1,746 research outputs found
Conversation among Physical Chemists: Strategies and Resources for Remote Teaching and Learning Catalyzed by a Global Pandemic
In the midst of a global pandemic in spring 2020, physical chemistry faculty gathered to share strategies and resources for teaching remotely. During this conversation, instructors created a shared document compiling the challenges they faced in spring 2020 and ways to improve teaching and learning in the physical chemistry classroom and laboratory when institutions reopened in the fall. We present a content analysis of the shared document that provides a snapshot of physical chemists’ thoughts at that moment in June 2020. The themes that emerged from our analysis are assessment, choice of learning objectives, course management, opportunities, resources, student motivation, and wellbeing. We have summarized the numerous strategies, resources, and implementation ideas that were shared by participants, many of which we believe will remain in use when traditional in-person instruction resumes. Finally, the conversation connected physical chemists, strengthening our community. Continued community engagement has occurred through further synchronous conversations, asynchronous conversations on our Slack workspace, and the creation of the repository PChem Inspired Pedagogical Electronic Resource (PIPER)
Project Cerberus: Flyby Mission to Pluto
The goal of the Cerberus Project was to design a feasible and cost-effective unmanned flyby mission to Pluto. The requirements in the request for proposal for an unmanned probe to Pluto are presented and were met. The design stresses proven technology that will avoid show stoppers which could halt mission progress. Cerberus also utilizes the latest advances in the spacecraft industry to meet the stringent demands of the mission. The topics covered include: (1) mission management, planning, and costing; (2) structures; (3) power and propulsion; (4) attitude, articulation, and control; (5) command, control, and communication; and (6) scientific instrumentation
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Fruit and vegetable intake: change with age across childhood and adolescence
Abstract
Eating fruit and vegetables (FV) offers important health benefits for children and adolescents, but their average intake is low. To explore if negative trends with age exist as children grow, this study modelled differences in fruit and vegetable consumption from childhood to young adulthood. A pseudo-panel was constructed using Years 1-4 (combined) of the Rolling Programme of the UK National Diet and Nutrition Survey (2008/09 – 2011/12). Intake of fruits and vegetables in the NDNS was recorded using 4- day unweighted food diaries. Data consisted of 2131 observations of individuals aged 2 to 23 years. Age-year-cohort decomposition regression analyses were used to separate age effects from year and cohort effects in the data. Total energy intake was included to account for age differences in overall energy consumption. Fruit intake started to decrease from the age of 7 for boys and girls and reached its lowest level during adolescence. By 17 years boys were consuming 0.93 (p = 0.037) less fruit portions compared to the age of two. By 15 years, girls were consuming 0.8 fruit portions less (p = 0.053). Vegetable intake changed little during childhood and adolescence (p = 0.0834 and p = 0.843 for change between 7 and 12 years, boys and girls respectively). There was unclear evidence of recovery of FV intakes in early adulthood. Efforts to improve FV intake should consider these trends, and focus attention on the factors influencing intake across childhood and adolescence in order to improve the nutritional quality of diets during these periods
Ecological Analysis of Teen Birth Rates: Association with Community Income and Income Inequality
Objectives : To examine whether per capita income and income inequality are independently associated with teen birth rate in populous U.S. counties. Methods : This study used 1990 U.S. Census data and National Center for Health Statistics birth data. Income inequality was measured with the 90:10 ratio, a ratio of percent of cumulative income held by the richest and poorest population deciles. Linear regression and analysis of variance were used to assess associations between county-level average income, income inequality, and teen birth rates among counties with population greater than 100,000. Results : Among teens aged 15–17, income inequality and per capita income were independently associated with birth rate; the mean birth rate was 54 per 1,000 in counties with low income and high income inequality, and 19 per 1,000 in counties with high income and low inequality. Among older teens (aged 18–19) only per capita income was significantly associated with birth rate. Conclusions : Although teen childbearing is the result of individual behaviors, these findings suggest that community-level factors such as income and income inequality may contribute significantly to differences in teen birth rates.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45324/1/10995_2004_Article_344014.pd
Soluble lipid binding proteins from relevant parasitic helminths: form structure to function
Parasitic helminths cause serious and difficult to treat diseases in humans, animals and plants. A high percentage of the earth’s population, mainly in developing countries, suffers from helminth infections. Helminth parasites have a restricted lipid metabolism and must acquire simple undo complex lipids from their hosts for energy metabolism, membrane construction, and lipid-based signaling, the latter possibly also encompassing modifications of the host’s immune and inflammatory defense systems. These organisms produce and release an unexpectedly wide range of lipid binding proteins (LBPs) types structurally distinct from those of their hosts. Some will be associated with specialized external functions, including acquisition and distribution of nutrients. Yet others will be involved in modulation of the host’s local tissue environment, and its innate and acquired immune systems by secreted lipids and carrier proteins. It is important to note that antihelmintic drugs are partially hydrophobic and may require parasite’s own carrier proteins for reaching their site of action.Facultad de Ciencias Médica
'To live and die [for] Dixie': Irish civilians and the Confederate States of America
