399 research outputs found
Measuring fast electron spectra and laser absorption in relativistic laser-solid interactions using differential bremsstrahlung photon detectors
A photon detector suitable for the measurement of bremsstrahlung spectra
generated in relativistically-intense laser-solid interactions is described.
The Monte Carlo techniques used to back-out the fast electron spectrum and
laser energy absorbed into fast electrons are detailed. A
relativistically-intense laser-solid experiment using frequency doubled laser
light is used to demonstrate the effective operation of the detector. The
experimental data was interpreted using the 3-spatial-dimension Monte Carlo
code MCNPX (Pelowitz 2008), and the fast electron temperature found to be 125
keV
A pin in appendix within Amyand's hernia in a six-years-old boy: case report and review of literature
<p>Abstract</p> <p>Introduction</p> <p>Presence of vermiform appendix (non-inflamed or inflamed) in inguinal hernia is called Amyand's hernia in honor to surgeon C. Amyand who published the first case of perforated appendicitis within inguinal hernia in a boy caused by ingested pin. This presentation of foreign body Amyand's hernia appendicitis is very rare, and here we present such a case.</p> <p>Case presentation</p> <p>A 6-year-old boy, white Kosovar ethnicity, presented with right groin pain, swelling and redness. Two days before admission the patient was injured by football during a children game in the right lower abdomen and the next day he complained of pain in the right inguinal area.</p> <p>On admission patient had a painful non-reducible mass in the right inguinal region and cellulitis. Plain abdominal x-ray showed no fluid-air levels, but a metallic foreign body (pin) under right superior pubic ramus was apparent. With preoperative diagnosis of suspect incarcerated inguinal hernia with cellulitis the patient was operated on under general anaesthesia in December 2, 2006. Intraoperatively we found the inflamed vermiform appendix perforated by a pin in the hernial sac. Appendectomy and herniotomy were performed. The wound was primary closed, without any post-operative complications and follow up for the patient is three years long.</p> <p>Conclusion</p> <p>Foreign body (pin) Amyand's hernia appendicitis seems to be extremely rare, maybe once in a century (Amyand 1735, Hall 1886, and our case in 2006). In patients with clinical signs of incarcerated inguinal hernia, with locally inflammatory signs, but without signs of intestinal obstruction Amyand's hernia appendicitis in differential diagnosis must be considered. In our case, it is possible that the injury during the football game might have induced perforation of the vermiform appendix with the foreign body in it.</p
S-wave Meson-Meson Scattering from Unitarized U(3) Chiral Lagrangians
An investigation of the s-wave channels in meson-meson scattering is
performed within a U(3) chiral unitary approach. Our calculations are based on
a chiral effective Lagrangian which includes the eta' as an explicit degree of
freedom and incorporates important features of the underlying QCD Lagrangian
such as the axial U(1) anomaly. We employ a coupled channel Bethe-Salpeter
equation to generate poles from composed states of two pseudoscalar mesons. Our
results are compared with experimental phase shifts up to 1.5 GeV and effects
of the eta' within this scheme are discussed.Comment: 18 pages, 6 figure
Analyticity, Crossing Symmetry and the Limits of Chiral Perturbation Theory
The chiral Lagrangian for Goldstone boson scattering is a power series
expansion in numbers of derivatives. Each successive term is suppressed by
powers of a scale, , which must be less than of order where is the Goldstone boson decay constant and is the
number of flavors. The chiral expansion therefore breaks down at or below . We argue that the breakdown of the chiral expansion is
associated with the appearance of physical states other than Goldstone bosons.
Because of crossing symmetry, some ``isospin'' channels will deviate from their
low energy behavior well before they approach the scale at which their low
energy amplitudes would violate unitarity. We argue that the estimates of
``oblique'' corrections from technicolor obtained by scaling from QCD are
untrustworthy.Comment: harvmac, 18 pages (3 figures), HUTP-92/A025, BUHEP-92-18, new version
fixes a TeX problem in little mod
Another look at scattering in the scalar channel
We set up a general framework to describe scattering below 1 GeV
based on chiral low-energy expansion with possible spin-0 and 1 resonances.
Partial wave amplitudes are obtained with the method, which satisfy
unitarity, analyticity and approximate crossing symmetry. Comparison with the
phase shift data in the J=0 channel favors a scalar resonance near the
mass.Comment: 17 pages, 5 figures, REVTe
Existence of the -meson below 1 GeV and glueball
On the basis of a simultaneous description of the isoscalar s-wave channel of
the scattering (from the threshold up to 1.9 GeV) and of the
process (from the threshold to 1.4 GeV) in the
model-independent approach, a confirmation of the -meson at 665
MeV and an indication for the glueball nature of the state are
obtained. It is shown that the large -background, usually obtained,
combines, in reality, the influence of the left-hand branch-point and the
contribution of a very wide resonance at 665 MeV. The coupling constants
of the observed states with the and systems and lengths of
the and scattering are obtained.Comment: 13 pages, 3 figures, LaTex; submitted to Physics Letters
Fast electron transport and heating in solid-density matter
Two experiments have been performed to investigate heating
by high-intensity laser-generated electrons, in the context of
studies of the fast ignitor approach to inertial confinement fusion
(ICF). A new spectrometer and layered targets have been used to detect
Kα emission from aluminum heated by a fast electron beam.
Results show that a temperature of about 40 eV is reached in solid
density aluminum up to a depth of about 100 μm
scattering in the -meson channel at finite temperature
We study scattering in the I=1, channel at finite
temperature in the framework of the extended Nambu-Jona-Lasinio model that
explicitly includes vector and axial-vector degrees of freedom in addition to
the usual scalar and pseudoscalar sector. The S-matrix in the coupled channels
and is constructed via -exchange in the -channel.
The self-energy of the -meson contains both quark and pion loop
contributions. The analytic structure of the S-matrix for is
investigated and the motion of the -pole as a function of coupling
constant and temperature is followed in the complex -plane. For
numerical calculations, parameters are chosen in order that ,
and the experimental phase shifts at zero temperature are
reproduced, and then the behavior of the -pole as well as the
cross section is investigated as a function of the temperature. We find that
the position of the mass stays practically constant for MeV, and then moves down in energy by about 200 MeV for 130 MeV MeV.Comment: 25 pages, 12 figures, to appear in Nucl. Phys.
An unusual location of retroperitoneal epidermoid cyst in a child: case report and a review of the literature
We report the case of a 4-year-old girl presenting with the retroperitoneal epidermoid cyst. The lesion presented as an intra-abdominal cyst on physical examination and was followed up with more specific investigations by ultrasound and computed tomographic scanning. The final diagnosis was obtained only after laparotomy where the cystic mass was completely excised and pathological examination was done. The patient is well at 3-year follow-up. epidermoid cyst of the reteroperitoneal space, although rare, should be considered in the differential diagnosis of incidentally discovered intra-abdominal cysts during investigation of irrelevant illnesses or during routine abdominal ultrasound scan
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