Volcanic aerosol records and tephrochronology of the Summit, Greenland, ice cores

The recently collected Greenland Ice Sheet Project 2 (GISP2) and Greenland Ice Core Project ice cores from Summit, Greenland, provide lengthy and highly resolved records of the deposition of both the aerosol (H2SO4) and silicate (tephra) components of past volcanism. Both types of data are very beneficial in developing the hemispheric to global chronology of explosive volcanism and evaluating the entire volcanism‐climate system. The continuous time series of volcanic SO42− for the last 110,000 years show a strong relationship between periods of increased volcanism and periods of climatic change. The greatest number of volcanic SO42− signals, many of very high magnitude, occur during and after the final stages of deglaciation (6000–17,000 years ago), possibly reflecting the increased crustal stresses that occur with changing volumes of continental ice sheets and with the subsequent changes in the volume of water in ocean basins (sea level change). The increase in the number of volcanic SO42− signals at 27,000–36,000 and 79,000–85,000 years ago may be related to initial ice sheet growth prior to the glacial maximum and prior to the beginning of the last period of glaciation, respectively. A comparison of the electrical conductivity of the GISP2 core with that of the volcanic SO42− record for the Holocene indicates that only about half of the larger volcanic signals are coincident in the two records. Other volcanic acids besides H2SO4 and other SO42− sources can complicate the comparisons, although the threshold level picked to make such comparisons is especially critical. Tephra has been found in both cores with a composition similar to that originating from the Vatnaöldur eruption that produced the Settlement Layer in Iceland (mid‐A.D. 870s), from the Icelandic eruption that produced the Saksunarvatn ash (∼10,300 years ago), and from the Icelandic eruption(s) that produced the Z2 ash zone in North Atlantic marine cores (∼52,700 years ago). The presence of these layers provides absolute time lines for correlation between the two cores and for correlation with proxy records from marine sediment cores and terrestrial deposits containing these same tephras. The presence of both rhyolitic and basaltic shards in the Z2 ash in theGISP2 core and the composition of the basaltic grains lend support to multiple Icelandic sources (Torfajökull area and Katla) for the Z2 layer. Deposition of the Z2 layer occurs at the beginning of a stadial event, further reflecting the possibility of a volcanic triggering by the effects of changing climatic conditions

Signalling standards for progress:Bridging the divide between a valid consent to use patient data under data protection law and the common law duty of confidentiality

In this article, we analyse the legal components of disclosing confidential patient information under the UK's common law duty of confidentiality (CLDoC) and processing personal (health) data under the UK's General Data Protection Regulation (GDPR) and Data Protection Act 2018. We describe the ostensible divide between the CLDoC and data protection law when it comes to the requirements of a valid signal of consent by a patient to use and disclose patient information, obtained by a health professional in the context of direct care, for health care and health research purposes. Ultimately, our analysis suggests that we are saddled, at least in the medium term, with two regimes operating with different standards of a valid consent-while putatively protecting similar interests. There is, however, opportunity for progress. It is possible to improve professional guidance on the interaction between the regimes and to achieve significant normative alignment without aligning the signalling standard for consent; this would promote consistent protection of reasonable expectations of patients across both regimes. Further coherence would require aligning not only the standard, but also the role played by consent under each regime. Here we argue that, in relation to direct care, any such shift should be away from consent as the normal justification. In relation to health research, on the contrary, it should be toward consent as the normal justification for use and disclosure of patient information under both the CLDoC and data protection law

Plans for the first balloon flight of the gamma-ray polarimeter experiment (GRAPE)

We have developed a design for a hard X-ray polarimeter operating in the energy range from 50 to 500 keV. This modular design, known as GRAPE (Gamma-Ray Polarimeter Experiment), has been successfully demonstrated in the lab using partially polarized gamma-ray sources and using fully polarized photon beams at Argonne National Laboratory. In June of 2007, a GRAPE engineering model, consisting of a single detector module, was flown on a high altitude balloon flight to further demonstrate the design and to collect background data. We are currently preparing a much larger balloon payload for a flight in the fall of 2011. Using a large (16-element) array of detector modules, this payload is being designed to search for polarization from known point sources of radiation, namely the Crab and Cygnus X-1. This first flight will not only provide a scientific demonstration of the GRAPE design (by measuring polarization from the Crab nebula), it will also lay the foundation for subsequent long duration balloon flights that will be designed for studying polarization from gamma-ray bursts and solar flares. Here we shall present data from calibration of the first flight module detectors, review the latest payload design and update the predicted polarization sensitivity for both the initial continental US balloon flight and the subsequent long-duration balloon flights

GRAPE: a balloon-borne gamma-ray polarimeter

The Gamma-RAy Polarimeter Experiment (GRAPE) is a concept for an astronomical hard X-ray Compton polarimeter operating in the 50 - 500 keV energy band. The instrument has been optimized for wide-field polarization measurements of transient outbursts from energetic astrophysical objects such as gamma-ray bursts and solar flares. The GRAPE instrument is composed of identical modules, each of which consists of an array of scintillator elements read out by a multi-anode photomultiplier tube (MAPMT). Incident photons Compton scatter in plastic scintillator elements and are subsequently absorbed in inorganic scintillator elements; a net polarization signal is revealed by a characteristic asymmetry in the azimuthal scattering angles. We have constructed a prototype GRAPE module that has been calibrated at a polarized hard X-ray beam and flown on an engineering balloon test flight. A full-scale scientific balloon payload, consisting of up to 36 modules, is currently under development. The first flight, a one-day flight scheduled for 2011, will verify the expected scientific performance with a pointed observation of the Crab Nebula. We will then propose long-duration balloon flights to observe gamma-ray bursts and solar flares

