Michelson and Morley's interferometric setup, mounted on a stone slab that floats in an annular trough of mercury. The Michelson. Michelson and Edward W. Morley at what is now Case Western Reserve University in Cleveland, Ohio, and published in November of the same year. The result was negative, in that the expected difference between the speed of light in the direction of movement through the presumed aether, and the speed at right angles, was found not to exist; this result is generally considered to be the first strong evidence against the then- prevalent aether theory, and initiated a line of research that eventually led to special relativity, which rules out a stationary aether. These include experiments from 1. More recent optical resonator experiments confirmed the absence of any aether wind at the 1. Because light can travel through a vacuum, it was assumed that even a vacuum must be filled with aether. Arteriosclerosis, Thrombosis, and Vascular Biology (ATVB) Circulation. Time course of left ventricular dilation after myocardial infarction: influence of infarct. Astrocytic endfoot Ca 2+ and BK channels determine both arteriolar dilation and constriction. Increased intracerebral blood flow in response to neuronal activity is a fundamental physiological. Because the speed of light is so large, and because material bodies pass through the aether without obvious friction or drag, it was assumed to have a highly unusual combination of properties. Designing experiments to test the properties of the aether was a high priority of 1. The Earth is in motion, so two main possibilities were considered: (1). Eventually, Fresnel's idea of an (almost) stationary aether was preferred because it appeared to be confirmed by the Fizeau experiment (1. A depiction of the concept of the . Although it would be possible, in theory, for the Earth's motion to match that of the aether at one moment in time, it was not possible for the Earth to remain at rest with respect to the aether at all times, because of the variation in both the direction and the speed of the motion. At any given point on the Earth's surface, the magnitude and direction of the wind would vary with time of day and season. By analyzing the return speed of light in different directions at various different times, it was thought to be possible to measure the motion of the Earth relative to the aether. The expected relative difference in the measured speed of light was quite small, given that the velocity of the Earth in its orbit around the Sun has a magnitude of about one hundredth of one percent of the speed of light. For instance, the Fizeau. A number of physicists therefore attempted to make measurements of indirect first- order effects not of the speed of light itself, but of variations in the speed of light (see First order aether- drift experiments). The Hoek experiment, for example, was intended to detect interferometricfringe shifts due to speed differences of oppositely propagating light waves through water at rest. In Vitro Hematological and In Vivo Vasoactivity Assessment of Dextran Functionalized Graphene. Minimally-Invasive Aortic Valve Replacement. The aortic valve is a one-way valve comprised of three leaflets that conducts blood flow from the main pumping chamber of. The results of such experiments were all negative. Partial aether- dragging would thwart attempts to measure any first order change in the speed of light. As pointed out by Maxwell (1. Michelson's 1. 88. Although ultimately it proved incapable of distinguishing between differing theories of aether- dragging, its construction provided important lessons for the design of Michelson and Morley's 1. In 1. 87. 7, while teaching at his alma mater, the United States Naval Academy in Annapolis, Michelson conducted his first known light speed experiments as a part of a classroom demonstration. MIT 7.01SC Fundamentals of Biology. 171 members, 5 questions Online. 1 Online Joining Stop Studying; Subject. OpenStudy decisions are final. Your Question has been sent! The Qualified Helper will join you in. Thrombosis, and Vascular Biology (ATVB. 19 There is a series of 1-way bicuspid valves located throughout the deep and superficial veins that open to allow flow toward the heart. Astronomy Earth Science Models. In 1. 88. 1, he left active U. S. Naval service while in Germany concluding his studies. In that year, Michelson used a prototype experimental device to make several more measurements. The device he designed, later known as a Michelson interferometer, sent yellow light from a sodium flame (for alignment), or white light (for the actual observations), through a half- silvered mirror that was used to split it into two beams traveling at right angles to one another. After leaving the splitter, the beams traveled out to the ends of long arms where they were reflected back into the middle by small mirrors. They then recombined on the far side of the splitter in an eyepiece, producing a pattern of constructive and destructive interference whose transverse displacement would depend on the relative time it takes light to transit the longitudinal vs. If the Earth is traveling through an aether medium, a beam reflecting back and forth parallel to the flow of aether would take longer than