| 1. |
- Arndt, D. S., et al.
(författare)
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State of the Climate in 2016
- 2017
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Ingår i: Bulletin of The American Meteorological Society - (BAMS). - 0003-0007 .- 1520-0477. ; 98:8, s. S1-S280
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Tidskriftsartikel (refereegranskat)abstract
- In 2016, the dominant greenhouse gases released into Earth's atmosphere-carbon dioxide, methane, and nitrous oxide-continued to increase and reach new record highs. The 3.5 +/- 0.1 ppm rise in global annual mean carbon dioxide from 2015 to 2016 was the largest annual increase observed in the 58-year measurement record. The annual global average carbon dioxide concentration at Earth's surface surpassed 400 ppm (402.9 +/- 0.1 ppm) for the first time in the modern atmospheric measurement record and in ice core records dating back as far as 800000 years. One of the strongest El Nino events since at least 1950 dissipated in spring, and a weak La Nina evolved later in the year. Owing at least in part to the combination of El Nino conditions early in the year and a long-term upward trend, Earth's surface observed record warmth for a third consecutive year, albeit by a much slimmer margin than by which that record was set in 2015. Above Earth's surface, the annual lower troposphere temperature was record high according to all datasets analyzed, while the lower stratospheric temperature was record low according to most of the in situ and satellite datasets. Several countries, including Mexico and India, reported record high annual temperatures while many others observed near-record highs. A week-long heat wave at the end of April over the northern and eastern Indian peninsula, with temperatures surpassing 44 degrees C, contributed to a water crisis for 330 million people and to 300 fatalities. In the Arctic the 2016 land surface temperature was 2.0 degrees C above the 1981-2010 average, breaking the previous record of 2007, 2011, and 2015 by 0.8 degrees C, representing a 3.5 degrees C increase since the record began in 1900. The increasing temperatures have led to decreasing Arctic sea ice extent and thickness. On 24 March, the sea ice extent at the end of the growth season saw its lowest maximum in the 37-year satellite record, tying with 2015 at 7.2% below the 1981-2010 average. The September 2016 Arctic sea ice minimum extent tied with 2007 for the second lowest value on record, 33% lower than the 1981-2010 average. Arctic sea ice cover remains relatively young and thin, making it vulnerable to continued extensive melt. The mass of the Greenland Ice Sheet, which has the capacity to contribute similar to 7 m to sea level rise, reached a record low value. The onset of its surface melt was the second earliest, after 2012, in the 37-year satellite record. Sea surface temperature was record high at the global scale, surpassing the previous record of 2015 by about 0.01 degrees C. The global sea surface temperature trend for the 21st century-to-date of +0.162 degrees C decade(-1) is much higher than the longer term 1950-2016 trend of +0.100 degrees C decade(-1). Global annual mean sea level also reached a new record high, marking the sixth consecutive year of increase. Global annual ocean heat content saw a slight drop compared to the record high in 2015. Alpine glacier retreat continued around the globe, and preliminary data indicate that 2016 is the 37th consecutive year of negative annual mass balance. Across the Northern Hemisphere, snow cover for each month from February to June was among its four least extensive in the 47-year satellite record. Continuing a pattern below the surface, record high temperatures at 20-m depth were measured at all permafrost observatories on the North Slope of Alaska and at the Canadian observatory on northernmost Ellesmere Island. In the Antarctic, record low monthly surface pressures were broken at many stations, with the southern annular mode setting record high index values in March and June. Monthly high surface pressure records for August and November were set at several stations. During this period, record low daily and monthly sea ice extents were observed, with the November mean sea ice extent more than 5 standard deviations below the 1981-2010 average. These record low sea ice values contrast sharply with the record high values observed during 2012-14. Over the region, springtime Antarctic stratospheric ozone depletion was less severe relative to the 1991-2006 average, but ozone levels were still low compared to pre-1990 levels. Closer to the equator, 93 named tropical storms were observed during 2016, above the 1981-2010 average of 82, but fewer than the 101 storms