Polarization switching kinetics at the nanoscale in ferroelectric copolymer Langmuir-Blodgett films

The polarization switching kinetics of ferroelectric Langmuir–Blodgett films of vinylidene fluoride-trifluoroethylene copolymer were investigated by piezoresponse force microscopy with a resolution of 100 nm. The switching time in response to a localized voltage pulse exhibits an exponential dependence on reciprocal voltage, which is consistent with nucleation-limited switching dynamics

27 Al NMR/MRI Studies of the Transport of Granular Al 2 O 3

The NMR/MRI techniques are applicable to the studies of motion of granular solids, providing information on the velocities, effective diffusivities and correlation times of the moving particles. The studies of transport of granular solids reported to-date are based on the detection of the 1H NMR signal of the liquid phase of liquid-containing solid materials. Yet, the solid phase of many granular solids contains magnetic nuclei, providing in principle an opportunity to study motion of such solids by directly detecting the NMR signal of the solid phase. In this paper, we demonstrate that this can be performed with the use of conventional echo pulse sequences in combination with the conventional motion encoding schemes. The detection of the 27Al NMR signal of the Al2O3 powder was used to obtain velocity maps of the powder packed in a spinning cylinder, and to measure the velocity distribution (average propagator) for the gravity driven transport of the same powder in a vertical pipe

Functional Sensory-Motor Performance Following Long Term Space Flight: The First Results of "Field Test" Experiment

The effect that extended-duration space flights may have on human space travelers, including exploration missions, is widely discussed at the present time. Specifically, there is an increasing amount of evidence showing that the physical capacity of cosmonauts is significantly reduced after long-duration space flights. It is evident that the most impaired functions are those that rely on gravity, particularly up right posture and gait. Because of the sensorimotor disturbances manifested in the neurology of the posture and gait space flight and postflight changes may also be observed in debilitating motion sickness. While the severity of particular symptoms varies, disturbances in spatial orientation and alterations in the accuracy of voluntary movements are persistently observed after long-duration space flights. At this time most of the currently available data are primarily descriptive and not yet suitable for predicting operational impacts of most sensorimotor decrements observed upon landing on planetary surfaces or asteroids. In particular there are no existing data on the recovery dynamics or functionality of neurological, cardiovascular or muscle performance making it difficult to model or simulate the cosmonauts' activity after landing and develop the appropriate countermeasure that will ensure the rapid and safe recovery of crewmembers immediately after landing in what could be hostile environments. However and as a starting position, the videos we have acquired during recent data collection following the long duration flights of cosmonauts and astronauts walking and performing other tasks shortly after return from space flight speak volumes about their level of deconditioning. A joint Russian-American team has developed a new study specifically to address the changes in crewmembers performance and the recovery of performance with the intent of filling the missing data gaps. The first (pilot) phase of this study includes recording body kinematics and quantifying the coordination and timing of relatively simple basic movements - transition from seated and prone positions to standing, walking, stepping over obstacles, tandem walking, muscle compliance, as well as characteristics of postural sway and orthostatic tolerance. Testing for changes in these parameters have been initiated in the medical tent at the landing site. The first set of experiments showed that during the first hour after landing, cosmonauts and astronauts were able to execute (although slower and with more effort than preflight) simple movements such as egress from a seated or prone position and also to remain standing for 3.5 minutes without exhibiting pronounced cardiovascular changes. More challenging tests, however, demonstrated a prominent reduction in coordination - the obstacle task, for example, was performed at much slower speed and with a marked overestimation of the obstacle height and tandem walking was greatly degraded suggesting significant changes in proprioception, brainstem and vestibular function. There is some speculation that the neural changes, either from the bottom-up or top down may be long lasting; requiring compensatory responses that will modify or mask the adverse responses we have observed. Furthermore, these compensatory responses may actually be beneficial, helping achieve a more rapid adaptation to both weightlessness and a return to earth

Impact of Cultivating Environment on the Terms of Persistence and Certain Properties of Cholera Vibrios

Objective of the study is to investigate the impact of cultivating temperature and medium on the terms of persistence, ctx gene retention, and enzymatic activity of V. cholerae O1 with various toxigenicity.Materials and methods. Utilized were the strains of V. cholerae El Tor: P-5879, P-19613, and also the strain P-19787.Results and conclusions. In the process of studying cholera vibrios El Tor with different genetic characteristics it was determined that the longest terms of persistence (19 days) on mineral substrates at 5 ºC were observed for toxigenic strains, while for non-toxigenic ones it made less than 17 days. At the same time cholera vibrios can persist continuously and even reproduce on mineral substrates under the conditions of subnormal lowered temperatures (not less than 10 °C). Toxigenic strains of Vibrio cholerae, irrespectively of cultivating medium and temperature, retained ctx gene in their genome and maintained enzymatic activity throughout the experiment. Such long-term persistence of cholera vibrios at low temperatures on mineral substrates may be regarded as possibility of preservation of V. cholerae toxigenic strains in case of import by the infected persons or vibrio-carriers

Clinical and laboratory characteristics of acute intestinal infections associated with hemocolitis.

