Several studies have suggested re-evaluation of the wind compensation system (WCS) of the International Ski Federation (FIS). It was introduced in 2009, and since then, the system has been modified ...considerably, but major shortcomings have still remained. The present study compared the effect of tail/head wind on two reference jumps with different aerodynamic properties (Cd and Cl) during the flight phase. Jump distance and total tangential wind speed data of world cup competitions of the season 2020/2021 were used to analyse the FIS WCS and to offer basic information of wind effects. The correlation between the total tangential wind speed and the jump distance varied strongly among the analysed jumping rounds and showed a big variation in the effect of FIS WCS. According to the computer simulation, a steady head/tail wind during the entire flight phase did not show big difference in jump distance between the jumps with different aerodynamic properties. However, wind had a “reverse” effect on the jumps: when applied to the early flight phase, tail wind increased, and head wind decreased the jumping distance. It seems that the favourable wind conditions at the early flight phase may result in an unfair advantage-disadvantage when the current FIS WCS is used. Therefore, based on the present results, the FIS WCS needs to be further discussed and quality of jumpers’ aerodynamic properties re-examined.
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In ski jumping low body weight development resulted in some serious underweight problems and therefore the International Ski Federation (FIS) decided to solve the problem by relating maximum ski ...length to Body Mass Index (BMI) in 2004. The present study examined the current relationship between body weight, ski length and performance (jumping distance) in ski jumping. By adopting the BMI regulation to specifications for competition equipment, the FIS succeeded in stopping the alarming development of underweight problems in ski jumping. However, as the results of the present study show, the BMI regulation adopted by the FIS has reduced the advantage of being light, but despite the use of shorter skis it is still beneficial to be light within certain limits. The present parametric study suggests that the weight of the jumper is a more sensitive factor to jump length than ski area (ski length). In fact, sensitivity analysis shows that reducing BMI by 1% requires a reduction of approximately 2.0% in ski area to compensate each other. Based on the available information of the complex relationship between body morphology and performance in ski jumping there seems to be no further need for a change in the BMI regulation.
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A single isolated ski was suspended from a six-component wind tunnel balance and three angles, the angle of attack, the yaw angle and the edge angle were adjustable during the test. Increasing yaw ...angle from 0 to 15° increased the lift coefficient
C
L
from 0.42 to 0.90 at edge angle 0° and from 0.70 to 0.87 at edge angle 10°, respectively. Increasing yaw angle also increased the sensitivity of the ski to changes in edge angle, i.e., increasing the edge angle (20°–45°) decreased the
C
L
and the ratio
C
L
2
/
C
D
with large yaw angles. However, to maximize the lift-to-drag ratio with a typical angle of attack of 30° in ski jumping, it may be reasonable to have an edge angle of 5°–10° on skis as the ratio
C
L
2
/
C
D
increased from 1.24 to 1.35 when edge angle increased from 0° to 10°.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The special wind compensation system recently adopted by Fédération Internationale de Ski (FIS; International Ski Federation) to consider the effects of changing wind conditions has caused some ...controversy. Here, the effect of wind on jumping distance in ski jumping was studied by means of computer simulation and compared with the wind compensation factors used by FIS during the World Cup season 2009/2010. The results showed clearly that the effect of increasing head/tail wind on jumping distance is not linear: +17.4 m/ − 29.1 m, respectively, for a wind speed of 3 m/s. The linear formula used in the trial period of the wind compensation system was found to be appropriate only for a limited range of jumping distances as the gradient of the landing slope slows down the rate of distance change in long jumps.
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The effect of skis on the force-time characteristics of the simulated ski jumping takeoff was examined in a wind tunnel. Takeoff forces were recorded with a force plate installed under the tunnel ...floor. Signals from the front and rear parts of the force plate were collected separately to examine the anteroposterior balance of the jumpers during the takeoff. Two ski jumpers performed simulated takeoffs, first without skis in nonwind conditions and in various wind conditions. Thereafter, the same experiments were repeated with skis. The jumpers were able to perform very natural takeoff actions (similar to the actual takeoff) with skis in wind tunnel. According to the subjective feeling of the jumpers, the simulated ski jumping takeoff with skis was even easier to perform than the earlier trials without skis. Skis did not much influence the force levels produced during the takeoff but they still changed the force distribution under the feet. Contribution of the forces produced under the rear part of the feet was emphasized probably because the strong dorsiflexion is needed for lifting the skis to the proper flight position. The results presented in this experiment emphasize that research on ski jumping takeoff can be advanced by using wind tunnels.
