Comparison of the scintillation noise above different observatories measured with MASS instruments

Scintillation noise is a major limitation of ground base photometric precision. An extensive dataset of stellar scintillation collected at 11 astronomical sites world-wide with MASS instruments was used to estimate the scintillation noise of large telescopes in the case of fast photometry and traditional long-exposure regime. Statistical distributions of the corresponding parameters are given. The scintillation noise is mostly determined by turbulence and wind in the upper atmosphere and comparable at all sites, with slightly smaller values at Mauna Kea and largest noise at Tolonchar in Chile. We show that the classical Young's formula under-estimates the scintillation noise.The temporal variations of the scintillation noise are also similar at all sites, showing short-term variability at time scales of 1 -- 2 hours and slower variations, including marked seasonal trends (stronger scintillation and less clear sky during local winter). Some correlation was found between nearby observatories.Comment: Accepted for publication in Astronomy and Astrophysics, 14 pages, 11 figure

The statistics of the photometric accuracy based on MASS data and the evaluation of high-altitude wind

The effect of stellar scintillation on the accuracy of photometric measurements is analyzed. We obtain a convenient form of estimaton of this effect in the long exposure regime, when the turbulence shift produced by the wind is much larger than the aperture of the telescope. A simple method is proposed to determine index $S_3$ introduced by perture of the Kenyon et al. (2006), directly from the measurements with the Multi Aperture Scintillation Sensor (MASS) without information on vertical profile of the wind. The statistics $S_3$ resulting from our campaign of 2005 -- 2007 at Maidanak observatory is presented. It is shown that these data can be used to estimate high-altitude winds at pressure level 70 -- 100 mbar. Comparison with the wind speed retrieved from the NCEP/NCAR global models shows a good agreement. Some prospects for retrieval of the wind speed profile from the MASS measurements are outlined.Comment: 11 pages, 9 figures, accepted for publication in Astronomy Letter

Coexistence or Separation of the Superconducting, Antiferromagnetic, and Paramagnetic Phases in Quasi One-Dimensional (TMTSF)2PF6 ?

We report on experimental studies of the character of phase transitions in the quasi-1D organic compound (TMTSF)2PF6 in the close vicinity of the borders between the paramagnetic metal PM, antiferromagnetic insulator AF, and superconducting SC states. In order to drive the system through the phase border P_0(T_0), the sample was maintained at fixed temperature T and pressure P, whereas the critical pressure P_0 was tuned by applying the magnetic field B. In this approach, the magnetic field was used (i) for tuning (P-P_0), and (ii) for identifying the phase composition (due to qualitatively different magnetoresistance behavior in different phases). Experimentally, we measured R(B) and its temperature dependence R(B,T) in the pressure range (0 - 1)GPa. Our studies focus on the features of the magnetoresistance at the phase transition between the PM and AF phases, in the close vicinity to the superconducting transition at T~1K. We found pronounced history effects arising when the AF/PM phase border is crossed by sweeping the magnetic field: the resistance depends on a trajectory which the system arrives at a given point of the P-B-T phase space. In the transition from the PM to AF phase, the features of the PM phase extends well into the AF phase. At the opposite transition from the AF to PM phase, the features of the AF phase are observed in the PM phase. These results evidence for a macroscopically inhomogeneous state, which contains macroscopic inclusions of the minority phase. When the system is driven away from the transition, the homogeneous state is restored; upon a return motion to the phase boundary, no signatures of the minority phase are observed up to the very phase boundary.Comment: 10 figures, 23 page

THE INFLUENCE OF COMPUTER-ASSISTED SURGERY ON CLINICAL AND RADIOGRAPHIC OUTCOMES OF PERIАRTICULAR FEMUR AND TIBIA OSTEOTOMIES IN OSTEOARTHRITIC PATIENTS (REVIEW)

Nowadays the clinical application of digital technologies became a growing trend at every stage of orthopedic patient treatment: from diagnostic procedures and pre-operative planning to intra-operative control of surgical manipulations and evaluation of final results later. The aim of thi sresearch was to analyze the studies dedicated to application of computer-assisted surgery (CAS) for femur and tibial osteotomies in patients with gonarthrosis. The hypothesis was that CAS improves the precision of leg alignment correction in frontal and sagittal planes that positively influencing both functional result of treatment and longevity of clinical effect. The PubMed, PubMedCentral, GoogleScholar and eLIBRARY searched for relevant studies using following key words: knee, osteoarthritis, gonarthrosis, osteotomy, CAS, navigation and its russian analogs. The majority of publications favored CAS in comparison to traditional osteotomy techniques both for leg alignment and tibial slope control. Despite generally researchers paid less attention to functional results after CASosteotomies than to precision of surgical manipulations it is possible of confirm that there is strong tendency to better knee scores after navigation while the difference is not always statistically significant. Rare publications dedicated to long term results favor CAS: 10 years survival rate is 97% that correspond to outcomes of modern total knee arthroplasty. Hence, the current literature confirms the hypothesis of our study and don’t reveal increase of complications rate associated with CAS

Health and disease markers correlate with gut microbiome composition across thousands of people.