recorded in 2015. Three basins-the North Atlantic, and eastern and western North Pacific-experienced above-normal activity in 2016. The Australian basin recorded its least active season since the beginning of the satellite era in 1970. Overall, four tropical cyclones reached the Saffir-Simpson category 5 intensity level. The strong El Nino at the beginning of the year that transitioned to a weak La Nina contributed to enhanced precipitation variability around the world. Wet conditions were observed throughout the year across southern South America, causing repeated heavy flooding in Argentina, Paraguay, and Uruguay. Wetter-than-usual conditions were also observed for eastern Europe and central Asia, alleviating the drought conditions of 2014 and 2015 in southern Russia. In the United States, California had its first wetter-than-average year since 2012, after being plagued by drought for several years. Even so, the area covered by drought in 2016 at the global scale was among the largest in the post-1950 record. For each month, at least 12% of land surfaces experienced severe drought conditions or worse, the longest such stretch in the record. In northeastern Brazil, drought conditions were observed for the fifth consecutive year, making this the longest drought on record in the region. Dry conditions were also observed in western Bolivia and Peru; it was Bolivia's worst drought in the past 25 years. In May, with abnormally warm and dry conditions already prevailing over western Canada for about a year, the human-induced Fort McMurray wildfire burned nearly 590000 hectares and became the costliest disaster in Canadian history, with $3 billion (U.S. dollars) in insured losses.
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| 2. |
- Arndt, D. S., et al.
(författare)
-
STATE OF THE CLIMATE IN 2017
- 2018
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Ingår i: Bulletin of The American Meteorological Society - (BAMS). - : American Meteorological Society. - 0003-0007 .- 1520-0477. ; 99:8, s. S1-S310
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Forskningsöversikt (refereegranskat)
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| 3. |
- Blunden, Jessica, et al.
(författare)
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State of the Climate in 2012
- 2013
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Ingår i: Bulletin of The American Meteorological Society - (BAMS). - 0003-0007 .- 1520-0477. ; 94:8, s. S1-S258
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Tidskriftsartikel (refereegranskat)abstract
- For the first time in serveral years, the El Nino-Southern Oscillation did not dominate regional climate conditions around the globe. A weak La Ni a dissipated to ENSOneutral conditions by spring, and while El Nino appeared to be emerging during summer, this phase never fully developed as sea surface temperatures in the eastern conditions. Nevertheless, other large-scale climate patterns and extreme weather events impacted various regions during the year. A negative phase of the Arctic Oscillation from mid-January to early February contributed to frigid conditions in parts of northern Africa, eastern Europe, and western Asia. A lack of rain during the 2012 wet season led to the worst drought in at least the past three decades for northeastern Brazil. Central North America also experienced one of its most severe droughts on record. The Caribbean observed a very wet dry season and it was the Sahel's wettest rainy season in 50 years. Overall, the 2012 average temperature across global land and ocean surfaces ranked among the 10 warmest years on record. The global land surface temperature alone was also among the 10 warmest on record. In the upper atmosphere, the average stratospheric temperature was record or near-record cold, depending on the dataset. After a 30-year warming trend from 1970 to 1999 for global sea surface temperatures, the period 2000-12 had little further trend. This may be linked to the prevalence of La Ni a-like conditions during the 21st century. Heat content in the upper 700 m of the ocean remained near record high levels in 2012. Net increases from 2011 to 2012 were observed at 700-m to 2000-m depth and even in the abyssal ocean below. Following sharp decreases in to the effects of La Ni a, sea levels rebounded to reach records highs in 2012. The increased hydrological cycle seen in recent years continued, with more evaporation in drier locations and more precipitation in rainy areas. In a pattern that has held since 2004, salty areas of the ocean surfaces and subsurfaces were anomalously salty on average, while fresher areas were anomalously fresh. Global tropical cyclone activity during 2012 was near average, with a total of 84 storms