922 research outputs found
TBP STRIPPING IN BUBBLE-CAP COLUMN AND CON-COMITANT PRODUCT EVAPORATION
A study was conducted to demonstrate the stripping and evaporation steps in a Purex-type uranium recovery prccess and to ascertain the operating behavior of the equipment under a range of conditions. The factors considered were control, effectiveness, and reliability of equipment and optimum feed pcint. Experimental procedures are described, and recominendations for equipment mcdifications are included. (J.R.D.
Generating Neutrino Mass in the 331 Model
A mechanism for generating small tree-level Majorana mass for neutrinos is
implemented in the 331 Model. No additional fermions or scalars need to be
added, and no mass scale greater than a few TeV is invoked.Comment: LaTex, 7 pages, no figures. Revised version to appear in Phys. Rev.
Direct composition profiling in III-V nanostructures by cross-sectional STM
Using cross-sectional STM we have studied the local composition in III–V nanostructures such as GaAs/InGaAs quantum wells, InGaNAs/InP quantum wells and quantum dots, and InAs/GaAs self-assembled quantum dots. We are able to determine the local composition by either simply counting the constituent atoms, measuring the local lattice constant or measuring the relaxation of the cleaved surface due to the elastic field of the buried strained nanostructures
A Systematic Search for Supersoft X-Ray Sources in the ROSAT All-Sky Survey
We have conducted a systematic search for supersoft X-ray sources using the
ROSAT all-sky survey data. With the optical identification of the selected
sources being almost complete, we discuss the statistics of the various source
classes and their observability. Besides supersoft close binary sources this
search also can be used to estimate the number of isolated neutron stars in the
Galaxy, such as those described by Stocke et al. 1995 and Walter et al. 1996.Comment: 4 pages postscript, Proc. of Workshop on Supersoft X-Ray Sources, to
appear in Lecture Notes in Physics vol. 472 (1996
Two-body decays in the minimal 331 model
The two-body decays of the extra neutral boson Z_2 predicted by the minimal
331 model are analyzed. At the three-level it can decay into standard model
particles as well as exotic quarks and the new gauge bosons predicted by the
model. The decays into a lepton pair are strongly suppressed, with and . In the bosonic
sector, Z_2 would decay mainly into a pair of bilepton gauge bosons, with a
branching ratio below the 0.1 level. The Z_2 boson has thus a leptophobic and
bileptophobic nature and it would decay dominantly into quark pairs. The
anomaly-induced decays and , which occurs
at the one-loop level are studied. It is found that and at most. As for the and decays, with H a relatively light Higgs boson, they
are induced via Z'-Z mixing. It is obtained that
and . We also examine the flavor changing neutral
current decays and , which may have branching
fractions as large as and , respectively, and thus may be of
phenomenological interest.Comment: 14 pages, 3 figures, submitted to Physical Review
Does routine uniportal thoracoscopy during rib fixation identify more injuries and impact outcomes?
Background: Flail chest and severely displaced rib fractures due to blunt trauma can be associated with intrathoracic injuries. At our institution, two thoracic surgeons perform all surgical stabilization of rib fractures (SSRF): one performs routine uniportal thoracoscopy (R-VATS) at the time of SSRF and the other for only select cases (S-VATS). In this pilot study, we hypothesized that R-VATS at the time of SSRF identifies and addresses intrathoracic injuries not seen on imaging and may impact patient outcomes. Methods: A retrospective review of all patients who underwent SSRF from 2013-2019 at our institution was performed for severely displaced rib fractures or flail chest. Data collected included demographics, imaging results, treatment strategy, and operative findings. Results: Ninety-nine patients underwent SSRF. Uniportal thoracoscopy was performed on 69% of these patients. When thoracoscopy was performed, 31 additional injuries were identified. R-VATS identified 23 additional intrathoracic findings at time of thoracoscopy not seen on CT scan compared to 8 findings in the S-VATS group (P=0.367). At 3 months follow-up, one empyema and one diaphragmatic hernia required reoperation-neither of which underwent thoracoscopy at time of SSRF. There were no differences in LOS, operative times, and overall mortality between the SSRF/thoracoscopy and SSRF only groups. Conclusions: R-VATS at the time of SSRF did not identify a statistically significant greater number of occult intrathoracic injuries compared to S-VATS. R-VATS was not associated with increased operative time, LOS, and mortality. Further study is needed to determine if there is benefit to R-VATS in patients meeting requirements for rib fracture repair
