Snow in the environment acts as a host to rich chemistry and provides a matrix for physical exchange of contaminants within the ecosystem. The goal of this review is to summarise the current state of ...knowledge of physical processes and chemical reactivity in surface snow with relevance to polar regions. It focuses on a description of impurities in distinct compartments present in surface snow, such as snow crystals, grain boundaries, crystal surfaces, and liquid parts. It emphasises the microscopic description of the ice surface and its link with the environment. Distinct differences between the disordered air-ice interface, often termed quasi-liquid layer, and a liquid phase are highlighted. The reactivity in these different compartments of surface snow is discussed using many experimental studies, simulations, and selected snow models from the molecular to the macro-scale. Although new experimental techniques have extended our knowledge of the surface properties of ice and their impact on some single reactions and processes, others occurring on, at or within snow grains remain unquantified. The presence of liquid or liquid-like compartments either due to the formation of brine or disorder at surfaces of snow crystals below the freezing point may strongly modify reaction rates. Therefore, future experiments should include a detailed characterisation of the surface properties of the ice matrices. A further point that remains largely unresolved is the distribution of impurities between the different domains of the condensed phase inside the snowpack, i.e. in the bulk solid, in liquid at the surface or trapped in confined pockets within or between grains, or at the surface. While surface-sensitive laboratory techniques may in the future help to resolve this point for equilibrium conditions, additional uncertainty for the environmental snowpack may be caused by the highly dynamic nature of the snowpack due to the fast metamorphism occurring under certain environmental conditions. Due to these gaps in knowledge the first snow chemistry models have attempted to reproduce certain processes like the long-term incorporation of volatile compounds in snow and firn or the release of reactive species from the snowpack. Although so far none of the models offers a coupled approach of physical and chemical processes or a detailed representation of the different compartments, they have successfully been used to reproduce some field experiments. A fully coupled snow chemistry and physics model remains to be developed.
The adoptive transfer of T lymphocytes reprogrammed to target tumour cells has demonstrated potential for treatment of various cancers
. However, little is known about the long-term potential and ...clonal stability of the infused cells. Here we studied long-lasting CD19-redirected chimeric antigen receptor (CAR) T cells in two patients with chronic lymphocytic leukaemia
who achieved a complete remission in 2010. CAR T cells remained detectable more than ten years after infusion, with sustained remission in both patients. Notably, a highly activated CD4
population emerged in both patients, dominating the CAR T cell population at the later time points. This transition was reflected in the stabilization of the clonal make-up of CAR T cells with a repertoire dominated by a small number of clones. Single-cell profiling demonstrated that these long-persisting CD4
CAR T cells exhibited cytotoxic characteristics along with ongoing functional activation and proliferation. In addition, longitudinal profiling revealed a population of gamma delta CAR T cells that prominently expanded in one patient concomitant with CD8
CAR T cells during the initial response phase. Our identification and characterization of these unexpected CAR T cell populations provide novel insight into the CAR T cell characteristics associated with anti-cancer response and long-term remission in leukaemia.
The Moderate Resolution Imaging Spectroradiometer (MODIS) is one of five instruments aboard the Terra Earth Observing System (EOS) platform launched in December 1999. After achieving final orbit, ...MODIS began Earth observations in late February 2000 and has been acquiring data since that time. The instrument is also being flown on the Aqua spacecraft, launched in May 2002. A comprehensive set of remote sensing algorithms for cloud detection and the retrieval of cloud physical and optical properties have been developed by members of the MODIS atmosphere science team. The archived products from these algorithms have applications in climate change studies, climate modeling, numerical weather prediction, as well as fundamental atmospheric research. In addition to an extensive cloud mask, products include cloud-top properties (temperature, pressure, effective emissivity), cloud thermodynamic phase, cloud optical and microphysical parameters (optical thickness, effective particle radius, water path), as well as derived statistics. We will describe the various algorithms being used for the remote sensing of cloud properties from MODIS data with an emphasis on the pixel-level retrievals (referred to as Level-2 products), with 1-km or 5-km spatial resolution at nadir. An example of each Level-2 cloud product from a common data granule (5 min of data) off the coast of South America will be discussed. Future efforts will also be mentioned. Relevant points related to the global gridded statistics products (Level-3) are highlighted though additional details are given in an accompanying paper in this issue.
