Axions and Photons In Terms of "Particles" and "Anti-Particles"

The axion photon system in an external magnetic field, when for example considered with the geometry of the experiments exploring axion photon mixing (which can be represented by a 1+1 effective model) displays a continuous axion-photon duality symmetry in the limit the axion mass is neglected. The conservation law that follows from this symmetry is obtained. The magnetic field interaction is seen to be equivalent to first order to the interaction of a complex charged field with an external electric potential, where this ficticious "electric potential" is proportional to the external magnetic field. This allows one to solve for the scattering amplitudes using already known scalar QED results. Axion photon oscillations can be understood as violations of a charge symmetry in the scalar QED language. Going beyond the linear theory, the axion photon system in a self consistent magnetic field is shown, using this formalism, to have interesting soliton solutions that represent new non gravitational ways of trapping light. Finally, generalizing the scalar QED formalism to 2+1 dimensions makes it clear that a photon and an axion splitt into two components in an inhomogeneous magnetic field, an effect that reminds us of the Stern Gerlach experiment.Comment: Talk given at the 4th Patras workshop on axions, WIMPs and WISPs, Hamburg, Gemany, 18-21 Jun 2008. Corrected reference in version

A Nonlinear Plancherel Theorem with Applications to Global Well-Posedness for the Defocusing Davey-Stewartson Equation and to the Inverse Boundary Value Problem of Calderón

We prove a Plancherel theorem for a nonlinear Fourier transform in two dimensions arising in the Inverse Scattering method for the defocusing Davey-Stewartson II equation. We then use it to prove global well-posedness and scattering in $L^2$ for defocusing DSII. This Plancherel theorem also implies global uniqueness in the inverse boundary value problem of Calder\'on in dimension $2$, for conductivities \sigma>0 with $\log \sigma \in \dot H^1$. The proof of the nonlinear Plancherel theorem includes new estimates on classical fractional integrals, as well as a new result on $L^2$-boundedness of pseudo-differential operators with non-smooth symbols, valid in all dimensions

Axions Scattering From a Quadrupole Magnetic Field

We study the 2D scattering of axions from an accelerator like quadrupole magnet using the eikonal approximation in order to learn whether or not such a setup could serve as a new possible method for detecting axions on terrestrial experiments. The eikonal approximation in 2D is introduced and explained. We also apply the eikonal approximation to two known cases in order to compare it with previous results, obtained using Born's approximation, and discuss its correctness

Why a New Code for Novae Evolution and Mass Transfer in Binaries?

One of the most interesting problems in Cataclysmic Variables is the long time scale evolution. This problem appears in long time evolution, which is also very important in the search for the progenitor of SN Ia. The classical approach to overcome this problem in the simulation of novae evolution is to assume: (1) A constant in time, rate of mass transfer. (2) The mass transfer rate that does not vary throughout the life time of the nova, even when many eruptions are considered. Here we show that these assumptions are valid only for a single thermonuclear flash and such a calculation cannot be the basis for extrapolation of the behavior over many flashes. In particular, such calculation cannot be used to predict under what conditions an accreting WD may reach the Chandrasekhar mass and collapse. We report on a new code to attack this problem. The basic idea is to create two parallel processes, one calculating the mass losing star and the other the accreting white dwarf. The two processes communicate continuously with each other and follow the time depended mass loss

Antiphase Synchronization in a Flagellar-Dominance Mutant of Chlamydomonas

Groups of beating flagella or cilia often synchronize so that neighboring filaments have identical frequencies and phases. A prime example is provided by the unicellular biflagellate Chlamydomonas reinhardtii, which typically displays synchronous in-phase beating in a low-Reynolds number version of breaststroke swimming. We report here the discovery that ptx1, a flagellar dominance mutant of C. reinhardtii, can exhibit synchronization in precise antiphase, as in the freestyle swimming stroke. Long-duration high-speed imaging shows that ptx1 flagella switch stochastically between in-phase and antiphase states, and that the latter has a distinct waveform and significantly higher frequency, both of which are strikingly similar to those found during phase slips that stochastically interrupt in-phase beating of the wildtype. Possible mechanisms underlying these observations are discussed.Comment: 5 pages, 4 figure

Stabilization of Neutral Thin Shells By Gravitational Effects From Electric Fields

We study the properties of a system consisting of an uncharged spherically symmetric two dimensional extended object which encloses a stationary point charge placed in the shell's center. We show that there can be a static and stable configuration for the neutral shell, using only the gravitational field of the charged source as a stabilizing mechanism. In particular, two types of shells are studied: a dust shell and a string gas shell. The dynamical possibilities are also analyzed, including the possibility of child universe creation.Comment: 5 pages, 1 figur

