Exotic crayfish in a brown water stream: effects on juvenile trout, invertebrates and algae

1. The impact of the introduced omnivorous signal crayfish (Pacifastacus leniusculus ) on trout fry, macroinvertebrates and algae was evaluated in a brown water stream in southern Sweden using in situ enclosures. We also examined the gut content of all surviving crayfish in the enclosures. Two crayfish densities in addition to a control without crayfish were used in replicate enclosures (1.26 m(2)) in a 1-month experiment. Additionally, 20 trout fry (Salmo trutta ) were stocked in each enclosure to assess the effects of crayfish on trout survival and growth. 2. Detritus was the most common food item in crayfish guts. Animal fragments were also frequent while algae and macrophytes were scarcer. Crayfish exuviae were found in crayfish guts, but the frequency of cannibalism was low. 3. Trout survival in enclosures was positively related to water velocity but was unaffected by crayfish. 4. Total invertebrate biomass and taxon richness were lower in crayfish treatments. The biomass of all predatory invertebrate taxa was reduced but only three of six non-predatory taxa were reduced in the crayfish treatments. 5. Epiphytic algal biomass (measured as chlorophyll a , on plastic strips) was not related to crayfish density, whereas the biomass of epilithic algae (measured as chlorophyll a ) was enhanced by high water velocity and high crayfish density. The latter was possibly mediated via improved light and nutrient conditions, as active crayfish re-suspend and/or remove detritus and senescent algal cells during periods of low water velocity. 6. We conclude that the introduced signal crayfish may affect stream communities directly and indirectly. Invaded communities will have reduced macroinvertebrate taxon richness and the signal crayfish will replace vulnerable invertebrate predators such as leeches. In streams that transport large amounts of sediment or organic matter, a high density of crayfish is likely to enhance benthic algal production through physical activity rather than via trophic effects

Passenger calculation of the public transport in Helsinki region

Joukkoliikenne Helsingin seudulla, tarkemmin HSL-alueella, muodostuu kuudesta eri liikennemuodosta, jotka ovat linja-auto-, raitiovaunu-, metro-, lähijuna- ja Suomenlinnan lauttaliikenne sekä Kutsuplus. Näiden kulkumuotojen matkustajalaskennat ovat monimuotoinen kokonaisuus ja niistä kerätään matkustajamäärätietoja matkakorttijärjestelmän, automaattisten matkustajalaskentajärjestelmien sekä manuaalisten laskentojen avulla. Kutsuplussassa matkustajamäärät saadaan suoraan tilauksista. Lisäksi HSL-alueen joukkoliikenteessä tehdään vuosittain useita tarkistus-, poikkileikkaus- ja profiililaskentoja käsinlaskentoina. HSL-alueen joukkoliikenteen matkustajalaskennoista ei ollut ennen tätä työtä tehty vastaavaa nykytilaselvitystä, joka kokoaa samojen kansien sisään yksityiskohtaiset tiedot jokaisen joukkoliikennemuodon matkustajalaskennasta. Nykytilaselvitystä varten haastateltiin useita asiantuntijoita sekä käytiin läpi monia HSL:n julkaisuja. Tietoja täydennettiin vielä sähköposteilla sekä Internetistä haetuilla tiedoilla. Tulokseksi saatiin kattava tietopaketti, jossa selviää, miten laskennat eri kulkumuotojen osalta tehdään, miten saatuja tietoja käsitellään ja miten ne kootaan yhteenvetoraportiksi. Automaation lisääntyessä matkustajalaskennoissa työssä tarkastellaan, miten automaattisten matkustajalaskentalaitteiden määrä kasvaa HSL-alueella. Työssä selvitetään myös, mikä olisi riittävä laskentalaitteellisten ajoneuvojen osuus, jotta matkustajamäärätietojen tuottaminen olisi tehokasta ja järjestelmän häiriöherkkyys pieni. Tämän perusteella on tehty ehdotus minimiosuuden nostamisesta 30 prosenttiin. Keskeistä työssä oli myös tutkia, mihin suuntaan laskennat ovat kehittymässä. Tulevaisuudessa pyritään selvittämään, miten joukkoliikenteen käyttäjien matkat suuntautuvat. HSL-alueella matkustajavirtainformaation tuottaminen aloitetaan suurella todennäköisyydellä metrossa WLAN-teknologiaan perustuvalla mobiililaskennalla. Kyseisen teknologian lisäksi työssä esitellään myös muita mahdollisia mobiiliteknologiaan perustuvia ratkaisuja matkustajavirtainformaation tuottamiseksi. Uusien matkustajalaskentateknologioiden ohessa työssä tarkastellaan myös avointa dataa ja sen merkitystä sekä yhteyttä mobiililaskentoihin. Erityisesti metron mahdollisen WLAN-laskennan sekä uuden mobiilisovelluksen keskiseen vuorovaikutukseen tutustaan työn loppuvaiheilla.Public transport in Helsinki region, more specific in HSL area, is formed from 6 different modes of transport which are bus, tram, subway, local train, Suomenlinna ferry and Kutsuplus. Passenger counting in these modes of transport is a complex entirety and passenger information is gathered from them with automated fare collection system, automated passenger counting systems and by manual passenger counting. In Kutsuplus, the number of passengers is obtained directly from the bookings. In addition, there are multiple recounts and cross section and profile calculations made manually in HSL area each year. Before this work, a current state report that contained detailed information under the same covers, considering passenger calculation of all the modes of public transport in HSL area, had not been done. Several experts were interviewed and many publications on the subject were read in order to gather the information for the current state report. The information was yet filled with knowlegde gathered from e-mails and the Internet. As a result, a comprehensive package of information was formed and it clarifies how passenger calculations in the different modes of public transport are conducted. Furthermore, the report states how the information from the passenger calculations is handled and how the information is put together in the summary report. As automation in passenger counting increases, it was crucial for this work to examine how the share of APC-equipped vehicles increases in HSL area. This work also studies, what would be the sufficient share for the APC-equipped vehicles in order to quarantee an efficient system for the production of passenger information with a small sensitivity to errors. Based on this study, a recommendation to increase the minimum share of the APC-equipped vehicles up to 30 %, was formed. Central for this work was also to study which direction passenger calculations are developing. In the future, it is important to be able to retrace how passengers direct their journeys in public transport. With high probability, the production of passenger flow information in HSL area will start in the subway with a WLAN-based mobile technology. In addition to this technology, this work also introduces other mobile technologies which can be used to produce passenger flow information. Open data and it’s meaning and connection to mobile technology based passenger counting are also viewed beside the mobile technologies. Especially the interaction between the possible WLAN-based passenger counting tecnology of the subway and the new HSL mobile application is studied on the final chapters of the work