compared with the 1981-2010 average of 89. Similar to 2010 and 2011, the North Atlantic was the only hurricane basin that experienced above-normal activity. In this basin, Sandy brought devastation to Cuba and parts of the eastern North American seaboard. All other basins experienced either near-or below-normal tropical cyclone activity. Only three tropical cyclones reached Category 5 intensity-all in Bopha became the only storm in the historical record to produce winds greater than 130 kt south of 7 N. It was also the costliest storm to affect the Philippines and killed more than 1000 residents. Minimum Arctic sea ice extent in September and Northern Hemisphere snow cover extent in June both reached new record lows. June snow cover extent is now declining at a faster rate (-17.6% per decade) than September sea ice extent (-13.0% per decade). Permafrost temperatures reached record high values in northernmost Alaska. A new melt extent record occurred on 11-12 July on the Greenland ice sheet; 97% of the ice sheet showed some form of melt, four times greater than the average melt for this time of year. The climate in Antarctica was relatively stable overall. The largest maximum sea ice extent since records begain in 1978 was observed in September 2012. In the stratosphere, warm air led to the second smallest ozone hole in the past two decades. Even so, the springtime ozone layer above Antarctica likely will not return to its early 1980s state until about 2060. Following a slight decline associated with the global 2 emissions from fossil fuel combustion and cement production reached a record 9.5 +/- 0.5 Pg C in 2011 and a new record of 9.7 +/- 0.5 Pg C is estimated for 2012. Atmospheric CO2 concentrations increased by 2.1 ppm in 2012, to 392.6 ppm. In spring 2012, 2 concentration exceeded 400 ppm at 7 of the 13 Arctic observation sites. Globally, other greenhouse gases including methane and nitrous oxide also continued to rise in concentration and the combined effect now represents a 32% increase in radiative forcing over a 1990 baseline. Concentrations of most ozone depleting substances continued to fall.
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| 4. |
- Kattge, Jens, et al.
(författare)
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TRY plant trait database - enhanced coverage and open access
- 2020
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Ingår i: Global Change Biology. - : Wiley-Blackwell. - 1354-1013 .- 1365-2486. ; 26:1, s. 119-188
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Tidskriftsartikel (refereegranskat)abstract
- Plant traits-the morphological, anatomical, physiological, biochemical and phenological characteristics of plants-determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait-based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits-almost complete coverage for 'plant growth form'. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait-environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives.
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| 5. |
- Szigeti, Andras, et al.
(författare)
-
Are Individualist Accounts of Collective Responsibility Morally Deficient?
- 2013
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Ingår i: Studies in the Philosophy of Sociality.
-
Bokkapitel (refereegranskat)abstract
- Individualists hold that moral responsibility can be ascribed to single human beings only. An important collectivist objection is that individualism is morally deficient because it leaves a normative residue. Without attributing responsibility to collectives there remains a “deficit in the accounting books” (Pettit). This collectivist strategy often uses judgment aggregation paradoxes to show that the collective can be responsible when no individual is. I argue that we do not need collectivism to handle such cases because the individualist analysis leaves no responsibility-deficit. Harm suffered in such situations can have only two sources. Harm is either due to culpable wrongdoing by individuals. Harm is then redressed by holding these individuals responsible. Or harm does not result from culpable wrongdoing. Such harm may have to be redressed too, but not because anyone is responsible for it. Therefore, the charge of moral insensitivity against individualist accounts can be rejected. Furthermore, in the last section of the paper I will show that collectivist talk about moral responsibility can be used for ethically questionable purposes as well. Collectivists cannot claim the moral high ground.
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| 6. |
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| 7. |
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| 8. |
- Achberger, Christine, 1968, et al.
