841 research outputs found
Embedding of theories with SU(2|4) symmetry into the plane wave matrix model
We study theories with SU(2|4) symmetry, which include the plane wave matrix
model, 2+1 SYM on RxS^2 and N=4 SYM on RxS^3/Z_k. All these theories possess
many vacua. From Lin-Maldacena's method which gives the gravity dual of each
vacuum, it is predicted that the theory around each vacuum of 2+1 SYM on RxS^2
and N=4 SYM on RxS^3/Z_k is embedded in the plane wave matrix model. We show
this directly on the gauge theory side. We clearly reveal relationships among
the spherical harmonics on S^3, the monopole harmonics and the harmonics on
fuzzy spheres. We extend the compactification (the T-duality) in matrix models
a la Taylor to that on spheres.Comment: 56 pages, 6 figures, v2:a footnote and references added, section 5.2
improved, typos corrected, v3:typos corrected, v4: some equations are
corrected, eq.(G.2) is added, conclusion is unchange
Algal removal by alum coagulation
Includes bibliographical references.Enumeration continues through succeeding title."The removal of algae in natural waters by coagulation with liquid alum was investigated
in the laboratory using the jar test technique. Various amounts of alum (up to
40 mg/l) were added to water samples collected from the Illinois River at Peoria. Algal
enumerations as well as some pertinent chemical analyses were performed before and after
the process of coagulation and flocculation. The efficiency of algal removal was found to
be dependent upon alum dosage, initial algal concentrations, and the types, shapes, and
other specific characteristics of the algae. Optimum coagulant dosage for algal reduction
was found to be similar to that for turbidity removal. Results should be useful in defining
problems encountered in water treatment plants where algae are troublesome.
Electroweak Radiative Corrections to Parity-Violating Electroexcitation of the
We analyze the degree to which parity-violating (PV) electroexcitation of the
resonance may be used to extract the weak neutral axial vector
transition form factors. We find that the axial vector electroweak radiative
corrections are large and theoretically uncertain, thereby modifying the
nominal interpretation of the PV asymmetry in terms of the weak neutral form
factors. We also show that, in contrast to the situation for elastic electron
scattering, the axial PV asymmetry does not vanish at the photon
point as a consequence of a new term entering the radiative corrections. We
argue that an experimental determination of these radiative corrections would
be of interest for hadron structure theory, possibly shedding light on the
violation of Hara's theorem in weak, radiative hyperon decays.Comment: RevTex, 76 page
Small Chondral Defects Affect Tibiofemoral Contact Area and Stress: Should a Lower Threshold Be Used for Intervention?
Background:
Chondral defects in the knee have biomechanical differences because of defect size and location. Prior literature only compares the maximum stress experienced with large defects.
Hypothesis:
It was hypothesized that pressure surrounding the chondral defect would increase with size and vary in location, such that a size cutoff exists that suggests surgical intervention.
Study Design:
Controlled laboratory study.
Methods:
Isolated chondral defects from 0.09 to 1.0 cm2 were created on the medial and lateral femoral condyles of 6 human cadaveric knees. The knees were fixed to a uniaxial load frame and loaded from 0 to 600 N at full extension. Another defect was created at the point of tibiofemoral contact at 30° of flexion. Tibiofemoral contact pressures were measured. Peak contact pressure was the highest value in the area delimited within a 3-mm rim around the defect. The location of the peak contact pressure was determined.
Results:
At full extension, the mean maximum pressures on the medial femoral condyle ranged from 4.30 to 6.91 MPa at 0.09 and 1.0 cm2, respectively (P < .01). The location of the peak pressure was found posteromedial in defects between 0.09 and 0.25 cm2, shifting anterolaterally at sizes 0.49 and 1.0 cm2 (P < .01). The maximum pressures on the lateral femoral condyle ranged from 3.63 to 5.81 MPa at 0.09 and 1.0 cm2, respectively (P = .02). The location of the peak contact pressure point was anterolateral in defects between 0.09 and 0.25 cm2, shifting posterolaterally at 0.49 and 1.0 cm2 (P < .01). No differences in contact pressure between full extension and 30° of flexion were found for either the lateral or medial condyles.
Conclusion:
Full-thickness chondral defects bilaterally had a significant increase in contact pressure between defect sizes of 0.49 and 1.0 cm2. The location of the maximum contact pressures surrounding the lesion also varied with larger defects. Contact area redistribution and cartilage stress change may affect adjacent cartilage integrity.
