V4743 Sgr, a magnetic nova?

Two XMM Newton observations of Nova V4743 Sgr (Nova Sgr 2002) were performed shortly after it returned to quiescence, 2 and 3.5 years after the explosion. The X-ray light curves revealed a modulation with a frequency of ~0.75 mHz, indicating that V4743 Sgr is most probably an intermediate polar (IP). The X-ray spectra have characteristics in common with known IPs, with a hard thermal plasma component that can be fitted only assuming a partially covering absorber. In 2004 the X-ray spectrum had also a supersoft blackbody-like component, whose temperature was close to that of the white dwarf (WD) in the supersoft X-ray phase following the outburst, but with flux by at least two orders of magnitude lower. In quiescent IPs, a soft X-ray flux component originates at times in the polar regions irradiated by an accretion column, but the supersoft component of V4743 Sgr disappeared in 2006, indicating a possible origin different from accretion. We suggest that it may have been due to an atmospheric temperature gradient on the WD surface, or to continuing localized thermonuclear burning at the bottom of the envelope, before complete turn-off. An optical spectrum obtained with SALT 11.5 years after the outburst showed a prominent He II 4686A line and the Bowen blend, which reveal a very hot region, but with peak temperature shifted to the ultraviolet (UV) range. V4743 Sgr is the third post-outburst nova and IP candidate showing a low-luminosity supersoft component in the X-ray flux a few years after the outburst.Comment: 9 pages, 5 figures, accepted to MNRA

Optical observations of "hot" novae returning to quiescence

We have monitored the return to quiescence of novae previously observed in outburst as supersoft X-ray sources, with optical photometry of the intermediate polar (IP) V4743 Sgr and candidate IP V2491 Cyg, and optical spectroscopy of these two and seven other systems. Our sample includes classical and recurrent novae, short period (few hours), intermediate period (1-2 days) and long period (symbiotic) binaries. The light curves of V4743 Sgr and V2491 Cyg present clear periodic modulations. For V4743 Sgr, the modulation occurs with the beat of the rotational and orbital periods. If the period measured for V2491 Cyg is also the beat of these two periods, the orbital one should be almost 17 hours. The recurrent nova T Pyx already shows fragmentation of the nebular shell less than 3 years after the outburst. While this nova still had strong [OIII] at this post-outburst epoch, these lines had already faded after 3 to 7 years in all the others. We did not find any difference in the ratio of equivalent widths of high ionization/excitation lines to that of the Hbeta line in novae with short and long orbital period, indicating that irradiation does not trigger high mass transfer rate from secondaries with small orbital separation. An important difference between the spectra of RS Oph and V3890 Sgr and those of many symbiotic persistent supersoft sources is the absence of forbidden coronal lines. With the X-rays turn-off, we interpret this as an indication that mass transfer in symbiotics recurrent novae is intermittent.Comment: In press in Monthly Notices of the Royal Astronomical Societ

ОСЛОЖНЕНИЯ НА ЭТАПЕ НЕОАДЪЮВАНТНОЙ ТЕРАПИИ РАКА ГОЛОВКИ ПОДЖЕЛУДОЧНОЙ ЖЕЛЕЗЫ

Aim: to study complications of preoperative chemoembolization of the gastroduodenal artery and external beam radiation therapy in patients with pancreatic head cancer.Material and Methods. Sixty patients underwent chemoembolization of the gastroduodenal artery and external beam radiation therapy. Femoral artery angiography was performed using the Seldinger’s technique. Lipiodol 5–7 ml and gemcitabine 400 mg/m2 were used for transarterial chemoembolization. Radiation therapy was given at a total dose of 50 Gy (2 Gy/fraction, 5 times a week, over 5 weeks) using AGAT -R apparatus.Results. Complications after chemoembolization of the gastroduodenal artery were observed in 18.3 % of patients: abdominal pain in 3.3 % of patients; pain and nausea in 3.3 %; pain, nausea and fever in 6.7 %; pain, nausea and increased blood amylase in 1.7 %; pain, nausea and fever, blood amylase in 1.7 %; nausea, fever and blood amylase in 1.7 %. Radiation-induced injuries were observed in 23.3 % of patients: erythema in 18.3 %, grade 1 leukopenia in 1.7% and grade 2 leukopenia in 3.3 %.Conclusion. Complications of neoadjuvant therapy in terms of frequency and severity were consistent with literature data, were manageable with conservative treatment, and did not increase the duration of the preoperative period.Цель исследования – изучить частоту осложнений предоперационного этапа (химиоэмболизация желудочно-двенадцатиперстнокишечной артерии и дистанционная лучевая терапия) комбинированного лечения больных раком головки поджелудочной железы.Материал и методы. В предоперационном периоде 60 пациентам проведены химиоэмболизация желудочно-двенадцатиперстнокишечной артерии и дистанционная лучевая терапия. Для проведения ангиографии применяли чрезбедренную катетеризацию по Сельдингеру. Вводили химиоэмболизат – липиодол 5–7 мл и гемцитабин 400 мг/м2. Лучевую терапию проводили на аппарате АГАТ-Р классическим фракционированием в РОД 2 Гр 5 раз в неделю до СОД 50 Гр на протяжении 5 нед.Результаты. При выполнении химиоэмболизации желудочно-двенадцатиперстнокишечной артерии в 18,3 % случаев возникли осложнения: в 3,3 % диагностирована боль в животе, в 3,3 % – боль и тошнота, в 6,7 % – боль, тошнота и повышение температуры тела, в 1,7 % – боль, тошнота и повышение амилазы крови, в 1,7 % – боль, тошнота и повышение температуры тела, амилазы крови, в 1,7 % – тошнота, повышение температуры тела и амилазы крови. При проведении дистанционной лучевой терапии в 23,3 % возникли лучевые повреждения: эритема I степени – в 18,3 % случаев, лейкопения I степени – в 1,7 %, лейкопения II степени – в 3,3 % наблюдений.Заключение. Осложнения неоадъювантной терапии больных раком головки поджелудочной железы по частоте и тяжести соответствуют литературным данным, купируются консервативными мероприятиями, не увеличивая продолжительности предоперационного периода комбинированного лечения

