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Seasonal macro‐demography of North American bird populations revealed through participatory science
No full textAvian population sizes fluctuate and change over vast spatial scales, but the mechanistic underpinnings remain poorly understood. A key question is whether spatial and annual variation in avian population dynamics is driven primarily by variation in breeding season recruitment or by variation in overwinter survival. We present a method using large‐scale volunteer‐collected data from project eBird to develop species‐specific indices of net population change as proxies for survival and recruitment, based on twice‐annual, rangewide snapshots of relative abundance in spring and fall. We demonstrate the use of these indices by examining spatially explicit annual variation in survival and recruitment in two well‐surveyed nonmigratory North American species, Carolina wren Thryothorus ludovicianus and northern cardinal Cardinalis cardinalis. We show that, while interannual variation in both survival and recruitment is slight for northern cardinal, eBird abundance data reveal strong and geographically coherent signals of interannual variation in the overwinter survival of Carolina wren. As predicted, variation in wintertime survival dominates overall interannual population fluctuations of wrens and is correlated with winter temperature and snowfall in the northeastern United States, but not the southern United States. This study demonstrates the potential of participatory science (also known as citizen science) datasets like eBird for inferring variation in demographic rates and introduces a new complementary approach towards illuminating the macrodemography of North American birds at comprehensive continental extents
The ability to value:an additional criterion for decision-making capacity
No full textIn the United States, the dominant model of decision-making capacity (DMC) is the “four abilities model,” which judges DMC according to four criteria: understanding, appreciation, reasoning, and communicating a choice. Some critics argue that this model is “too cognitive” because it ignores the role of emotions and values in decision-making. But so far there is no consensus about how to incorporate such factors into a model of DMC while still ensuring that patients with unusual or socially disapproved values still have their autonomous decisions respected. In this paper, we aim to give an account of the role of values in decision-making which can answer some of the lingering questions about capacity. In the current literature, defenders of the inclusion of values in DMC tend to propose solutions which focus on the distorted or incoherent attributes of the values themselves. We argue that shifting the focus onto valuing as an ability is a better solution and that a complete picture of capacity includes understanding, appreciation, reasoning, communicating a choice, and the ability to value. On the basis of a conceptual analysis of the necessary conditions for autonomous decision-making, we derive a conception of the ability to value. On our account, the ability to value has four components: the possession of values, the ability to access those values, the ability to engage in practical reasoning with one's values, and the ability to act on the result of that reasoning. We describe the positive components of the ability to value, some indicators of impairment, and some implications of our account
A detailed investigation of particle energisation mechanisms in models of collapsing magnetic traps
No full textIn this paper, we provide a detailed investigation of the energization processes in two-dimensional, two and a half-dimensional, and three-dimensional collapsing magnetic trap models. Using kinematic magnetohydrodynamic models of collapsing magnetic traps, we examine the importance of Fermi acceleration in comparison with betatron acceleration in these models. We extend previous work by investigating particle orbits in two-dimensional models without and with a guide field component and from full three-dimensional models. We compare the outcomes for the different models and how they depend on the chosen initial conditions. While in the literature betatron acceleration has been emphasized as the major mechanism for particle energization in collapsing magnetic traps, we find that Fermi acceleration can play a significant role as well for particle orbits with suitable initial conditions
Limited decrease of Southern Ocean sulfur productivity across the penultimate termination
No full textProductivity in the Pleistocene glacial Southern Ocean was probably enhanced owing to iron fertilization by aeolian dust. Marine sediments indicate such an increase north of the modern Antarctic Polar Front but reduced biogenic activity south of it. However, quantitative estimates for the integrated net effect are difficult to obtain. Here we use the SO42− isotopic composition and other geochemical ice core records from the Atlantic sector of the Southern Ocean to reconstruct net changes in integrated biogenic sulfur productivity in the surface ocean over the penultimate glacial termination. We show that biogenic SO42− aerosol contributes 58% and 85% to the sulfate budget in Dronning Maud Land during glacial and interglacial times, respectively, and that biogenic sulfate is derived predominately from the seasonal sea ice zone. Using our quantitative reconstruction of biogenic aerosol production in the Southern Ocean source region, we show that the average biogenic sulfate production integrated over the Atlantic sector was 16% higher in the penultimate glacial 137,000–153,000 years ago compared with the later Last Interglacial 120,000–125,000 years ago. An intermittent decrease in productivity observed during early peak interglacial warming suggests that a reduction in the seasonal sea ice zone may disrupt Southern Ocean ecosystems
Predicting the effects of climate change on the fertility of aquatic animals using a meta-analytic approach