DOES MAGNETIC RESONANCE IMAGING PROVIDE SUPERIOR RELIABILITY FOR ACHILLES AND PATELLAR TENDON CROSS-SECTIONAL AREA MEASUREMENTS COMPARED WITH ULTRASOUND IMAGING?

This study investigated the reliability of Achilles and patellar tendon cross-sectional area (CSA) measurement using ultrasound imaging (USI) and magnetic resonance imaging (MRI). Fifteen healthy adults were imaged twice on two occasions, interrupted by a tendon loading protocol. Tendon CSA segmentations were conducted by an experienced and an inexperienced rater blinded to information regarding subject, session and loading status. USI provided good test-retest reliability (intra-class correlation coefficient [ICC] 2,1 > 0.85, standard error of measurement [SEM] 5%-6%), while with MRI it was excellent (ICC 2,1 > 0.92, SEM 4%) for the experienced rater. This study suggests that MRI provides superior reliability for tendon CSA measurements compared with USI. However, the difference in reliability between the methods was small, and the results were inconclusive regarding objectivity and sensitivity to change when assessed based on the effect of loading. We concluded that both methods can be used for reliable CSA measurements of the Achilles and patellar tendons when using a highly standardized measurement protocol and when conducted by an experienced rater. (C) 2019 World Federation for Ultrasound in Medicine & Biology. All rights reserved.Peer reviewe

Assessment of drinking water quality at the tap using fluorescence spectroscopy

Treated drinking water may become contaminated while travelling in the distribution system on the way to consumers. Elevated dissolved organic matter (DOM) at the tap relative to the water leaving the treatment plant is a potential indicator of contamination, and can be measured sensitively, inexpensively and potentially on-line via fluorescence and absorbance spectroscopy. Detecting elevated DOM requires potential contamination events to be distinguished from natural fluctuations in the system, but how much natural variation to expect in a stable distribution system is unknown. In this study, relationships between DOM optical properties, microbial indicator organisms and trace elements were investigated for households connected to a biologically-stable drinking water distribution system. Across the network, humic-like fluorescence intensities showed limited variation (RSD = 3.5-4.4%), with half of measured variation explained by interactions with copper. After accounting for quenching by copper, fluorescence provided a very stable background signal (RSD

Slower Walking Speed in Older Men Improves Triceps Surae Force Generation Ability

