80 research outputs found

    Localization and the interface between quantum mechanics, quantum field theory and quantum gravity I (The two antagonistic localizations and their asymptotic compatibility)

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    It is shown that there are significant conceptual differences between QM and QFT which make it difficult to view the latter as just a relativistic extension of the principles of QM. At the root of this is a fundamental distiction between Born-localization in QM (which in the relativistic context changes its name to Newton-Wigner localization) and modular localization which is the localization underlying QFT, after one separates it from its standard presentation in terms of field coordinates. The first comes with a probability notion and projection operators, whereas the latter describes causal propagation in QFT and leads to thermal aspects of locally reduced finite energy states. The Born-Newton-Wigner localization in QFT is only applicable asymptotically and the covariant correlation between asymptotic in and out localization projectors is the basis of the existence of an invariant scattering matrix. In this first part of a two part essay the modular localization (the intrinsic content of field localization) and its philosophical consequences take the center stage. Important physical consequences of vacuum polarization will be the main topic of part II. Both parts together form a rather comprehensive presentation of known consequences of the two antagonistic localization concepts, including the those of its misunderstandings in string theory.Comment: 63 pages corrections, reformulations, references adde

    What's in the water? – Target and suspect screening of contaminants of emerging concern in raw water and drinking water from Europe and Asia

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    There is growing worry that drinking water can be affected by contaminants of emerging concern (CECs), potentially threatening human health. In this study, a wide range of CECs ( n = 177), including pharmaceuticals, pesticides, perfluoroalkyl substances (PFASs) and other compounds, were analysed in raw water and in drinking water collected from drinking water treatment plants (DWTPs) in Europe and Asia ( n = 13). The impact of human activities was reflected in large numbers of compounds detected ( n = 115) and high variation in concentrations in the raw water (range 15-7995 ng L & minus;1 for E177 CECs). The variation was less pronounced in drinking water, with total concentration ranging from 35 to 919 ng L & minus;1 . Treatment efficiency was on average 65 +/- 28%, with wide variation between different DWTPs. The DWTP with the highest ECEC concentrations in raw water had the most efficient treatment procedure (average treatment efficiency 89%), whereas the DWTP with the lowest E177 CEC concentration in the raw water had the lowest average treatment efficiency (2.3%). Suspect screening was performed for 500 compounds ranked high as chemicals of concern for drinking water, using a prioritisation tool (SusTool). Overall, 208 features of interest were discovered and three were confirmed with reference standards. There was co-variation between removal efficiency in DWTPs for the target compounds and the suspected features detected using suspect screening, implying that removal of known contaminants can be used to predict overall removal of potential CECs for drinking water production. Our results can be of high value for DWTPs around the globe in their planning for future treatment strategies to meet the increasing concern about human ex-posure to unknown CECs present in their drinking water.(c) 2021 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/

    Investigating the uptake and fate of poly- and perfluoroalkylated substances (PFAS) in sea ice using an experimental sea ice chamber

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    Poly- and perfluoroalkyl substances (PFAS) are contaminants of emerging Arctic concern and are present in the marine environments of the polar regions. Their input to and fate within the marine cryosphere are poorly understood. We conducted a series of laboratory experiments to investigate the uptake, distribution, and release of 10 PFAS of varying carbon chain length (C4–C12) in young sea ice grown from artificial seawater (NaClsolution). We show that PFAS are incorporated into bulk sea ice during ice formation and regression analyses for individual PFAS concentrations in bulk sea ice were linearly related to salinity (r2 = 0.30 to 0.88, n = 18, p < 0.05). This shows that their distribution is strongly governed by the presence and dynamics of brine (high salinity water) within the sea ice. Furthermore, long-chain PFAS (C8–C12), were enriched in bulk ice up to 3-fold more than short-chain PFAS (C4–C7) and NaCl. This suggests that chemical partitioning of PFAS between the different phases of sea ice also plays a role in their uptake during its formation. During sea ice melt, initial meltwater fractions were highly saline and predominantly contained short-chain PFAS, whereas the later, fresher meltwater fractions predominantly contained long-chain PFAS. Our results demonstrate that in highly saline parts of sea ice (near the upper and lower interfaces and in brine channels) significant chemical enrichment (ε) of PFAS can occur with concentrations in brine channels greatly exceeding those in seawater from which it forms (e.g., for PFOA, εrinebrine = 10 ± 4). This observation has implications for biological exposure to PFAS present in brine channels, a common feature of first-year sea ice which is the dominant ice type in a warming Arctic

    Glyphosate targets fish monoaminergic systems leading to oxidative stress and anxiety