Spin Density Matrix Elements in Exclusive ρ0\rho ^0 Meson Muoproduction

We report on a measurement of Spin Density Matrix Elements (SDMEs) in hard exclusive $\rho ^0$ meson muoproduction at COMPASS using 160~GeV/$c$ polarised $\mu ^{+}$ and $\mu ^{-}$ beams impinging on a liquid hydrogen target. The measurement covers the kinematic range 5.0~GeV/$c^2$ $< W <$ 17.0~GeV/$c^2$, 1.0 (GeV/$c$)$^2$ $< Q^2 <$ 10.0 (GeV/$c$)$^2$ and 0.01 (GeV/$c$)$^2$ $< p_{\rm{T}}^2 <$ 0.5 (GeV/$c$)$^2$. Here, $W$ denotes the mass of the final hadronic system, $Q^2$ the virtuality of the exchanged photon, and $p_{\rm{T}}$ the transverse momentum of the $\rho ^0$ meson with respect to the virtual-photon direction. The measured non-zero SDMEs for the transitions of transversely polarised virtual photons to longitudinally polarised vector mesons ($\gamma^*_T \to V^{ }_L$) indicate a violation of $s$-channel helicity conservation. Additionally, we observe a dominant contribution of natural-parity-exchange transitions and a very small contribution of unnatural-parity-exchange transitions, which is compatible with zero within experimental uncertainties. The results provide important input for modelling Generalised Parton Distributions (GPDs). In particular, they may allow one to evaluate in a model-dependent way the role of parton helicity-flip GPDs in exclusive $\rho ^0$ production

Collins and Sivers transverse-spin asymmetries in inclusive muoproduction of ρ0\rho^0 mesons

The production of vector mesons in deep inelastic scattering is an interesting yet scarsely explored channel to study the transverse spin structure of the nucleon and the related phenomena. The COMPASS collaboration has performed the first measurement of the Collins and Sivers asymmetries for inclusively produced $\rho^0$ mesons. The analysis is based on the data set collected in deep inelastic scattering in $2010$ using a $160\,\,\rm{GeV}/c$ $\mu^+$ beam impinging on a transversely polarized $\rm{NH}_3$ target. The $\rho^{0}$ mesons are selected from oppositely charged hadron pairs, and the asymmetries are extracted as a function of the Bjorken-$x$ variable, the transverse momentum of the pair and the fraction of the energy $z$ carried by the pair. Indications for positive Collins and Sivers asymmetries are observed

Double J/ψJ/\psi production in pion-nucleon scattering at COMPASS

We present the study of the production of double $J/\psi$ mesons using COMPASS data collected with a 190 GeV/$c$ $\pi^-$ beam scattering off NH$_{3}$, Al and W targets. Kinematic distributions of the collected double $J/\psi$ events are analysed, and the double $J/\psi$ production cross section is estimated for each of the COMPASS targets. The results are compared to predictions from single- and double-parton scattering models as well as the pion intrinsic charm and the tetraquark exotic resonance hypotheses. It is demonstrated that the single parton scattering production mechanism gives the dominant contribution that is sufficient to describe the data. An upper limit on the double intrinsic charm content of pion is evaluated. No significant signatures that could be associated with exotic tetraquarks are found in the double $J/\psi$ mass spectrum.Comment: 12 pages, 4 figure

Triangle Singularity as the Origin of the a1(1420)