Purpose Older adults walk slower than young adults, but it is not known why. Previous research suggests that ankle plantarflexors may have a crucial role in the reduction of walking speed. The purpose of this study was to investigate age-related differences in triceps surae muscle–tendon function during walking to further investigate the role of plantarflexors in the age-related reduction of walking speed. Methods Medial gastrocnemius and soleus muscle fascicle lengths were measured using ultrasound imaging during walking from 13 young (25 ± 4 yr) men at preferred walking speed and from 13 older (73 ± 5 yr) men at preferred speed and at the young men’s preferred speed. Muscle–tendon unit lengths were calculated from joint kinematics, and tendinous tissue lengths were calculated by subtracting muscle lengths from muscle–tendon unit lengths. In addition, ground reaction forces and electromyographic activity of medial gastrocnemius and soleus were measured. Results In both medial gastrocnemius and soleus, it was observed that at preferred walking speed, older men used a narrower muscle fascicle operating range and lower shortening velocity at the estimated time of triceps surae peak force generation compared with young men. Fascicles also accounted for a lower proportion of muscle–tendon unit length changes during the stance phase in older compared with young men. Significant differences in triceps surae muscle function were not observed between age groups when compared at matched walking speed. Conclusions In older men, walking at preferred speed allows triceps surae muscles to generate force with more favorable shortening velocity and to enhance use of tendinous tissue elasticity compared with walking at young men’s preferred speed. The results suggest that older men may prefer slower walking speeds to compensate for decreased plantarflexor strength

Open-source software library for real-time inertial measurement unit data-based inverse kinematics using OpenSim

Background Inertial measurements (IMUs) facilitate the measurement of human motion outside the motion laboratory. A commonly used open-source software for musculoskeletal simulation and analysis of human motion, OpenSim, includes a tool to enable kinematics analysis of IMU data. However, it only enables offline analysis, i.e., analysis after the data has been collected. Extending OpenSim’s functionality to allow real-time kinematics analysis would allow real-time feedback for the subject during the measurement session and has uses in e.g., rehabilitation, robotics, and ergonomics. Methods We developed an open-source software library for real-time inverse kinematics (IK) analysis of IMU data using OpenSim. The software library reads data from IMUs and uses multithreading for concurrent calculation of IK. Its operation delays and throughputs were measured with a varying number of IMUs and parallel computing IK threads using two different musculoskeletal models, one a lower-body and torso model and the other a full-body model. We published the code under an open-source license on GitHub. Results A standard desktop computer calculated full-body inverse kinematics from treadmill walking at 1.5 m/s with data from 12 IMUs in real-time with a mean delay below 55 ms and reached a throughput of more than 90 samples per second. A laptop computer had similar delays and reached a throughput above 60 samples per second with treadmill walking. Minimal walking kinematics, motion of lower extremities and torso, were calculated from treadmill walking data in real-time with a throughput of 130 samples per second on the laptop and 180 samples per second on the desktop computer, with approximately half the delay of full-body kinematics. Conclusions The software library enabled real-time inverse kinematical analysis with different numbers of IMUs and customizable musculoskeletal models. The performance results show that subject-specific full-body motion analysis is feasible in real-time, while a laptop computer and IMUs allowed the use of the method outside the motion laboratory

An EMG-Assisted Muscle-Force Driven Finite Element Analysis Pipeline to Investigate Joint- and Tissue-Level Mechanical Responses in Functional Activities : Towards a Rapid Assessment Toolbox

Publisher Copyright: © 1964-2012 IEEE.Joint tissue mechanics (e.g., stress and strain) are believed to have a major involvement in the onset and progression of musculoskeletal disorders, e.g., knee osteoarthritis (KOA). Accordingly, considerable efforts have been made to develop musculoskeletal finite element (MS-FE) models to estimate highly detailed tissue mechanics that predict cartilage degeneration. However, creating such models is time-consuming and requires advanced expertise. This limits these complex, yet promising, MS-FE models to research applications with few participants and makes the models impractical for clinical assessments. Also, these previously developed MS-FE models have not been used to assess activities other than gait. This study introduces and verifies a semi-automated rapid state-of-the-art MS-FE modeling and simulation toolbox incorporating an electromyography- (EMG) assisted MS model and a muscle-force driven FE model of the knee with fibril-reinforced poro(visco)elastic cartilages and menisci. To showcase the usability of the pipeline, we estimated joint- and tissue-level knee mechanics in 15 KOA individuals performing different daily activities. The pipeline was verified by comparing the estimated muscle activations and joint mechanics to existing experimental data. To determine the importance of the EMG-assisted MS analysis approach, results were compared to those from the same FE models but driven by static-optimization-based MS models. The EMG-assisted MS-FE pipeline bore a closer resemblance to experiments compared to the static-optimization-based MS-FE pipeline. Importantly, the developed pipeline showed great potential as a rapid MS-FE analysis toolbox to investigate multiscale knee mechanics during different activities of individuals with KOA.Peer reviewe

