44,240 research outputs found
Midline (dermoid) cysts of the floor of the mouth: report of 16 cases and review of surgical techniques.
EXPERIMENTS DURING FLOW BOILING OF A R22 DROP-IN: R422D ADIABATIC PRESSURE GRADIENTS
R22, the HCFC most widely used in refrigeration and air-conditioning systems in the last years, is phasing-out. R422D, a zero ozone-depleting mixture of R125, R134a and R600a (65.1%/31.5%/3.4% by weight, respectively), has been recently proposed as a drop-in substitute. For energy consumption calculations and temperature control, it is of primary importance to estimate operating conditions after substitution. To determine pressure drop in the evaporator and piping line to the compressor, in this paper the experimental adiabatic pressure gradients during flow boiling of R422D are reported for a circular smooth horizontal tube (3.00 mm inner radius) in a range of operating conditions of interest for dry-expansion evaporators.
The data are used to establish the best predictive method for calculations and its accuracy: the Moreno-Quibèn and Thome method provided the best predictions for the whole database and also for the segregated data in the annular flow regime.
Finally, the experimental data have been compared with the adiabatic pressure gradients of both R22 and its much used alternative R407C available in the literature
Carbon Dioxide Heat Transfer Coefficients And Pressure Drops During Flow Boiling: Assessment Of Predictive Methods
Among the alternatives to the HCFCs and HFCs, carbon dioxide emerged as one of the most promising environmentally friendly refrigerants. In past years many works were carried out about CO2 flow boiling and very different two-phase flow characteristics from conventional fluids were found.
In order to assess the best predictive methods for the evaluation of CO2 heat transfer coefficients and pressure gradients in macro-channels, in the current article a literature survey of works and a collection of the results of statistical comparisons available in literature are furnished.
In addition the experimental data from University of Naples are used to run a deeper analysis. Both a statistical and a direct comparison against some of the most quoted predictive methods are carried out. Methods implemented both for low–medium pressure refrigerants and specifically developed for R744 are used in the comparison.
Some general indications about the choice of the predictive methods dependently on the operating conditions are given
Lacunary generating functions of Hermite polynomials and symbolic methods
We employ an umbral formalism to reformulate the theory of Hermite polynomials and the derivation of the associated lacunary generating functions
Telephone-cord instabilities in thin smectic capillaries
Telephone-cord patterns have been recently observed in smectic liquid crystal
capillaries. In this paper we analyse the effects that may induce them. As long
as the capillary keeps its linear shape, we show that a nonzero chiral
cholesteric pitch favors the SmA*-SmC* transition. However, neither the
cholesteric pitch nor the presence of an intrinsic bending stress are able to
give rise to a curved capillary shape.
The key ingredient for the telephone-cord instability is spontaneous
polarization. The free energy minimizer of a spontaneously polarized SmA* is
attained on a planar capillary, characterized by a nonzero curvature. More
interestingly, in the SmC* phase the combined effect of the molecular tilt and
the spontaneous polarization pushes towards a helicoidal capillary shape, with
nonzero curvature and torsion.Comment: Submitte
Primordial Gravitational Waves Enhancement
We reconsider the enhancement of primordial gravitational waves that arises
from a quantum gravitational model of inflation. A distinctive feature of this
model is that the end of inflation witnesses a brief phase during which the
Hubble parameter oscillates in sign, changing the usual Hubble friction to
anti-friction. An earlier analysis of this model was based on numerically
evolving the graviton mode functions after guessing their initial conditions
near the end of inflation. The current study is based on an equation which
directly evolves the normalized square of the magnitude. We are also able to
make a very reliable estimate for the initial condition using a rapidly
converging expansion for the sub-horizon regime. Results are obtained for the
energy density per logarithmic wave number as a fraction of the critical
density. These results exhibit how the enhanced signal depends upon the number
of oscillatory periods; they also show the resonant effects associated with
particular wave numbers.Comment: 25 pages, 14 figure
Intensity correlations, entanglement properties and ghost imaging in multimode thermal-seeded parametric downconversion: Theory
We address parametric-downconversion seeded by multimode pseudo-thermal
fields. We show that this process may be used to generate multimode pairwise
correlated states with entanglement properties that can be tuned by controlling
the seed intensities. Multimode pseudo-thermal fields seeded
parametric-downconversion represents a novel source of correlated states, which
allows one to explore the classical-quantum transition in pairwise correlations
and to realize ghost imaging and ghost diffraction in regimes not yet explored
by experiments.Comment: 9 pages, 3 figure
The Brera Multi-scale Wavelet (BMW) ROSAT HRI source catalog. II: application to the HRI and first results
The wavelet detection algorithm (WDA) described in the accompanying paper by
Lazzati et al. is made suited for a fast and efficient analysis of images taken
with the High Resolution Imager (HRI) instrument on board the ROSAT satellite.
