2,165 research outputs found
Controllable spin-current blockade in a Hubbard chain
We investigate the spin/charge transport in a one-dimensional strongly
correlated system by using the adaptive time-dependent density-matrix
renormalization group method. The model we consider is a non-half-filled
Hubbard chain with a bond of controllable spin-dependent electron hoppings,
which is found to cause a blockade of spin current with little influence on
charge current. We have considered (1) the spread of a wave packet of both spin
and charge in the Hubbard chain and (2) the spin and charge currents induced by
a spin-dependent voltage bias that is applied to the ideal leads attached at
the ends of this Hubbard chain. It is found that the spin-charge separation
plays a crucial role in the spin-current blockade, and one may utilize this
phenomenon to observe the spin-charge separation directly.Comment: 5 pages, 5 figure
Generating nonclassical correlations without fully aligning measurements
We investigate the scenario where spatially separated parties perform
measurements in randomly chosen bases on an N-partite
Greenberger-Horne-Zeilinger state. We show that without any alignment of the
measurements, the observers will obtain correlations that violate a Bell
inequality with a probability that rapidly approaches 1 as N increases and that
this probability is robust against noise. We also prove that restricting these
randomly chosen measurements to a plane perpendicular to a common direction
will always generate correlations that violate some Bell inequality.
Specifically, if each observer chooses their two measurements to be locally
orthogonal, then the N observers will violate one of two Bell inequalities by
an amount that increases exponentially with N. These results are also robust
against noise and perturbations of each observer's reference direction from the
common direction.Comment: v2: Essentially published version (with typos fixed, results updated
in Table 2 and Figure 4 replaced); v1: 16 pages, 5 figures, 2 tables,
comments welcom
The F-Landscape: Dynamically Determining the Multiverse
We evolve our Multiverse Blueprints to characterize our local neighborhood of
the String Landscape and the Multiverse of plausible string, M- and F-theory
vacua. Building upon the tripodal foundations of i) the Flipped SU(5) Grand
Unified Theory (GUT), ii) extra TeV-Scale vector-like multiplets derived out of
F-theory, and iii) the dynamics of No-Scale Supergravity, together dubbed
No-Scale F-SU(5), we demonstrate the existence of a continuous family of
solutions which might adeptly describe the dynamics of distinctive universes.
This Multiverse landscape of F-SU(5) solutions, which we shall refer to as the
F-Landscape, accommodates a subset of universes compatible with the presently
known experimental uncertainties of our own universe. We show that by
secondarily minimizing the minimum of the scalar Higgs potential of each
solution within the F-Landscape, a continuous hypervolume of distinct minimum
minimorum can be engineered which comprise a regional dominion of universes,
with our own universe cast as the bellwether. We conjecture that an
experimental signal at the LHC of the No-Scale F-SU(5) framework's
applicability to our own universe might sensibly be extrapolated as
corroborating evidence for the role of string, M- and F-theory as a master
theory of the Multiverse, with No-Scale supergravity as a crucial and pervasive
reinforcing structure.Comment: 15 Pages, 7 Figures, 1 Tabl
CO in Protostars (COPS): -SPIRE Spectroscopy of Embedded Protostars
We present full spectral scans from 200-670m of 26 Class 0+I
protostellar sources, obtained with -SPIRE, as part of the
"COPS-SPIRE" Open Time program, complementary to the DIGIT and WISH Key
programs. Based on our nearly continuous, line-free spectra from 200-670
m, the calculated bolometric luminosities () increase by 50%
on average, and the bolometric temperatures () decrease by 10% on
average, in comparison with the measurements without Herschel. Fifteen
protostars have the same Class using and /. We identify rotational transitions of CO lines from J=4-3 to J=13-12,
along with emission lines of CO, HCO, HO, and [CI]. The ratios
of CO to CO indicate that CO emission remains optically
thick for < 13. We fit up to four components of temperature from
the rotational diagram with flexible break points to separate the components.
The distribution of rotational temperatures shows a primary population around
100 K with a secondary population at 350 K. We quantify the correlations
of each line pair found in our dataset, and find the strength of correlation of
CO lines decreases as the difference between -level between two CO lines
increases. The multiple origins of CO emission previously revealed by
velocity-resolved profiles are consistent with this smooth distribution if each
physical component contributes to a wide range of CO lines with significant
overlap in the CO ladder. We investigate the spatial extent of CO emission and
find that the morphology is more centrally peaked and less bipolar at high-
lines. We find the CO emission observed with SPIRE related to outflows, which
consists two components, the entrained gas and shocked gas, as revealed by our
rotational diagram analysis as well as the studies with velocity-resolved CO
emission.Comment: 50 pages, 18 figures, accepted to ApJS. Revised for Table 6 and
Figure
The Golden Strip of Correlated Top Quark, Gaugino, and Vectorlike Mass In No-Scale, No-Parameter F-SU(5)
We systematically establish the hyper-surface within the tan(beta), top quark
mass m_t, universal gaugino mass M_1/2, and vectorlike mass M_V parameter
volume which is compatible with the application of the No-Scale Supergravity
boundary conditions, particularly the vanishing of the Higgs bilinear soft term
B_mu, near to the Planck mass at the point M_F of ultimate F-lipped SU(5)
unification. M_F is elevated from the penultimate partial unification near the
traditional GUT scale at a mass M_32 by the inclusion of extra F-theory derived
heavy vectorlike multiplets. We demonstrate that simultaneous adherence to all
current experimental constraints, most importantly contributions to the muon
anomalous magnetic moment (g-2)_mu, the branching ratio limit on (b \to s
gamma), and the 7-year WMAP relic density measurement, dramatically reduces the
allowed solutions to a highly non-trivial "golden strip" with tan(beta) \sim
15, m_t = 173.0-174.4 GeV, M_1/2 = 455-481 GeV, and M_V = 691-1020 GeV,
effectively eliminating all extraneously tunable model parameters. We emphasize
that the consonance of the theoretically viable m_t range with the
experimentally established value is an independently correlated "postdiction".