Exploration of muscle–tendon biomechanics one year after Achilles tendon rupture and the compensatory role of flexor hallucis longus

Achilles tendon (AT) rupture leads to long-term structural and functional impairments. Currently, the predictors of good recovery after rupture are poorly known. Thus, we aimed to explore the interconnections between structural, mechanical, and neuromuscular parameters and their associations with factors that could explain good recovery in patients with non-surgically treated AT rupture. A total of 35 patients with unilateral rupture (6 females) participated in this study. Muscle-tendon structural, mechanical, and neuromuscular parameters were measured 1-year after rupture. Interconnections between the inter-limb differences (Δ) were explored using partial correlations, followed by multivariable linear regression to find associations between the measured factors and the following markers that indicate good recovery: 1) tendon length, 2) tendon non-uniform displacement, and 3) flexor hallucis longus (FHL) normalized EMG amplitude difference between limbs. Δmedial gastrocnemius (MG) (β = −0.12, p = 0.007) and Δlateral gastrocnemius (β = −0.086, p = 0.030) subtendon lengths were associated with MG tendon Δstiffness. MG (β = 11.56, p = 0.003) and soleus (β = 2.18, p = 0.040) Δsubtendon lengths explained 48 % of variance in FHL EMG amplitude. Regression models for tendon length and non-uniform displacement were not significant. Smaller inter-limb differences in Achilles subtendon lengths were associated with smaller differences in the AT stiffness between limbs, and a smaller contribution of FHL muscle to the plantarflexion torque. In the injured limb, the increased contribution of FHL appears to partially counteract a smaller contribution from MG due to the elongated tendon, however the role of FHL should not be emphasized during rehabilitation to allow recovery of the TS muscles

The Achilles tendon is mechanosensitive in older adults: adaptations following 14 weeks versus 1.5 years of cyclic strain exercise.

The aging musculoskeletal system experiences a general decline in structure and function, characterized by a reduced adaptability to environmental stress. We investigated whether the older human Achilles tendon (AT) demonstrates mechanosensitivity (via biomechanical and morphological adaptations) in response to long-term mechanical loading. Thirty-four female adults (60-75 years) were allocated to either a medium-term (14 weeks; N=21) high AT strain cyclic loading exercise intervention or a control group (N=13), with 12 participants continuing with the intervention for 1.5 years. AT biomechanical properties were assessed using ultrasonography and dynamometry. Tendon cross-sectional area (CSA) was investigated by means of magnetic resonance imaging. A 22% exercise-related increment in ankle plantarflexion joint moment, along with increased AT stiffness (598.2±141.2 versus 488.4±136.9 N mm(-1) at baseline), Young's modulus (1.63±0.46 versus 1.37±0.39 GPa at baseline) and about 6% hypertrophy along the entire free AT were identified after 14 weeks of strength training, with no further improvement after 1.5 years of intervention. The aging AT appears to be capable of increasing its stiffness in response to 14 weeks of mechanical loading exercise by changing both its material and dimensional properties. Continuing exercise seems to maintain, but not cause further adaptive changes in tendons, suggesting that the adaptive time-response relationship of aging tendons subjected to mechanical loading is nonlinear

Near infrared spectroscopic evaluation of biochemical and crimp properties of knee joint ligaments and patellar tendon

Knee ligaments and tendons play an important role in stabilizing and controlling the motions of the knee. Injuries to the ligaments can lead to abnormal mechanical loading of the other supporting tissues (e.g., cartilage and meniscus) and even osteoarthritis. While the condition of knee ligaments can be examined during arthroscopic repair procedures, the arthroscopic evaluation suffers from subjectivity and poor repeatability. Near infrared spectroscopy (NIRS) is capable of non-destructively quantifying the composition and structure of collagen-rich connective tissues, such as articular cartilage and meniscus. Despite the similarities, NIRS-based evaluation of ligament composition has not been previously attempted. In this study, ligaments and patellar tendon of ten bovine stifle joints were measured with NIRS, followed by chemical and histological reference analysis. The relationship between the reference properties of the tissue and NIR spectra was investigated using partial least squares regression. NIRS was found to be sensitive towards the water (R2CV = .65) and collagen (R2CV = .57) contents, while elastin, proteoglycans, and the internal crimp structure remained undetectable. As collagen largely determines the mechanical response of ligaments, we conclude that NIRS demonstrates potential for quantitative evaluation of knee ligaments.publishedVersionPeer reviewe