The effectiveness of men\u27s lacrosse shoulder pads in the attenuation of linear impact forces

BACKGROUND/PURPOSE: Men’s lacrosse is a sport that is growing in popularity. The mandatory shoulder pads have no limit of use standards and are rarely studied. The purpose of the study was to measure peak impact force (IF) of new and used lacrosse shoulder pads. METHODS: Six lacrosse shoulder pads, three new models (Warrior MPG 8.0 shoulder pad, STX Jolt shoulder pad and Warrior Player’s Club Hitlyte shoulder pad) and three used models of the same shoulder pads with at least four seasons of use (Warrior MPG shoulder pad, STX Jolt shoulder pad and Warrior Player’s Club Hitlyte shoulder pad) were tested. A drop mechanism was built that released a weighted ball on the thorax region of the shoulder pads to replicate game-like forces. Peak IF was measured with a motion analysis system (Peak Motus version 6.0) via a Bertec force plate (#K00606, Bertec Columbus, OH, USA). ANALYSIS: To compare impact force between the pairs of new and used shoulder pads, three separate independent t-tests were run. A one-way ANOVA was run to determine if significant differences in IF exist among all six shoulder pads. Lastly, a one-way ANOVA was conducted to determine if price (as a latent variable) of shoulder pads differed by IF among the three new models. RESULTS: The new models of shoulder pads reduced peak IF more effectively with the most expensive pads performing the best followed by the cheapest shoulder pad then the moderately priced shoulder pads. CONCLUSION: New shoulder pads reduce peak IF better than older shoulder pads. Additionally, the cost of the shoulder pad may not be a true indicator of peak IF reduction

Laser-SNMS-Analysen an Aerosol-Partikeln mit Hilfe eines neu implementierten VUV-Excimer-Lasersystems zur Einphotonenionisierung

Im Rahmen dieser Arbeit wurde für Laser-SNMS-Analysen ein VUV-Excimer-Lasersystem an ein bestehendes Flugzeitmassenspektrometer implementiert. Mit der nun für den nicht-resonanten Nachionisierungsprozess zur Verfügung stehenden Photonenenergie von 7,9 eV lassen sich 2/3 der Elemente des Periodensystems im Einphotonenprozess ionisieren. Die Analysen an Modellsystemen polyzyklischer aromatischer Kohlenwasserstoffe (PAK) führten aufgrund der Einphotonenionisierung zu deutlich gesteigerten Ausbeuten gegenüber den anderen verwendeten massenspektrometrischen Analyseverfahren. Bei der Untersuchung von Aerosol-Partikeln spielen sowohl die metallischen als auch molekulare Bestandteile ein bedeutende Rolle. PAKs konnte mit Hilfe des optimierten Nachionisierungsschrittes durch Laser-SNMS-Analysen auf einzelnen Partikeln identifiziert und abgebildet werden. Unter Zuhilfenahme von statistischen Auswerteverfahren ließen sich zudem Unterschiede in der Zusammensetzung einzelner Partikel abbilden

Antibunched photons emitted by a dc-biased Josephson junction

We show experimentally that a dc biased Josephson junction in series with a high-enough-impedance microwave resonator emits antibunched photons. Our resonator is made of a simple microfabricated spiral coil that resonates at 4.4 GHz and reaches a 1.97kΩ characteristic impedance. The second order correlation function of the power leaking out of the resonator drops down to 0.3 at zero delay, which demonstrates the antibunching of the photons emitted by the circuit at a rate of 6×10^7 photons per second. Results are found in quantitative agreement with our theoretical predictions. This simple scheme could offer an efficient and bright single-photon source in the microwave domain

A qualitative study of community perception and acceptance of biological larviciding for malaria mosquito control in rural Burkina Faso