Take-off aerodynamics in ski jumping Virmavirta, Mikko; Kivekäs, Juha; Komi, Paavo V
Journal of biomechanics,
04/2001, Volume:
34, Issue:
4
Journal Article
Peer reviewed
The effect of aerodynamic forces on the force–time characteristics of the simulated ski jumping take-off was examined in a wind tunnel. Vertical and horizontal ground reaction forces were recorded ...with a force plate installed under the wind tunnel floor. The jumpers performed take-offs in non-wind conditions and in various wind conditions (21–33
m
s
−1). EMGs of the important take-off muscles were recorded from one jumper. The dramatic decrease in take-off time found in all jumpers can be considered as the result of the influence of aerodynamic lift. The loss in impulse due to the shorter force production time with the same take-off force is compensated with the increase in lift force, resulting in a higher vertical velocity (
V
v) than is expected from the conventional calculation of
V
v from the force impulse. The wind conditions emphasized the explosiveness of the ski jumping take-off. The aerodynamic lift and drag forces which characterize the aerodynamic quality of the initial take-off position (static in-run position) varied widely even between the examined elite ski jumpers. According to the computer simulation these differences can decisively affect jumping distance. The proper utilization of the prevailing aerodynamic forces before and during take-off is a very important prerequisite for achieving a good flight position.
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Introduction
Balloon Eustachian tuboplasty (BET) is used to treat obstructive Eustachian tube dysfunction (OETD) and recurrent otitis media with effusion (OME). However, there are no indisputable ...evidence of its efficacy. Here, we present a multicenter, double‐blinded, randomized, placebo‐controlled trial (MDRCT) design to evaluate the efficacy of BET, and the results of a pilot trial with 3‐ and 12‐months' follow‐up.
Material and Methods
This was a prospective MDRCT. For a pilot study, OETD (n = 10) and OME (n = 5) patients were recruited and followed. Detailed inclusion and exclusion criteria were used. Participants were randomized at beginning of the operation to active or sham surgery. All procedures were performed under local anesthesia. Controls were performed in double‐blinded manner (both patient and physician), at 3 and 12 months after the procedure.
Results
Altogether, 20 ears were treated and followed for 12 months, including 14 active BETs and 6 sham surgeries. Both the active and sham surgery were performed under local anesthesia without problems or deviations from the protocol. There were no differences in the preoperative symptoms (ETDQ‐7) or objective measures (tympanometry, Valsalva and Toynbee maneuvers, tubomanometry, Eustachian tube score) between active and sham surgery arms. During follow‐up, we noticed largely similar reduction in subjective symptoms and improvement in Eustachian tube score both in active and sham surgery arms.
Conclusions
The pilot study demonstrates that our MDRCT protocol is feasible, and that blinded RCTs are dearly needed to objectively measure the efficacy of BET.
Level of Evidence
2 Laryngoscope, 134:1874–1881, 2024
This was a multicenter double‐blinded randomized placebo‐controlled trial. Here we present the trial design to evaluate the efficacy of BET, and the results of a pilot study with 3‐ and 12‐months' follow‐up. The pilot study demonstrates that our protocol is feasible, and that blinded RCTs are dearly needed.
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Auroras can be regarded as the most fascinating manifestation of space weather and they are continuously observed by ground‐based and, nowadays more and more, also by space‐based measurements. ...Investigations of auroras and geospace comprise the main research goals of the Suomi 100 nanosatellite, the first Finnish space research satellite, which has been measuring the Earth's ionosphere since its launch on 3 December 2018. In this work, we present a case study where the satellite's camera observations of an aurora over Northern Europe are combined with ground‐based observations of the same event. The analyzed image is, to the authors' best knowledge, the first auroral image ever taken by a CubeSat. Our data analysis shows that a satellite vantage point provides complementary, novel information of such phenomena. The 3D auroral location reconstruction of the analyzed auroral event demonstrates how information from a 2D image can be used to provide location information of auroras under study. The location modeling also suggests that the Earth's limb direction, which was the case in the analyzed image, is an ideal direction to observe faint auroras. Although imaging on a small satellite has some large disadvantages compared with ground‐based imaging (the camera cannot be repaired, a fast moving spinning satellite), the data analysis and modeling demonstrate how even a small 1‐Unit (size: 10 × 10 × 10 cm) CubeSat and its camera, build using cheap commercial off‐the‐shelf components, can open new possibilities for auroral research, especially, when its measurements are combined with ground‐based observations.
