Micromachining of Invar Foils with GHz, MHz and kHz Femtosecond Burst Modes

In this work, a burst mode laser is used for micromachining of 20 µm–250 µm thick Invar (Fe64/Ni36) foils. Holes were drilled by firing multiple pulses transversely onto the sample without moving the beam (percussion drilling). The utilized laser system generates a burst of a controllable number of pulses (at 1030 nm) with tunable pulse-to-pulse time spacing ranging from 200 ps to 16 ns. The sub-pulses within the burst have equal amplitudes and a constant duration of 300 fs that do not change regardless of the spacing in time between them. In such a way, the laser generates GHz to MHz repetition rate pulse bursts with a burst repetition rate ranging from 100 kHz to a single shot. Drilling of the material is compared with the non-burst mode of kHz repetition rate. In addition, we analyze the drilling speed and the resulting dependence of the quality of the holes on the number of pulses per burst as well as the average laser power to find the optimal micromachining parameters for percussion drilling. We demonstrate that the micromachining throughput can be of an order of magnitude higher when using the burst mode as compared to the best results of the conventional kHz case; however, excess thermal damage was also evident in some cases.

118 Comparison of Contact and Scald Burns in a Porcine Model

Introduction Whether the depth and healing of scalds and contact burns are similar is controversial. Prior studies have not compared scalds and contact burns using identical temperatures and durations of exposure limiting direct comparison. We hypothesized that when exposed to similar temepratures and durations of exposure, burns caused by hot water and contact with hot metal would be similar. Methods Multiple 2.5 or 5 cm diameter standardized cutaneous burns were created in two anesthetized female domestic pigs (~45kg) using a brass bar or circulating heated water in replicates. The temperatures were controlled and kept constant using thermosensors. In one pig, the temperature was kept constant (95 degrees C) while the duration of exposure varied (5, 10, 15 sec.) In the second pig, the exposure time was kept constant (10 sec.) while the temperature of exposure varied (70, 80, 98 degrees C). Burns were covered with a topical antibiotic ointment and frequent dressing changes were performed for 4 weeks. Periodic punch biospies were taken to determine burn depth immediately after injury, percentage burns reepithelialized within 21 days, and depth of scar at 28 days. Analysis was performed using analysis of variance. Results When temperature was held constant, duration of exposure (5, 10, and 15 sec.) was associated with scar depth (2.1 vs 3.8 vs 5.0 mm respectively, P=0.001) and there was a trend for an association with burn depth (2.0 vs 2.2 vs 2.3 mm respectively, P=0.10). When exposure duration was held constant, temperature (70, 80, 98 degrees C) was associated with scar depth (0.6 vs 1.7 vs 3.6, P< 0.001) but not significantly associated with burn depth (1.2 vs 1.5 vs 1.7 mm respectively, P=0.21). For each pig a comparison of burn and scar depth by device generally showed that depths were greater for scald than contact burns although not significantly greater. Only scar depth in the first pig showed a difference with a significance of less than 0.10 (2.9 for contact vs 4.1 mm for scalds, P=0.08). After controlling for temperature the difference between scalds and contact burns was statistically significant (marginal means 3.0 for contact burns, 4.3 for scalds, P=0.008). When combining data from both pigs and controlling for temperatures and duration, scar depths for scalds (2.7 mm) vs contacts (1.9 mm) showed a significant difference (P=0.02) while burn depth was not quite significant (1.7 vs 1.5 mm, P=0.07). Almost all burns were reepithelialized by day 21. Conclusions Burns created in swine with circulating hot water tend to be deeper and result in deeper scars than those created by contact with a brass bar when controlling for temperature and duration of exposure. Applicability of Research to Practice Scalds of similar temperature and exposure times result in deeper scars than contact burns.

INFORMATION PARAMETERS OF CODES THAT ARE SYNTHESIZED ON THE BASIS OF ONE MODULE

The advantages of digital methods of processing, displaying, storing and transmitting information. Currently, various conversion methods and efficient coding methods are used to increase the speed of information transfer, maintain high accuracy and provide the required latent accuracy. In particular, timer (temporary) signal constructions, which, in comparison with other coding methods, for example, positional (bitwise) coding, can reduce costs by more than two times. In the work, the information parameters of the code ensembles synthesized at a constant duration "m" are evaluated. Determined the conditions for the formation of a code ensemble and calculate the number of code dictionary implementations on a segment of a nyquist elements.In order to use the communication channel efficiently, the proposed increase in the entropy of the transmitted ensemble is due to the use of code sets with different number of information segments and at a constant length of the code word. A significant increase in the weight of the synthesized ensemble ensured an increase in the value of the module А0 =19 integer times K є 8:18 .The maximum values of the module are calculated in which the greatest number of code words is synthesized: At: КА0 =13, Np=8; КА0 =14, Np=10 КА0 =15, Np=15; КА0 =17, Np=16 КА0 =18, Np=10; КА0 =19, Np=6 КА0 =20, Np=1 For these КА0 values, the entropy value is H=3.269, which is less than the entropy of the Russian text H=4.35. In accordance with code words that satisfy the conditions of the quality equation. The methods and algorithms of reliable reception of code words under the influence of interference in the channel used were analyzed.Studies and calculations have shown that the use of temporary signal structures synthesized on the basis of a onemodule can significantly reduce the value of entropy for the transmission of Russian text.