The article analyzes clinical and laboratory features of acute intestinal infection (AII) in children with hemocolitis. The analysis of the results revealed that the presence of hemocolitis in patients with acute intestinal infections requires the use of several methods of etiological diagnosis.В статье проанализированы клинико-лабораторные особенности течения острой кишечной инфекции (ОКИ) у детей, сопровождающиеся гемоколитом. Выявлено, что наличие гемоколита у больных острыми кишечными инфекциями требует применения нескольких методов этиологической диагностики

CONNECTION OF SELF-REGULATION WITH ACTIVITY OF RUSSIAN YOUTH

The article assesses the relationship between the self-regulation of youth behavior in the regions of Russia and their activity. Regional and gender differences in the severity of the processes and properties of self-regulation are analyzed, the distribution of types and the level of expression of socio-political and religious activity by region is revealed. Correlations are established and the dependence between sell-regulation, types of social and political activity, religious affiliation of young people is checked.В работе дается характеристика саморегуляции поведения российской молодежи и оценка ее связи с активностью студенчества в регионах России. Анализируются региональные и половые различия в выраженности процессов и свойств саморегуляции как личностного предиктора социальной активности и политических предпочтений учащейся молодежи. Проверяется зависимость между саморегуляцией и видами активности студенчества с учетом социально-демографических характеристик молодых людей

Pilot Field Test: Recovery from a Simulated Fall and Quiet Stance Stability After Long-Duration Space Flight

Astronauts returning from the International Space Station (ISS) are met by a team of recovery personnel typically providing physical assistance and medical support immediately upon landing. That is because long-duration spaceflight impacts astronauts' functional abilities. Future expeditions to planets or asteroids beyond the low Earth orbit, however, may require crewmembers to egress the vehicle and perform other types of physical tasks unassisted. It is therefore important to characterize the extent and longevity of functional deficits experienced by astronauts in order to design safe exploration class missions. Pilot Field Test (PFT) experiment conducted with participation of ISS crewmembers traveling on Soyuz expeditions 34S - 41S comprised several tasks designed to study the recovery of sensorimotor abilities of astronauts during the first 24 hours after landing and beyond

Pilot Field Test: Performance of a Sit-to-Stand Test After Long-Duration Space Flight

BACKGROUND: Astronauts returning from the International Space Station are met by a team of recovery personnel typically providing physical assistance and medical support immediately upon landing. That is because long-duration spaceflight impacts astronauts' functional abilities. Future expeditions to planets or asteroids beyond the low Earth orbit, however, may require crewmembers to egress the vehicle and perform other types of physical tasks unassisted. It is therefore important to characterize the extent and longevity of functional deficits experienced by astronauts in order to design safe exploration class missions. Pilot Field Test (PFT) experiment conducted with participation of ISS crewmembers traveling on Soyuz expeditions 34S - 41S comprised several tasks designed to study the recovery of sensorimotor abilities of astronauts during the first 24 hours after landing and beyond. METHODS: The first test in the PFT battery sequence, and also the least demanding one from the sensorimotor perspective, was a Sit-to-Stand test. Test subjects were seated in the chair and had to stand up on command and remain standing for ten seconds. The subjects were instructed to stand up unassisted as quickly as they were able to, while maintaining postural control. Synchronized wireless inertial sensors mounted on the head, chest, lower back, wrists, and ankles were used to continuously log body kinematics. Crewmembers' blood pressure and heart rate were monitored and recorded with the Portapres and Polar systems. Each session was recorded with a digital video camera. During data collections occurring within the 24-hour postflight period, crewmembers were also asked to (1) evaluate their perceived motion sickness symptoms on a 20-point scale before and after completion of the test and (2) estimate how heavy they felt compared to their normal (preflight) body weight. Consent to participate in PFT was obtained from 18 crewmembers (11 US Orbital Segment [USOS] astronauts and 7 Russian cosmonauts). For 10 subjects, the first set of data was collected in the medical tent in Soyuz landing zone (1-2 hours after landing); the other 8 subjects were tested at the Kazakhstan deployment airport (4-5 hours after landing). 8 of the 11 astronauts were tested twice more within the first 24 hours postflight, at a refueling stop on the way to Houston (approximately 13 hours after landing) and at the Johnson Space Center (approximately 24 hours after landing). Later postflight data were collected in the first two weeks on some crewmembers. Finally, 6 astronauts were tested 60+ days after landing to establish a delayed baseline. RESULTS/DISCUSSION: Two of the 18 PFT participants felt too ill to attempt any tests in Kazakhstan (at either the landing zone or deployment airport). The remaining test subjects completed the Sit-to-Stand test and their reported motion sickness scores were unaffected by this task. The task completion times and body kinematics data analysis are currently underway. Preliminary analysis of astronaut data shows a steep improvement in the time to complete the task on the second data take, and in some cases, the trend continues through day six postflight. Head and trunk pitch angles and pitch rates were also examined and increases in all measures are evident throughout the observed recovery period (60+ days postflight). Interesting patterns of head and trunk pitch coordination have also emerged. One of the data analysis objectives is comparison of initial postflight performance and recovery of experienced crewmembers and first-time fliers. Another one - possible differences in performance between USOS and Russian crewmembers