1,620 research outputs found
Pseudo-saturating power converter
Relative performance of three basic configurations of electronic conversion units (saturating, pseudo-saturating, nonsaturating) requiring low power levels is compared. Pseudo-saturating mode exhibits best overall performance, nonsaturating a close second, saturating a poor third
Recent Developments in The Wisconsin-Illinois-Iowa Lead-Zinc District
One of the oldest mining districts in the United States, and one from which lead and zinc ores were mined in substantial quantity during the last five years or so is situated in the upper area of drainage of the Mississippi River. The district lies in the geologic province that has been known for several decades as the Driftless Area, and is characterized by gently-rolling topography, which extends from the nearly-level uplands to the well-dissected areas bordering the major rivers. The Mississippi on the west, the Wisconsin River on the north, and the Rock River on the east virtually bound the district. The area of major mining activity includes roughly some 2500 square miles, most of which lies in Wisconsin. The land is fairly well wooded, particularly where greatly dissected, while the uplands and bottomlands contain acreage valuable for farming. The district is characterized by dairy farms and industries based upon dairy products. The area involved has a temperate climate with moderate precipitation. Its secondary roads are well kept, the road metal being both from tailings piles of mining operations as well as from quarries
Use of Interactive Simulations in Fundamentals of Biochemistry, a LibreText Online Educational Resource, to Promote Understanding of Dynamic Reactions
Biology is perhaps the most complex of the sciences, given the incredible
variety of chemical species that are interconnected in spatial and temporal
pathways that are daunting to understand. Their interconnections lead to
emergent properties such as memory, consciousness, and recognition of self and
non-self. To understand how these interconnected reactions lead to cellular
life characterized by activation, inhibition, regulation, homeostasis, and
adaptation, computational analyses and simulations are essential, a fact
recognized by the biological communities. At the same time, students struggle
to understand and apply binding and kinetic analyses for the simplest reactions
such as the irreversible first-order conversion of a single reactant to a
product. This likely results from cognitive difficulties in combining
structural, chemical, mathematical, and textual descriptions of binding and
catalytic reactions. To help students better understand dynamic reactions and
their analyses, we have introduced two kinds of interactive graphs and
simulations into the online educational resource, Fundamentals of Biochemistry,
a multivolume biochemistry textbook that is part of the LibreText collection.
One type is available for simple binding and kinetic reactions. The other
displays progress curves (concentrations vs time) for both simple reactions and
more complex metabolic and signal transduction pathways, including those
available through databases using systems biology markup language (SBML) files.
Users can move sliders to change dissociation and kinetic constants as well as
initial concentrations and see instantaneous changes in the graphs. They can
also export data into a spreadsheet for further processing, such as producing
derivative Lineweaver-Burk and traditional Michaelis-Menten graphs of initial
velocity (v0) vs substrate concentration.Comment: 17 pages, 2 tables, 8 figures. Submitted to Biochemistry and
Molecular Biology Education. Funding: MiniSidewinder: NIH/NIGMS (Grant
R01-GM123032-04) LibreText: Department of Education Open Textbook Pilot
Project, the UC Davis Office of the Provost, the UC Davis Library, the
California State University Affordable Learning Solutions Program, and Merlo
Are changes in ADHD course reflected in differences in IQ and executive functioning from childhood to young adulthood?