a beam reflecting perpendicular to the aether because the time gained from traveling downwind is less than that lost traveling upwind. Michelson expected that the Earth's motion would produce a fringe shift equal to 0. He did not observe the expected shift; the greatest average deviation that he measured (in the northwest direction) was only 0. His conclusion was that Fresnel's hypothesis of a stationary aether with partial aether dragging would have to be rejected, and thus he confirmed Stokes' hypothesis of complete aether dragging. Michelson's apparatus was subject to experimental errors far too large to say anything conclusive about the aether wind. Definitive measurement of the aether wind would require an experiment with greater accuracy and better controls than the original. Nevertheless, the prototype was successful in demonstrating that the basic method was feasible. This figure illustrates the folded light path used in the Michelson. Michelson suffered a nervous breakdown in September 1. October 1. 88. 5. Morley ascribed this breakdown to the intense work of Michelson during the preparation of the experiments. In 1. 88. 6, Michelson and Morley successfully confirmed Fresnel's drag coefficient . Michelson and Morley created an improved version of the Michelson experiment with more than enough accuracy to detect this hypothetical effect. The experiment was performed in several periods of concentrated observations between April and July 1. Adelbert Dormitory of WRU (later renamed Pierce Hall, demolished in 1. At this length, the drift would be about 0. To make that easily detectable, the apparatus was assembled in a closed room in the basement of the heavy stone dormitory, eliminating most thermal and vibrational effects. Vibrations were further reduced by building the apparatus on top of a large block of sandstone (Fig. They estimated that effects of about 0. Fringe pattern produced with a Michelson interferometer using white light. As configured here, the central fringe is white rather than black. Michelson and Morley and other early experimentalists using interferometric techniques in an attempt to measure the properties of the luminiferous aether, used (partially) monochromatic light only for initially setting up their equipment, always switching to white light for the actual measurements. The reason is that measurements were recorded visually. Purely monochromatic light would result in a uniform fringe pattern. Lacking modern means of environmental temperature control, experimentalists struggled with continual fringe drift even though the interferometer might be set up in a basement. Because the fringes would occasionally disappear due to vibrations caused by passing horse traffic, distant thunderstorms and the like, an observer could easily . The advantages of white light, which produced a distinctive colored fringe pattern, far outweighed the difficulties of aligning the apparatus due to its low coherence length. As Dayton Miller wrote, . The hypothesis of aether drift implies that because one of the arms would inevitably turn into the direction of the wind at the same time that another arm was turning perpendicularly to the wind, an effect should be noticeable even over a period of minutes. The expectation was that the effect would be graphable as a sine wave with two peaks and two troughs per rotation of the device. This result could have been expected because during each full rotation, each arm would be parallel to the wind twice (facing into and away from the wind giving identical readings) and perpendicular to the wind twice. Additionally, due to the Earth's rotation, the wind would be expected to show periodic changes in direction and magnitude during the course of a sidereal day. Because of the motion of the Earth around the Sun, the measured data were also expected to show annual variations. Most famous . Michelson and Morley's results. The upper solid line is the curve for their observations at noon, and the lower solid line is that for their evening observations. Note that the theoretical curves and the observed curves are not plotted at the same scale: the dotted curves, in fact, represent only one- eighth of the theoretical displacements. After all this thought and preparation, the experiment became what has been called the most famous failed experiment in history. The expected deviation of the interference fringes from the zero should have been 0. As displacement is proportional to squares of the relative velocities it follows that if the ether does slip past the relative velocity is less than one sixth of the earth. The Fizeau experiment and its 1. Michelson and Morley apparently confirmed the stationary aether with partial aether dragging, and refuted complete aether dragging. On the other hand, the much more precise Michelson. These problems and their solution led to the development of the Lorentz transformation and special relativity. After the . Expected differential phase shift between light traveling the longitudinal versus the transverse arms of the Michelson. It passes through the half- silvered mirror at the origin at T=0. The reflecting mirror is at that moment at distance L. The beam hits the mirror at time T1. At this time, the mirror has traveled the distance v. T1. The same consideration applies to the backward journey, with the sign of v. The total travel time Tl=T1+T2. This was corrected by Alfred Potier (1. Lorentz (1. 