(författare)
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State of the Climate in 2011
- 2012
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Ingår i: Bulletin of the American Meteorological Society. - 0003-0007. ; 93:7
-
Tidskriftsartikel (refereegranskat)abstract
- Large-scale climate patterns influenced temperature and weather patterns around the globe in 2011. In particular, a moderate-to-strong La Nina at the beginning of the year dissipated during boreal spring but reemerged during fall. The phenomenon contributed to historical droughts in East Africa, the southern United States, and northern Mexico, as well the wettest two-year period (2010-11) on record for Australia, particularly remarkable as this follows a decade-long dry period. Precipitation patterns in South America were also influenced by La Nina. Heavy rain in Rio de Janeiro in January triggered the country's worst floods and landslides in Brazil's history. The 2011 combined average temperature across global land and ocean surfaces was the coolest since 2008, but was also among the 15 warmest years on record and above the 1981-2010 average. The global sea surface temperature cooled by 0.1 degrees C from 2010 to 2011, associated with cooling influences of La Nina. Global integrals of upper ocean heat content for 2011 were higher than for all prior years, demonstrating the Earth's dominant role of the oceans in the Earth's energy budget. In the upper atmosphere, tropical stratospheric temperatures were anomalously warm, while polar temperatures were anomalously cold. This led to large springtime stratospheric ozone reductions in polar latitudes in both hemispheres. Ozone concentrations in the Arctic stratosphere during March were the lowest for that period since satellite records began in 1979. An extensive, deep, and persistent ozone hole over the Antarctic in September indicates that the recovery to pre-1980 conditions is proceeding very slowly. Atmospheric carbon dioxide concentrations increased by 2.10 ppm in 2011, and exceeded 390 ppm for the first time since instrumental records began. Other greenhouse gases also continued to rise in concentration and the combined effect now represents a 30% increase in radiative forcing over a 1990 baseline. Most ozone depleting substances continued to fall. The global net ocean carbon dioxide uptake for the 2010 transition period from El Nino to La Nina, the most recent period for which analyzed data are available, was estimated to be 1.30 Pg C yr(-1), almost 12% below the 29-year long-term average. Relative to the long-term trend, global sea level dropped noticeably in mid-2010 and reached a local minimum in 2011. The drop has been linked to the La Nina conditions that prevailed throughout much of 2010-11. Global sea level increased sharply during the second half of 2011. Global tropical cyclone activity during 2011 was well-below average, with a total of 74 storms compared with the 1981-2010 average of 89. Similar to 2010, the North Atlantic was the only basin that experienced above-normal activity. For the first year since the widespread introduction of the Dvorak intensity-estimation method in the 1980s, only three tropical cyclones reached Category 5 intensity level-all in the Northwest Pacific basin. The Arctic continued to warm at about twice the rate compared with lower latitudes. Below-normal summer snowfall, a decreasing trend in surface albedo, and above-average surface and upper air temperatures resulted in a continued pattern of extreme surface melting, and net snow and ice loss on the Greenland ice sheet. Warmer-than-normal temperatures over the Eurasian Arctic in spring resulted in a new record-low June snow cover extent and spring snow cover duration in this region. In the Canadian Arctic, the mass loss from glaciers and ice caps was the greatest since GRACE measurements began in 2002, continuing a negative trend that began in 1987. New record high temperatures occurred at 20 m below the land surface at all permafrost observatories on the North Slope of Alaska, where measurements began in the late 1970s. Arctic sea ice extent in September 2011 was the second-lowest on record, while the extent of old ice (four and five years) reached a new record minimum that was just 19% of normal. On the opposite pole, austral winter and spring temperatures were more than 3 degrees C above normal over much of the Antarctic continent. However, winter temperatures were below normal in the northern Antarctic Peninsula, which continued the downward trend there during the last 15 years. In summer, an all-time record high temperature of -12.3 degrees C was set at the South Pole station on 25 December, exceeding the previous record by more than a full degree. Antarctic sea ice extent anomalies increased steadily through much of the year, from briefly setting a record low in April, to well above average in December. The latter trend reflects the dispersive effects of low pressure on sea ice and the generally cool conditions around the Antarctic perimeter.
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| 9. |
- Ademuyiwa, Adesoji O., et al.