Workshop Media Pembelajaran Digital Bagi Guru Dengan Teknologi AI (Artificial Intelligence)

Workshop Media Pembelajaran Digital Bagi Guru dengan Teknologi AI (Artificial Intelligence) merupakan kegiatan pengabdian yang bertujuan untuk meningkatkan keterampilan guru dalam memanfaatkan teknologi kecerdasan buatan (AI) dalam proses pembelajaran. Workshop ini fokus pada pengembangan kemampuan guru dalam menciptakan materi pembelajaran yang interaktif dan personalisasi, memanfaatkan berbagai alat dan aplikasi berbasis AI. Selain aspek praktis, kegiatan ini juga membahas konsep dasar AI, etika penggunaannya, dan cara mengatasi tantangan yang mungkin muncul. Metode yang dilakukan dalam kegiatan ini adalah metode demontrasi secara langsung dan metode ceramah. Hasilnya adalah Para peserta workshop berkolaborasi dalam sesi-sesi interaktif, berbagi pengalaman, dan menggali potensi teknologi AI untuk meningkatkan efektivitas pembelajaran di kelas. Hasilnya, diharapkan para guru dapat mengintegrasikan teknologi AI secara kreatif dan etis, menciptakan lingkungan pembelajaran yang responsif dan inovatif. Kesimpulannya, workshop ini menjadi langkah penting dalam mempersiapkan pendidik untuk menghadapi tuntutan pendidikan abad ke-21 dan memaksimalkan manfaat teknologi AI dalam proses pembelajaran

Субъективное благополучие китайских студентов на разных этапах обучения в вузах России и Китая

The paper brings forward the results of a comparative study of subjective well-being of Chinese students training in institutes of higher education of China and Russia. The works of psychologists focus primarily on the problem of adaptation of foreign students.However, difficulties can arise and provoke stress in senior years of education. It is important to know how Chinese students cope with stress at different stages of training. The level of subjective well-being is a significant indicator of the success of coping with stress.The empirical study involved 366 Chinese students at the age from 19 to 25 years – men and women – first-year and third-year bachelor students of and first-year MA students of institutes of higher education of China and Russia. The Index of Well-Being Questionnaire (A. Campbell et al.), adapted by Yao Chunsheng, He Nailing and Shen Qi [19, 21] was a method of studying the level of subjective well-being.The results of the study showed that the students of institutes of higher education of Russia scored lower in the assessment of their subjective well-being than the students of institutes of higher education of China. The firsts-year MA students trained in China scored higher in the assessment of subjective well-being than the third-year bachelor students. The firsts-year MA students trained in Russian universities scored lower in the assessment of subjective well-being than the thirdyear bachelor students. The authors put forward a hypothesis that, if to compare with students studying in China, a relatively lower subjective well-being of Chinese students trained in Russian institutes of higher education concerned not only difficulties in adapting toconditions of living and studying abroad, but also stress about future employment. This stress was higher in MA students.В статье приводятся результаты сравнительного исследования субъективного благополучия китайских студентов, обучающихся в вузах Китая и России. Труды психологов посвящены главным образом проблеме адаптации иностранных студентов младших курсов. Однако трудности могут возникать и провоцировать стресс также на старших курсах. Важно знать, как китайские студенты справляются со стрессом на разных этапах обучения. Существенным показателем успешности совладания со стрессом является уровень субъективного благополучия человека. В представленном эмпирическом исследовании приняли участие 366 китайских студентов от 19 до 25 лет, мужчин и женщин, обучающихся на 1 и 3 курсах бакалавриата и 1 курсе магистратуры вузов КНР и РФ. Для определения уровня субъективного благополучия использовался опросник Index of Well-Being (A. Campbell et al.), адаптированный Yao Chunsheng, He Nailing и Shen Qi [19, 21]. Результаты исследования показали, что студенты, обучающиеся на разных курсах в вузах РФ, ниже оценивают свое субъективное благополучие, чем студенты, обучающиеся в вузах КНР. У обучающихся в КНР студентов 1 курса магистратуры оценка субъективного благополучия выше, чем у студентов 3 курса бакалавриата. У обучающихся в вузах РФ студентов 1 курса магистратуры оценка уровня субъективного благополучия ниже, чем у студентов 3 курса бакалавриата. Формулируется предположение о том, что относительно более низкое субъективное благополучие китайских студентов, обучающихся в российских вузах, по сравнению со студентами, обучающимися в Китае, связано не только с трудностями адаптации к условиям жизни и учебы за рубежом, но также с напряжением по поводу будущего трудоустройства; в наибольшей степени это напряжение выражено у студентов магистратуры