Variation in the human gut microbiome can reflect host lifestyle and behaviors and influence disease biomarker levels in the blood. Understanding the relationships between gut microbes and host phenotypes are critical for understanding wellness and disease. Here, we examine associations between the gut microbiota and ~150 host phenotypic features across ~3,400 individuals. We identify major axes of taxonomic variance in the gut and a putative diversity maximum along the Firmicutes-to-Bacteroidetes axis. Our analyses reveal both known and unknown associations between microbiome composition and host clinical markers and lifestyle factors, including host-microbe associations that are composition-specific. These results suggest potential opportunities for targeted interventions that alter the composition of the microbiome to improve host health. By uncovering the interrelationships between host diet and lifestyle factors, clinical blood markers, and the human gut microbiome at the population-scale, our results serve as a roadmap for future studies on host-microbe interactions and interventions

Modeling the Wind of the Be Star SS 2883

Observations of eclipses of the radio pulsar B1259-63 by the disk of its Be-star companion SS 2883 provide an excellent opportunity to study the winds of stars of this type. The eclipses lead to variations in the radio flux (due to variations in the free-free absorption), dispersion measure, rotation measure, and linear polarization of the pulsar. We have carried out numerical modeling of the parameters of the Be-star wind and compared the results with observations.Comment: 6 pages, 7 figure

Novel Phases in the Field Induced Spin Density Wave State in (TMTSF)_2PF_6

Magnetoresistance measurements on the quasi one-dimensional organic conductor (TMTSF)_2PF_6 performed in magnetic fields B up to 16T, temperatures T down to 0.12K and under pressures P up to 14kbar have revealed new phases on its P-B-T phase diagram. We found a new boundary which subdivides the field induced spin density wave (FISDW) phase diagram into two regions. We showed that a low-temperature region of the FISDW diagram is characterized by a hysteresis behavior typical for the first order transitions, as observed in a number of studies. In contrast to the common believe, in high temperature region of the FISDW phase diagram, the hysteresis and, hence, the first order transitions were found to disappear. Nevertheless, sharp changes in the resistivity slope are observed both in the low and high temperature domains indicating that the cascade of transitions between different subphases exists over all range of the FISDW state. We also found that the temperature dependence of the resistance (at a constant B) changes sign at about the same boundary. We compare these results with recent theoretical models.Comment: LaTex, 4 pages, 4 figure

TREATMENT OF INSUFFICIENT JOINT EXTENSOR MECHANISM IN PRIMARY AND REVISION KNEE REPLACEMENT

Insufficiency  of the  knee  joint  extensor  mechanism  is the  absolute  contraindication for total  knee  arthroplasty. Therefore, it is necessary to restore the extensor  mechanism before arthroplasty or to change the treatment approach.Purpose of the study  – to evaluate  the  outcomes  of surgical  reconstruction of the  knee joint  extensor  mechanism during primary or revision knee arthroplasty.Materials and methods. 25 reconstructions of extensor  mechanisms  (24 patients) were performed  in the period from 2006 to 2015. Five procedures out of 25 were performed in primary TKA and 20 in revision TKA. Indications for extensor mechanism  reconstruction were as follows: patellar  tendon  rupture in 15 cases (60,0%),  fracture  of patella  in 5 cases (20,0%), quadriceps tendon  rupture in 3 cases (12,0%) and other indications in 2 cases (8,0%). One of the following four techniques was used to restore  the extensor  mechanism: “Frame / Loop” allograft of patellar  tendon  in 6 cases (24,0%); bone – patellar  tendon  – bone allograft in 9 cases (36,0%); quadriceps tendon  – patella-patellar tendon  – bone allografts in 7 cases (28,0%); weber’s internal fixation of patella in 3 cases (12,0%).Results.  All patients were  evaluated based  on  clinical  examination,  KSS  and  WOMAC  scores  (18  patients), and standard x-rays (13 patients). The mean follow-up  period  in the  present  study  was 44 months  postoperatively. Reconstruction of the knee joint extensor  mechanism  resulted  in a significant  reduction of pain in 38.8% of patients, the knee stability was restored  in 83,3% of patients and the active  knee extension  improved  significantly  in the vast majority  of patients.Conclusion. Despite  the  objective  improvement of the  knee  joint  function  after  the  reconstructions of extensor mechanism,  the  KSS and WOMAC evaluation scores remained  low which  should  be taken  into  consideration during preoperative planning

Periosteal Flaps Enhance Prefabricated Engineered Bone Reparative Potential

The clinical translation of bone tissue engineering for reconstructing large bone defects has not advanced without hurdles. The in vivo bioreactor (IVB) concept may therefore bridge between bone tissue engineering and reconstructive surgery by employing the patient body for prefabricating new prevascularized tissues. Ideally, IVB should minimize the need for exogenous growth factors/cells. Periosteal tissues are promising for IVB approaches to prefabricate tissue-engineered bone (TEB) flaps. However, the significance of preserving the periosteal vascular supply has not been adequately investigated. This study assessed muscle IVB with and without periosteal/pericranial grafts and flaps for prefabricating TEB flaps to reconstruct mandibular defects in sheep. The sheep (n = 14) were allocated into 4 groups: muscle IVB (M group; n(M) = 3), muscle + periosteal graft (MP group; n(MP) = 4), muscle + periosteal flap (MVP group; n(MVP) = 4), and control group (n(Control) = 3). In the first surgery, alloplastic bone blocks were implanted in the brachiocephalic muscle (M) with a periosteal graft (MP) or with a vascularized periosteal flap (MVP). After 9 wk, the prefabricated TEB flaps were transplanted to reconstruct a mandibular angle defect. In the control group, the defects were reconstructed by non-prevascularized bone blocks. Computed tomography (CT) scans were performed after 13 wk and after 23 wk at termination, followed by micro-CT (mu CT) and histological analyses. Both CT and mu CT analysis revealed enhanced new bone formation and decreased residual biomaterial volume in the MVP group compared with control and MP groups, while the M group showed less new bone formation and more residual biomaterial. The histological analysis showed that most of the newly formed bone emerged from defect edges, but larger areas of new bone islands were found in MP and MVP groups. The MVP group showed enhanced vascularization and higher biomaterial remodeling rates. The periosteal flaps boosted the reconstructive potential of the prefabricated TEB flaps. The regenerative potential of the periosteum was manifested after the transplantation into the mechanically stimulated bony defect microenvironment.Peer reviewe