(författare)
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Determinants of morbidity and mortality following emergency abdominal surgery in children in low-income and middle-income countries
- 2016
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Ingår i: BMJ Global Health. - : BMJ Publishing Group Ltd. - 2059-7908. ; 1:4
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Tidskriftsartikel (refereegranskat)abstract
- Background: Child health is a key priority on the global health agenda, yet the provision of essential and emergency surgery in children is patchy in resource-poor regions. This study was aimed to determine the mortality risk for emergency abdominal paediatric surgery in low-income countries globally.Methods: Multicentre, international, prospective, cohort study. Self-selected surgical units performing emergency abdominal surgery submitted prespecified data for consecutive children aged <16 years during a 2-week period between July and December 2014. The United Nation's Human Development Index (HDI) was used to stratify countries. The main outcome measure was 30-day postoperative mortality, analysed by multilevel logistic regression.Results: This study included 1409 patients from 253 centres in 43 countries; 282 children were under 2 years of age. Among them, 265 (18.8%) were from low-HDI, 450 (31.9%) from middle-HDI and 694 (49.3%) from high-HDI countries. The most common operations performed were appendectomy, small bowel resection, pyloromyotomy and correction of intussusception. After adjustment for patient and hospital risk factors, child mortality at 30 days was significantly higher in low-HDI (adjusted OR 7.14 (95% CI 2.52 to 20.23), p<0.001) and middle-HDI (4.42 (1.44 to 13.56), p=0.009) countries compared with high-HDI countries, translating to 40 excess deaths per 1000 procedures performed.Conclusions: Adjusted mortality in children following emergency abdominal surgery may be as high as 7 times greater in low-HDI and middle-HDI countries compared with high-HDI countries. Effective provision of emergency essential surgery should be a key priority for global child health agendas.
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| 10. |
- Adrian-Martinez, S., et al.
(författare)
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The First Combined Search For Neutrino Point-Sources In The Southern Hemisphere With The Antares And Icecube Neutrino Telescopes
- 2016
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 823:1
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Tidskriftsartikel (refereegranskat)abstract
- We present the results of searches for point-like sources of neutrinos based on the first combined analysis of data from both the ANTARES and IceCube neutrino telescopes. The combination of both detectors, which differ in size and location, forms a window in the southern sky where the sensitivity to point sources improves by up to a factor of 2 compared with individual analyses. Using data recorded by ANTARES from 2007 to 2012, and by IceCube from 2008 to 2011, we search for sources of neutrino emission both across the southern sky and from a preselected list of candidate objects. No significant excess over background has been found in these searches, and flux upper limits for the candidate sources are presented for E-2.5 and E-2 power-law spectra with different energy cut-offs.
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| 11. |
- Brauß, Thilo F., et al.
(författare)
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The RNA-binding protein HuR inhibits expression of CCL5 and limits recruitment of macrophages into tumors
- 2017
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Ingår i: Molecular Carcinogenesis. - : Wiley. - 0899-1987. ; 56:12, s. 2620-2629
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Tidskriftsartikel (refereegranskat)abstract
- The RNA-binding protein HuR promotes tumor growth by affecting proliferation, metastasis, apoptosis, and angiogenesis. Although immune cells, especially tumor-associated macrophages, are critical components of the tumor stroma, the influence of HuR in tumors on the recruitment of immune cells remains poorly understood. In the present study, we, therefore, aimed to elucidate the impact of tumor cell HuR on the interaction between tumor cells and macrophages. To this end, we stably depleted HuR in human MCF-7 breast cancer cells. We found that HuR-deficient cells not only showed reduced proliferation, they further expressed elevated levels of the chemokine CCL5. HuR-dependent repression of CCL5 was neither caused by altered CCL5 mRNA stability, nor by changes in CCL5 translation. Instead, loss of HuR augmented transcription of CCL5, which was mediated via an interferon-stimulated response element in the CCL5 promoter. Furthermore, HuR depletion enhanced macrophage recruitment into MCF-7 tumor spheroids, an effect which was completely lost upon neutralization of CCL5. HuR expression further negatively correlated with CCL5 expression and macrophage appearance in a cohort of breast tumors. Thus, while HuR is well-characterized to support various pro-tumorigenic features in tumor cells, we provide evidence that it limits the recruitment of macrophages into tumors by repressing CCL5. As macrophage infiltration is associated with poor prognosis, our findings underline the highly cell-type and context specific role of HuR in tumorigenesis.