88. 6). The derivation in the transverse direction can be given as follows (analoguous to the derivation of time dilation using a light clock): The beam is propagating at the speed of light c. At the same time, the mirror has traveled the distance v. T3. So in order to hit the mirror, the travel path of the beam is L. Efficiency of vibration exercise for glycemic control in type 2 diabetes patients Int J Med Sci. Trainingsinstitut Prof. Efficiency of vibration exercise for glycemic control in type 2 diabetes patients. Int J Med Sci 2. 00. Available from. http: //www. Abstract. Although it is well documented that persons suffering from diabetes type 2 profit from muscular activities, just a negligible amount of patients take advantage of physical exercises. During the last decade, vibration exercise (VE) could be established as an effective measure to prevent muscular atrophy and osteoporosis with low expenditure of overall exercise- time. Unfortunately, little is known about the metabolic effects of VE. In the present study we compared VE with the influence of strength training and a control group (flexibility training) on glycemic control in type 2 diabetes patients. Forty adult non- insulin dependent patients participated in the intervention. Fasting glucose concentration, an oral glucose tolerance test (OGTT), haemoglobin A1c (Hb. A1c), the isometric maximal torque of quadriceps muscles, and endurance capacity were evaluated at baseline and after 1. The main findings are: Fasting glucose concentrations remind unchanged after training. The area under curve and maximal glucose concentration of OGTT were reduced in the vibration and strength training group. Hb. A1c values tended to decrease below baseline date in the vibration training group while it increased in the two other intervention groups. Theses findings suggest that vibration exercise may be an effective and low time consuming tool to enhance glycemic control in type 2 diabetes patients. Keywords: diabetes, vibration exercise, strength training, Hb. A1c, glycemic control 1. Introduction. Since some decades it is known that beside pharmacological treatments and body weight reduction endurance related exercises are able to enhance glycemic control in type II diabetes patients . More recently, strength training also became an established treatment in that world- wide spreading metabolic disease . However, till today only a negligible amount of patients take advantage of any sport activity. There are some reasons to explain that phenomenon, one of the most important may be that nearly all patients are obese and follow a lifelong sedentary life style. Obviously, these patients can hardly be motivated for longer lasting physical activities. Vibration exercise is a new and effective measure to prevent muscular atrophy and osteoporosis . It is assumed that vibrations with an amplitude of 2 to 6 mm and a frequency of 2. Hz evoke muscle contractions probably induced via the monosynaptic stretch reflex . Compared to traditional training regimes, VE needs significant less time and, therefore, can be expected to reach a higher compliance in previously inactive patients. Unfortunately, rare information exists about the metabolic consequences of VE. It is just known that oxygen consumption increases with body weight as well as frequency and amplitude of VE . In the present study we investigated the influence of a three month vibration- exercise period on parameters of glucose metabolism in type II diabetes patients. The results were compared to a control group (FT- group) and a group performing strength training (ST). Research Design and Methods. Subjects characteristics and general experimental design. Prior to recruitment of subjects the study protocol was approved by the ethic committee of the German Sports University. Volunteers were included if they met three conditions: A diagnosed type II diabetes, not insulin depending, and not regularly involved in sport activities. All patients were under oral medication. Subjects were excluded if they suffered from retinopathy or other medical problems which did not allow for participating in vibration exercises or strength training. Patients were encouraged to follow their habitual life style including medication throughout the whole investigation period. After verbal introduction of the study 4. Table 1). Subjects were randomly divided into three groups: A flexibility training group, a strength training group and a vibration training group. They trained for 1. All sessions were supervised and participation assessed. Training volume and intensity were stepwise increased after 6 and 9 weeks. The detailed training regimen was as follows: Flexibility training. Each FT session consisted of eight static exercises which involved main muscles of the upper and lower body. During the initial six weeks, one set was performed with the positions kept for 2. From week 7 to 9 volume was increased by one more set. During the last three weeks two sets with exercise durations of 3. The total training duration did not exceed 1. Strength training. Commercially available weight machines (Conex. Eight stations were included in each session, e. Subjects performed dynamic contractions with intermittent relaxations after each concentric- eccentric phase in order avoid critical blood pressure responses . After familiarization with the correct movements, the one repetition maximum (1. RM) was established prior to the training period. During the first six weeks of training, 1 set with 1. RM was performed. From week 7 to 9 volume was increased by an additional set. In weeks 1. 