Invasive plant survey methods that are practical and economical are needed to describe established colonies and detect nascent invaders. We compared results from random and roadside surveys of ...Alliaria petiolata (Bieb.) Cavara & Grande across a 5730-ha subwatershed. The random survey included 150 1-ha plots; the roadside survey examined 0.1-mile increments (10-m deep) along paved roads (totaling 1104 0.16-ha plots). In the random survey, agriculture was the dominant land use (49% of sampled area), and most A. petiolata patches were in wooded, shaded riparian, and waste areas (34%, 34%, and 29% of patches, respectively). In the roadside survey, right-of-way land use was dominant (38% of sampled area), and most A. petiolata patches were in right-of-way, wooded, and shaded riparian areas (53%, 22%, and 19% of patches, respectively). According to generalized linear model analysis, survey methods did not differ in the overall probability of finding A. petiolata (P=0.17 and 0.11 for random and roadside surveys, respectively). Shaded riparian, wooded, and mixed-species right-of-way land uses were the dominant habitat for A. petiolata in both surveys, but only the random survey indicated waste areas as significant habitat. Alliaria petiolata occurred mostly as small patches in roadsides, but as large patches in random plots, suggesting faster spread in the roadside. Results indicated that disturbed lands along roadsides were important for invasion and spread of A. petiolata; therefore, the roadside survey was a useful, practical method for detecting nascent invasions and management planning. The random sampling lacked a land use bias, and provided data that could be generalized across the subwatershed; however, this method required at least four times more person hours to complete than the roadside survey for a similar amount of area. Although roadside sampling did not provide a completely reliable assessment of target plant populations within the landscape, it may provide an adequate approximation, depending on the specific goals of the survey. Concurrent surveys would provide the most complete information.PUBLICATION ABSTRACT
Abstract We determined the nervous system targeting of interferon-β1b (IFN-β1b), a 20 kDa protein used to treat the relapsing–remitting form of multiple sclerosis, following intranasal administration ...in anesthetized, adult cynomolgus monkeys. Five animals received an intranasal bolus of 125 I-labeled IFN-β1b, applied bilaterally to the upper nasal passages. Serial blood samples were collected for 45 min, after which the animals were euthanized by transcardial perfusion–fixation. High resolution phosphor imaging of tissue sections and gamma counting of microdissected tissue were used to obtain the distribution and concentration profiles of 125 I-IFN-β1b in central and peripheral tissues. Intranasal administration resulted in rapid, widespread targeting of nervous tissue. The olfactory bulbs and trigeminal nerve exhibited 125 I-IFN-β1b levels significantly greater than in peripheral organs and at least one order of magnitude higher than any other nervous tissue area sampled. The basal ganglia exhibited highest 125 I-IFN-β1b levels among CNS regions other than the olfactory bulbs. Preferential IFN-β1b distribution to the primate basal ganglia is a new finding of possible clinical importance. Our study suggests both IFN-β and IFN-α, which share the same receptor, may be bound with relatively high affinity in these structures, possibly offering new insight into a neurovegetative syndrome induced by IFN-α therapy and suspected to involve altered dopamine neurotransmission in the basal ganglia. Most importantly, our results suggest intranasally applied macromolecules may bypass the blood–brain barrier and rapidly enter the primate CNS along olfactory- and trigeminal-associated extracellular pathways, as shown previously in the rat. This is the first study to finely detail the central distribution of a labeled protein after intranasal administration in non-human primates.
Predicting and mitigating changes in soil carbon (C) stocks under global change requires a coherent understanding of the factors regulating soil organic matter (SOM) formation and persistence, ...including knowledge of the direct sources of SOM (plants vs. microbes). In recent years, conceptual models of SOM formation have emphasized the primacy of microbial‐derived organic matter inputs, proposing that microbial physiological traits (e.g., growth efficiency) are dominant controls on SOM quantity. However, recent quantitative studies have challenged this view, suggesting that plants make larger direct contributions to SOM than is currently recognized by this paradigm. In this review, we attempt to reconcile these perspectives by highlighting that variation across estimates of plant‐ versus microbial‐derived SOM may arise in part from methodological limitations. We show that all major methods used to estimate plant versus microbial contributions to SOM have substantial shortcomings, highlighting the uncertainty in our current quantitative estimates. We demonstrate that there is significant overlap in the chemical signatures of compounds produced by microbes, plant roots, and through the extracellular decomposition of plant litter, which introduces uncertainty into the use of common biomarkers for parsing plant‐ and microbial‐derived SOM, especially in the mineral‐associated organic matter (MAOM) fraction. Although the studies that we review have contributed to a deeper understanding of microbial contributions to SOM, limitations with current methods constrain quantitative estimates. In light of recent advances, we suggest that now is a critical time to re‐evaluate long‐standing methods, clearly define their limitations, and develop a strategic plan for improving the quantification of plant‐ and microbial‐derived SOM. From our synthesis, we outline key questions and challenges for future research on the mechanisms of SOM formation and stabilization from plant and microbial pathways.