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| 12. |
- Fridley, Jason D., et al.
(författare)
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Perspectives on the scientific legacy of J. Philip Grime
- 2023
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Ingår i: Journal of Ecology. - : John Wiley & Sons. - 0022-0477 .- 1365-2745. ; 111:9, s. 1814-1831
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Forskningsöversikt (refereegranskat)abstract
- Perhaps as much as any other scientist in the 20th century, J.P. Grime transformed the study of plant ecology and helped shepherd the field toward international prominence as a nexus of ideas related to global environmental change. Editors at the Journal of Ecology asked a group of senior plant ecologists to comment on Grime's scientific legacy. This commentary piece includes individual responses of 14 scientists from around the world attesting to Grime's foundational role in plant functional ecology, including his knack for sparking controversy, his unique approach to theory formulation involving clever experiments and standardized trait measurements of large numbers of species, and the continued impact of his work on ecological science and policy.
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| 13. |
- Frieler, Katja, et al.
(författare)
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Understanding the weather signal in national crop-yield variability
- 2017
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Ingår i: Earth's Future. - 2328-4277. ; 5:6, s. 605-616
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Tidskriftsartikel (refereegranskat)abstract
- Year-to-year variations in crop yields can have major impacts on the livelihoods of subsistence farmers and may trigger significant global price fluctuations, with severe consequences for people in developing countries. Fluctuations can be induced by weather conditions, management decisions, weeds, diseases, and pests. Although an explicit quantification and deeper understanding of weather-induced crop-yield variability is essential for adaptation strategies, so far it has only been addressed by empirical models. Here, we provide conservative estimates of the fraction of reported national yield variabilities that can be attributed to weather by state-of-the-art, process-based crop model simulations. We find that observed weather variations can explain more than 50% of the variability in wheat yields in Australia, Canada, Spain, Hungary, and Romania. For maize, weather sensitivities exceed 50% in seven countries, including the United States. The explained variance exceeds 50% for rice in Japan and South Korea and for soy in Argentina. Avoiding water stress by simulating yields assuming full irrigation shows that water limitation is a major driver of the observed variations in most of these countries. Identifying the mechanisms leading to crop-yield fluctuations is not only fundamental for dampening fluctuations, but is also important in the context of the debate on the attribution of loss and damage to climate change. Since process-based crop models not only account for weather influences on crop yields, but also provide options to represent human-management measures, they could become essential tools for differentiating these drivers, and for exploring options to reduce future yield fluctuations.
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| 14. |
- Handa, I. Tanya, et al.
(författare)
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Consequences of biodiversity loss for litter decomposition across biomes
- 2014
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 509:7499, s. 218-221
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Tidskriftsartikel (refereegranskat)abstract
- The decomposition of dead organic matter is a major determinant of carbon and nutrient cycling in ecosystems, and of carbon fluxes between the biosphere and the atmosphere(1-3). Decomposition is driven by a vast diversity of organisms that are structured in complex food webs(2,4). Identifying the mechanisms underlying the effects of biodiversity on decomposition is critical(4-6) given the rapid loss of species worldwide and the effects of this loss on human well-being(7-9). Yet despite comprehensive syntheses of studies on how biodiversity affects litter decomposition(4-6,10), key questions remain, including when, where and how biodiversity has a role and whether general patterns and mechanisms occur across ecosystems and different functional types of organism(4,9-12). Here, in field experiments across five terrestrial and aquatic locations, ranging from the subarctic to the tropics, we show that reducing the functional diversity of decomposer organisms and plant litter types slowed the cycling of litter carbon and nitrogen. Moreover, we found evidence of nitrogen transfer from the litter of nitrogen-fixing plants to that of rapidly decomposing plants, but not between other plant functional types, highlighting that specific interactions in litter mixtures control carbon and nitrogen cycling during decomposition. The emergence of this general mechanism and the coherence of patterns across contrasting terrestrial and aquatic ecosystems suggest that biodiversity loss has consistent consequences for litter decomposition and the cycling of major elements on broad spatial scales.