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    Artículo científico indizadoGlyphosate is the active ingredient of some of the most highly produced and used herbicides worldwide. The intensive applications of glyphosate-based herbicides and its half-life in water lead to its presence in many aquatic ecosystems. Whereas recent studies have reported neurotoxic effects of glyphosate including autism- related effects, most of them used extremely high (mg/L to g/L) concentrations, so it is still unclear if chronic, low environmentally relevant concentrations of this compound (ng/L to μg/L) can induce neurotoxicity. In this study we analyzed the neurotoxicity of glyphosate in adult zebrafish after waterborne exposure to environmentally relevant concentrations (0.3 and 3 μg/L) for two weeks. Our data showed that exposed fish presented a significant impairment of exploratory and social behaviors consistent with increased anxiety. The anterior brain of the exposed fish presented a significant increase in dopamine and serotonin levels, as well as in the DOPAC/dopamine and homovanillic acid/dopamine turnover ratios. Moreover, the expression of genes involved in the dopaminergic system, as th1, th2, comtb, and scl6a3 was downregulated. Finally, the brain of exposed fish presented a significant increase in the catalase and superoxide dismutase activities, with a concomitant decrease of glutathione stores. These changes in the antioxidant defense system are consistent with the observed increase in oxidative stress, reflected by the increase in the levels of lipid peroxidation in the brain. The presented results show that current glyphosate concentrations commonly found in many aquatic ecosystems may have detrimental consequences on fish survival by decreasing exploration of the environment or altering social interactions. Furthermore, as zebrafish is also a vertebrate model widely used in human neurobehavioral studies, these results are relevant not only for environmental risk assessment, but also for understanding the risk of chronic low-dose exposures on human health.This work was supported by the Spanish Government with FEDER Funds (CTM2017-83242-R; D.R.) and the network of recognized research groups by the Catalan Government (2017 SGR_902). J.B. was supported by a Spanish fellowship PRE2018-083513. Mention of spe- cific products or trade names does not indicate endorsement by the US federal government

    Berlin statement on legacy and emerging contaminants in polar regions

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    Polar regions should be given greater consideration with respect to the monitoring, risk assessment, and management of potentially harmful chemicals, consistent with requirements of the precautionary principle. Protecting the vulnerable polar environments requires (i) raising political and public awareness and (ii) restricting and preventing global emissions of harmful chemicals at their sources. The Berlin Statement is the outcome of an international workshop with representatives of the European Commission, the Arctic Council, the Antarctic Treaty Consultative Meeting, the Stockholm Convention on Persistent Organic Pollutants (POPs), environmental specimen banks, and data centers, as well as scientists from various international research institutions. The statement addresses urgent chemical pollution issues in the polar regions and provides recommendations for improving screening, monitoring, risk assessment, research cooperation, and open data sharing to provide environmental policy makers and chemicals management decision-makers with relevant and reliable contaminant data to better protect the polar environments. The consensus reached at the workshop can be summarized in just two words: “Act now!” Specifically, “Act now!” to reduce the presence and impact of anthropogenic chemical pollution in polar regions by. •Establishing participatory co-development frameworks in a permanent multi-disciplinary platform for Arctic-Antarctic collaborations and establishing exchanges between the Arctic Monitoring and Assessment Program (AMAP) of the Arctic Council and the Antarctic Monitoring and Assessment Program (AnMAP) of the Scientific Committee on Antarctic Research (SCAR) to increase the visibility and exchange of contaminant data and to support the development of harmonized monitoring programs. •Integrating environmental specimen banking, innovative screening approaches and archiving systems, to provide opportunities for improved assessment of contaminants to protect polar regions

    Identification of β-Lactams Active against Mycobacterium tuberculosis by a Consortium of Pharmaceutical Companies and Academic Institutions

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    Rising antimicrobial resistance challenges our ability to combat bacterial infections. The problem is acute for tuberculosis (TB), the leading cause of death from infection before COVID-19. Here, we developed a framework for multiple pharmaceutical companies to share proprietary information and compounds with multiple laboratories in the academic and government sectors for a broad examination of the ability of β-lactams to kill Mycobacterium tuberculosis (Mtb). In the TB Drug Accelerator (TBDA), a consortium organized by the Bill & Melinda Gates Foundation, individual pharmaceutical companies collaborate with academic screening laboratories. We developed a higher order consortium within the TBDA in which four pharmaceutical companies (GlaxoSmithKline, Sanofi, MSD, and Lilly) collectively collaborated with screeners at Weill Cornell Medicine, the Infectious Disease Research Institute (IDRI), and the National Institute of Allergy and Infectious Diseases (NIAID), pharmacologists at Rutgers University, and medicinal chemists at the University of North Carolina to screen ∼8900 β-lactams, predominantly cephalosporins, and characterize active compounds. In a striking contrast to historical expectation, 18% of β-lactams screened were active against Mtb, many without a β-lactamase inhibitor. One potent cephaloporin was active in Mtb-infected mice. The steps outlined here can serve as a blueprint for multiparty, intra- and intersector collaboration in the development of anti-infective agents
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