The COMPASS Collaboration experiment recently discovered a new isovector resonancelike signal with axial-vector quantum numbers, the a(1)(1420), decaying to f(0)(980)(pi). With a mass too close to and a width smaller than the axial-vector ground state a(1)(1260), it was immediately interpreted as a new light exotic meson, similar to the X, Y, Z states in the hidden-charm sector. We show that a resonancelike signal fully matching the experimental data is produced by the decay of the a(1) (1260) resonance into K* (-> K pi) (K) over bar and subsequent rescattering through a triangle singularity into the coupled f(0)(980)p channel. The amplitude for this process is calculated using a new approach based on dispersion relations. The triangle-singularity model is fitted to the partial-wave data of the COMPASS experiment. Despite having fewer parameters, this fit shows a slightly better quality than the one using a resonance hypothesis and thus eliminates the need for an additional resonance in order to describe the data. We thereby demonstrate for the first time in the lightmeson sector that a resonancelike structure in the experimental data can be described by rescattering through a triangle singularity, providing evidence for a genuine three-body effect

Monitoring the antibiotic resistance in the intensive care unit of a multidisciplinary hospital

Background. Infectious complications remain a serious post-transplant problem and make a major cause of poor outcome. Given the active development of transplant services at a regional level, the problem of infectious complications becomes increasingly important and requires monitoring of the etiological structure and level of antibiotic resistance in each hospital dealing with this problem.The purpose was to analyze the changes over time in the structure and antimicrobial resistance of the most common pathogens in various nosology, including in patients after organ transplantation, regardless gender and age.Material and methods. The study included 37,103 patients, of whom 8,091 (21.8%) were treated in the Intensive Care Unit (ICU) of the Vitebsk Regional Clinical Hospital (VRCH) for the period from 2015 to 2017; infectious complications after organ transplantation made 3%. The clinical samples were studied for bacteriology in the Republican Scientific and Practical Center "Infection in Surgery"; 20,280 clinical isolates were investigated.Results. Staphylococcus aureus (20.96%) dominated in the general structure of microorganisms cultured mainly from the wound surface in thermal burns; meanwhile, in the ICU, gram-negative microflora dominated and was presented with Acinetobacter spp. (22.75%) and Pseudomonas aeruginosa (22.74%) in the majority of cases. By 2017, there had been an increase in resistant isolates of Klebsiella spp. (22.87%) and Acinetobacter spp. (23.09%) and a reduction of P. aeruginosa (13.31%) and S. aureus (18.88%) seeding. The protocol of the antibacterial therapy initiation was set up in the ICU of Vitebsk Regional Clinical Hospital, based on the obtained results demonstrating that all S. aureus isolates were sensitive to linezolid, vancomycin and teicoplanin, while P. aeruginosa was sensitive to colistin. All isolated Acinetobacter spp. were sensitive to colistin and 80% of the isolates were sensitive to sulbactam. More than 95% of K. pneumonia isolates were sensitive to colistin and tigecycline.Conclusion. The current epidemiology is characterized by the prevalence of S. aureus (20.96%) in the overall structure of microorganisms, while Acinetobacter spp. (22.25%) and P. aeruginosa (22.74%) dominate in the ICU. Based on the microbiology study results, the protocol of antibacterial therapy initiation was established in the ICU of Vitebsk Regional Clinical Hospital. It is necessary to monitor the resistance of common microorganisms to certain antibiotics in order to develop algorithms for rational antibacterial treatment in each hospital

COMPLICATIONS OF NEOADYAVANT THERAPY FOR CANCER OF THE HEAD OF THE PANCREAS

Aim: to study complications of preoperative chemoembolization of the gastroduodenal artery and external beam radiation therapy in patients with pancreatic head cancer.Material and Methods. Sixty patients underwent chemoembolization of the gastroduodenal artery and external beam radiation therapy. Femoral artery angiography was performed using the Seldinger’s technique. Lipiodol 5–7 ml and gemcitabine 400 mg/m2 were used for transarterial chemoembolization. Radiation therapy was given at a total dose of 50 Gy (2 Gy/fraction, 5 times a week, over 5 weeks) using AGAT -R apparatus.Results. Complications after chemoembolization of the gastroduodenal artery were observed in 18.3 % of patients: abdominal pain in 3.3 % of patients; pain and nausea in 3.3 %; pain, nausea and fever in 6.7 %; pain, nausea and increased blood amylase in 1.7 %; pain, nausea and fever, blood amylase in 1.7 %; nausea, fever and blood amylase in 1.7 %. Radiation-induced injuries were observed in 23.3 % of patients: erythema in 18.3 %, grade 1 leukopenia in 1.7% and grade 2 leukopenia in 3.3 %.Conclusion. Complications of neoadjuvant therapy in terms of frequency and severity were consistent with literature data, were manageable with conservative treatment, and did not increase the duration of the preoperative period