Soil organic matter (SOM) comprises ~80% of global terrestrial carbon stocks, much of which is stored as mineral‐associated organic matter (MAOM). MAOM is derived from both plant and microbial biomolecules, but the quantitative contributions of each remain uncertain (represented by the mixing of red and blue into purple). There is substantial overlap in the compounds produced by microbes, plant roots and those released through the extracellular decomposition of plant litter, and limitations in our current methods constrain quantification. We review the methods used to quantify plant‐ and microbial‐derived SOM, examining their limitations and key future research priorities towards elucidating the plant and microbial pathways of SOM formation.
First Results from the THEMIS Mission Angelopoulos, V.; Sibeck, D.; Carlson, C. W. ...
Space science reviews,
12/2008, Letnik:
141, Številka:
1-4
Journal Article
Recenzirano
Odprti dostop
THEMIS was launched on February 17, 2007 to determine the trigger and large-scale evolution of substorms. During the first seven months of the mission the five satellites coasted near their injection ...orbit to avoid differential precession in anticipation of orbit placement, which started in September 2007 and led to a commencement of the baseline mission in December 2007. During the coast phase the probes were put into a string-of-pearls configuration at 100 s of km to 2 R
E
along-track separations, which provided a unique view of the magnetosphere and enabled an unprecedented dataset in anticipation of the first tail season. In this paper we describe the first THEMIS substorm observations, captured during instrument commissioning on March 23, 2007. THEMIS measured the rapid expansion of the plasma sheet at a speed that is commensurate with the simultaneous expansion of the auroras on the ground. These are the first unequivocal observations of the rapid westward expansion process in space and on the ground. Aided by the remote sensing technique at energetic particle boundaries and combined with ancillary measurements and MHD simulations, they allow determination and mapping of space currents. These measurements show the power of the THEMIS instrumentation in the tail and the radiation belts. We also present THEMIS Flux Transfer Events (FTE) observations at the magnetopause, which demonstrate the importance of multi-point observations there and the quality of the THEMIS instrumentation in that region of space.
Research hypotheses have been a cornerstone of science since before Galileo. Many have argued that hypotheses (1) encourage discovery of mechanisms, and (2) reduce bias—both features that should ...increase transferability and reproducibility. However, we are entering a new era of big data and highly predictive models where some argue the hypothesis is outmoded. We hypothesized that hypothesis use has declined in ecology and evolution since the 1990s, given the substantial advancement of tools further facilitating descriptive, correlative research. Alternatively, hypothesis use may have become more frequent due to the strong recommendation by some journals and funding agencies that submissions have hypothesis statements. Using a detailed literature analysis (N = 268 articles), we found prevalence of hypotheses in eco–evo research is very low (6.7%–26%) and static from 1990–2015, a pattern mirrored in an extensive literature search (N = 302,558 articles). Our literature review also indicates that neither grant success nor citation rates were related to the inclusion of hypotheses, which may provide disincentive for hypothesis formulation. Here, we review common justifications for avoiding hypotheses and present new arguments based on benefits to the individual researcher. We argue that stating multiple alternative hypotheses increases research clarity and precision, and is more likely to address the mechanisms for observed patterns in nature. Although hypotheses are not always necessary, we expect their continued and increased use will help our fields move toward greater understanding, reproducibility, prediction, and effective conservation of nature.
We use a quantitative literature review to show that use of a priori hypotheses is still rare in the fields of ecology and evolution. We provide suggestions about the group and individual‐level benefits of hypothesis use.
The neuro-anatomical substrates of major depressive disorder (MDD) are still not well understood, despite many neuroimaging studies over the past few decades. Here we present the largest ever ...worldwide study by the ENIGMA (Enhancing Neuro Imaging Genetics through Meta-Analysis) Major Depressive Disorder Working Group on cortical structural alterations in MDD. Structural T1-weighted brain magnetic resonance imaging (MRI) scans from 2148 MDD patients and 7957 healthy controls were analysed with harmonized protocols at 20 sites around the world. To detect consistent effects of MDD and its modulators on cortical thickness and surface area estimates derived from MRI, statistical effects from sites were meta-analysed separately for adults and adolescents. Adults with MDD had thinner cortical gray matter than controls in the orbitofrontal cortex (OFC), anterior and posterior cingulate, insula and temporal lobes (Cohen's d effect sizes: -0.10 to -0.14). These effects were most pronounced in first episode and adult-onset patients (>21 years). Compared to matched controls, adolescents with MDD had lower total surface area (but no differences in cortical thickness) and regional reductions in frontal regions (medial OFC and superior frontal gyrus) and primary and higher-order visual, somatosensory and motor areas (d: -0.26 to -0.57). The strongest effects were found in recurrent adolescent patients. This highly powered global effort to identify consistent brain abnormalities showed widespread cortical alterations in MDD patients as compared to controls and suggests that MDD may impact brain structure in a highly dynamic way, with different patterns of alterations at different stages of life.
PDF
