610 research outputs found
Stories From The Tuskegee Era
A study of botanical healing ways recalled by elder African American women in the Mississippi Delta brought stories of healing as well as stirring memories of events that occurred during the same period as the 40 year Tuskegee Syphilis Study. The original research was an ethno nursing study that included an ethno nursing history. Within this ethno nursing history, memories from the elders tumbled forth; memories, both-happy and sad, reflected the times and conditions of the past. The stories recalled were often difficult for the researcher to hear but the stories were shared freely by the participants. The researcher felt a sense of obligation and duty to share the stories without dissection or evaluation so others may hear the voice of the elders and understand the way of life that existed for African Americans during the time of the Tuskegee Syphilis Study. The stories allow a glimpse into the life of African Americans and demonstrated the innocence of the people during a time of unethical scientific experimentation
Coisotropic deformations of associative algebras and dispersionless integrable hierarchies
The paper is an inquiry of the algebraic foundations of the theory of
dispersionless integrable hierarchies, like the dispersionless KP and modified
KP hierarchies and the universal Whitham's hierarchy of genus zero. It stands
out for the idea of interpreting these hierarchies as equations of coisotropic
deformations for the structure constants of certain associative algebras. It
discusses the link between the structure constants and the Hirota's tau
function, and shows that the dispersionless Hirota's bilinear equations are,
within this approach, a way of writing the associativity conditions for the
structure constants in terms of the tau function. It also suggests a simple
interpretation of the algebro-geometric construction of the universal Whitham's
equations of genus zero due to Krichever.Comment: minor misprints correcte
Effect of membrane character and solution chemistry on microfiltration performance
To help understand and predict the role of natural organic matter (NOM) in the fouling of low-pressure membranes, experiments were carried out with an apparatus that incorporates automatic backwashing and long filtration runs. Three hollow fibre membranes of varying character were included in the study, and the filtration of two different surface waters was compared. The hydrophilic membrane had greater flux recovery after backwashing than the hydrophobic membranes, but the efficiency of backwashing decreased at extended filtration times. NOM concentration of these waters (7.9 and 9.1 mg/L) had little effect on the flux of the membranes at extended filtration times, as backwashing of the membrane restored the flux to similar values regardless of the NOM concentration. The solution pH also had little effect at extended filtration times. The backwashing efficiency of the hydrophilic membrane was dramatically different for the two waters, and the presence of colloid NOM alone could not explain these differences. It is proposed that colloidal NOM forms a filter cake on the surface of the membranes and that small molecular weight organics that have an adsorption peak at 220 nm but not 254 nm were responsible for “gluing” the colloids to the membrane surface. Alum coagulation improved membrane performance in all instances, and this was suggested to be because coagulation reduced the concentration of “glue” that holds the organic colloids to the membrane surface
Non-Commutativity and Unitarity Violation in Gauge Boson Scattering
We examine the unitarity properties of spontaneously broken non-commutative
gauge theories. We find that the symmetry breaking mechanism in the
non-commutative Standard Model of Chaichian et al. leads to an unavoidable
violation of tree-level unitarity in gauge boson scattering at high energies.
We then study a variety of simplified spontaneously broken non-commutative
theories and isolate the source of this unitarity violation. Given the group
theoretic restrictions endemic to non-commutative model building, we conclude
that it is difficult to build a non-commutative Standard Model under the
Weyl-Moyal approach that preserves unitarity.Comment: 31 page
Photon-axion conversion in intergalactic magnetic fields and cosmological consequences
Photon-axion conversion induced by intergalactic magnetic fields causes an
apparent dimming of distant sources, notably of cosmic standard candles such as
supernovae of type Ia (SNe Ia). We review the impact of this mechanism on the
luminosity-redshift relation of SNe Ia, on the dispersion of quasar spectra,
and on the spectrum of the cosmic microwave background. The original idea of
explaining the apparent dimming of distant SNe Ia without cosmic acceleration
is strongly constrained by these arguments. However, the cosmic equation of
state extracted from the SN Ia luminosity-redshift relation remains sensitive
to this mechanism. For example, it can mimic phantom energy.Comment: (14 pages, 9 eps figures) Contribution to appear in a volume of
Lecture Notes in Physics (Springer-Verlag) on Axion
Natural Theories of Ultra-Low Mass PNGB's: Axions and Quintessence
We consider the Wilson Line PNGB which arises in a U(1)^N gauge theory,
abstracted from a latticized, periodically compactified extra dimension U(1).
