Optical properties of ice and snow Warren, Stephen G
Philosophical transactions - Royal Society. Mathematical, Physical and engineering sciences/Philosophical transactions - Royal Society. Mathematical, physical and engineering sciences,
06/2019, Volume:
377, Issue:
2146
Journal Article
Peer reviewed
Open access
The interactions of electromagnetic radiation with ice, and with ice-containing media such as snow and clouds, are determined by the refractive index and absorption coefficient (the 'optical ...constants') of pure ice as functions of wavelength. Bulk reflectance, absorptance and transmittance are further influenced by grain size (for snow), bubbles (for glacier ice and lake ice) and brine inclusions (for sea ice). Radiative transfer models for clouds can also be applied to snow; the important differences in their radiative properties are that clouds are optically thinner and contain smaller ice crystals than snow. Absorption of visible and near-ultraviolet radiation by ice is so weak that absorption of sunlight at these wavelengths in natural snow is dominated by trace amounts of light-absorbing impurities such as dust and soot. In the thermal infrared, ice is moderately absorptive, so snow is nearly a blackbody, with emissivity 98-99%. The absorption spectrum of liquid water resembles that of ice from the ultraviolet to the mid-infrared. At longer wavelengths they diverge, so microwave emission can be used to detect snowmelt on ice sheets, and to discriminate between sea ice and open water, by remote sensing. Snow and ice are transparent to radio waves, so radar can be used to infer ice-sheet thickness. This article is part of the theme issue 'The physics and chemistry of ice: scaffolding across scales, from the viability of life to the formation of planets'.
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In a work that will interest researchers in ecology, genetics, botany, entomology, and parasitology, Warren Abrahamson and Arthur Weis present the results of more than twenty-five years of studying ...plant-insect interactions. Their study centers on the ecology and evolution of interactions among a host plant, the parasitic insect that attacks it, and the suite of insects and birds that are the natural enemies of the parasite. Because this system provides a model that can be subjected to experimental manipulations, it has allowed the authors to address specific theories and concepts that have guided biological research for more than two decades and to engage general problems in evolutionary biology. The specific subjects of research are the host plant goldenrod ( Solidago ), the parasitic insect Eurosta solidaginis (Diptera: Tephritidae ) that induces a gall on the plant stem, and a number of natural enemies of the gallfly. By presenting their detailed empirical studies of the Solidago-Eurosta natural enemy system, the authors demonstrate the complexities of specialized enemy- victim interactions and, thereby, the complex interactive relationships among species more broadly. By utilizing a diverse array of field, laboratory, behavioral, genetic, chemical, and statistical techniques, Abrahamson and Weis present the most thorough study to date of a single system of interacting species. Their interest in the evolutionary ecology of plant-insect interactions leads them to insights on the evolution of species interactions in general. This major work will interest anyone involved in studying the ways in which interdependent species interact.
•A sensitive method to measure nine urinary metabolites of organophosphate ester flame retardants (OPFRs) is presented.•The novel method is based on solid phase extraction and ultra performance ...liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS).•The method detection limits were between 0.08 and 0.25ng/mL for target metabolites; average recoveries of isotope-labeled standards spiked in synthetic urine were between 77.6% and 108%.•Urinary OPFR metabolites were determined at low ppb levels in 24 urine samples collected from pregnant Canadian women.
Over the last few years, the use of organophosphate flame retardants (OPFRs) has been on the rise; however, there are knowledge gaps in both the human health effects of OPFRs and levels of human exposure. Currently, human biomonitoring data on the levels of OPFR metabolites in the Canadian population are still non-existent. Herein we describe a novel method to measure nine urinary OPFR metabolites using solid phase extraction and ultra performance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS). The method detection limits were between 0.08 and 0.25ng/mL for target metabolites. The newly developed and validated method was applied to the analysis of 24 urine samples collected in 2010–12 from pregnant Canadian women. The most frequently detected OPFR metabolite in urine of study participants (detection frequency: 97%) was diphenyl phosphate (DPHP), with concentrations ranging between <0.13–25.2ng/mL, followed (75%) by the sum of two metabolites (DoCP: Di-o-cresyl phosphate and DpCP: Di-p- cresyl phosphate) of tricresyl phosphate, with concentrations between <0.13–4.38ng/mL. With the exception of desbutyl-tris-(2-butoxy-ethyl) phosphate which was not detected in any of the samples, all other OPFR metabolites measured were found among study participants with variable detection frequency, suggesting pregnant Canadian women may be exposed to OPFRs.
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Significance Terrestrial locomotion is thought to be generated by the actions of a circuit of interconnected interneurons (central pattern generator) in the spinal cord that drive the patterned ...activity of pools of motor neurons, causing sequential contraction of dozens of leg muscles. Sensory feedback exerts a strong modulatory influence on this pattern; nevertheless, it remains unclear whether sensory feedback also plays a role in the generation of the normal locomotor pattern. Through the use of a combination of electrophysiology, behavior, and mouse genetics, we provide evidence that the absence of proprioceptive sensory feedback degrades locomotor pattern, indicating that proprioceptive feedback is required for the construction of locomotor pattern.
