1,180 research outputs found
Constitution Day: An Opportunity for Honors Colleges to Promote Civic Engagement
The United States Constitution is the bedrock upon which government and society rest, yet its precepts remain generally unfamiliar to contemporary college students. Considering the extent of its impact and the misinformation regarding its purpose, content, efficacy, and limits, the authors provide suggestions for civic learning based on this seminal document. While all American educational institutions receiving federal funding must celebrate the U.S. Constitution each year on or near September 17th, research suggests that comprehensive and integrative instruction is scarce. Citing a lack of formal Constitution Day programming among honors colleges, the authors present a multi-modal framework for honors students to conduct research, stimulate critical thinking, showcase their findings, and engage in civic dialogues. Historical underpinnings of Constitution Day legislation are provided, and curricular guidelines are included
Microbial effects
Includes bibliographical references (pages 167-176).The recommendations for microbiological research needs are based on the following general scenario: a) increased atmospheric CO2 will increase crop productivities by 10-40%, depending on crop and geographic area, which in turn will increase biomass and soil organic matter by 5-40%; b) additional root-derived materials and crop residue in the soil will increase soil microbial activities, producing a greater flux in most major cycles and possibly some changes in pool sizes of -10% to +30%; c) these effects will increase biological Nz fixation, and the increased demand for N will place significant limitations on phosphorus and other mineral nutrients; d) no significant changes will occur in soil O2 or CO2. The postulated doubling of atmospheric CO2 is not likely to have a direct effect on soil microbial activity because during the growing season, the concentration of CO2 in the soil atmosphere is already ten to fifty times higher than existing atmospheric CO2. Based on all available experimental information, it is estimated that a doubling of atmospheric CO2 will cause an increase in primary productivity of ten to forty percent, depending on locale. The increase in biomass will, in turn, produce a limitation of available soil nutrients, especially nitrogen and phosphorus. Increased organic carbon together with nitrogen and/or phosphorus limitation will result in a preferential increase in nitrogen fixation and mycorrhizal activities as the expedient means for supplying required nutrients to sustain the predicted increase in primary productivity. Therefore, increased emphasis should be placed on fundamental research related to soil microbiology with special reference to nitrogen-fixing, nitrifying and denitrifying bacteria, and to the mycorrhizal fungi
Field-Induced Magnetization Steps in Intermetallic Compounds and Manganese Oxides: The Martensitic Scenario
Field-induced magnetization jumps with similar characteristics are observed
at low temperature for the intermetallic germanide Gd5Ge4and the mixed-valent
manganite Pr0.6Ca0.4Mn0.96Ga0.04O3. We report that the field location -and even
the existence- of these jumps depends critically on the magnetic field sweep
rate used to record the data. It is proposed that, for both compounds, the
martensitic character of their antiferromagnetic-to-ferromagnetic transitions
is at the origin of the magnetization steps.Comment: 4 pages,4 figure
Underground gamma-ray measurements of radium isotopes from hydrothermal plumes in the deep Pacific Ocean
© The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Hult, M., Charette, M., Lutter, G., Marissens, G., Henderson, P., Sobiech-Matura, K., & Simgen, H. Underground gamma-ray measurements of radium isotopes from hydrothermal plumes in the deep Pacific Ocean. Applied Radiation and Isotopes, 153, (2019): 108831, doi:10.1016/j.apradiso.2019.108831.The radium isotopes 226Ra and 228Ra can provide important data on the dynamics of deep-sea hydrothermal plumes that travel the oceans for decades and have great impact on the ocean chemistry. This study focuses on parameters important for obtaining low detection limits for 228Ra using gamma-ray spectrometry. It is present at mBq-levels in samples collected during the US GEOTRACES 2013 cruise to the Southeast Pacific Ocean.The work of the HADES-staff of Euridice at SCK•CEN is gratefully acknowledged. We are most grateful to Dr. Faidra Tzika for her work in the precursor to this project. Many thanks to Heiko Stroh for quality control and measurements in HADES. This research was supported in part by grants from the U.S. National Science Foundation, Ocean Sciences division (OCE-1232669 and OCE-1736277)
Signatures of natural selection in a foundation tree along Mediterranean climatic gradients
Temperature and precipitation regimes are rapidly changing, resulting in forest dieback and extinction events, particularly in Mediterranean-type climates (MTC). Forest management that enhance forests’ resilience is urgently required, however adaptation to climates in heterogeneous landscapes with multiple selection pressures is complex. For widespread trees in MTC we hypothesized that: patterns of local adaptation are associated with climate; precipitation is a stronger factor of adaptation than temperature; functionally related genes show similar signatures of adaptation; and adaptive variants are independently sorting across the landscape. We sampled 28 populations across the geographic distribution of Eucalyptus marginata (jarrah), in South-west Western Australia, and obtained 13,534 independent single nucleotide polymorphic (SNP) markers across the genome. Three genotype-association analyses that employ different ways of correcting population structure were used to identify putatively adapted SNPs associated with independent climate variables. While overall levels of population differentiation were low (FST = 0.04), environmental association analyses found a total of 2336 unique SNPs associated with temperature and precipitation variables, with 1440 SNPs annotated to genic regions. Considerable allelic turnover was identified for SNPs associated with temperature seasonality and mean precipitation of the warmest quarter, suggesting that both temperature and precipitation are important factors in adaptation. SNPs with similar gene functions had analogous allelic turnover along climate gradients, while SNPs among temperature and precipitation variables had uncorrelated patterns of adaptation. These contrasting patterns provide evidence that there may be standing genomic variation adapted to current climate gradients, providing the basis for adaptive management strategies to bolster forest resilience in the future
