2,223 research outputs found
Interval oscillation theorems for asecond-order linear differential equation
AbstractInterval oscillation criteria are given for the forced second-order linear differential equation Ly(t) = (p(t)y′)′ + q(t)y = ƒ(t), tε (0, ∞), where p, q, ƒ are locally integrable functions and p(t) > 0, for t > 0. No restriction is imposed on ƒ(t) to be the second derivative of an oscillatory function as assumed by Kartsatos [1). Our results also allow both q and f to change sign in the neighborhood at infinity. In particular, we show that all solutions of y″ + c(sin t)y = tβ cos t with β ≥ 0 are oscillatory, for c ≥ 1.3448. This improves an estimate given by Nasr [2] for the linear equation
Revisiting the -Meson Production at the Hadronic Colliders
The production of heavy-flavored hadron at the hadronic colliders provides a
challenging opportunity to test the validity of pQCD predictions. There are two
mechanisms for the hadroproduction, i.e. the gluon-gluon fusion
mechanism via the subprocess and the
extrinsic heavy quark mechanism via the subprocesses and , both of which shall have sizable
contributions in proper kinematic region. Different from the
fixed-flavor-number scheme (FFNS) previously adopted in the literature, we
study the hadroproduction under the general-mass
variable-flavor-number scheme (GM-VFNS), in which we can consistently deal with
the double counting problem from the above two mechanisms. Properties for the
hadroproduction are discussed. To be useful reference, a
comparative study of FFNS and GM-VFNS is presented. Both of which can provide
reasonable estimations for the hadroproduction. At the Tevatron,
the difference between these two schemes is small, however such difference is
obvious at the LHC. The forthcoming more precise data on LHC shall provide a
good chance to check which scheme is more appropriate to deal with the
-meson production and to further study the heavy quark components in
hadrons.Comment: 18 pages, 8 figures, 4 tables. To match the published version. To be
published in Eur.Phys.J.
Study of Bc --> J/psi pi, etac pi decays with perturbative QCD approach
The Bc --> J/psi pi, etac pi decays are studied with the perturbative QCD
approach. It is found that form factors and branching ratios are sensitive to
the parameters w, v, f_J/psi and f_etac, where w and v are the parameters of
the charmonium wave functions for Coulomb potential and harmonic oscillator
potential, respectively, f_J/psi and f_etac are the decay constants of the
J/psi and etac mesons, respectively. The large branching ratios and the clear
signals of the final states make the Bc --> J/psi pi, etac pi decays to be the
prospective channels for measurements at the hadron collidersComment: 21 pages, revtex
3D visualization and 3D printing in abnormal gastrointestinal system manifestations of situs ambiguus
Situs ambiguus is a rare congenital condition whereby
sufferers have abnormally positioned viscera (1,2). In such
cases, it is dangerous to perform traditional diagnostic
examinations, such as colonoscopy, thus anatomy is explored
through invasive surgeries instead. By reconstructing
a patient’s viscera three-dimensionally, it is possible to
trace the physical origins of the patient’s symptoms, while
eliminating the necessity for invasive surgery. We present a
case of situs ambiguus with use of a combination of different
approaches including 3D visualizations and patient-specific
3D printing technique to assist clinical diagnosis and patient
management. This case highlights the potential value of
utilising the latest visualization tools in the diagnostic
assessment of complicated pathologies
Associative effects in diets composed of alfalfa and corn soybean concentrate fed to growing cashmere goats
The associative effects resulting from the proportions of neutral detergent fibre (NDF) and non fibre carbohydrate (NFC) were explored and assessed by in vitro gas production . Total mixed rations (TMR) composed primarily of alf a lfa and corn soybean concentrate were fed to growing cashmere goats. Treatments were defined by three proportions of NFC and NDF namely 2.00 ( TMR1), 2.35 ( TMR2), and 3.00 ( that were used to grow cashmere goats , and these TRMs were incubated for 48 h ours to evaluate their influence on associative effects. The results indicated that the associative influences of these treatments on gas production occurred within the cultures predominantly at 2 8 hours, and disappeared gradually as culture time was ex tended . TMR 2 and TMR3 incubation increased gas production compared with that observed in the other groups at all incubation times P > 0.05), and these groups exhibited positive associative effects, particularly during the early hours of incubation P <0.05 )). TMR 3 displayed the best associative effect
Paclitaxel-octreotide conjugates inhibit growth of human non-small cell lung cancer cells in vitro
Aim: To evaluate the effects of paclitaxel-octreotide conjugates on the growth of cultured non-small cell lung cancer cells. Methods: RT-PCR was performed to detect mRNA for the subtypes of the human somatostatin receptor (SSTR) using specific primers. MTT-based cytotoxicity assay was used to evaluate the cell viability after treatment with paclitaxel and the conjugates. Cell cycle perturbations were determined using a Fluorescence-Activated Cell Sorter. Results: Non-small cell lung cancer A549 and Calu-6 cells expressed mRNA for SSTR2 and SSTR5. Paclitaxel and the conjugates effectively inhibited the growth of A549 and Calu-6 cells in a concentration- and time-dependent manner. In SSTR-negative fibroblasts, the conjugates were less cytotoxic than paclitaxel. The conjugates and paclitaxel could induce the increase of G2/M phase ratio in A549 cells. Conclusion: The paclitaxel-octreotide conjugates can be used as selective-targeted chemotherapeutic agents for treating non-small cell lung cancer.Цель: оценить эффект конъюгатов паклитаксела-октреотида на рост культивированных клеток немелкоклеточного рака
легкого человека. Методы: для определения мРНК подтипов рецептора соматостатина человека (SSTR) применяли ОT-ПЦР.