Mammalian locomotor programs are thought to be directed by the actions of spinal interneuron circuits collectively referred to as “central pattern generators.” The contribution of proprioceptive sensory feedback to the coordination of locomotor activity remains less clear. We have analyzed changes in mouse locomotor pattern under conditions in which proprioceptive feedback is attenuated genetically and biomechanically. We find that locomotor pattern degrades upon elimination of proprioceptive feedback from muscle spindles and Golgi tendon organs. The degradation of locomotor pattern is manifest as the loss of interjoint coordination and alternation of flexor and extensor muscles. Group Ia/II sensory feedback from muscle spindles has a predominant influence in patterning the activity of flexor muscles, whereas the redundant activities of group Ia/II and group Ib afferents appear to determine the pattern of extensor muscle firing. These findings establish a role for proprioceptive feedback in the control of fundamental aspects of mammalian locomotor behavior.
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Debate about what proportion of the Earth to protect often overshadows the question of how nature should be conserved and by whom. We present a systematic review and narrative synthesis of 169 ...publications investigating how different forms of governance influence conservation outcomes, paying particular attention to the role played by Indigenous peoples and local communities. We find a stark contrast between the outcomes produced by externally controlled conservation, and those produced by locally controlled efforts. Crucially, most studies presenting positive outcomes for both well-being and conservation come from cases where Indigenous peoples and local communities play a central role, such as when they have substantial influence over decision making or when local institutions regulating tenure form a recognized part of governance. In contrast, when interventions are controlled by external organizations and involve strategies to change local practices and supersede customary institutions, they tend to result in relatively ineffective conservation at the same time as producing negative social outcomes. Our findings suggest that equitable conservation, which empowers and supports the environmental stewardship of Indigenous peoples and local communities represents the primary pathway to effective long-term conservation of biodiversity, particularly when upheld in wider law and policy. Whether for protected areas in biodiversity hotspots or restoration of highly modified ecosystems, whether involving highly traditional or diverse and dynamic local communities, conservation can become more effective through an increased focus on governance type and quality, and fostering solutions that reinforce the role, capacity, and rights of Indigenous peoples and local communities. We detail how to enact progressive governance transitions through recommendations for conservation policy, with immediate relevance for how to achieve the next decade's conservation targets under the UN Convention on Biological Diversity.
Acute respiratory distress syndrome (ARDS), an inflammatory condition with high mortality rates, is common in severe COVID-19, whose risk is reduced by metformin rather than other anti-diabetic ...medications. Given evidence of inflammasome assembly in post-mortem COVID-19 lungs, we asked whether and how metformin inhibits inflammasome activation and exerts its anti-inflammatory effect. We show that metformin inhibited NLRP3 inflammasome activation and interleukin (IL)-1β production in cultured and alveolar macrophages along with inflammasome-independent IL-6 secretion, thus attenuating lipopolysaccharide (LPS)- and SARS-CoV-2-induced ARDS. Metformin blocked LPS-induced ATP-dependent synthesis of the NLRP3 ligand mtDNA independently of AMP-activated protein kinase (AMPK) or NF-κB. Myeloid-specific ablation of LPS-induced cytidine monophosphate kinase 2 (CMPK2), which is rate limiting for mtDNA synthesis, reduced ARDS severity without a direct effect on IL-6. Thus, inhibition of ATP and mtDNA synthesis is sufficient for ARDS amelioration.
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•Metformin inhibits macrophage IL-1β and IL-6 production and blunts ARDS severity•Metformin inhibits cytosolic Ox-mtDNA production and NLRP3 inflammasome activation•By targeting ETCCI, metformin blocks macrophage ATP-dependent mtDNA synthesis•Myeloid targeted inhibition of mtDNA synthesis blunts IL-1β production and ARDS
The exact mechanism by which metformin exerts its anti-inflammatory effects is still not known. Xian et al. shows that metformin’s inhibition of ETCCI blocks ATP-dependent mtDNA synthesis, cytoplasmic ox-mtDNA generation and NLRP3 inflammasome activation in macrophages, independent of AMPK and NF-κB. By limiting IL-1β production, metformin blunts pulmonary inflammation.