Two-divisibility of the coefficients of certain weakly holomorphic modular forms
We study a canonical basis for spaces of weakly holomorphic modular forms of
weights 12, 16, 18, 20, 22, and 26 on the full modular group. We prove a
relation between the Fourier coefficients of modular forms in this canonical
basis and a generalized Ramanujan tau-function, and use this to prove that
these Fourier coefficients are often highly divisible by 2.Comment: Corrected typos. To appear in the Ramanujan Journa
Gravitational Lensing by Nearby Clusters of Galaxies
We present an estimation of the expected number of arcs and arclets in a
sample of nearby (z<0.1) clusters of galaxies, that takes into account the
magnitude limit of the objects as well as seeing effects. We show that strong
lensing effects are not common, but also they are not as rare as usually
stated. Indeed, for a given cluster, they present a strong dependence with the
magnitude limit adopted in the analysis and the seeing of the observations. We
also describe the procedures and results of a search for lensing effects in a
sample of 33 clusters spanning the redshift range of 0.014 to 0.076,
representative of the local cluster distribution. This search produced two arc
candidates. The first one is in A3408 (z=0.042), the same arc previously
discovered by Campusano & Hardy (1996), with z=0.073 and associated to the
brightest cluster galaxy. The second candidate is in the cluster A3266
(z=0.059) and is near a bright elliptical outside the cluster center, requiring
the presence of a very massive sub-structure around this galaxy to be produced
by gravitational lensing.Comment: 22 pages including 9 Figures and 2 Tables, submitted to A
Induction of non-d-wave order-parameter components by currents in d-wave superconductors
It is shown, within the framework of the Ginzburg-Landau theory for a
superconductor with d_{x^2-y^2} symmetry, that the passing of a supercurrent
through the sample results, in general, in the induction of order-parameter
components of distinct symmetry. The induction of s-wave and
d_{xy(x^2-y^2)-wave components are considered in detail. It is shown that in
both cases the order parameter remains gapless; however, the structure of the
lines of nodes and the lobes of the order parameter are modified in distinct
ways, and the magnitudes of these modifications differ in their dependence on
the (a-b plane) current direction. The magnitude of the induced s-wave
component is estimated using the results of the calculations of Ren et al.
[Phys. Rev. Lett. 74, 3680 (1995)], which are based on a microscopic approach.Comment: 15 pages, includes 2 figures. To appear in Phys. Rev.
Are Interaction-free Measurements Interaction Free?
In 1993 Elitzur and Vaidman introduced the concept of interaction-free
measurements which allowed finding objects without ``touching'' them. In the
proposed method, since the objects were not touched even by photons, thus, the
interaction-free measurements can be called as ``seeing in the dark''. Since
then several experiments have been successfully performed and various
modifications were suggested. Recently, however, the validity of the term
``interaction-free'' has been questioned. The criticism of the name is briefly
reviewed and the meaning of the interaction-free measurements is clarified.Comment: 11 pages, 3 eps figures. Contribution to the ICQO 2000, Raubichi,
Belaru
Psychological mechanisms mediating effects between trauma and psychotic symptoms: the role of affect regulation, intrusive trauma memory, beliefs, and depression
Evidence suggests a causal role for trauma in psychosis, particularly for childhood victimization. However, the establishment of underlying trauma-related mechanisms would strengthen the causal argument. In a sample of peo-ple with relapsing psychosis (n = 228), we tested hypoth-esized mechanisms specifically related to impaired affect regulation, intrusive trauma memory, beliefs, and depres-sion. The majority of participants (74.1%) reported vic-timization trauma, and a fifth (21.5%) met symptomatic criteria for Posttraumatic Stress Disorder. We found a specific link between childhood sexual abuse and auditory hallucinations (adjusted OR = 2.21, SE = 0.74, P = .018). This relationship was mediated by posttraumatic avoid-ance and numbing (OR = 1.48, SE = 0.19, P = .038) and hyperarousal (OR = 1.44, SE = 0.18, P = .045), but not intrusive trauma memory, negative beliefs or depression. In contrast, childhood emotional abuse was specifically associated with delusions, both persecutory (adjusted OR = 2.21, SE = 0.68, P = .009) and referential (adjusted OR = 2.43, SE = 0.74, P = .004). The link with persecutory delusions was mediated by negative-other beliefs (OR = 1.36, SE = 0.14, P = .024), but not posttraumatic stress symptoms, negative-self beliefs, or depression. There was no evidence of mediation for referential delusions. No rela-tionships were identified between childhood physical abuse and psychosis. The findings underline the role of cognitive-affective processes in the relationship between trauma and symptoms, and the importance of assessing and treating victimization and its psychological consequences in people with psychosis
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