Plain Language Summary
Auroras, or polar lights, have been imaged by ground‐based terrestrial cameras for a long time. However, auroras can also be observed from space with cameras mounted on spacecraft. In the last few years, a number of very small satellites, so‐called nanosatellites with masses less than 10 kg, have been developed and launched into so‐called low Earth orbits at altitudes between 300 and 600 km. These small and light satellites are much cheaper than traditional large and heavy satellites, the masses of which could easily exceed hundreds of kilograms. Therefore, it is anticipated that nanosatellites will provide new possibilities to investigate auroras. In this study, we analyze, to our knowledge, the first image of an aurora taken by a nanosatellite. The satellite is a small, 10 × 10 × 10 cm, Suomi 100 satellite which was launched in December 2018. We show how the obtained auroral image can provide new information about auroras when it is combined with ground‐based observations and numerical modeling. When additional cameras will be included in the design and fabrication of small satellites, we will be able to increase our understanding of auroras and, consequently, the effects of the Sun on the Earth and beyond.
Key Points
The concept of imaging aurora toward the Earth's limb by a CubeSat camera is demonstrated
The dark background available in the Earth‐limb viewing direction facilitates imaging of dim auroras, e.g., for auroral tomography purposes
The analysis shows that auroral imaging at low Earth orbit can provide a new context for ground‐based auroral and ionospheric observations
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Objectives/Hypothesis
To explore long‐term hearing results, quality of life (QoL), quality of hearing (QoH), work‐related stress, tinnitus, and balance problems after idiopathic sudden sensorineural ...hearing loss (ISSNHL).
Study Design
Cross‐sectional study.
Methods
We reviewed the audiograms of 680 patients with unilateral ISSNHL on average 8 years after the hearing impairment, and then divided the patients into two study groups based on whether their ISSNHL had recovered to normal (pure tone average PTA ≤ 30 dB) or not (PTA > 30 dB). The inclusion criteria were a hearing threshold decrease of 30 dB or more in at least three contiguous frequencies occurring within 72 hours in the affected ear and normal hearing in the contralateral ear. Audiograms of 217 patients fulfilled the criteria. We reviewed their medical records; measured present QoL, QoH, and work‐related stress with specific questionnaires; and updated the hearing status.
Results
Poor hearing outcome after ISSNHL was correlated with age, severity of hearing loss, and vertigo together with ISSNHL. Quality of life and QoH were statistically significantly better in patients with recovered hearing, and the patients had statistically significantly less tinnitus and balance problems. During the 8‐year follow‐up, the PTA of the affected ear deteriorated on average 7 dB, and healthy ear deteriorated 6 dB.
Conclusion
Idiopathic sudden sensorineural hearing loss that failed to recover had a negative impact on long‐term QoL and QoH. The hearing deteriorated as a function of age similarly both in the affected and the healthy ear, and there were no differences between the groups. The cumulative recurrence rate for ISSNHL was 3.5%.
Level of Evidence
4 Laryngoscope, 127:927–931, 2017
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An important outcome measure of patient care is the impact on the patient’s health-related quality of life (HRQoL). Current ear-specific HRQoL instruments are designed for one diagnosis and emphasize ...different subdivisions such as symptoms, hearing problems, psychosocial impact, and the need for care. The optimal length of the recall period has not been studied. For these reasons, a new survey is needed that would cover most chronic ear diseases.
A preliminary 24-item survey (EOS-24) was created. Untreated adult patients (included n = 186) with one of seven different chronic otologic conditions from all university hospitals in Finland were recruited to respond to EOS-24 and the 15D general HRQoL instrument. The recruiting otologists evaluated the severity of the disease and the disability caused by it. A control group was recruited. Based on the patients’ responses in different diagnosis groups, the items were reduced according to pre-defined criteria. The resulting survey was validated using a thorough statistical analysis.
The relevance and necessity of the original 24 items were thoroughly investigated, leading to the exclusion of 8 items and the modification of 1. The remaining 16 items were well-balanced between subdivisions and were useful in all seven diagnosis groups, thus constituting the final instrument, EOS-16. The most suitable recall period was three months.
EOS-16 has been created according to the HRQoL survey guidelines with a versatile nationwide patient population. The survey has been validated and can be used for a wide range of chronic ear diseases as a HRQoL instrument.
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