Clinical Relevance:
Size cutoffs may exist earlier in the natural history of chondral defects than previously realized, suggesting a lower threshold for intervention
Surface and capillary transitions in an associating binary mixture model
We investigate the phase diagram of a two-component associating fluid mixture
in the presence of selectively adsorbing substrates. The mixture is
characterized by a bulk phase diagram which displays peculiar features such as
closed loops of immiscibility. The presence of the substrates may interfere the
physical mechanism involved in the appearance of these phase diagrams, leading
to an enhanced tendency to phase separate below the lower critical solution
point. Three different cases are considered: a planar solid surface in contact
with a bulk fluid, while the other two represent two models of porous systems,
namely a slit and an array on infinitely long parallel cylinders. We confirm
that surface transitions, as well as capillary transitions for a large
area/volume ratio, are stabilized in the one-phase region. Applicability of our
results to experiments reported in the literature is discussed.Comment: 12 two-column pages, 12 figures, accepted for publication in Physical
Review E; corrected versio
Emergency department visits for acute gastrointestinal illness after a major water pipe break in 2010
Background: When a water pipe breaks, contaminants can enter the drinking water system and cause waterborne illnesses such as acute gastrointestinal illness. In May 2010, a major water pipe broke near Boston, MA, and a boil water order was issued to nearly two million residents. Methods: Using a case-crossover study design, we examined the association between the water pipe break and subsequent emergency department visits for acute gastrointestinal illness. We identified cases of illness according to ICD-9-CM diagnosis codes and selected control dates 2 weeks before and after each case. We estimated the risk of visiting the emergency department during the 0-3 and 4-7 days after the water pipe break using conditional logistic regression models. Results: Our analysis included 5,726 emergency department visits for acute gastrointestinal illness from 3 April 2010 to 5 June 2010. Overall, there was a 1.3-fold increased odds for visiting the emergency department for acute gastrointestinal illness during the 0-3 days after the water pipe break (odds ratio [OR] = 1.3; 95% confidence interval [CI] = 1.1, 1.4) compared with referent dates selected 2 weeks before and after. During the 4-7 days after the break, the association diminished overall (OR = 1.1; 95% CI = 0.96, 1.2). However, in communities over 12 miles from the break, the 4- to 7-day association was elevated (OR = 1.4; 95% CI = 1.1, 1.8). Conclusions: This study suggests that a major water pipe break was associated with emergency department visits for acute gastrointestinal illness, particularly during the 0-3 days after the break, when a boil water order was in effect
Radio Bursts Associated with Flare and Ejecta in the 13 July 2004 Event
We investigate coronal transients associated with a GOES M6.7 class flare and
a coronal mass ejection (CME) on 13 July 2004. During the rising phase of the
flare, a filament eruption, loop expansion, a Moreton wave, and an ejecta were
observed. An EIT wave was detected later on. The main features in the radio
dynamic spectrum were a frequency-drifting continuum and two type II bursts.
Our analysis shows that if the first type II burst was formed in the low
corona, the burst heights and speed are close to the projected distances and
speed of the Moreton wave (a chromospheric shock wave signature). The
frequency-drifting radio continuum, starting above 1 GHz, was formed almost two
minutes prior to any shock features becoming visible, and a fast-expanding
piston (visible as the continuum) could have launched another shock wave. A
possible scenario is that a flare blast overtook the earlier transient, and
ignited the first type II burst. The second type II burst may have been formed
by the same shock, but only if the shock was propagating at a constant speed.
This interpretation also requires that the shock-producing regions were located
at different parts of the propagating structure, or that the shock was passing
through regions with highly different atmospheric densities. This complex
event, with a multitude of radio features and transients at other wavelengths,
presents evidence for both blast-wave-related and CME-related radio emissions.Comment: 14 pages, 6 figures; Solar Physics Topical Issue, in pres
Antiflow of kaons in relativistic heavy ion collisions
We compare relativistic transport model calculations to recent data on the
sideward flow of neutral strange K^0_s mesons for Au+Au collisions at 6 AGeV. A
soft nuclear equation of state is found to describe very well the positive
proton flow data measured in the same experiment. In the absence of kaon
potential, the K^0 flow pattern is similar to that of protons. The kaon flow
becomes negative if a repulsive kaon potential determined from the impulse
approximation is introduced. However, this potential underestimates the data
which exhibits larger antiflow. An excellent agreement with the data is
obtained when a relativistic scalar-vector kaon potential, that has stronger
density dependence, is used. We further find that the transverse momentum
dependence of directed and elliptic flow is quite sensitive to the kaon
potential in dense matter.Comment: 5 pages, Revtex, 4 figure
Testing a novel large-N reduction for N=4 super Yang-Mills theory on RxS^3
Recently a novel large-N reduction has been proposed as a maximally
supersymmetric regularization of N=4 super Yang-Mills theory on RxS^3 in the
planar limit. This proposal, if it works, will enable us to study the theory
non-perturbatively on a computer, and hence to test the AdS/CFT correspondence
analogously to the recent works on the D0-brane system. We provide a nontrivial
check of this proposal by performing explicit calculations in the large-N
reduced model, which is nothing but the so-called plane wave matrix model,
around a particular stable vacuum corresponding to RxS^3. At finite temperature
and at weak coupling, we reproduce precisely the deconfinement phase transition
in the N=4 super Yang-Mills theory on RxS^3. This phase transition is
considered to continue to the strongly coupled regime, where it corresponds to
the Hawking-Page transition on the AdS side. We also perform calculations
around other stable vacua, and reproduce the phase transition in super
Yang-Mills theory on the corresponding curved space-times such as RxS^3/Z_q and
RxS^2.Comment: 24 pages, 4 figure
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