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"Parker, H."
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Global interactions in the early modern age, 1400-1800
\"Interdisciplinary introduction to cross-cultural encounters in the early modern age (1400-1800) and their influences on the development of world societies. In the aftermath of Mongol expansion across Eurasia, the unprecedented rise of imperial states in the early modern period set in motion interactions between people from around the world. These included new commercial networks, large-scale migration streams, global biological exchanges, and transfers of knowledge across oceans and continents. These in turn wove together the major regions of the world. In an age of extensive cultural, political, military, and economic contact, a host of individuals, companies, tribes, states, and empires were in competition. Yet they also cooperated with one another, leading ultimately to the integration of global space\"--Provided by publisher.
Book
Measurement of the fine-structure constant as a test of the Standard Model
The fine-structure constant, α, is a dimensionless constant that characterizes the strength of the electromagnetic interaction between charged elementary particles. Related by four fundamental constants, a precise determination of α allows for a test of the Standard Model of particle physics. Parker et al. used matter-wave interferometry with a cloud of cesium atoms to make the most accurate measurement of α to date. Determining the value of α to an accuracy of better than 1 part per billion provides an independent method for testing the accuracy of quantum electrodynamics and the Standard Model. It may also enable searches of the so-called “dark sector” for explanations of dark matter. Science , this issue p. 191 Atom interferometry provides a precise measurement of the fine-structure constant. Measurements of the fine-structure constant α require methods from across subfields and are thus powerful tests of the consistency of theory and experiment in physics. Using the recoil frequency of cesium-133 atoms in a matter-wave interferometer, we recorded the most accurate measurement of the fine-structure constant to date: α = 1/137.035999046(27) at 2.0 × 10 −10 accuracy. Using multiphoton interactions (Bragg diffraction and Bloch oscillations), we demonstrate the largest phase (12 million radians) of any Ramsey-Bordé interferometer and control systematic effects at a level of 0.12 part per billion. Comparison with Penning trap measurements of the electron gyromagnetic anomaly g e − 2 via the Standard Model of particle physics is now limited by the uncertainty in g e − 2; a 2.5σ tension rejects dark photons as the reason for the unexplained part of the muon’s magnetic moment at a 99% confidence level. Implications for dark-sector candidates and electron substructure may be a sign of physics beyond the Standard Model that warrants further investigation.
Journal Article
Predominant role of active versus facilitative glucose transport for glucagon-like peptide-1 secretion
Aims/hypothesis
Several glucose-sensing pathways have been implicated in glucose-triggered secretion of glucagon-like peptide-1 (GLP-1) from intestinal L cells. One involves glucose metabolism and closure of ATP-sensitive K
+
channels, and another exploits the electrogenic nature of Na
+
-coupled glucose transporters (SGLTs). This study aimed to elucidate the role of these distinct mechanisms in glucose-stimulated GLP-1 secretion.
Methods
Glucose uptake into L cells (either GLUTag cells or cells in primary cultures, using a new transgenic mouse model combining proglucagon promoter-driven
Cre
recombinase with a ROSA26tdRFP reporter) was monitored with the FLII
12
Pglu-700μδ6 glucose sensor. Effects of pharmacological and genetic interference with SGLT1 or facilitative glucose transport (GLUT) on intracellular glucose accumulation and metabolism (measured by NAD(P)H autofluorescence), cytosolic Ca
2+
(monitored with Fura2) and GLP-1 secretion (assayed by ELISA) were assessed.
Results
L cell glucose uptake was dominated by GLUT-mediated transport, being abolished by phloretin but not phloridzin. NAD(P)H autofluorescence was glucose dependent and enhanced by a glucokinase activator. In GLUTag cells, but not primary L cells, phloretin partially impaired glucose-dependent secretion, and suppressed an amplifying effect of glucose under depolarising high K
+
conditions. The key importance of SGLT1 in GLUTag and primary cells was evident from the impairment of secretion by phloridzin or
Sglt1
knockdown and failure of glucose to trigger cytosolic Ca
2+
elevation in primary L cells from
Sglt1
knockout mice.
Conclusions/interpretation
SGLT1 acts as the luminal glucose sensor in L cells, but intracellular glucose concentrations are largely determined by GLUT activity. Although L cell glucose metabolism depends partially on glucokinase activity, this plays only a minor role in glucose-stimulated GLP-1 secretion.
