921 research outputs found
Convection-induced nonlinear-symmetry-breaking in wave mixing
We show that the combined action of diffraction and convection (walk-off) in
wave mixing processes leads to a nonlinear-symmetry-breaking in the generated
traveling waves. The dynamics near to threshold is reduced to a Ginzburg-Landau
model, showing an original dependence of the nonlinear self-coupling term on
the convection. Analytical expressions of the intensity and the velocity of
traveling waves emphasize the utmost importance of convection in this
phenomenon. These predictions are in excellent agreement with the numerical
solutions of the full dynamical model.Comment: 5 page
Generalized Borcea-Voisin Construction
C. Voisin and C. Borcea have constructed mirror pairs of families of
Calabi-Yau threefolds by taking the quotient of the product of an elliptic
curve with a K3 surface endowed with a non-symplectic involution. In this
paper, we generalize the construction of Borcea and Voisin to any prime order
and build three and four dimensional Calabi-Yau orbifolds. We classify the
topological types that are obtained and show that, in dimension 4, orbifolds
built with an involution admit a crepant resolution and come in topological
mirror pairs. We show that for odd primes, there are generically no minimal
resolutions and the mirror pairing is lost.Comment: 15 pages, 2 figures. v2: typos corrected & references adde
Pretransplant assessment of human liver grafts by plasma lecithin: cholesterol acyltransferase (LCAT) activity in multiple organ donors.
In spite of the improved outcome of orthotopic liver transplantation (OLTx), primary graft nonfunction remains one of the life-threatening problems following OLTx. The purpose of this study was to evaluate plasma lecithin: cholesterol acyltransferase (LCAT) activity in multiple organ donors as a predictor of liver allograft viability prior to OLTx. Thirty-nine donors were studied during a 5-month period between April and August 1988. Allograft hepatectomy was performed using a rapid technique or its minor modification with hilar dissections, and the allografts were stored cold (4 degrees C) in University of Wisconsin (UW) solution. Early post-transplant allograft function was classified as good, fair, or poor, according to the highest SGOT, SGPT, and prothrombin time within 5 days following OLTx. Procurement records were reviewed to identify donor data, which included conventional liver function tests, duration of hospital stay, history of cardiac arrest, and graft ischemic time. Blood samples from the donors were drawn immediately prior to aortic crossclamp, and from these plasma LCAT activity was determined. Plasma LCAT activity of all donors was significantly lower than that of healthy controls (12.4 +/- 8.0 vs 39.2 +/- 13.3 micrograms/ml per hour, P less than 0.01). LCAT activity (16.4 +/- 8.3 micrograms/ml per hour) in donors of grafts with good function was significantly higher than that in those with fair (8.6 +/- 4.5 micrograms/ml per hour, P less than 0.01) or poor (7.3 +/- 2.4 micrograms/ml per hour, P less than 0.01) function.(ABSTRACT TRUNCATED AT 250 WORDS
BPS Monopole Equation in Omega-background
We study deformed supersymmetries in N=2 super Yang-Mills theory in the
Omega-backgrounds characterized by two complex parameters . When one of the -parameters vanishes, the theory has
extended supersymmetries. We compute the central charge of the algebra and
obtain the deformed BPS monopole equation. We examine supersymmetries preserved
by the equation.Comment: 14 pages, typos corrected, published version in JHE
Measurement of forward neutral pion transverse momentum spectra for = 7TeV proton-proton collisions at LHC
The inclusive production rate of neutral pions in the rapidity range greater
than has been measured by the Large Hadron Collider forward (LHCf)
experiment during LHC \,TeV proton-proton collision operation in
early 2010. This paper presents the transverse momentum spectra of the neutral
pions. The spectra from two independent LHCf detectors are consistent with each
other and serve as a cross check of the data. The transverse momentum spectra
are also compared with the predictions of several hadronic interaction models
that are often used for high energy particle physics and for modeling
ultra-high-energy cosmic-ray showers.Comment: 18 Pages, 10 figures, submitted to Phys. Rev.
