Energy Calibration of the JLab Bremsstrahlung Tagging System

In this report, we present the energy calibration of the Hall B bremsstrahlung tagging system at the Thomas Jefferson National Accelerator Facility. The calibration was performed using a magnetic pair spectrometer. The tagged photon energy spectrum was measured in coincidence with $e^+e^-$ pairs as a function of the pair spectrometer magnetic field. Taking advantage of the internal linearity of the pair spectrometer, the energy of the tagging system was calibrated at the level of $\pm 0.1$. The absolute energy scale was determined using the $e^+e^-$ rate measurements close to the end-point of the photon spectrum. The energy variations across the full tagging range were found to be $<3$ MeV.Comment: 15 pages, 12 figure

Antibiotic resistance – what can be done? A review

Serious work is being carried out in the world in the field of combating antibiotic resistance: reducing the prescribing of antibiotics, banning the use of antibiotics as stimulators of animal growth, improving infection control. Antimicrobial resistance is systematically monitored not only in every medical center, but also at the national level. The collected data is successfully used to implement local and national recommendations on the optimal use of antibiotics

ФАКТОРЫ РИСКА И НОЗОКОМИАЛЬНЫЕ ИНФЕКЦИИ, ВЫЗЫВАЕМЫЕ ЭНТЕРОКОККАМИ

Aim: to analyze nosocomial infections and risk factors caused by enterococci. Review of the foreign and domestic literature on biology and virulence factors of enterococci being the leading causative agents of nosocomial infections is done. Information on risk factors and postoperative infectious complications, pathogens of which are enterococci, in surgical hospitals and hospitals for organ transplantations is provided. The growth of antibiotic resistance in enterococci and the relationship between mortality rate and prevalence rate of antibiotic resistant strains are emphasizedЦель: анализ нозокомиальных инфекций и факторов риска, вызываемых энтерококками. Представлен обзор данных зарубежной и отечественной литературы по биологии, факторам вирулентности энтерококков – ведущих возбудителей нозокомиальных инфекций. Приводятся сведения о факторах риска и послеоперационных инфекционных осложнениях, возбудителями которых являются энтерококки, в хирургических клиниках и клиниках по трансплантации органов. Подчеркивается нарастание антибиотикорезистентности энтерококков и связь между показателями летальности и частотой распространения антибиотикорезистентных штаммов

ГОСПИТАЛЬНАЯ МИКРОФЛОРА И БИОПЛЕНКИ

The review presents data on the role of biofilms formation by opportunistic microbes in surgery. It gives in- formation about the microbial structure of biofilms, their architecture and physiology. The attention was payed to significal importance of microbial communities, which form biofilms in surgery. Mechanisms of increased resistance of biofilms bacteria are compared with plankton. The review includes literature data on the process of formation biofilms on intravascular catheters and methods of inhibition and protection. Methods of studing formation and inhibition of biofilms in vitro and in vivo are presented. Different biotechnology methods, based on using antiadhesive, antiseptic, biophysical resources and biomaterials are discussed. В обзоре изложены данные литературы о значении образования биопленок условнопатогенными бакте- риями в хирургии. Представлены сведения о микробном составе биопленок, архитектуре и физиологии. Обращено внимание на значение микробных сообществ, образующих биопленки, в хирургии. Разбира- ются механизмы повышенной резистентности биопленочных бактерий по сравнению с планктонными. Приводятся данные литературы о процессах образования биопленок на внутрисосудистых катетерах и методы их ингибиции и протекции. Излагаются методы изучения образования и подавления биопленок in vitro и in vivo на медицинских устройствах. Обсуждаются различные биотехнологические приемы, основанные на использовании антиадгезивных, антисептических, биофизических средств и биопрепара- тов, которые будут способствовать снижению и предупреждению инфекционных осложнений в хирургии и в трансплантологии.

Hysteresis Effects During the Phase Transition in Solutions of Temperature Sensitive Polymers

It is demonstrated, for the first time,that well-known phase transitions induced by changes in temperature in solutions of polymers containing both hydrophilic and hydrophobic functional groups could be followed by noticeable hysteresis effects. A well-known phase transitions accompanied by a sharp change in fluid properties, in particular its optical density can be induced by many external influences, including temperature changes occurring in the solutions of polymers containing both hydrophilic and hydrophobic functional groups. Since intensification subsequent hydrophobic interactions, leading to loss of solubility of the polymer molecules, resulting, in particular, a significant increase in the turbidity of the medium and are accompanied by a pronounced hysteresis phenomena. Hysteresis phenomena in the processes of molecular-scale play an important theoretical and practical interest in linkage with the development of advanced nano-level technology. In particular, the issue of the development of molecular "trigger" switches, and other analog electronic systems, implemented on submolecular level was actively discussed. In fact, under the same physical conditions of the environment of macromolecules system can be in two different states, which resolves the issue of programming such molecules. State of these polymers depends on their way of formation and thermodynamic variables. Observed effect could be utilized directly for information recording into the structure on the basis of stimulus-sensitive macromolecular chains. In fact, it is a first step towards creating memory of quasi-biological elements

Induced polarization of {\Lambda}(1116) in kaon electroproduction

We have measured the induced polarization of the ${\Lambda}(1116)$ in the reaction $ep\rightarrow e'K^+{\Lambda}$, detecting the scattered $e'$ and $K^+$ in the final state along with the proton from the decay $\Lambda\rightarrow p\pi^-$.The present study used the CEBAF Large Acceptance Spectrometer (CLAS), which allowed for a large kinematic acceptance in invariant energy $W$ ($1.6\leq W \leq 2.7$ GeV) and covered the full range of the kaon production angle at an average momentum transfer $Q^2=1.90$ GeV$^2$.In this experiment a 5.50 GeV electron beam was incident upon an unpolarized liquid-hydrogen target. We have mapped out the $W$ and kaon production angle dependencies of the induced polarization and found striking differences from photoproduction data over most of the kinematic range studied. However, we also found that the induced polarization is essentially $Q^2$ independent in our kinematic domain, suggesting that somewhere below the $Q^2$ covered here there must be a strong $Q^2$ dependence. Along with previously published photo- and electroproduction cross sections and polarization observables, these data are needed for the development of models, such as effective field theories, and as input to coupled-channel analyses that can provide evidence of previously unobserved $s$-channel resonances.Comment: 13 figure

Comment on the narrow structure reported by Amaryan et al

The CLAS Collaboration provides a comment on the physics interpretation of the results presented in a paper published by M. Amaryan et al. regarding the possible observation of a narrow structure in the mass spectrum of a photoproduction experiment.Comment: to be published in Physical Review