Journal Article
Increasing low-energy-dense foods and decreasing high-energy-dense foods differently influence weight loss trial outcomes
Background/Objective:Although reducing energy density (ED) enhances weight loss, it is unclear whether all dietary strategies that reduce ED are comparable, hindering effective ED guidelines for obesity treatment. This study examined how changes in number of low-energy-dense (LED) (<4.186 kJ/1.0 kcal g-1 ) and high-energy-dense (HED) (>12.56 kJ/3.0 kcal g-1 ) foods consumed affected dietary ED and weight loss within an 18-month weight loss trial.Methods:This secondary analysis examined data from participants randomized to an energy-restricted lifestyle intervention or lifestyle intervention plus limited non-nutrient dense, energy-dense food variety (n=183). Number of daily LED and HED foods consumed was calculated from three, 24-h dietary recalls and anthropometrics were measured at 0, 6 and 18 months. Multivariable-adjusted generalized linear models and repeated-measures mixed linear models examined associations between 6-month changes in number of LED and HED foods and changes in ED, body mass index (BMI), and percent weight loss at 6 and 18 months.Results:Among mostly female (58%), White (92%) participants aged 51.9 years following an energy-restricted diet, increasing number of LED foods or decreasing number of HED foods consumed was associated with 6- and 18-month reductions in ED (β=-0.25 to -0.38 kJ g-1 (-0.06 to -0.09 kcal g-1 ), P<0.001). Only increasing number of LED foods consumed was associated with 6- and 18-month reductions in BMI (β=-0.16 to -0.2 kg m- 2 , P<0.05) and 6-month reductions in percent weight loss (β=-0.5%, P<0.05). Participants consuming [els]2 HED foods per day and [egs]6.6 LED foods per day experienced better weight loss outcomes at 6- and 18-month than participants only consuming [els]2 HED foods per day.Conclusion:Despite similar reductions in ED from reducing number of HED foods or increasing number of LED foods consumed, only increasing number of LED foods related to weight loss. This provides preliminary evidence that methods used to reduce dietary ED may differentially influence weight loss trajectories. Randomized controlled trials are needed to inform ED recommendations for weight loss.
Journal Article
The \Fire Stick Farming\ Hypothesis: Australian Aboriginal Foraging Strategies, Biodiversity, and Anthropogenic Fire Mosaics
Aboriginal burning in Australia has long been assumed to be a \"resource management\" strategy, but no quantitative tests of this hypothesis have ever been conducted. We combine ethnographic observations of contemporary Aboriginal hunting and burning with satellite image analysis of anthropogenic and natural landscape structure to demonstrate the processes through which Aboriginal burning shapes arid-zone vegetational diversity. Anthropogenic landscapes contain a greater diversity of successional stages than landscapes under a lightning fire regime, and differences are of scale, not of kind. Landscape scale is directly linked to foraging for small, burrowed prey (monitor lizards), which is a specialty of Aboriginal women. The maintenance of small-scale habitat mosaics increases small-animal hunting productivity. These results have implications for understanding the unique biodiversity of the Australian continent, through time and space. In particular, anthropogenic influences on the habitat structure of paleolandscapes are likely to be spatially localized and linked to less mobile, \"broad-spectrum\" foraging economies.
Journal Article
The problem of Susan and other stories
\"Two stories and two poems. All wondrous and imaginative about the tales we tell and experience. Where the incarnations of the months of the year sit around a campfire sharing stories, where an older college professor recounts a Narnian childhood, where the apocalypse unfolds, and where the importance of generational storytelling is seen through the Goldilocks fairytale.\"--Provided by publisher.
Book
Effect of surficial geology mapping scale on modelled ground ice in Canadian Shield terrain
Ground ice maps at small scales offer generalized depictions of abundance across broad circumpolar regions. In this paper, the effect of surficial geology mapping scale on modelled ground ice abundance is examined in the Slave Geological Province of the Canadian Shield, a region where the geological and glacial legacy has produced a landscape with significant variation in surface cover. Existing model routines from the Ground ice map of Canada (GIMC) were used with a 1:125 000-scale regional surficial geology compilation and compared to the national outputs, which are based on surficial geology at a 1:5 000 000 scale. Overall, the regional-scale modelling predicts much more ground ice than the GIMC due to greater representation of unconsolidated sediments in the region. Improved modelling accuracy is indicated by comparison of the outputs to empirical datasets due to improved representation of the inherent regional heterogeneity in surficial geology. The results demonstrate that the GIMC significantly underestimates the abundance and distribution of ground ice over Canadian Shield terrain. In areas with limited information on ground ice, regional-scale modelling may provide useful reconnaissance-level information to help guide the field-based investigations required for planning infrastructure development. The use of current small-scale ground ice mapping in risk or cost assessments related to permafrost thaw may significantly influence the accuracy of outputs in areas like the Canadian Shield, where surficial materials range from bedrock to frost-susceptible deposits over relatively short distances.
Journal Article