No full textGiven that reproductive physiology is highly sensitive to thermal stress, there is increasing concern about the effects of climate change on animal fertility. Even a slight reduction in fertility can have consequences for population growth and survival, so it is critical to better understand and predict the potential effects of climate change on reproductive traits. We synthesised 1894 effect sizes across 276 studies on 241 species to examine thermal effects on fertility in aquatic animals. Our meta-analysis revealed that external fertilisers tend to be more vulnerable to warming than internal fertilisers, especially in freshwater species. We also found that increased temperature is particularly detrimental for gametes and that under certain conditions, female fertility is more sensitive to warming than male fertility, challenging the prevailing view that males are more vulnerable. This work provides valuable new insights into the effects of temperature on fertility, with potential consequences for population viability
Differential mediation of biogeochemical processes through bioturbation by fiddler and sesarmid mangrove crabs
No full textMacrobenthic bioturbation is vital to facilitate nutrient turnover in estuarine ecosystems and drives spatial heterogeneity in the sediment matrix. In this study, we compared the sediment physico-chemical properties, microbial community structure and functional genes in vertically-stratified sediment samples from bioturbated (burrows of Parasesarma bidens and Tubuca arcuata) and non-bioturbated area in mangrove ecosystems (the Hanjiang River Estuary, Southern China). The result indicated that bioturbation by P. bidens and T. arcuata had significantly different effects on sediment properties, with the action of P. bidens enhancing nutrient accumulation while T. arcuata promoted N2O emission. Burrow microhabitats harbored distinctive microbial communities although the dominant phylum and genera shared considerable similarity with the control sediment surface with Woeseia dominating in vertical profiles across different habitats. Co-occurrence network analysis revealed that crab bioturbation promoted formation of less complex but more functionally-specialized microbial communities. Crab bioturbation enhanced nutrient metabolism and separated clusters in dendrogram demonstrated the species-specific effect between P. bidens and T. arcuata. Our work verified the significance of bioturbators in regulating biogeochemical processes and highlighted the species-specific bioturbation effect between two dominant mangrove crabs (P. bidens vs. T. arcuata).</p
Studying Kurdishness in Turkey:a review of existing research
No full textKnowledge production on marginalized identities is frequently shaped by epistemic violence, which limits both the scope and methodologies of research. One example of this is the case of Kurdish identity in Turkey, where we find that methodological and epistemic problems are evident particularly in social psychological research. To summarize social psychological studies on Kurdishness, Kurdish identity and conflict in Turkey we've conducted a systematic review that includes a total of 63 studies on topics related to Kurdishness. We utilize qualitative content analysis (Schreier, 2012) to address: (1) whether samples in the studies in our review represent Kurds, (2) which topics the studies mostly focus on, (3) how Kurdish identity and Kurds as a group are conceptualized and (4) how the Kurdish issue is conceptualized. We discuss our findings in light of epistemic violence and methodological nationalism and identify the key gaps in the literature and offer a critical, inclusive understanding of the social psychological studies on Kurdish identity and state violence in Turkey
New insights into Sistani intellectual culture under the Saffarids
No full textThis article investigates patterns of scholarly patronage relating to Khalaf b. Aḥmad (r. 963–1003 CE, d. 1009), placing them in their broader Saffarid and regional contexts. Of the extant works we can link to Khalaf, a little studied medical text, the Kunnāsh, is arguably the single most insightful in exposing Khalaf as patron and in placing him in the context of earlier and later Saffarid and Sistani support for the medical sciences. The article argues that Khalaf being both an author of a work on dream interpretation and a patron of medical literature is not a combination unique to him. In fact, it fits rather well with the pattern of patronage activities of the Khwārazmshāhs in the early eleventh century. This study suggests that Eastern Iranian areas may have developed a greater degree of self-definition as intellectual centres of scholarship than previously acknowledged, and that this will have happened both through competition with one another and by retelling their legacies of past patronage
Flux-rope-mediated turbulent magnetic reconnection
No full textWe present a new model of magnetic reconnection in the presence of turbulence. The new model differs from the Lazarian–Vishniac turbulent reconnection theory by emphasizing the role of locally coherent magnetic structures, whose existence is shown to be permitted by the properties of magnetic field line separation in turbulent plasma. Local coherence allows storage of magnetic helicity inside the reconnection layer in the form of locally coherent twisted flux ropes. We then introduce the "Alfvén horizon" to explain why the global reconnection rate can be governed by locally coherent magnetic field structure instead of by field line wandering, formally extending to 3D the principle that reconnection can be made fast by fragmentation of the global current layer. Coherence is shown to dominate over field line dispersion if the anisotropy of the turbulence at the perpendicular scale matching the thickness of a marginally stable current layer exceeds the aspect ratio of the current layer. Finally, we conjecture that turbulence generated within the reconnection layer may produce a critically balanced state that maintains the system in the flux-rope-mediated regime. The new model successfully accounts for the major features of 3D numerical simulations of self-generated turbulent reconnection, including reconnection rates of 0.01 in resistive MHD and 0.1 with collisionless physics