Tidal Response of Mars Constrained From Laboratory-Based Viscoelastic Dissipation Models and Geophysical Data
We employ laboratory-based grain-size- and temperature-sensitive rheological models to
16 describe the viscoelastic behavior of terrestrial bodies with focus on Mars. Shear modulus
17 reduction and attenuation related to viscoelastic relaxation occur as a result of diffusion-
18 and dislocation-related creep and grain-boundary processes. We consider five rheological
19 models, including extended Burgers, Andrade, Sundberg-Cooper, a power-law approxima-
20 tion, and Maxwell, and determine Martian tidal response. However, the question of which
21 model provides the most appropriate description of dissipation in planetary bodies, re-
22 mains an open issue. To examine this, crust and mantle models (density and elasticity) are
23 computed self-consistently through phase equilibrium calculations as a function of pres-
24 sure, temperature, and bulk composition, whereas core properties are based on an Fe-FeS
25 parameterisation. We assess the compatibility of the viscoelastic models by inverting the
26 available geophysical data for Mars (tidal response and mean density and moment of in-
27 ertia) for temperature, elastic, and attenuation structure. Our results show that although
28 all viscoelastic models are consistent with data, their predictions for the tidal response at
29 other periods and harmonic degrees are distinct. The results also show that Maxwell is
30 only capable of fitting data for unrealistically low viscosities. Our approach can be used
31 quantitatively to distinguish between the viscoelastic models from seismic and/or tidal ob-
32 servations that will allow for improved constraints on interior structure (e.g., with InSight).
33 Finally, the methodology presented here is generally formulated and applicable to other so-
34 lar and extra-solar system bodies where the study of tidal dissipation presents an important
35 means for determining interior structure
Top quark physics in hadron collisions
The top quark is the heaviest elementary particle observed to date. Its large
mass makes the top quark an ideal laboratory to test predictions of
perturbation theory concerning heavy quark production at hadron colliders. The
top quark is also a powerful probe for new phenomena beyond the Standard Model
of particle physics. In addition, the top quark mass is a crucial parameter for
scrutinizing the Standard Model in electroweak precision tests and for
predicting the mass of the yet unobserved Higgs boson. Ten years after the
discovery of the top quark at the Fermilab Tevatron top quark physics has
entered an era where detailed measurements of top quark properties are
undertaken. In this review article an introduction to the phenomenology of top
quark production in hadron collisions is given, the lessons learned in Tevatron
Run I are summarized, and first Run II results are discussed. A brief outlook
to the possibilities of top quark research a the Large Hadron Collider,
currently under construction at CERN, is included.Comment: 84 pages, 32 figures, accepted for publication by Reports on Progress
in Physic
Renewing Criminalized and Hegemonic Cultural Landscapes
The Mafia's long historical pedigree in Mezzogiorno, Southern Italy, has empowered the Mafioso as a notorious, uncontested, and hegemonic figure. The counter-cultural resistance against the mafiosi culture began to be institutionalized in the early 1990s. Today, Libera Terra is the largest civil society organization in the country that uses the lands confiscated from the Mafia as a space of cultural repertoire to realize its ideals. Deploying labor force through volunteer participation, producing biological fruits and vegetables, and providing information to the students on the fields are the principal cultural practices of this struggle. The confiscated lands make the Italian experience of anti-Mafia resistance a unique example by connecting the land with the ideals of cultural change. The sociocultural resistance of Libera Terra conveys a political message through these practices and utters that the Mafia is not invincible. This study draws the complex panorama of the Mafia and anti-Mafia movement that uses the âconfiscated landsâ as cultural and public spaces for resistance and socio-cultural change. In doing so, this article sheds new light on the relationship between rural criminology and crime prevention policies in Southern Italy by demonstrating how community development practice of Libera Terra changes the meaning of landscape through iconographic symbolism and ethnographic performance