Palpable pediatric thyroid abnormalities – diagnostic pitfalls necessitate a high index of clinical suspicion: a case report
A 12-year-old girl presented with a 4 year history of an enlarged, firm thyroid gland. On exam, her thyroid was firm and fixed and an enlarged cervical lymph node was palpable as well. Though a thyroid ultrasound prior to referral was read as thyroiditis, clinical suspicion for thyroid carcinoma mandated continued investigation. The diagnosis of papillary thyroid cancer was established and her workup revealed lymph node metastases as well as a tremendous burden of pulmonary metastases. Pediatric thyroid cancer is extremely rare, but often presents with aggressive disease. Palpable thyroid abnormalities in an individual under 20-years-old should be viewed with suspicion and should be thoroughly investigated to rule out malignancy even in the face of negative diagnostic procedures. Though pediatric papillary thyroid cancer often presents with loco-regional and even distant metastatic disease, mortality rates in follow-up for as long as 20 years are very favorable
Precise measurement on the binding energy of hypertriton from the nuclear emulsion data using analysis with machine learning
6 pags., 3 figs.A machine learning model has been developed to search for events of production and decay of a hypertriton in nuclear emulsion data, which
is used for measuring the binding energy of the hypertriton at the best precision. The developed model employs an established technique
for object detection and is trained with surrogate images generated by Monte Carlo simulations and image transfer techniques. The first
hypertriton event has already been detected with the developed method only with 10−4 of the total emulsion data. It implies that a sufficient
number of hypertriton events will soon be detected for the precise measurement of the hypertriton binding energy
Novel high-throughput fluorescence-based assay for the identification of nematocidal compounds that target the blood-feeding pathway
Hookworm infections cause a neglected tropical disease (NTD) affecting ~740 million people worldwide, principally those living in disadvantaged communities. Infections can cause high morbidity due to their impact on nutrient uptake and their need to feed on host blood, resulting in a loss of iron and protein, which can lead to severe anaemia and impaired cognitive development in children. Currently, only one drug, albendazole is efficient to treat hookworm infection and the scientific community fears the rise of resistant strains. As part of on-going efforts to control hookworm infections and its associated morbidities, new drugs are urgently needed. We focused on targeting the blood-feeding pathway, which is essential to the parasite survival and reproduction, using the laboratory hookworm model Nippostrongylus brasiliensis (a nematode of rodents with a similar life cycle to hookworms). We established an in vitro-drug screening assay based on a fluorescent-based measurement of parasite viability during blood-feeding to identify novel therapeutic targets. A first screen of a library of 2654 natural compounds identified four that caused decreased worm viability in a blood-feeding-dependent manner. This new screening assay has significant potential to accelerate the discovery of new drugs against hookworms
Macroscopic quantum fluctuations in noise-sustained optical patterns
We investigate quantum effects in pattern formation for a degenerate optical parametric oscillator with walk-off. This device has a convective regime in which macroscopic patterns are both initiated and sustained by quantum noise. Familiar methods based on linearization about a pseudoclassical field fail in this regime and new approaches are required. We employ a method in which the pump field is treated as a c-number variable but is driven by the c-number representation of the quantum subharmonic signal field. This allows us to include the effects of the fluctuations in the signal on the pump, which in turn act back on the signal. We find that the nonclassical effects, in the form of squeezing, survive just above the threshold of the convective regime. Further, above threshold, the macroscopic quantum noise suppresses these effects
Polarization transfer in the O reaction at forward angles and structure of the spin-dipole resonances
Cross sections and polarization transfer observables in the O
reactions at 392 MeV were measured at several angles between
0 and 14. The non-spin-flip () and spin-flip
() strengths in transitions to several discrete states and broad
resonances in O were extracted using a model-independent method. The
giant resonances in the energy region of 27 MeV were found to be
predominantly excited by transitions. The strength distribution
of spin-dipole transitions with and were deduced.
The obtained distribution was compared with a recent shell model calculation.
Experimental results are reasonably explained by distorted-wave impulse
approximation calculations with the shell model wave functions.Comment: 28 pages RevTex, including 9 figures, to be published in Phys. Rev.
C.; a typo in Eq. (3b) was correcte
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