Novel Mutations in PTH1R Associated with Primary Failure of Eruption and Osteoarthritis
Autosomal dominant mutations in PTH1R segregate with primary failure of eruption (PFE), marked by clinical eruption failure of adult teeth without mechanical obstruction. While the diagnosis of PFE conveys a poor dental prognosis, there are no reports of PFE patients who carry PTH1R mutations and exhibit any other skeletal problems. We performed polymerase chain reaction–based mutational analysis of the PTH1R gene to determine the genetic contribution of PTH1R in 10 families with PFE. Sequence analysis of the coding regions and intron-exon boundaries of the PTH1R gene in 10 families (n = 54) and 7 isolated individuals revealed 2 novel autosomal dominant mutations in PTH1R (c.996_997insC and C.572delA) that occur in the coding region and result in a truncated protein. One family showed incomplete penetrance. Of 10 families diagnosed with PFE, 8 did not reveal functional (nonsynonymous) mutations in PTH1R; furthermore, 4 families and 1 sporadic case carried synonymous single-nucleotide polymorphisms. Five PFE patients in 2 families carried PTH1R mutations and presented with osteoarthritis. We propose that the autosomal dominant mutations of PTH1R that cause PFE may also be associated with osteoarthritis; a dose-dependent model may explain isolated PFE and osteoarthritis in the absence of other known symptoms in the skeletal system
Discrete symmetries, invisible axion and lepton number symmetry in an economic 3-3-1 model
We show that Peccei-Quinn and lepton number symmetries can be a natural
outcome in a 3-3-1 model with right-handed neutrinos after imposing a Z_11 x
Z_2 symmetry. This symmetry is suitably accommodated in this model when we
augmented its spectrum by including merely one singlet scalar field. We work
out the breaking of the Peccei-Quinn symmetry, yielding the axion, and study
the phenomenological consequences. The main result of this work is that the
solution to the strong CP problem can be implemented in a natural way, implying
an invisible axion phenomenologically unconstrained, free of domain wall
formation and constituting a good candidate for the cold dark matter.Comment: 17 pages, Revtex
Simulating (electro)hydrodynamic effects in colloidal dispersions: smoothed profile method
Previously, we have proposed a direct simulation scheme for colloidal
dispersions in a Newtonian solvent [Phys.Rev.E 71,036707 (2005)]. An improved
formulation called the ``Smoothed Profile (SP) method'' is presented here in
which simultaneous time-marching is used for the host fluid and colloids. The
SP method is a direct numerical simulation of particulate flows and provides a
coupling scheme between the continuum fluid dynamics and rigid-body dynamics
through utilization of a smoothed profile for the colloidal particles.
Moreover, the improved formulation includes an extension to incorporate
multi-component fluids, allowing systems such as charged colloids in
electrolyte solutions to be studied. The dynamics of the colloidal dispersions
are solved with the same computational cost as required for solving
non-particulate flows. Numerical results which assess the hydrodynamic
interactions of colloidal dispersions are presented to validate the SP method.
The SP method is not restricted to particular constitutive models of the host
fluids and can hence be applied to colloidal dispersions in complex fluids
On the Nature and Genesis of EUV Waves: A Synthesis of Observations from SOHO, STEREO, SDO, and Hinode
A major, albeit serendipitous, discovery of the SOlar and Heliospheric
Observatory mission was the observation by the Extreme Ultraviolet Telescope
(EIT) of large-scale Extreme Ultraviolet (EUV) intensity fronts propagating
over a significant fraction of the Sun's surface. These so-called EIT or EUV
waves are associated with eruptive phenomena and have been studied intensely.
However, their wave nature has been challenged by non-wave (or pseudo-wave)
interpretations and the subject remains under debate. A string of recent solar
missions has provided a wealth of detailed EUV observations of these waves
bringing us closer to resolving their nature. With this review, we gather the
current state-of-art knowledge in the field and synthesize it into a picture of
an EUV wave driven by the lateral expansion of the CME. This picture can
account for both wave and pseudo-wave interpretations of the observations, thus
resolving the controversy over the nature of EUV waves to a large degree but
not completely. We close with a discussion of several remaining open questions
in the field of EUV waves research.Comment: Solar Physics, Special Issue "The Sun in 360",2012, accepted for
publicatio
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