that have been gained into the molecular principles of c-di-GMP synthesis and degradation, which are mediated by diguanylate cyclases and c-di-GMP-specific phosphodiesterases, respectively, and the cellular functions that are exerted by c-di-GMP-binding effectors and their diverse targets. Finally, we provide a short overview of the signalling versatility of other CDNs, including c-di-AMP and cGMP-AMP (cGAMP)

    Cyclic di-GMP mediates a histidine kinase/phosphatase switch by noncovalent domain cross-linking

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    Histidine kinases are key components of regulatory networks in bacteria. Although many of these enzymes are bifunctional, mediating both phosphorylation and dephosphorylation of downstream targets, the molecular details of this central regulatory switch are unclear. We showed recently that the universal second messenger cyclic di-guanosine monophosphate (c-di-GMP) drives Caulobacter crescentus cell cycle progression by forcing the cell cycle kinase CckA from its default kinase into phosphatase mode. We use a combination of structure determination, modeling, and functional analysis to demonstrate that c-di-GMP reciprocally regulates the two antagonistic CckA activities through noncovalent cross-linking of the catalytic domain with the dimerization histidine phosphotransfer (DHp) domain. We demonstrate that both c-di-GMP and ADP (adenosine diphosphate) promote phosphatase activity and propose that c-di-GMP stabilizes the ADP-bound quaternary structure, which allows the receiver domain to access the dimeric DHp stem for dephosphorylation. In silico analyses predict that c-di-GMP control is widespread among bacterial histidine kinases, arguing that it can replace or modulate canonical transmembrane signaling

    C-di-GMP acts as a cell cycle oscillator to drive chromosome replication

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    Cyclic di-GMP (c-di-GMP) is an omnipresent bacterial second Messenger molecule which has been recognized as a central regulator of Lifestyle transitions. Generally, high levels of c-di-GMP promote a biofilm associated, surface attached lifestyle, while low levels of c-di-GMP favor a single cell, motile lifestyle. A wide range of c-di-GMP effector proteins are known which control various cellular functions. It has long been assumed that c-di-GMP is involved in the regulation of cell cycle progression. In this work the role of c-di-GMP on the G1-S transition is described in the aquatic bacterium Caulobacter crescentus. C. crescentus is an ideal model organism since G1-S transition is developmentally linked to the swarmer to stalked cell transition and therefore easily observable. Moreover, c-di-GMP influences several processes at the swarmer to stalked cell transition. Thus, disturbing the c-di-GMP-dependent processes causes specific phenotypes. In the first part of this work, the effect of c-di-GMP on core components of the C. crescentus cell cycle control machinery is assessed. It is described that the essential histidine kinase CckA (Cell cycle kinase A) is regulated by c-di-GMP. Binding of CckA to c-di-GMP activates the phosphatase activity of CckA and leads to dephosphorylation of the transcription factor CtrA (Central transcriptional activator A) which ultimately initiates chromosome replication. Furthermore it is shown that c-di-GMP is required in the predivisional cell to establish a CckA-dependent CtrA phosphorylation gradient. The second part describes the mechanism by which c-di-GMP activates CckA phosphatase activity. It was possible to isolate several mutations in CckA which specifically target certain activities of CckA and thereby give an insight into the intramolecular signaling mechanisms. Additionally, a recently solved Crystal structure of CckA in complex with c-di-GMP will increase our understanding of the activation of phosphatse activity. The third part of this work deals with the regulation of several histidine kinases by a single domain response regulator. The single domain response Regulator MrrA (Multifunctional response regulator A) is shown to be a central part of the C. crescentus stress response pathway. MrrA is phorphorylated by two cognate histidine kinases and additionally acts as a repressor of one of the kinases. The downstream target of MrrA is the histidine kinase LovK which is the main activator of the general stress response. It is demonstrated that phosphorylated MrrA is an allosteric activator of LovK. Taken together this work increases the understanding of how c-di-GMP regulates cell cycle progression and additionally gives insight into the modes of regulation of histidine kinases

    Ratcheting ambition to limit warming to 1.5 °C–trade-offs between emission reductions and carbon dioxide removal