An extensive testing is carried out on the detection pipeline: HRI fields with
different exposure times are simulated and analysed in the same fashion as the
real data. Positions are recovered with few arcsecond errors, whereas fluxes
are within a factor of two from their input values in more than 90% of the
cases in the deepest images. At variance with the ``sliding-box'' detection
algorithms, the WDA provides also a reliable description of the source
extension, allowing for a complete search of e.g. supernova remnant or cluster
of galaxies in the HRI fields. A completeness analysis on simulated fields
shows that for the deepest exposures considered (~120 ks) a limiting flux of
\~3x10^{-15} erg/cm2/s can be reached over the entire field of view. We test
the algorithm on real HRI fields selected for their crowding and/or presence of
extended or bright sources (e.g. cluster of galaxies and of stars, supernova
remnants). We show that our algorithm compares favorably with other X-ray
detection algorithms such as XIMAGE and EXSAS. A complete catalog will result
from our analysis: it will consist of the Brera Multi-scale Wavelet Bright
Source Catalog (BMW-BSC) with sources detected with a significance >4.5 sigma
and of the Faint Source Catalog (BMW-FSC) with sources at >3.5 sigma. A
conservative estimate based on the extragalactic log(N)-log(S) indicates that
at least 16000 sources will be revealed in the complete analysis of the whole
HRI dataset.Comment: 6 pages, 11 PostScript figures, 1 gif figure, ApJ in pres
Preliminary study on electrophysiological changes after cellular autograft in age-related macular degeneration
Background: Evolving atrophic macular degeneration represents at least 80% of all macular degenerations and is currently without a standardized care. Autologous fat transplantation (AFT) efficacy was demonstrated by several studies, since these cells are able to produce growth factors. The aim of the work was to demonstrate possible therapeutic effect of the joined suprachoroidal graft of adipocytes, adipose derived stem-cells (ADSCs) in tissue adipose’s stromal vascular fractions (SVF), and platelet rich plasma (PRP).
Methods: Twelve eyes in 12 dry age macular degeneration (AMD) patients, aged 71.25 (SD ± 6.8) between 62 and 80 years, were analyzed. A complete ocular evaluation was performed using: best corrected visual acuity (BCVA), retinographic analysis, spectral-domain optical coherence tomography, microperimetry, computerized visual field, and standard electroretinogram (ERG). Each eye received a cell in graft between choroid and sclera by means of the variant second Limoli, grafting of mature fat cells and ADSCs in SVF enriched with PRP (LRRT). In order to test if the differences pre- and post-treatment were significant the Wilcoxon signed rank test has been performed.
Results: Adverse effects were not reported in the patients. After surgery with LRRT the most significant increase in the ERG values was recorded by scotopic rod-ERG (answer coming from the rods), from 41.26 to 60.83 μVolts (µV) with an average increase of 47.44% highly significant (p<0.05). Moderately significant was the one recorded by scotopic maximal ERG (answer coming from the rods and cones), from 112.22 to 129.68 μV with an average increase of 15.56% (p<0.1).
Conclusions: Cell-mediated therapy based on growth factors used appears interesting because it can improve the retinal functionality responses in the short term. The ERG could, therefore, be used to monitor the effect of cell-mediated regenerative therapies
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