Potential atmospheric impact of the Toba Mega‐Eruption ∼71,000 years ago

An ∼6‐year long period of volcanic sulfate recorded in the GISP2 ice core about 71,100 ± 5000 years ago may provide detailed information on the atmospheric and climatic impact of the Toba mega‐eruption. Deposition of these aerosols occur at the beginning of an ∼1000‐year long stadial event, but not immediately before the longer glacial period beginning ∼67,500 years ago. Total stratospheric loading estimates over this ∼6‐year period range from 2200 to 4400 Mt of H2SO4 aerosols. The range in values is given to compensate for uncertainties in aerosol transport. Magnitude and longevity of the atmospheric loading may have led directly to enhanced cooling during the initial two centuries of this ∼1000‐year cooling event

Simulations of a monolithic lanthanum bromide gamma-ray detector

We have been working on the development of a detector design for a large area coded aperture imaging system operating in the 10-600 keV energy range. The detector design is based on an array of Lanthanum Bromide (LaBr3) scintillators, each directly coupled to a Hamamatsu 64-channel multi-anode photomultiplier tube (MAPMT). This paper focuses on the development of the GEANT4-based simulations as an aid in the optimization of the detector design. The simulations have been validated by comparisons with various laboratory data sets. We will summarize the current status and latest findings from this study

Ecophysiological traits of grasses: resolving the effects of photosynthetic pathway and phylogeny

C4 photosynthesis is an important example of convergent evolution in plants, having arisen in eudicots, monocots and diatoms. Comparisons between such diverse groups are confounded by phylogenetic and ecological differences, so that only broad generalisations can be made about the role of C4 photosynthesis in
determining ecophysiological traits. However, 60% of C4 species occur in the grasses (Poaceae) and molecular phylogenetic techniques confirm that there are between 8 and 17 independent origins of C4 photosynthesis in the Poaceae. In a screening experiment, we compared leaf physiology and growth traits across several major
independent C3 & C4 groups within the Poaceae, asking 1) which traits differ consistently between photosynthetic
types and 2) which traits differ consistently between clades within each photosynthetic type

Adapting predictive models to reduce fungicide sprays on tomatoes in Iowa

Iowa tomato growers face critical challenges in pest control. The public is concerned about the health risks of pesticide residues on fruits and vegetables as well as environmental contamination; the result has been fewer, more restricted, more expensive pesticide products for minor crops such as tomatoes. At the same time, the market continues to demand high-quality, abundant, blemish-free produce

The therapeutic efficacy and macrofilaricidal activity of doxycycline for the treatment of river blindness

Background. Onchocerca volvulus and lymphatic filariae, causing river blindness and elephantiasis, depend on endosymbiotic Wolbachia bacteria for growth, development, fertility, and survival. Clinical trials have shown that doxycycline treatment eliminates Wolbachia, causing long-term sterilization of adult female filariae and effecting potent macrofilaricidal activity. The continual reinfection by drug-naive worms that occurs in these trial settings dilutes observable anti-Wolbachia and antifilarial effects, making it difficult to estimate therapeutic efficacy and compare different doxycycline regimens, evaluated at different times after treatment. Methods. A meta-analytical modeling framework is developed to link all usable data collected from clinical trials measuring the Wolbachia status and viability of individual female adult worms collected at various times after treatment with 4, 5, or 6 weeks of daily 100 or 200 mg oral doxycycline. The framework is used to estimate efficacy parameters that are not directly measurable as trial outcomes. Results. The estimated efficacy of doxycycline (the maximum proportional reduction in the percentage of adult female O. volvulus positive for Wolbachia) is 91%–94% on average, irrespective of the treatment regimen. Efficacy is >95% in the majority of trial participants. The life span of Wolbachia-depleted worms is reduced by 70%–80%, from approximately 10 years to 2–3 years. Conclusions. The efficacy parameters are pertinent to the prospects of using doxycycline on a “test and treat” basis for onchocerciasis control and confirm doxycycline as a potent macrofilaricidal therapy. The modeling approach is more generally relevant to the design and evaluation of clinical trials for antifilarial drugs conducted in endemic settings

The dynamic switch mechanism that leads to activation of LRRK2 is embedded in the DFGψ motif in the kinase domain.

Leucine-rich repeat kinase 2 (LRRK2) is a large multidomain protein, and LRRK2 mutants are recognized risk factors for Parkinson's disease (PD). Although the precise mechanisms that control LRRK2 regulation and function are unclear, the importance of the kinase domain is strongly implicated, since 2 of the 5 most common familial LRRK2 mutations (G2019S and I2020T) are localized to the conserved DFGψ motif in the kinase core, and kinase inhibitors are under development. Combining the concept of regulatory (R) and catalytic (C) spines with kinetic and cell-based assays, we discovered a major regulatory mechanism embedded within the kinase domain and show that the DFG motif serves as a conformational switch that drives LRRK2 activation. LRRK2 is quite unusual in that the highly conserved Phe in the DFGψ motif, which is 1 of the 4 R-spine residues, is replaced with tyrosine (DY2018GI). A Y2018F mutation creates a hyperactive phenotype similar to the familial mutation G2019S. The hydroxyl moiety of Y2018 thus serves as a "brake" that stabilizes an inactive conformation; simply removing it destroys a key hydrogen-bonding node. Y2018F, like the pathogenic mutant I2020T, spontaneously forms LRRK2-decorated microtubules in cells, while the wild type and G2019S require kinase inhibitors to form filaments. We also explored 3 different mechanisms that create kinase-dead pseudokinases, including D2017A, which further emphasizes the highly synergistic role of key hydrophobic and hydrophilic/charged residues in the assembly of active LRRK2. We thus hypothesize that LRRK2 harbors a classical protein kinase switch mechanism that drives the dynamic activation of full-length LRRK2