Planck scale breaking of the PNGB's global symmetry is suppressed, providing
natural candidates for the axion and quintessence. We construct an explicit
model in which the axion may be viewed as the 5th component of the U(1)_Y gauge
field in a 1+4 latticized periodically compactified extra dimension. We also
construct a quintessence PNGB model where the ultra-low mass arises from
Planck-scale suppressed physics itself.Comment: 20 pages, fixed typo and reference
Meditation-induced bliss viewed as release from conditioned neural (thought) patterns that block reward signals in the brain pleasure center
The nucleus accumbens orchestrates processes related to reward and pleasure,
including the addictive consequences of repeated reward (e.g., drug addiction and
compulsive gambling) and the accompanying feelings of craving and anhedonia.
The neurotransmitters dopamine and endogenous opiates play interactive roles in
these processes. They are released by natural rewards (i.e., food, water, sex, money,
play, etc.) and are released or mimicked by drugs of abuse. Repeated drug use
induces conditioned down-regulation of these neurotransmitters, thus causing
painful suppression of everyday pleasure. As with many spiritual traditions,
Buddhism provides strong advice against the pursuit of worldly pleasures to
attain the ‘‘good life.’’ In contrast, many forms of meditation give rise to an
immense and abiding joy. Most of these practices involve ‘‘stilling the mind,’’
whereby all content-laden thought (e.g., fantasies, daydreams, plans) ceases, and
the mind enters a state of openness, formlessness, clarity, and bliss. This can be
explained by the Buddhist suggestion that almost all of our everyday thoughts are
a form of addiction. It follows that if we turn off this internal ‘‘gossip of ego,’’ we
will find relief from the biochemical dopamine/opiate down-regulation, which is,
perhaps, the perpetual concomitant of our daily rumination
Unified dark energy models : a phenomenological approach
A phenomenological approach is proposed to the problem of universe
accelerated expansion and of the dark energy nature. A general class of models
is introduced whose energy density depends on the redshift in such a way
that a smooth transition among the three main phases of the universe evolution
(radiation era, matter domination, asymptotical de Sitter state) is naturally
achieved. We use the estimated age of the universe, the Hubble diagram of Type
Ia Supernovae and the angular size - redshift relation for compact and
ultracompact radio structures to test whether the model is in agreement with
astrophysical observation and to constrain its main parameters. Although
phenomenologically motivated, the model may be straightforwardly interpreted as
a two fluids scenario in which the quintessence is generated by a suitably
chosen scalar field potential. On the other hand, the same model may also be
read in the context of unified dark energy models or in the framework of
modified Friedmann equation theories.Comment: 12 pages, 10 figures, accepted for publication on Physical Review
Answering a Basic Objection to Bang/Crunch Holography
The current cosmic acceleration does not imply that our Universe is basically
de Sitter-like: in the first part of this work we argue that, by introducing
matter into *anti-de Sitter* spacetime in a natural way, one may be able to
account for the acceleration just as well. However, this leads to a Big Crunch,
and the Euclidean versions of Bang/Crunch cosmologies have [apparently]
disconnected conformal boundaries. As Maldacena and Maoz have recently
stressed, this seems to contradict the holographic principle. In the second
part we argue that this "double boundary problem" is a matter not of geometry
but rather of how one chooses a conformal compactification: if one chooses to
compactify in an unorthodox way, then the appearance of disconnectedness can be
regarded as a *coordinate effect*. With the kind of matter we have introduced
here, namely a Euclidean axion, the underlying compact Euclidean manifold has
an unexpectedly non-trivial topology: it is in fact one of the 75 possible
underlying manifolds of flat compact four-dimensional Euclidean spaces.Comment: 29 pages, 3 figures, added references and comparison with "cyclic"
cosmology, JHEP versio
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