Анализ цитотоксичности в МТТ-тесте применяли для оценки выживаемости клеток после их инкубации с паклитакселом
и конъюгатами. Нарушения клеточного цикла определяли с применением FACS — клеточного сортера. Результаты:
установлено, что клеточные линии немелкоклеточного рака легкого A549 и Calu-6 экспрессируют SSTR2 и SSTR5 мРНК.
Отмечено эффективное дозо- и времязависимое угнетение роста клеток A549 и Calu-6 паклитакселом и конъюгатами.
Для SSTR-негативных фибробластов конъюгаты менее цитотоксичны, чем паклитаксел. Конъюгаты и паклитаксел могут
индуцировать повышение соотношения фаз G2
/M в клетках A549. Выводы: конъюгаты паклитаксел-октреотида могут быть
использованы как селективные химиотерапевтические агенты для воздействия на немелкоклеточный рак легкого
Generalized measurements by linear elements
I give a first characterization of the class of generalized measurements that
can be exactly realized on a pair of qudits encoded in indistinguishable
particles, by using only linear elements and particle detectors. Two immediate
results follow from this characterization. (i) The Schmidt number of each POVM
element cannot exceed the number of initial particles. This rules out any
possibility of performing perfect Bell-measurements for qudits. (ii) The
maximum probability of performing a generalized incomplete Bell-measurement is
1/2.Comment: 4 pages. Submitted to Phys. Rev.
Exceptionally Slow Rise in Differential Reflectivity Spectra of Excitons in GaN: Effect of Excitation-induced Dephasing
Femtosecond pump-probe (PP) differential reflectivity spectroscopy (DRS) and
four-wave mixing (FWM) experiments were performed simultaneously to study the
initial temporal dynamics of the exciton line-shapes in GaN epilayers. Beats
between the A-B excitons were found \textit{only for positive time delay} in
both PP and FWM experiments. The rise time at negative time delay for the
differential reflection spectra was much slower than the FWM signal or PP
differential transmission spectroscopy (DTS) at the exciton resonance. A
numerical solution of a six band semiconductor Bloch equation model including
nonlinearities at the Hartree-Fock level shows that this slow rise in the DRS
results from excitation induced dephasing (EID), that is, the strong density
dependence of the dephasing time which changes with the laser excitation
energy.Comment: 8 figure
Effects of crossed states on photoluminescence excitation spectroscopy of InAs quantum dots
In this report, the influence of the intrinsic transitions between bound-to-delocalized states (crossed states or quasicontinuous density of electron-hole states) on photoluminescence excitation (PLE) spectra of InAs quantum dots (QDs) was investigated. The InAs QDs were different in size, shape, and number of bound states. Results from the PLE spectroscopy at low temperature and under a high magnetic field (up to 14 T) were compared. Our findings show that the profile of the PLE resonances associated with the bound transitions disintegrated and broadened. This was attributed to the coupling of the localized QD excited states to the crossed states and scattering of longitudinal acoustical (LA) phonons. The degree of spectral linewidth broadening was larger for the excited state in smaller QDs because of the higher crossed joint density of states and scattering rate
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