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| 15. |
- Jonsson, Karin, 1974-
(författare)
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Effect of Hyporheic Exchange on Conservative and Reactive Solute Transport in Streams : Model Assessments Based on Tracer Tests
- 2003
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Understanding of the processes affecting solute transport in flowing water is important for the possibility to predict the evolution with time of polluted stream systems. This thesis presents tracer experiment methodology and model developments for solute transport in streams, with special focus on retention processes and their effect on solute stream transport. Results are presented from a tracer experiment in the Säva Stream, Uppland County, Sweden, where both a conservative (3H as tritiated water) and a reactive (51Cr as trivalent chromium ion) tracer were injected simultaneously. The time and length scales of the experiment were prolonged compared to previous studies, which allowed for new critical tests of different model concepts. It was found that the hyporheic exchange greatly affected the solute transport of both tracers. However, the retention of chromium was significantly more pronounced. About 76% of the injected chromium was lost from the stream water phase directly after the passage of the pulse 30 km downstream of the injection point. The inventory of chromium in the sediments indicated that the main part was retrieved in the hyporheic zone. Both a diffusive and an advective hyporheic exchange model were developed and evaluated versus independent observations in the stream water and hyporheic zone. Analytical expressions for the central temporal moments of the breakthrough curve and semi-analytical solutions for the solute concentration in the Laplace domain were derived. Both models were found useful in representing the observations.For the transport of the reactive solute, it was found essential to consider a kinetic sorption on to particulate matter in the hyporheic zone. The time needed for a wash-out of 75% of the maximum uptake in the hyporheic zone was found to be ~85 times longer for the reactive solute, compared to the conservative solute. Neglecting the sorption kinetics in the transport model yielded significant errors in the central temporal moments, which implied an incorrect description of the wash-out process from the hyporheic zone. Independent observations in the stream water and hyporheic zone as well as choice of evaluation method are essential for a correct interpretation of the processes.A first attempt was also made to link model parameters such as the residence time in the hyporheic zone with measurable parameters of the stream. Such a relationship offers the possibility to generalize results for other streams and stream conditions. A generic study of the transport of an inert solute in the Lule River, Sweden, using this kind of relationship, indicated that the hyporheic exchange can have a large practical implication.
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| 16. |
- Mertens, Christina, et al.
(författare)
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Macrophage-derived lipocalin-2 transports iron in the tumor microenvironment
- 2018
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Ingår i: OncoImmunology. - 2162-4011. ; 7:3
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Tidskriftsartikel (refereegranskat)abstract
- While the importance of iron for tumor development is widely appreciated, the exact sources of tumor-supporting iron largely remain elusive. The possibility that iron might be provided by stromal cells in the tumor microenvironment was not taken into account so far. In the present study, we show that tumor-associated macrophages (TAM) acquire an iron-release phenotype upon their interaction with tumor cells, thereby increasing the availability of iron in the tumor microenvironment. Mechanistically, TAM expressed elevated levels of the high-affinity iron-binding protein lipocalin-2 (LCN-2), which appeared to be critical for the export of iron from TAM, and in turn enhanced tumor cell proliferation. Moreover, in PyMT-mouse tumors as well as in primary human breast tumors LCN-2 was predominantly expressed in the tumor stroma as compared to tumor cells. LCN-2 expression in the stroma further correlated with enhanced tumor proliferation in vivo. Our data suggest a dominant role of TAM in the tumor iron-management and identify LCN-2 as a critical iron transporter in this context. Targeting the LCN-2 iron export mechanism selectively in stromal cells might open for future iron-targeted tumor therapeutic approaches.