0 to 1. RM were realized. About 4. 5 minutes was needed for a training session of the last three weeks. Vibration exercise. Subjects exercised on a horizontal swinging platform with an amplitude of 2 mm (Vibrogym Professional. Vibration frequency was set to 3. Hz from weeks 1 to 9 and to 3. Hz during the last three weeks. The duration of a single exercise bout was constant throughout the training period and amounted to 3. A training session consisted of 8 different exercises including muscles of the whole body (Fig. Subjects were encouraged to work isometricaly against the swinging platform. The number of sets was identical with the strength training regimen. It took about 2. 0 minutes to fulfill a training session of the last three weeks. Table 1. Baseline subjects characteristics. Time of drug ingestion was individually kept constant prior to both tests. Micro- blood samples were taken from an ear lobe before and for 2,5 h every 3. Dextro. Blood samples were analyzed by means of Hemo. Cue. Hb. A1. C levels were determined by a HPLC- System (Tosoh G7, Eurogenics) from a blood sample taken from the antecubital vein. On separate days, maximal torque of quadriceps muscles and endurance capacity were tested. Maximal torque was detected isometrically with participants in an upright sitting posture and the hip and knee joint flexed to 9. A force transducer (Digimax. The best of three trials of each leg were taken for further computation. Endurance capacity was determined by an incremental cycle ergometry (Ergoline Ergoscript 2. EL). Load was increased every 3 min for 2. Heart rate (ECG leads) and lactic acid concentration (Accutrend. The mean values of the initial and last five sessions were taken for further computations. Statistical analysis. Statistical analysis was conducted using SPSS version 1. Windows. If not otherwise stated data are expressed as mean and standard deviation. The data were analyzed by analysis of variance for repeated measurements (factors: time and training form). In case that the two- factorial analysis yielded a significant result (p < 0,0. Newman- Keuls test was performed as a posteriori test. Results. Subjects characteristics. Body weight did not significantly change during the 3- month intervention. A mean reduction of 1,6. Systolic blood pressure decreased significantly (p < 0,0. Hg . Diastolic blood pressure did not change significantly. Three subjects decreased their oral hypoglycemic medication dosage (two persons in ST and one person in VT group). No major complications or injuries were reported from either stretching, strength, or vibration training. Endurance performance parameters. No significant differences in endurance capacity could be detected between pre and post- training in any group. Subjects reached 4 mmol . In contrast, at these loads heart rate was reduced after the training intervention in all groups (Fig. VT. Figure 2. Mean heart rates at loads corresponding to a lactic acid concentration of 4 mmol / l. A significant increase of 1. ST group (Fig. Figure 3. Relative maximal isometric torques of the quadriceps muscles. Left top: Flexibility training group, left bottom: strength training group, right top: vibration training group. Right bottom: mean of individual maximal glucose concentrations. Within the 1. 50 minutes observation period of OGTT, pre- and posttraining results in the FT group were nearly identical. In both ST and VT the integrals were reduced by 5,6 % and 6,3 %, respectively (p < 0,0. Table 2. Plasma fasting glucose concentrations before and after training intervention. After training intervention a small decrease in Hb. A1c occurred in the VT- group (n. In contrast, Hb. A1c values in the FT and ST group were elevated. Figure 5. Net changes in Hb. A1c. Discussion. Twelve weeks of strength training increased muscular strength and did not affect the endurance capacity while stretching and vibration exercise improved neither strength nor endurance significantly. These results on physical performance parameters reflect just in part the outcome of glycemic control parameters: As it could be expected flexibility training failed to improve glycemic control and strength training showed beneficial effects. Although the duration of VT training sessions were about half of thoses of the strength group, the effect on OGGT was comparable. Obviously, there is a beneficial effect of vibration- exercise on glycemic control without detectable changes in physical performance parameters. A dominant influence of body weight changes appears unlikely since weight reduction was weakest in the VT group and strongest in the FT group. Vibrations applied on skeletal muscles activate muscle spindle receptors .
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