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    Mitigation scenarios to limit global warming to 1.5 °C or less in 2100 often rely on large amounts of carbon dioxide removal (CDR), which carry significant potential social, environmental, political and economic risks. A precautionary approach to scenario creation is therefore indicated. This letter presents the results of such a precautionary modelling exercise in which the models C-ROADS and En-ROADS were used to generate a series of 1.5 °C mitigation scenarios that apply increasingly stringent constraints on the scale and type of CDR available. This allows us to explore the trade-offs between near-term stringency of emission reductions and assumptions about future availability of CDR. In particular, we find that regardless of CDR assumptions, near-term ambition increase ('ratcheting') is required for any 1.5 °C pathway, making this letter timely for the facilitative, or Talanoa, dialogue to be conducted by the UNFCCC in 2018. By highlighting the difference between net and gross reduction rates, often obscured in scenarios, we find that mid-term gross CO2emission reduction rates in scenarios with CDR constraints increase to levels without historical precedence. This in turn highlights, in addition to the need to substantially increase CO2reduction rates, the need to improve emission reductions for non-CO2greenhouse gases. Further, scenarios in which all or part of the CDR is implemented as non-permanent storage exhibit storage loss emissions, which partly offset CDR, highlighting the importance of differentiating between net and gross CDR in scenarios. We find in some scenarios storage loss trending to similar values as gross CDR, indicating that gross CDR would have to be maintained simply to offset the storage losses of CO2sequestered earlier, without any additional net climate benefit

    Leaf litter decomposition rates increase with rising mean annual temperature in Hawaiian tropical montane wet forests

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    Decomposing litter in forest ecosystems supplies nutrients to plants, carbon to heterotrophic soil microorganisms and is a large source of CO2 to the atmosphere. Despite its essential role in carbon and nutrient cycling, the temperature sensitivity of leaf litter decay in tropical forest ecosystems remains poorly resolved, especially in tropical montane wet forests where the warming trend may be amplified compared to tropical wet forests at lower elevations. We quantified leaf litter decomposition rates along a highly constrained 5.2 ◦C mean annual temperature (MAT) gradient in tropical montane wet forests on the Island ofHawaii. Dominant vegetation, substrate type and age, soil moisture, and disturbance history are all nearly constant across this gradient, allowing us to isolate the effect of rising MAT on leaf litter decomposition and nutrient release. Leaf litter decomposition rates were a positive linear function of MAT, causing the residence time of leaf litter on the forest floor to decline by ∼31 days for each 1 ◦C increase in MAT. Our estimate of the Q10 temperature coefficient for leaf litter decomposition was 2.17, within the commonly reported range for heterotrophic organic matter decomposition (1.5–2.5) across a broad range of ecosystems. The percentage of leaf litter nitrogen (N) remaining after six months declined linearly with increasing MAT from ∼88% of initial N at the coolest site to ∼74% at the warmest site. The lack of net N immobilization during all three litter collection periods at all MAT plots indicates that N was not limiting to leaf litter decomposition, regardless of temperature. These results suggest that leaf litter decay in tropical montane wet forests may be more sensitive to rising MAT than in tropical lowland wet forests, and that increased rates of N release from decomposing litter could delay or prevent progressive N limitation to net primary productivity with climate warming

    Translational Research and Medicine at NASA: From Earth to Space and Back Again

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    The Space Environment provides many challenges to the human physiology and therefore to extended habitation and exploration. Translational research and medical strategies are meeting these challenges by combining Earth based medical solutions with innovative and developmental engineering approaches. Translational methodologies are current applied to spaceflight related dysregulations in the areas of: (1) cardiovascular fluid shifts, intracranial hypertension and neuro-ocular impairment 2) immune insufficiency and suppression/viral re-expression, 3) bone loss and fragility (osteopenia/osteoporosis) and muscle wasting, and finally 4) radiation sensitivity and advanced ageing. Over 40 years of research into these areas have met with limited success due to lack of tools and basic understanding of central issues that cause physiologic maladaptaion and distrupt homeostatis. I will discuss the effects of living in space (reduced gravity, increased radiation and varying atmospheric conditions [EVA]) during long-duration, exploration-class missions and how translational research has benefited not only space exploration but also Earth based medicine. Modern tools such as telemedicine advances in genomics, proteomics, and metabolomics (Omicssciences) has helped address syndromes, at the systemic level by enlisting a global approach to assessing spaceflight physiology and to develop countermeasures thereby permitting our experience in space to be translated to the Earth's medical community
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