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| 17. |
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| 18. |
- Petchey, Owen L., et al.
(författare)
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The ecological forecast horizon, and examples of its uses and determinants
- 2015
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Ingår i: Ecology Letters. - : Wiley. - 1461-023X .- 1461-0248. ; 18:7, s. 597-611
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Tidskriftsartikel (refereegranskat)abstract
- Forecasts of ecological dynamics in changing environments are increasingly important, and are available for a plethora of variables, such as species abundance and distribution, community structure and ecosystem processes. There is, however, a general absence of knowledge about how far into the future, or other dimensions (space, temperature, phylogenetic distance), useful ecological forecasts can be made, and about how features of ecological systems relate to these distances. The ecological forecast horizon is the dimensional distance for which useful forecasts can be made. Five case studies illustrate the influence of various sources of uncertainty (e.g. parameter uncertainty, environmental variation, demographic stochasticity and evolution), level of ecological organisation (e.g. population or community), and organismal properties (e.g. body size or number of trophic links) on temporal, spatial and phylogenetic forecast horizons. Insights from these case studies demonstrate that the ecological forecast horizon is a flexible and powerful tool for researching and communicating ecological predictability. It also has potential for motivating and guiding agenda setting for ecological forecasting research and development.
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| 19. |
- Petersson, Björn, et al.
(författare)
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Collectivity and Circularity
- 2008
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Ingår i: Concepts of Sharedness - Essays on Collective Intentionality. - 9783938793961
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- The common claim that the notion of collective action must figure in the content of the attitudes of the parties to a collective action gives rise to a circularity challenge. Standard responses to this challenge are criticized. This article’s solution exploits a notion of collectivity that does not presuppose intention: a purely causal conception that can be explicated in terms of dispositions and causal agency. Participants in a jointly intentional collective action do not need to possess a stronger notion of collectivity than this. In particular, they do not need to possess the concept of a jointly intentional collective action.
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| 20. |
- Vogt, Viola Lara, et al.
(författare)
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Current standards of neuropsychological assessment in epilepsy surgery centers across Europe.
- 2017
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Ingår i: Epilepsia. - : Wiley. - 1528-1167 .- 0013-9580. ; 58:3, s. 343-355
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Tidskriftsartikel (refereegranskat)abstract
- We explored the current practice with respect to the neuropsychological assessment of surgical epilepsy patients in European epilepsy centers, with the aim of harmonizing and establishing common standards. Twenty-six epilepsy centers and members of "E-PILEPSY" (a European pilot network of reference centers in refractory epilepsy and epilepsy surgery), were asked to report the status of neuropsychological assessment in adults and children via two different surveys. There was a consensus among these centers regarding the role of neuropsychology in the presurgical workup. Strong agreement was found on indications (localization, epileptic dysfunctions, adverse drugs effects, and postoperative monitoring) and the domains to be evaluated (memory, attention, executive functions, language, visuospatial skills, intelligence, depression, anxiety, and quality of life). Although 186 different tests are in use throughout these European centers, a core group of tests reflecting a moderate level of agreement could be discerned. Variability exists with regard to indications, protocols, and paradigms for the assessment of hemispheric language dominance. For the tests in use, little published evidence of clinical validity in epilepsy was provided. Participants in the survey reported a need for improvement concerning the validity of the tests, tools for the assessment of everyday functioning and accelerated forgetting, national norms, and test co-normalization. Based on the present survey, we documented a consensus regarding the indications and principles of neuropsychological testing. Despite the variety of tests in use, the survey indicated that there may be a core set of tests chosen based on experience, as well as on published evidence. By combining these findings with the results of an ongoing systematic literature review, we aim for a battery that can be recommended for the use across epilepsy surgical centers in Europe.
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| 21. |
- Aad, G., et al.
(författare)
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- 2010
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swepub:Mat__t
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| 22. |
- Aad, G., et al.
(författare)
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- 2012
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Tidskriftsartikel (refereegranskat)
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