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A compilation of the spectral absorption coefficient of ice Ih is presented for temperatures near the melting point, superseding the compilation of Warren (1984). Significant changes are made to ...nearly all spectral regions. The blue and near‐ultraviolet absorption is much weaker than the prior estimates, which were already very small. The near‐infrared absorption coefficient differs by as much as a factor of 2 from the prior compilation at some wavelengths. The midinfrared absorption coefficient is rather uncertain in the weakly absorbing regions near 9 and 20 μm. New far‐infrared measurements at low temperatures are extrapolated to higher temperatures, which shifts the peak positions. New microwave measurements find absorption much weaker than previously reported, by factors of 2–5. The real part of the index of refraction is computed using Kramers‐Kronig analysis; it differs from the prior compilation only in the far infrared. Tables of the revised optical constants are available on a website.
Future climate change projections for phase 5 of the Coupled Model Intercomparison Project (CMIP5) are presented for the Community Earth System Model version 1 that includes the Community Atmospheric ...Model version 5 CESM1(CAM5). These results are compared to the Community Climate System Model, version 4 (CCSM4) and include simulations using the representative concentration pathway (RCP) mitigation scenarios, and extensions for those scenarios beyond 2100 to 2300. Equilibrium climate sensitivity of CESM1 (CAM5) is 4.10°C, which is higher than the CCSM4 value of 3.20°C. The transient climate response is 2.33°C, compared to the CCSM4 value of 1.73°C. Thus, even though CESM1(CAM5) includes both the direct and indirect effects of aerosols (CCSM4 had only the direct effect), the overall climate system response including forcing and feedbacks is greater in CESM1(CAM5) compared to CCSM4. The Atlantic Ocean meridional overturning circulation (AMOC) in CESM1(CAM5) weakens considerably in the twenty-first century in all the RCP scenarios, and recovers more slowly in the lower forcing scenarios. The total aerosol optical depth (AOD) changes from ∼0.12 in 2006 to ∼0.10 in 2100, compared to a preindustrial 1850 value of 0.08, so there is less negative forcing (a net positive forcing) from that source during the twenty-first century. Consequently, the change from 2006 to 2100 in aerosol direct forcing in CESM1(CAM5) contributes to greater twenty-first century warming relative to CCSM4. There is greater Arctic warming and sea ice loss in CESM1(CAM5), with an ice-free summer Arctic occurring by about 2060 in RCP8.5 (2040s in September) as opposed to about 2100 in CCSM4 (2060s in September).
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Purpose
While sustainability experts point to interrelated social, economic and environmental goals, students may think about sustainability primarily as natural resources. To prepare students to ...tackle global challenges to well-being, this paper aims to show that educators need to assess and address students’ shortcomings in considering socioeconomic dimensions.
Design/methodology/approach
This study coded essays on the meaning and components of sustainability written by 93 undergraduate and graduate students in environmental policy, business and engineering courses at US and Austrian universities. Then, the study reviewed a teaching strategy using diverse experts, case studies and assignments. Finally, the analysis evaluated students’ final projects proposing sustainability legislation with social, economic and environmental dimensions.
Findings
Students usually connect sustainability with limited natural resources affecting current and future generations, but seldom think that sustainability means acting on prominent socioeconomic challenges like poverty, food insecurity, pandemics and violence. Teaching in diverse courses through multidimensional case studies and legislation broadened and deepened students’ understanding and preparedness to act.
Originality/value
Despite experts’ attention to the interconnected Sustainable Development Goals, educators and policymakers need information on whether students associate sustainability with socioeconomic challenges. Open-response questions can reveal gaps in the respondents’ sustainability beliefs. In a wide range of courses, teaching can use diverse experts and multidimensional case studies and legislative assignments.
•Unknown if proprioception differs for points on different body regions.•Young adults reached to touch stationary and moving body landmarks.•Blindfolded reaches to head/trunk targets had similar ...errors to reaches with vision.•Blindfolded reaches to limb targets were less accurate than to head/trunk targets.•Higher acuity may be due to higher daily frequency of reaches to head/trunk targets.
We accurately sense locations of objects touching various points on the body and, if they are irritants, make accurate rapid movements to remove them. Such movements require accurate proprioception of orientation and motion of the reaching limb and of the target. However, it is unknown whether acuity of these sensations is similar for different points on the body. We investigated accuracy of comfortable speed reaching movements of the right index-tip by 10 subjects (five females) to touch 12 different body locations with and without vision with the body part stationary in different locations and moving in different directions. Reaching movements to points on the face/head and trunk had mean errors averaging less than 0.2 cm greater than under vision conditions. Mean errors for reaches to touch points on the left arm and digits were less accurate (p < 0.05), but average less than 1 cm relative to vision conditions. Mean errors for reaches to touch points on the left lower limb were least accurate (p < 0.05), with mean errors averaging 1.5–3.1 cm relative to movements made with vision. We conclude that there is high proprioceptive acuity for locations of points on axial structures and the left upper limb including the digits, which contrasts with previous reports of greatly distorted proprioceptive maps of the face/head and hand. Apparently low proprioceptive acuity for points on the leg may be task sensitive as many lower limb motor tasks can be performed accurately without vision.
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