Background: Vector and malaria parasite’s rising resistance against pyrethroid-impregnated bed nets and antimalarial drugs highlight the need for additional control measures. Larviciding against malaria vectors is experiencing a renaissance with the availability of environmentally friendly and target species-specific larvicides. In this study,we analyse the perception and acceptability of spraying surface water collections with the biological larvicide Bacillus thuringiensis israelensis in a single health district in Burkina Faso. Methods: A total of 12focus group discussions and 12key informant interviews were performed in 10 rural villages provided with coverage of various larvicide treatments (all breeding sites treated, the most productive breeding sites treated, and untreated control). Results: Respondents’ knowledge about the major risk factors for malaria transmission was generally good. Most interviewees stated they performed personal protective measures against vector mosquitoes including the use of bed nets and sometimes mosquito coils and traditional repellents. The acceptance of larviciding in and around the villages was high and the majority of respondents reported a relief in mosquito nuisance and malarial episodes. There was high interest in the project and demand for future continuation. Conclusion: This study showed that larviciding interventions received positive resonance from the population. People showed a willingness to be involved and financially support the program. The positive environment with high acceptance for larviciding programs would facilitate routine implementation. An essential factor for the future success of such programs would be inclusion in regional or national malaria control guidelines

Signal height in silicon pixel detectors irradiated with pions and protons

Pixel detectors are used in the innermost part of multi purpose experiments at the Large Hadron Collider (LHC) and are therefore exposed to the highest fluences of ionising radiation, which in this part of the detectors consists mainly of charged pions. The radiation hardness of the detectors has thoroughly been tested up to the fluences expected at the LHC. In case of an LHC upgrade the fluence will be much higher and it is not yet clear up to which radii the present pixel technology can be used. In order to establish such a limit, pixel sensors of the size of one CMS pixel readout chip (PSI46V2.1) have been bump bonded and irradiated with positive pions up to 6E14 Neq/cm^2 at PSI and with protons up to 5E15 Neq/cm^2. The sensors were taken from production wafers of the CMS barrel pixel detector. They use n-type DOFZ material with a resistance of about 3.7kOhm cm and an n-side read out. As the performance of silicon sensors is limited by trapping, the response to a Sr-90 source was investigated. The highly energetic beta-particles represent a good approximation to minimum ionising particles. The bias dependence of the signal for a wide range of fluences will be presented.Comment: Contribution to the 7th International Conference on Radiation Effects on Semiconductor Materials, Detectors and Devices October 15-17, 2008 Firenze, Ital

Observation of resonance fluorescence and the Mollow triplet from a coherently driven site-controlled quantum dot

This work was funded by project SIQUTE (contract EXL02) of the European Metrology Research Programme (EMRP). The EMRP is jointly funded by the EMRP participating countries within EURAMET and the European Union. Support was provided from the Villum Foundation via the VKR Centre of Excellence NATEC.Resonant excitation of solid state quantum emitters has the potential to deterministically excite a localized exciton while ensuring maximally coherent emission. In this work, we demonstrate the coherent coupling of an exciton localized in a lithographically positioned, site-controlled semiconductor quantum dot to an external resonant laser field. For strong continuous-wave driving we observe the characteristic Mollow triplet and analyze the Rabi splitting and sideband widths as a function of driving strength and temperature. The sideband widths increase linearly with temperature and the square of the driving strength, which we explain via coupling of the exciton to longitudinal acoustic phonons. We also find an increase of the Rabi splitting with temperature, which indicates a temperature-induced delocalization of the excitonic wave function resulting in an increase of the oscillator strength. Finally, we demonstrate coherent control of the exciton excited state population via pulsed resonant excitation and observe a damping of the Rabi oscillations with increasing pulse area, which is consistent with our excitonx2013;photon coupling model. We believe that our work outlines the possibility to implement fully scalable platforms of solid state quantum emitters. Such scalability is one of the key prerequisites for more advanced, integrated nanophotonic quantum circuits.PostprintPeer reviewe

Generating Two Continuous Entangled Microwave Beams Using a dc-Biased Josephson Junction

We show experimentally that a dc-biased Josephson junction in series with two microwave resonators emits entangled beams of microwaves leaking out of the resonators. In the absence of a stationary phase reference for characterizing the entanglement of the outgoing beams, we measure second-order coherence functions to prove the entanglement. The experimental results are found in quantitative agreement with theory, proving that the low-frequency noise of the dc bias is the main limitation for the coherence time of the entangled beams. This agreement allows us to evaluate the entropy of entanglement of the resonators, estimate the entanglement flux at their output, and to identify the improvements that could bring this device closer to a useful bright source of entangled microwaves for quantum-technological applications