1,697 research outputs found
A systematic review of motivational and attentional variables on children’s fundamental movement skill development: The OPTIMAL theory.
Resolution studies of cosmic-ray tracks in a TPC with GEM readout
A large volume TPC is a leading candidate for the central tracking detector
at a future high energy linear collider. To improve the resolution a new
readout based on micro-pattern gas detectors is being developed. Measurements
of the spatial resolution of cosmic-ray tracks in a GEM TPC are presented. We
find that the resolution suffers if the readout pads are too wide with respect
to the charge distribution at the readout plane due to insufficient charge
sharing. For narrow pads of 2 x 6 mm**2 we measure a resolution of 100
micometer at short drift distances in the absence of an axial magnetic field.
The dependence of the spatial resolution as a function of drift distance allows
the determination of the underlying electron statistics. Our results show that
the present technique uses about half the statistical power available from the
number of primary electrons. The track angle effect is observed as expected.Comment: 18 pages, 8 figures, version as published in Nucl. Inst. Met
Wild-sourced Chamelaucium uncinatum have no resistance to Puccinia psidii (myrtle rust)
Reader’s Guide
The United States began as a nation of farmers living in remote areas, but over a period of two hundred years the country became the wealthiest and most powerful industrial nation of the world. During the American Industrial Revolution inventors and innovators created new and improved machines for manufacturing, while a new breed of American businessmen created revolutionary methods of conducting business and managing labor. The road to industrialization was not always heroic. Ruthlessness and greed were often key ingredients in advancing industry. While a few found wealth and power, multitudes of workers and farmers suffered, and small businesses were crushed by the powerful new corporations. Reformers, unions, and protestors against big business played a crucial role in the industrialization process as they pressed for the rights of workers and regulations on business to help farmers and consumers. The diverse people and events that forever changed the nation from a rural farming economy to an industrialized urban nation create a dramatic story that lies at the heart of U.S. history. xiii Coverage and features Development of the Industrial U.S.: Biographies profiles twenty-six significant figures who participated in American industrialization. The biographies cover a wide spectrum of people, from the creators of the first factories, such as Samuel Slater and Francis Cabot Lowell, to inventors and innovators
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Can Male Circumcision Have an Impact on the HIV Epidemic in Men Who Have Sex with Men?
Background: Three trials have demonstrated the prophylactic effect of male circumcision (MC) for HIV acquisition among heterosexuals, and MC interventions are underway throughout sub-Saharan Africa. Similar efforts for men who have sex with men (MSM) are stymied by the potential for circumcised MSM to acquire HIV easily through receptive sex and transmit easily through insertive sex. Existing work suggests that MC for MSM should reach its maximum potential in settings where sexual role segregation is historically high and relatively stable across the lifecourse; HIV incidence among MSM is high; reported willingness for prophylactic circumcision is high; and pre-existing circumcision rates are low. We aim to identify the likely public health impact that MC interventions among MSM would have in one setting that fulfills these conditions—Peru—as a theoretical upper bound for their effectiveness among MSM generally. Methods and Findings: We use a dynamic, stochastic sexual network model based in exponential-family random graph modeling and parameterized from multiple behavioral surveys of Peruvian MSM. We consider three enrollment criteria (insertive during 100%, >80% or >60% of UAI) and two levels of uptake (25% and 50% of eligible men); we explore sexual role proportions from two studies and different frequencies of switching among role categories. Each scenario is simulated 10 times. We estimate that efficiency could reach one case averted per 6 circumcisions. However, the population-level impact of an optimistic MSM-MC intervention in this setting would likely be at most ∼5–10% incidence and prevalence reductions over 25 years. Conclusions: Roll-out of MC for MSM in Peru would not result in a substantial reduction in new HIV infections, despite characteristics in this population that could maximize such effects. Additional studies are needed to confirm these results for other MSM populations, and providers may consider the individual health benefits of offering MC to their MSM patients
SURVEY OF THE DEPENDENCE ON TEMPERATURE OF THE COERCIVITY OF GARNET-FILMS
The temperature dependence of the domain-wall coercive field of epitaxial magnetic garnets films
has been investigated in the entire temperature range of the ferrimagnetic phase, and has been found
to be described by a set of parametric exponents. In subsequent temperature regions different slopes
were observed, with breaking points whose position was found to be sample dependent. A survey
ba.ed on literature Data as well as on a large number of our own samples shows the general
existence of this piecewise exponential dependence and the presence of the breaking points. This
type of domain-wall coercive field temperature dependence was found in all samples in the large
family of the epitaxial garnets (about 30 specimens of more than ten chemical compositionsj and
also in another strongly anisotropic material (TbFeCo)
Symmetry Decomposition of Chaotic Dynamics
Discrete symmetries of dynamical flows give rise to relations between
periodic orbits, reduce the dynamics to a fundamental domain, and lead to
factorizations of zeta functions. These factorizations in turn reduce the labor
and improve the convergence of cycle expansions for classical and quantum
spectra associated with the flow. In this paper the general formalism is
developed, with the -disk pinball model used as a concrete example and a
series of physically interesting cases worked out in detail.Comment: CYCLER Paper 93mar01
Properties of the Strange Axial Mesons in the Relativized Quark Model
We studied properties of the strange axial mesons in the relativized quark
model. We calculated the decay constant in the quark model and showed how
it can be used to extract the mixing angle
() from the weak decay . The ratio is the most sensitive
measurement and also the most reliable since the largest of the theoretical
uncertainties factor out. However the current bounds extracted from the
TPC/Two-Gamma collaboration measurements are rather weak: we typically obtain
at 68\% C.L. We also calculated the
strong OZI-allowed decays in the pseudoscalar emission model and the flux-tube
breaking model and extracted a mixing angle of . Our analysis also indicates that the heavy quark limit does not give a
good description of the strange mesons.Comment: Revised version to be published in Phys. Rev. D. Minor changes. Latex
file uses revtex version 3 and epsfig, 4 postcript figures are attached. The
full postcript version with embedded figures is available at
ftp://ftp.physics.carleton.ca/pub/theory/godfrey/ocipc9512.ps.
Search for Yukawa Production of a Light Neutral Higgs Boson at LEP
Within a Two-Higgs-Doublet Model (2HDM) a search for a light Higgs boson in
the mass range of 4-12 GeV has been performed in the Yukawa process e+e- -> b
bbar A/h -> b bbar tau+tau-, using the data collected by the OPAL detector at
LEP between 1992 and 1995 in e+e- collisions at about 91 GeV centre-of-mass
energy. A likelihood selection is applied to separate background and signal.
The number of observed events is in good agreement with the expected
background. Within a CP-conserving 2HDM type II model the cross-section for
Yukawa production depends on xiAd = |tan beta| and xihd = |sin alpha/cos beta|
for the production of the CP-odd A and the CP-even h, respectively, where tan
beta is the ratio of the vacuum expectation values of the Higgs doublets and
alpha is the mixing angle between the neutral CP-even Higgs bosons. From our
data 95% C.L. upper limits are derived for xiAd within the range of 8.5 to 13.6
and for xihd between 8.2 to 13.7, depending on the mass of the Higgs boson,
assuming a branching fraction into tau+tau- of 100%. An interpretation of the
limits within a 2HDM type II model with Standard Model particle content is
given. These results impose constraints on several models that have been
proposed to explain the recent BNL measurement of the muon anomalous magnetic
moment.Comment: 24 pages, 9 figures, Submitted to Euro. Phys. J.
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