Tapering and Repeated High-Intensity Effort Ability in Young Elite Rugby Union Players: Influence of Pretaper Fatigue Level

Purpose: To assess the effects of a short-term taper on the ability to perform repeated high-intensity efforts, depending on players’ fatigue level following an intensive training block. Method: After a 3-day off-season camp, 13 players followed the same 3-week preseason training block followed by a 7-day exponential taper. Performance was assessed by a repeated high-intensity effort test before and after the taper. Total sprint time, percentage of decrement, and the number of sprints equal to or higher than 90% of the best sprint were retained for analysis. Players were a posteriori classified in normal training or acute fatigue groups based on their readiness to perform prior to the taper, assessed through the magnitude of difference in psychological (Profile of Mood State Questionnaire), cardiovascular (submaximal constant-duration cycling), and neuromuscular (countermovement jump) tests between the preintensive and postintensive training blocks. Results: Training load declined by 55% (9%) during the taper (P = .001, g = −2.54). The overall group showed a small improvement in total sprint time (−3.40% [3.90%], P = .04, g = −0.39) following the taper. Relative changes tended to be higher in the acute fatigue compared with the normal training group (−5.07% [4.52%] vs −1.45% [1.88%], respectively; P = .08; d = 1.01). No taper-induced improvement was observed in percentage of decrement or number of sprints equal to or higher than 90% of the best sprint. Conclusion: A 7-day taper consisting of 55% training load reduction improved repeated high-intensity effort performance in young elite rugby union players. Pretaper level of fatigue seems to be a key determinant in the taper supercompensation process, as acutely fatigued players at the end of the intensive training block tended to benefit more from the taper.

The influence of acupuncture TENS currents on the proliferation of cancer cells tested in vitro

Introduction: Transcutaneous Electrical Nerve Stimulation (TENS) is a very popular, non-pharmacological antianalgetic method. Nonetheless, knowledge on using this method is very limited in the treatment of patients with cancer anamnesis. Unfortunately, there are not many results of research referring to the application of this method. It is much more difficult to exclude the possibility of proneoplastic activity regarding these methods than to confirm this action. Aim: The aim of the study was to evaluate the influence of TENS currents on the proliferation of cancer cells tested in vitro. Materials and methods: The following human cell lines were used - A549, ES-2, HT29, MCF-7. The cells were plated 24 h before treatment. Then, the cells were exposed to AL-TENS currents (0.1 mA, 1.0 mA and 10 mA), t imp. 200μs; f 2Hz, constant; duration: 20 min. The in vitro cytotoxic effects were examined after 96 h in SRB assay. In the other experiment, there were three expositions – 24, 48 and 72 hours from the beginning of the experiment. Results: In this assay, the acceleration of cancer cell proliferation after single or triple-dose expositions to AL-TENS currents was not observed. Conclusions: The AL-TENS current after repeated doses did not accelerate proliferation of cancer cells in in vitro conditions.

Experimental and theoretical study of velocity fluctuations during slow movements in humans

Moving smoothly is generally considered as a higher-order goal of motor control and moving jerkily as a witness of clumsiness or pathology, yet many common and well-controlled movements (e.g., tracking movements) have irregular velocity profiles with widespread fluctuations. The origin and nature of these fluctuations have been associated with the operation of an intermittent process but in fact remain poorly understood. Here we studied velocity fluctuations during slow movements, using combined experimental and theoretical tools. We recorded arm movement trajectories in a group of healthy participants performing back-and-forth movements at different speeds, and we analyzed velocity profiles in terms of series of segments (portions of velocity between 2 minima). We found that most of the segments were smooth (i.e., corresponding to a biphasic acceleration) and had constant duration irrespective of movement speed and linearly increasing amplitude with movement speed. We accounted for these observations with an optimal feedback control model driven by a staircase goal position signal in the presence of sensory noise. Our study suggests that one and the same control process can explain the production of fast and slow movements, i.e., fast movements emerge from the immediate tracking of a global goal position and slow movements from the successive tracking of intermittently updated intermediate goal positions. NEW & NOTEWORTHY We show in experiments and modeling that slow movements could result from the brain tracking a sequence of via points regularly distributed in time and space. Accordingly, slow movements would differ from fast movement by the nature of the guidance and not by the nature of control. This result could help in understanding the origin and nature of slow and segmented movements frequently observed in brain disorders.

Local Contractions Regulate E-Cadherin Adhesions, Rigidity Sensing and Epithelial Cell Sorting

E-cadherin is a major cell-cell adhesion molecule involved in mechanotransduction at cell-cell contacts in tissues. Since epithelial cells respond to rigidity and tension in the tissue through E-cadherin, there must be active processes that test and respond to the mechanical properties of these adhesive contacts. Using sub-micrometer, E-cadherin-coated PDMS pillars, we find that cells generate local contractions between E-cadherin adhesions and pull to a constant distance for a constant duration, irrespective of pillar rigidity. These cadherin contractions require non-muscle myosin IIB, tropomyosin 2.1, α-catenin and binding of vinculin to α-catenin; plus, they are correlated with rigidity-dependent cell spreading. Without contractions, cells fail to spread to different areas on soft and rigid surfaces and to maintain monolayer integrity. We further observe that cadherin contractions enable cells to test myosin IIA-mediated tension of neighboring cells, and sort out myosin IIA-depleted cells. Thus, we suggest that epithelial cells test and respond to the mechanical characteristics of neighboring cells through cadherin contractions.

Hydrodynamics of defecation

Animals discharge feces within a nearly constant duration.