The predicted range of M_V is testable at the Large Hadron Collider (LHC). The
partial lifetime for proton decay in the leading (e+|mu+) pi0 channels falls
around 4.6 X 10^34 Y, testable at the future DUSEL and Hyper-Kamiokande
facilities.Comment: V2, As accepted for publication in Physics Letters B; 7 pages, 3
figure
Tracheotomy care simulation training program for inpatient providers
Objectives: Tracheotomy complications can be life-threatening. Many of these complications may be avoided with proper education of health care providers. Unfortunately, access to high-quality tracheotomy care curricula is limited. We developed a program to address this gap in tracheotomy care education for inpatient providers. This study aimed to assess the efficacy of this training program in improving trainee knowledge and comfort with tracheotomy care.
Methods: The curriculum includes asynchronous online modules coupled with a self-directed hands-on simulation activity using a low-cost tracheotomy care task trainer. The program was offered to inpatient providers including medical students, residents, medical assistants, nurses, and respiratory therapists. Efficacy of the training was assessed using pre-training and post-training surveys of learner comfort, knowledge, and qualitative feedback.
Results: Data was collected on 41 participants. After completing the program, participants exhibited significantly improved comfort in performing tracheotomy care activities and 15% improvement in knowledge scores, with large effect sizes respectively and greater gains among those with little prior tracheotomy care experience.
Conclusion: This study has demonstrated that completion of this integrated online and hands-on tracheotomy simulation curriculum training increases comfort and knowledge, especially for less-experienced learners. This training addresses an important gap in tracheotomy care education among health care professionals with low levels of tracheotomy care experience and ultimately aims to improve patient safety and quality of care. This curriculum is easily transferrable as it requires only access to the online modules and low-cost simulation materials and could be used in other hospitals, long-term care facilities, outpatient clinics, and home settings
The Mid-infrared Evolution of the FU Orionis Disk
We present new SOFIA-FORCAST observations obtained in 2016 February of the archetypal outbursting low-mass young stellar object FU Orionis, and we compare the continuum, solid-state, and gas properties with mid-infrared data obtained at the same wavelengths in 2004 with Spitzer-IRS. In this study, we conduct the first mid-infrared spectroscopic comparison of an FUor over a long time period. Over a 12-year period, UBVR monitoring indicates that FU Orionis has continued its steady decrease in overall brightness by ~14%. We find that this decrease in luminosity occurs only at wavelengths ≾20 μm. In particular, the continuum shortward of the silicate emission complex at 10 μm exhibits a ~12% (~3σ) drop in flux density but no apparent change in slope; both the Spitzer and SOFIA spectra are consistent with a 7200 K blackbody. Additionally, the detection of water absorption is consistent with the Spitzer spectrum. The silicate emission feature at 10 μm continues to be consistent with unprocessed grains, unchanged over 12 years. We conclude that either the accretion rate in FU Orionis has decreased by ~12–14% over this time baseline or the inner disk has cooled, but the accretion disk remains in a superheated state outside the innermost region
A Higgs Mass Shift to 125 GeV and A Multi-Jet Supersymmetry Signal: Miracle of the Flippons at the \sqrt{s} = 7 TeV LHC
We describe a model named No-Scale F-SU(5) which is simultaneously capable of
explaining the dual signals emerging at the LHC of i) a 124-126 GeV Higgs boson
mass m_h, and ii) tantalizing low-statistics excesses in the multi-jet data
which may attributable to supersymmetry. These targets tend to be mutually
exclusive in more conventional approaches. The unified mechanism responsible
for both effects is the introduction of a rather unique set of vector-like
multiplets at the TeV scale, dubbed flippons, which i) can elevate m_h by
around 3-4 GeV via radiative loop corrections, and ii) flatten the running of
the strong coupling and color-charged gaugino, resulting in a prominent
collider signal from production of light gluino pairs. This well motivated
theoretical framework maintains consistency with all key phenomenological
constraints, and all residual parameterization freedom may in principle be
fixed by a combination of the two experiments described. We project that the
already collected luminosity of 5 fb^-1 may be sufficient to definitively
establish the status of this model, given appropriate data selection cuts.Comment: Physics Letters B version, 10 pages, 3 figures, 2 tables. arXiv admin
note: text overlap with arXiv:1105.398
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