338 research outputs found
Single decay-lepton angular distributions in polarized e+e- --> t tbar and simple angular asymmetries as a measure of CP-violating top dipole couplings
In the presence of an electric dipole coupling of t-tbar to a photon, and an
analogous "weak" dipole coupling to the Z, CP violation in the process e+e- -->
t tbar results in modified polarization of the top and anti-top. This
polarization can be analyzed by studying the angular distributions of decay
charged leptons when the top or anti-top decays leptonically. Analytic
expressions are presented for these distributions when either t or tbar decays
leptonically, including O(alpha_s) QCD corrections in the soft-gluon
approximation. The angular distributions are insensitive to anomalous
interactions in top decay. Two types of simple CP-violating polar-angle
asymmetries and two azimuthal asymmetries, which do not need the full
reconstruction of the t or tbar, are studied. Independent 90% CL limits that
may be obtained on the real and imaginary parts of the electric and weak dipole
couplings at a linear collider operating at sqrt{s}=500 GeV with integrated
luminosity 500 fb^{-1} and also at sqrt{s}=1000 GeV with integrated luminosity
1000 fb^{-1} have been evaluated. The effect of longitudinal electron and/or
positron beam polarizations has been included.Comment: 26 pages, latex, figures included as latex files, version appearing
in Pramana - Journal of Physics, minor corrections and note added in proo
Rescue of stranded Hawksbill turtle in Kollam, Kerala
On 27th March, 2019, fisher folks of Kakkathoppu, a coastal area of Kollam district in Kerala, India, found a Hawksbill turtle (Eretmochelys imbricata), stranded in the rocky seashore (Fig1). The turtle was live female that weighed approximately 50 kg having a carapace length of 48 cm. According to the local fishermen, the turtle was unable to swim back to sea due to ruptured carapace and fatigued condition. On primary evaluation, barnacles were observed to be covering a part of its body and the carapace as well as head region were found exposed to sunburn
Probing Top-Quark Couplings at Polarized NLC
The energy spectrum of the lepton(s) in e^+e^- --> tt-bar --> l^{+-}
...../l^+l^-..... at next linear colliders (NLC) is studied for arbitrary
longitudinal beam polarizations as a possible test of new physics in top-quark
couplings. The most general non-standard couplings for gamma-tt-bar, Ztt-bar
and Wtb vertices are considered. Expected precision of the
non-standard-parameter determination is estimated applying the
optimal-observable procedure.Comment: Final version, To appear in Phys. Rev.
Post-melting encapsulation of glass microwires for multipath light waveguiding within phosphate glasses
Glass waveguides remain the fundamental component of advanced photonic
circuits and with a significant role in other applications such as quantum
information processing, light generation, imaging, data storage, and sensing
platforms. Up to date, the fabrication of glass waveguides relies mainly on
demanding chemical processes or on the employment of expensive ultrafast laser
equipment. In this work, we demonstrate the feasibility of a simple,
low-temperature, post-melting encapsulation procedure for the development of
advanced glass waveguides. Namely, silver iodide phosphate glass microwires
(MWs) are drawn from typical splat-quenched samples. Following this, the MWs
are incorporated in a controlled manner within previously prepared transparent
silver phosphate glass rectangular prisms. The composition of the employed
glasses is chosen so that the host phosphate glass has a lower refractive index
than the embedded MWs. In such case, the waveguide mechanism relies on the
propagation of light inside the encapsulated higher refractive index MWs.
Moreover, the presence of silver nanoparticles within the MWs enhances the
light transmission due to scattering effects. Waveguide devices with either one
or two incorporated MWs were fabricated. Remarkably, in the latter case, the
transmission of light of different colors and in multipath direction is
possible, rendering the developed waveguides outstanding candidates for various
photonic circuits, optoelectronic, and smart sign glass applications
Huge Giant manta ray landed
A Giant manta ray, Mobula birostris locally known as “Aana Thirandi ” weighing around 900 kg was landed at Neendakara Fishing Harbour on 14th April 2023
QCD corrections to decay-lepton polar and azimuthal angular distributions in e+e- -> t tbar in the soft-gluon approximation
QCD corrections to order alpha_s in the soft-gluon approximation to angular
distributions of decay charged leptons in the process e+e- -> t tbar followed
by semileptonic decay of t or tbar, are obtained in the e+e- centre-of-mass
frame. As compared to distributions in the top rest frame, these have the
advantage that they would allow direct comparison with experiment without the
need to reconstruct the top rest frame. The results also do not depend on the
choice of a spin quantization axis for t or tbar. Analytic expression for the
triple distribution in the polar angle of t and polar and azimuthal angles of
the lepton is obtained. Analytic expression is also derived for the
distribution in the charged-lepton polar angle. Numerical values are discussed
for total c.m. energies of 400 GeV, 800 GeV and 1500 GeV.Comment: 21 pages, Latex, 6 figures included in the submission. To appear in
Pramana - Journal of Physics; expanded version of hep-ph/0011321, v
Rare occurrence of cirrate octopod Opisthoteuthis sp.
A single specimen of cirrate octopod
Opisthoteuthis sp. was collected from
Sakthikulangara Fisheries Harbour in
Kollam district on 12th April 2022
(Fig.1). It was a by-catch in a bottom
trawl operated at a depth of 200m.
Three species of Opisthoteuthis are
currently known to occur in the
Indian Ocean. These are O. phillipi,
O
Multicenter, Prospective, Longitudinal Study of the Recurrence, Surgical Site Infection, and Quality of Life After Contaminated Ventral Hernia Repair Using Biosynthetic Absorbable Mesh: The COBRA Study
OBJECTIVE:
The aim of the study was to evaluate biosynthetic absorbable mesh in single-staged contaminated (Centers for Disease Control class II and III) ventral hernia (CVH) repair over 24 months.
BACKGROUND:
CVH has an increased risk of postoperative infection. CVH repair with synthetic or biologic meshes has reported chronic biomaterial infections and high hernia recurrence rates.
METHODS:
Patients with a contaminated or clean-contaminated operative field and a hernia defect at least 9 cm had a biosynthetic mesh (open, sublay, retrorectus, or intraperitoneal) repair with fascial closure (n = 104). Endpoints included overall Kaplan-Meier estimates for hernia recurrence and postoperative wound infection rates at 24 months, and the EQ-5D and Short Form 12 Health Survey (SF-12). Analyses were conducted on the intent-to-treat population, and health outcome measures evaluated using paired t tests.
RESULTS:
Patients had a mean age of 58 years, body mass index of 28 kg/m, 77% had contaminated wounds, and 84% completed 24-months follow-up. Concomitant procedures included fistula takedown (n = 24) or removal of infected previously placed mesh (n = 29). Hernia recurrence rate was 17% (n = 16). At the time of CVH repair, intraperitoneal placement of the biosynthetic mesh significantly increased the risk of recurrences (P ≤ 0.04). Surgical site infections (19/104) led to higher risk of recurrence (P < 0.01). Mean 24-month EQ-5D (index and visual analogue) and SF-12 physical component and mental scores improved from baseline (P < 0.05).
CONCLUSIONS:
In this prospective longitudinal study, biosynthetic absorbable mesh showed efficacy in terms of long-term recurrence and quality of life for CVH repair patients and offers an alternative to biologic and permanent synthetic meshes in these complex situations
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