Around 20,000 Irishmen served in the Confederate army in the Civil War. As a result, they left behind, in various Southern towns and cities, large numbers of friends, family, and community leaders. As with native-born Confederates, Irish civilian support was crucial to Irish participation in the Confederate military effort. Also, Irish civilians served in various supporting roles: in factories and hospitals, on railroads and diplomatic missions, and as boosters for the cause. They also, however, suffered in bombardments, sieges, and the blockade. Usually poorer than their native neighbours, they could not afford to become 'refugees' and move away from the centres of conflict. This essay, based on research from manuscript collections, contemporary newspapers, British Consular records, and Federal military records, will examine the role of Irish civilians in the Confederacy, and assess the role this activity had on their integration into Southern communities. It will also look at Irish civilians in the defeat of the Confederacy, particularly when they came under Union occupation. Initial research shows that Irish civilians were not as upset as other whites in the South about Union victory. They welcomed a return to normalcy, and often 'collaborated' with Union authorities. Also, Irish desertion rates in the Confederate army were particularly high, and I will attempt to gauge whether Irish civilians played a role in this. All of the research in this paper will thus be put in the context of the Drew Gilpin Faust/Gary Gallagher debate on the influence of the Confederate homefront on military performance. By studying the Irish civilian experience one can assess how strong the Confederate national experiment was. Was it a nation without a nationalism
Chemical Abundances Of Three Metal-Poor Globular Clusters (NGC 6287, NGC 6293, And NGC 6541) In The Inner Halo
We present a chemical abundance study of three inner old halo clusters NGC
6287, NGC 6293, and NGC 6541, finding [Fe/H] = -2.01 +/- 0.05, -1.99 +/- 0.02,
and -1.76 +/- 0.02, respectively, and our metallicity measurements are in good
agreement with previous estimates. The mean alpha-element abundances of our
program clusters are in good agreement with other globular clusters, confirming
previous results. However, the individual alpha-elements appear to follow
different trends. The silicon abundances of the inner halo clusters appear to
be enhanced and the titanium abundances appear to be depleted compared to the
intermediate halo clusters. Our results also appear to oppose to those of
metal-rich bulge giants studied by McWilliam and Rich, who found that bulge
giants are titanium enhanced and silicon deficient. In particular, [Si/Ti]
ratios appear to be related to Galactocentric distances,in the sense that
[Si/Ti] ratios decrease with Galactocentric distance. We propose that
contributions from different masses of the SNe II progenitors that enriched
proto-globular cluster clouds' elemental abundances and the different initial
physical environments surrounding the proto-globular clusters clouds are
responsible for this gradient in [Si/Ti] ratios versus Galactocentric distances
of the "old halo" globular clusters. On the other hand, our program clusters'
enhanced s-process elemental abundances suggest that the formation timescale of
our program clusters might be as short as a few times 10^8 yr after the star
formation is initiated in the Galaxy's central regions, if the s-process site
is intermediate mass AGB stars.Comment: Accepted for publication in AJ (Sept. 2002
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The Effects of Forest Fuel-Reduction Treatments in the United States
The current conditions of many seasonally dry forests in the western and southern United States, especially those that once experienced low- to moderate-intensity fire regimes, leave them uncharacteristically susceptible to high-severity wildfire. Both prescribed fire and its mechanical surrogates are generally successful in meeting short-term fuel-reduction objectives such that treated stands are more resilient to high-intensity wildfire. Most available evidence suggests that these objectives are typically accomplished with few unintended consequences, since most ecosystem components (vegetation, soils, wildlife, bark beetles, carbon sequestration) exhibit very subtle effects or no measurable effects at all. Although mechanical treatments do not serve as complete surrogates for fire, their application can help mitigate costs and liability in some areas. Desired treatment effects on fire hazards are transient, which indicates that after fuel-reduction management starts, managers need to be persistent with repeated treatment, especially in the faster-growing forests in the southern United States.Keywords: wildfire, forest conservation, forest management, fire surrogates, fire ecolog
Two-Photon Excitation Laser Scanning Microscopy of Human, Porcine, and Rabbit Nasal Septal Cartilage
Regularity Properties and Pathologies of Position-Space Renormalization-Group Transformations
We reconsider the conceptual foundations of the renormalization-group (RG)
formalism, and prove some rigorous theorems on the regularity properties and
possible pathologies of the RG map. Regarding regularity, we show that the RG
map, defined on a suitable space of interactions (= formal Hamiltonians), is
always single-valued and Lipschitz continuous on its domain of definition. This
rules out a recently proposed scenario for the RG description of first-order
phase transitions. On the pathological side, we make rigorous some arguments of
Griffiths, Pearce and Israel, and prove in several cases that the renormalized
measure is not a Gibbs measure for any reasonable interaction. This means that
the RG map is ill-defined, and that the conventional RG description of
first-order phase transitions is not universally valid. For decimation or
Kadanoff transformations applied to the Ising model in dimension ,
these pathologies occur in a full neighborhood of the low-temperature part of the first-order
phase-transition surface. For block-averaging transformations applied to the
Ising model in dimension , the pathologies occur at low temperatures
for arbitrary magnetic-field strength. Pathologies may also occur in the
critical region for Ising models in dimension . We discuss in detail
the distinction between Gibbsian and non-Gibbsian measures, and give a rather
complete catalogue of the known examples. Finally, we discuss the heuristic and
numerical evidence on RG pathologies in the light of our rigorous theorems.Comment: 273 pages including 14 figures, Postscript, See also
ftp.scri.fsu.edu:hep-lat/papers/9210/9210032.ps.
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