Constraints on Models for the Higgs Boson with Exotic Spin and Parity in VH â VbÂŻb Final States
This is the published version. Copyright © 2014 American Physical SocietyWe present constraints on models containing non-standard-model values for the spin J and parity P of the Higgs boson H in up to 9.7ââfbâ1 of ppÂŻ collisions at sâ=1.96ââTeV collected with the D0 detector at the Fermilab Tevatron Collider. These are the first studies of Higgs boson JP with fermions in the final state. In the ZHâââbbÂŻ, WHââÎœbbÂŻ, and ZHâΜΜbbÂŻ final states, we compare the standard model (SM) Higgs boson prediction, JP=0+, with two alternative hypotheses, JP=0â and JP=2+. We use a likelihood ratio to quantify the degree to which our data are incompatible with non-SM JP predictions for a range of possible production rates. Assuming that the production rate in the signal models considered is equal to the SM prediction, we reject the JP=0â and JP=2+ hypotheses at the 97.6% CL and at the 99.0% CL, respectively. The expected exclusion sensitivity for a JP=0â (JP=2+) state is at the 99.86% (99.94%) CL. Under the hypothesis that our data are the result of a combination of the SM-like Higgs boson and either a JP=0â or a JP=2+ signal, we exclude a JP=0â fraction above 0.80 and a JP=2+ fraction above 0.67 at the 95% CL. The expected exclusion covers JP=0â (JP=2+) fractions above 0.54 (0.47)
Mother's and children's ADHD genetic risk, household chaos and children's ADHD symptoms:A geneâenvironment correlation study
BACKGROUND: Chaotic home environments may contribute to children's attentionâdeficit hyperactivity disorder (ADHD) symptoms. However, ADHD genetic risk may also influence household chaos. This study investigated whether children in chaotic households had more ADHD symptoms, if mothers and children with higher ADHD genetic risk lived in more chaotic households, and the joint association of genetic risk and household chaos on the longitudinal course of ADHD symptoms across childhood. METHODS: Participants were mothers and children from the Environmental Risk (EâRisk) Longitudinal Twin Study, a UK populationârepresentative birth cohort of 2,232 twins. Children's ADHD symptoms were assessed at ages 5, 7, 10 and 12âyears. Household chaos was rated by research workers at ages 7, 10 and 12, and by mother's and twin's selfâreport at age 12. Genomeâwide ADHD polygenic risk scores (PRS) were calculated for mothers (nâ=â880) and twins (nâ=â1,999); of these, nâ=â871 mothers and nâ=â1,925 children had information on children's ADHD and household chaos. RESULTS: Children in more chaotic households had higher ADHD symptoms. Mothers and children with higher ADHD PRS lived in more chaotic households. Children's ADHD PRS was associated with household chaos over and above mother's PRS, suggesting evocative geneâenvironment correlation. Children in more chaotic households had higher baseline ADHD symptoms and a slower rate of decline in symptoms. However, sensitivity analyses estimated that geneâenvironment correlation accounted for a large proportion of the association of household chaos on ADHD symptoms. CONCLUSIONS: Children's ADHD genetic risk was independently associated with higher levels of household chaos, emphasising the active role of children in shaping their home environment. Our findings suggest that household chaos partly reflects children's genetic risk for ADHD, calling into question whether household chaos directly influences children's core ADHD symptoms. Our findings highlight the importance of considering parent and child genetic risk in relation to apparent environmental exposures
Measurement of the B0s Lifetime in the Flavor-Specific Decay Channel B0sâDâsÎŒ+ÎœX
This is the published version. Copyright 2015 American Physical SocietyWe present an updated measurement of the B0s lifetime using the semileptonic decays B0sâDâsÎŒ+ÎœX, with DâsâÏÏâ and ÏâK+Kâ (and the charge conjugate process). This measurement uses the full Tevatron Run II sample of proton-antiproton collisions at sâ=1.96ââTeV, comprising an integrated luminosity of 10.4ââfbâ1. We find a flavor-specific lifetime Ïfs(B0s)=1.479±0.010(stat)±0.021(syst)ââps. This technique is also used to determine the B0 lifetime using the analogous B0âDâÎŒ+ÎœX decay with DââÏÏâ and ÏâK+Kâ, yielding Ï(B0)=1.534±0.019(stat)±0.021(syst)ââps. Both measurements are consistent with the current world averages, and the B0s lifetime measurement is one of the most precise to date. Taking advantage of the cancellation of systematic uncertainties, we determine the lifetime ratio Ïfs(B0s)/Ï(B0)=0.964±0.013(stat)±0.007(syst)
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