A spectroscopic analysis of the chemically peculiar star HD207561

In this paper we present a high-resolution spectroscopic analysis of the chemically peculiar star HD207561. During a survey programme to search for new roAp stars in the Northern hemisphere, Joshi et al. (2006) observed significant photometric variability on two consecutive nights in the year 2000. The amplitude spectra of the light curves obtained on these two nights showed oscillations with a frequency of 2.79 mHz [P~6-min]. However, subsequent follow-up observations could not confirm any rapid variability. In order to determine the spectroscopic nature of HD207561, high-resolution spectroscopic and spectro-polarimetric observations were carried out. A reasonable fit of the calculated Hbeta line profile to the observed one yields the effective temperature (Teff) and surface gravity (log g) as 7300 K and 3.7 dex, respectively. The derived projected rotational velocity (vsin i) for HD207561 is 74 km/sec indicative of a relatively fast rotator. The position of HD207561 in the H-R diagram implies that this is slightly evolved from the main-sequence and located well within the delta-Scuti instability strip. The abundance analysis indicates the star has slight under-abundances of Ca and Sc and mild over-abundances of iron-peak elements. The spectro-polarimetric study of HD207561 shows that the effective magnetic field is within the observational error of 100 gauss (G). The spectroscopic analysis revealed that the star has most of the characteristics similar to an Am star, rather than an Ap star, and that it lies in the delta-Scuti instability strip; hence roAp pulsations are not expected in HD207561, but low-overtone modes might be excited.Comment: 8 pages, 7 figures, 3 tables. Accepted for pubblication in MNRA

Ятрогенные повреждения лучевого нерва при остеосинтезе плечевой кости. Профилактика, диагностика и лечение

THE RELEVANCE is determined by the significant frequency of iatrogenic injuries of the radial nerve during internal osteosynthesis of the humerus, long-lasting functional disorders, a large number of unsatisfactory results, as well as the lack of a unified approach to diagnosis and treatment.MATERIAL AND METHODS. The causes of iatrogenic damage to the radial nerve were studied in 22 patients who underwent internal fixation during fractures of the humeral diaphysis. The ultrasound examination was used to visualize the radial nerve. In 13 patients (59.1%), a pathogenetic treatment was used, including medication, physical and mechanical therapy.RESULTS AND DISCUSSION. In plate osteosynthesis, a greater number of iatrogenic damage to the radial nerve was observed than during osteosynthesis with screws. The ultrasound method had high diagnostic values to determine the continuity of the nerve trunk and identify conflicts with solid structures. The use of pathogenetic therapy of neuropathy led to a more rapid clinical recovery of limb function.CONCLUSION. To prevent iatrogenic injuries and avoid gross manipulations, the access with sufficient visualization of the radial nerve is necessary in plate osteosynthesis and distal blocking outside the projection of the radial nerve is necessary in intramedullary osteosynthesis. Indications for early revision after iatrogenic damage are neurotmesis and a nerve conflict with bone fragments or an implant.АКТУАЛЬНОСТЬ. Определяется значительной частотой ятрогенных повреждений лучевого нерва при внутреннем остеосинтезе плечевой кости, длительно сохраняющимися функциональными расстройствами, большим количеством неудовлетворительных результатов, а также отсутствием единого подхода к диагностике и лечению.МАТЕРИАЛ И МЕТОДЫ. Изучены причины ятрогенных повреждений лучевого нерва у 22 пациентов, которым при переломах диафиза плечевой кости был выполнен погружной остеосинтез. Для визуализации лучевого нерва использовали ультразвуковое исследование (УЗИ). У 13 пациентов (59,1%) применили патогенетическую схему лечения, включающую медикаментозную, физио- и механотерапию.РЕЗУЛЬТАТЫ И ОБСУЖДЕНИЕ. При остеосинтезе плечевой кости пластинами наблюдали большее число ятрогенных повреждений лучевого нерва, чем при остеосинтезе штифтами. Метод УЗИ имеет высокие показатели диагностической ценности для определения непрерывности нервного ствола и выявления конфликта с твердыми структурами. Применение патогенетической терапии нейропатии приводило к более быстрому клиническому восстановлению функции конечности.ЗАКЛЮЧЕНИЕ. Для профилактики ятрогенных повреждений, кроме избегания грубых манипуляций при накостном остеосинтезе, необходим доступ с достаточной визуализацией лучевого нерва, а при интрамедуллярном остеосинтезе — выполнение дистального блокирования вне проекции лучевого нерва. Показаниями к ранней ревизии после ятрогенного повреждения являются нейротмезис и конфликт нерва с костными отломками или имплантом

Many-particle interference beyond many-boson and many-fermion statistics

Identical particles exhibit correlations even in the absence of inter-particle interaction, due to the exchange (anti)symmetry of the many-particle wavefunction. Two fermions obey the Pauli principle and anti-bunch, whereas two bosons favor bunched, doubly occupied states. Here, we show that the collective interference of three or more particles leads to a much more diverse behavior than expected from the boson-fermion dichotomy known from quantum statistical mechanics. The emerging complexity of many-particle interference is tamed by a simple law for the strict suppression of events in the Bell multiport beam splitter. The law shows that counting events are governed by widely species-independent interference, such that bosons and fermions can even exhibit identical interference signatures, while their statistical character remains subordinate. Recent progress in the preparation of tailored many-particle states of bosonic and fermionic atoms promises experimental verification and applications in novel many-particle interferometers.Comment: 12 pages, 5 figure

Hybrid kinematic control for rigid body pose stabilization using dual quaternions

In this paper, we address the rigid body pose stabilization problem using dual quaternion formalism. We propose a hybrid control strategy to design a switching control law with hysteresis in such a way that the global asymptotic stability of the closed-loop system is guaranteed and such that the global attractivity of the stabilization pose does not exhibit chattering, a problem that is present in all discontinuous-based feedback controllers. Using numerical simulations, we illustrate the problems that arise from existing results in the literature—as unwinding and chattering—and verify the effectiveness of the proposed controller to solve the robust global pose stability problem

Control theory from the geometric viewpoint

This book presents some facts and methods of the Mathematical Control Theory treated from the geometric viewpoint. It is devoted to finite-dimensional deterministic control systems governed by smooth ordinary differential equations. The problems of controllability, state and feedback equivalence, and optimal control are studied. Some of the topics treated by the authors are covered in monographic or textbook literature for the first time while others are presented in a more general and flexible setting than elsewhere

Association Fields via Cuspless Sub-Riemannian Geodesics in SE(2)

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